Forehead Movement Discrepancies After Botulinum Toxin Injections: A Review of Etiology, Correction, and Prevention

BACKGROUND

Forehead rhytides are a popular target for botulinum toxin injections, but neuromodulation of the frontalis can be fraught with complications because of its anatomic complexity and integral role in brow position and expressivity.

OBJECTIVE

This article explores common forehead movement discrepancies that can occur after neuromodulation of the frontalis, as well as how to correct and prevent them.

METHODS

A review of the literature was conducted and combined with clinical experience to examine underlying forehead anatomy, etiology and correction of forehead movement discrepancies, and important factors to consider before injecting the frontalis with botulinum toxin.

RESULTS AND CONCLUSION

Variable anatomy from person to person necessitates an individualized treatment approach to achieve the best cosmetic results and prevent the occurrence of forehead movement discrepancies.

A 119dB Dynamic Range Charge Counting Light-to-Digital Converter For Wearable PPG/NIRS Monitoring Applications

This paper presents a low power, high dynamic range (DR), reconfigurable light-to-digital converter (LDC) for photoplethysmogram (PPG), and near-infrared spectroscopy (NIRS) sensor readouts. The proposed LDC utilizes a current integration and a charge counting operation to directly convert the photocurrent to a digital code, reducing the noise contributors in the system. This LDC consists of a latched comparator, a low-noise current reference, a counter, and a multi-function integrator, which is used in both signal amplification and charge counting based data quantization. Furthermore, a current DAC is used to further increase the DR by canceling the baseline current. The LDC together with LED drivers and auxiliary digital circuitry are implemented in a standard 0.18 μm CMOS process and characterized experimentally. The LDC and LED drivers consume a total power of 196 μW while achieving a maximum 119 dB DR. The charge counting clock, and the pulse repetition frequency of the LED driver can be reconfigured, providing a wide range of power-resolution trade-off. At a minimum power consumption of 87 μW, the LDC still achieves 95 dB DR. The LDC is also validated with on-body PPG and NIRS measurement by using a photodiode (PD) and a silicon photomultiplier (SIPM), respectively.

Design of Multi-Wavelength Optical Sensor Module for Depth-Dependent Photoplethysmography

The multi-wavelength photoplethysmography sensors were introduced to measure depth-dependent blood volume based on that concept that the longer the light wavelength, the deeper the penetration depth near visible spectrum band. In this study, we propose an omnidirectional optical sensor module that can measure photoplethysmogram while using multiple wavelengths, and describe implementation detail. The developed sensor is manufactured by making a hole in a metal plate and mounting an LED therein, and it has four wavelength LEDs of blue (460 nm), green (530 nm), red (660 nm), and IR (940 nm), being arranged concentrically around a photodetector. Irradiation light intensity was measured by photoluminescent test, and photoplethymogram was measured with each wavelength simultaneously at a periphery of the human body such as fingertip, earlobe, toe, forehead, and wrist, in order to evaluate the developed sensor. As a result, the developed sensor module showed a linear increase of irradiating light intensity according to the number of LEDs increases, and pulsatile waveforms were observed at all four wavelengths in all measuring sites.

Internal precooling decreases forehead and core temperature but does not alter choice reaction time during steady state exercise in hot, humid conditions

This study aimed to determine if precooling via crushed ice ingestion reduces forehead skin temperature (T_head) and core temperature (T_core) during exercise in the heat and whether it has an effect on choice reaction time (CRT). Ten males commenced a 30 min precooling period, ingesting either 7 g kg^-1 of crushed ice (ICE) or room temperature water (CON) prior to cycling 60 min at 55% V̇O_2peak in hot, humid conditions (35.0 ± 0.3 °C, 50.2 ± 2.1% Relative Humidity). The CRT task was completed upon arrival and after the precooling period in the lab, then at 15 min intervals during exercise in the heat. Precooling reduced T_head and T_core to a greater degree in ICE (T_head: -0.8 ± 0.31 °C; T_core: -0.9 ± 0.3 °C) compared with CON (T_head: -0.2 ± 0.3 °C; T_core: -0.2 ± 0.2 °C) (p ≤ 0.001). Choice reaction time performance improved throughout the cycle for both conditions (p ≤ 0.05). Ice ingestion lowered thermal sensation (p = 0.003) and skin temperature (d = 0.88; T_skin), while heart rate, ratings of perceived exertion and thirst were similar between conditions (p > 0.05). Precooling effectively reduced T_head and T_core but did not provide additional improvement in CRT during moderate exercise in the heat. Further investigation is required to determine whether the lower central and peripheral temperature after ice ingestion is beneficial for tasks of greater cognitive effort.

Identifying Ketamine Responses in Treatment-Resistant Depression Using a Wearable Forehead EEG

This study explores responses to ketamine in patients with treatment-resistant depression (TRD) using a wearable forehead electroencephalography (EEG) device. We recruited and randomly assigned 55 outpatients with TRD into three approximately equal-sized groups (A: 0.5-mg/kg ketamine; B: 0.2-mg/kg ketamine; and C: normal saline) under double-blind conditions. The ketamine responses were measured by EEG signals and Hamilton depression rating scale scores. At baseline, the responders showed significantly weaker EEG theta power than the non-responders (p < 0.05). Compared to the baseline, the responders exhibited higher EEG alpha power but lower EEG alpha asymmetry and theta cordance post-treatment (p < 0.05). Furthermore, our baseline EEG predictor classified the responders and non-responders with 81.3 ± 9.5% accuracy, 82.1 ± 8.6% sensitivity, and 91.9 ± 7.4% specificity. In conclusion, the rapid antidepressant effects of mixed doses of ketamine are associated with prefrontal EEG power, asymmetry, and cordance at baseline and early post-treatment changes. Prefrontal EEG patterns at baseline may serve as indicators of ketamine effects. Our randomized double-blind placebo-controlled study provides information regarding the clinical impacts on the potential targets underlying baseline identification and early changes from the effects of ketamine in patients with TRD.

Evaluation of a novel noninvasive continuous core temperature measurement system with a zero heat flux sensor using a manikin of the human body

Reliable continuous perioperative core temperature measurement is of major importance. The pulmonary artery catheter is currently the gold standard for measuring core temperature but is invasive and expensive. Using a manikin, we evaluated the new, noninvasive SpotOn™ temperature monitoring system (SOT). With a sensor placed on the lateral forehead, SOT uses zero heat flux technology to noninvasively measure core temperature; and because the forehead is devoid of thermoregulatory arteriovenous shunts, a piece of bone cement served as a model of the frontal bone in this study. Bias, limits of agreements, long-term measurement stability, and the lowest measurable temperature of the device were investigated. Bias and limits of agreement of the temperature data of two SOTs and of the thermistor placed on the manikin's surface were calculated. Measurements obtained from SOTs were similar to thermistor values. The bias and limits of agreement lay within a predefined clinically acceptable range. Repeat measurements differed only slightly, and stayed stable for hours. Because of its temperature range, the SOT cannot be used to monitor temperatures below 28°C. In conclusion, the new SOT could provide a reliable, less invasive and cheaper alternative for measuring perioperative core temperature in routine clinical practice. Further clinical trials are needed to evaluate these results.

A Wearable Thermometry for Core Body Temperature Measurement and Its Experimental Verification

A wearable thermometry for core body temperature (CBT) measurement has both healthcare and clinical applications. On the basis of the mechanism of bioheat transfer, we earlier designed and improved a wearable thermometry using the dual-heat-flux method for CBT measurement. In this study, this thermometry is examined experimentally. We studied a fast-changing CBT measurement (FCCM, 55 min, 12 subjects) inside a thermostatic chamber and performed long-term monitoring of CBT (LTM, 24 h, six subjects). When compared with a reference, the CoreTemp CM-210 by Terumo, FCCM shows 0.07 °C average difference and a 95% CI of [-0.27, 0.12] °C. LTM shows no significant difference in parameters for the inference of circadian rhythm. The FCCM and LTM both simulated scenarios in which this thermometry could be used for intensive monitoring and daily healthcare, respectively. The results suggest that because of its convenient design, this thermometry may be an ideal choice for conventional CBT measurements.

Reliable emotion recognition system based on dynamic adaptive fusion of forehead biopotentials and physiological signals

In this study, we proposed a new adaptive method for fusing multiple emotional modalities to improve the performance of the emotion recognition system. Three-channel forehead biosignals along with peripheral physiological measurements (blood volume pressure, skin conductance, and interbeat intervals) were utilized as emotional modalities. Six basic emotions, i.e., anger, sadness, fear, disgust, happiness, and surprise were elicited by displaying preselected video clips for each of the 25 participants in the experiment; the physiological signals were collected simultaneously. In our multimodal emotion recognition system, recorded signals with the formation of several classification units identified the emotions independently. Then the results were fused using the adaptive weighted linear model to produce the final result. Each classification unit is assigned a weight that is determined dynamically by considering the performance of the units during the testing phase and the training phase results. This dynamic weighting scheme enables the emotion recognition system to adapt itself to each new user. The results showed that the suggested method outperformed conventional fusion of the features and classification units using the majority voting method. In addition, a considerable improvement, compared to the systems that used the static weighting schemes for fusing classification units, was also shown. Using support vector machine (SVM) and k-nearest neighbors (KNN) classifiers, the overall classification accuracies of 84.7% and 80% were obtained in identifying the emotions, respectively. In addition, applying the forehead or physiological signals in the proposed scheme indicates that designing a reliable emotion recognition system is feasible without the need for additional emotional modalities.

Regional variations in percutaneous absorption

BACKGROUND

In its simplest definition, percutaneous absorption (PA) is the amount of substance that passes through the stratum corneum compared with the amount applied. The study of the PA of substances is relevant to the fields of dermatopharmacology and occupational medicine. The quantity and rate in which a given chemical absorbs through the skin depend on a multitude of variables. One obvious determinant of PA is the application site. This overview summarizes currently available data on the topic of regional variations in PA and possibly suggests a direction for future research efforts.

METHODS

Searches were performed in Medline and EMBASE. Extensive bibliographical research was performed in order to identify additional relevant data sets using Web of Science. Results were screened for inclusion of more than one anatomical site, the use of validated methods, and the use of human subjects.

RESULTS

We identified eight relevant studies, from which we present data.

CONCLUSION

Determining regional variations in PA is a complex yet critically important task. Current data sets are scarce and inadequate for drawing complete conclusions, but the data seem to suggest increased PA in the forehead and genital skin compared with other anatomical regions. It is our hope that, with the advent of new technologies, an anatomical PA map will begin to emerge from the data. Such descriptive understanding will guide investigation into the mechanisms involved in determining anatomical site differences in PA.

[Skin temperature and lactate threshold during muscle work in sportsmen]

The purpose of the investigation was to estimate change of a thermal condition of an organism during exhausting work (maximal aerobic test) on cycle ergometer on the basis of studying of dynamics of temperature of a forehead skin. Regularly training 20 men have taken part in the research--sportsmen of various specializations (skiers, rock-climbers, boxers, etc.). Temperature of forehead skin was registered by infrared thermovision chamber Nec TH 9100SL. These results compared with the data of measurements of heart rate, gas exchange, the lactate concentration in peripheral blood, and also with anthropometrical characteristics. It was shown that on dynamics of skin temperature at maximal work load it was possible to divide all subjects into 2 unequal groups: 1 (2/3 subjects, the majority of which trains endurance) - after temperature decrease take place its smooth increase up to refusal ofwork; 2 (1/3 subjects, concerning various sports specializations)--from the moment of the beginning of active evaporation of sweat the temperature decreases to the work termination. In group 1 lactate threshold (lactate concentration in blood--4 mm/l) corresponds to the beginning of rise in temperature after its decrease as a result of sweat evaporation. In group 2 lactate threshold was necessary on a phase of decrease in temperature at the moment of active evaporation of sweat. Distinctions between groups in structure of correlation relationship between the measured indicators are revealed, inversion of a sign ofcorrelation quotient in some cases were shown. Thus significant distinctions between groups in the level of the working capacity indicators were not revealed. All it testifies to existence possibility at least two various successful strategy of urgent adaptation of system of thermoregulation to intense muscular work.

Accelerometer-based method for correcting signal baseline changes caused by motion artifacts in medical near-infrared spectroscopy

In medical near-infrared spectroscopy (NIRS), movements of the subject often cause large step changes in the baselines of the measured light attenuation signals. This prevents comparison of hemoglobin concentration levels before and after movement. We present an accelerometer-based motion artifact removal (ABAMAR) algorithm for correcting such baseline motion artifacts (BMAs). ABAMAR can be easily adapted to various long-term monitoring applications of NIRS. We applied ABAMAR to NIRS data collected in 23 all-night sleep measurements and containing BMAs from involuntary movements during sleep. For reference, three NIRS researchers independently identified BMAs from the data. To determine whether the use of an accelerometer improves BMA detection accuracy, we compared ABAMAR to motion detection based on peaks in the moving standard deviation (SD) of NIRS data. The number of BMAs identified by ABAMAR was similar to the number detected by the humans, and 79% of the artifacts identified by ABAMAR were confirmed by at least two humans. While the moving SD of NIRS data could also be used for motion detection, on average 2 out of the 10 largest SD peaks in NIRS data each night occurred without the presence of movement. Thus, using an accelerometer improves BMA detection accuracy in NIRS.

Application of near-infrared spectroscopy to measurement of hemodynamic signals accompanying stimulated saliva secretion

We aim to test the feasibility of using near-infrared spectroscopy (NIRS) for indirect measurement of human saliva secretion in response to taste stimuli for potential application to organoleptic testing. We use an NIRS system to measure extracranial hemodynamics (Hb-signals around the temples) of healthy participants when taste stimuli are taken in their mouths. First, the Hb-signals and volume of expelled saliva (stimulated by distilled-water or sucrose-solution intake) are simultaneously measured and large Hb-signal changes in response to the taste stimuli (Hb-responses) are found. Statistical analysis show that both the Hb response and saliva volume are larger for the sucrose solution than for the distilled water with a significant correlation between them (r = 0.81). The effects of swallowing on the Hb-signals are investigated. Similar Hb responses, differing from the sucrose solution and distilled water, are obtained even though the participants swallow the mouth contents. Finally, functional magnetic resonance imaging is used to identify possible sources of the Hb signals corresponding to salivation. Statistical analysis indicates similar responses in the extracranial regions, mainly around the middle meningeal artery. In conclusion, the identified correlation between extracranial hemodynamics and the saliva volume suggests that NIRS is applicable to the measurement of hemodynamic signals accompanying stimulated saliva secretion.

The acoustic field on the forehead of echolocating Atlantic bottlenose dolphins (Tursiops truncatus)

Arrays of up to six broadband suction cup hydrophones were placed on the forehead of two bottlenose dolphins to determine the location where the beam axis emerges and to examine how signals in the acoustic near-field relate to signals in the far-field. Four different array geometries were used; a linear one with hydrophones arranged along the midline of the forehead, and two around the front of the melon at 1.4 and 4.2 cm above the rostrum insertion, and one across the melon in certain locations not measured by other configurations. The beam axis was found to be close to the midline of the melon, approximately 5.4 cm above the rostrum insert for both animals. The signal path coincided with the low-density, low-velocity core of the melon; however, the data suggest that the signals are focused mainly by the air sacs. Slight asymmetry in the signals were found with higher amplitudes on the right side of the forehead. Although the signal waveform measured on the melon appeared distorted, when they are mathematically summed in the far-field, taking into account the relative time of arrival of the signals, the resultant waveform matched that measured by the hydrophone located at 1 m.

Accuracy and reliability of thermal threshold measurement in the chin using heat flux technique

BACKGROUND

Neurosensory disturbance (NSD) occasionally develops in the chin following dental treatments, and evaluation of the involved nerve damage is important for treatment. The thermal-threshold test is a method of evaluating nerve sensations, but it is not widely used because its accuracy and reliability have not yet been determined.

PURPOSE

This study aimed to determine the accuracy and reliability of thermal-threshold measurement of the chin by using the heat-flux technique.

MATERIALS AND METHODS

The subjects were 19 healthy volunteers (7 women, 12 men), aged 21 to 36 years (mean age +/- SD, 27.2 +/- 4.5 years). The thermal thresholds, including the warm and cold heat-flux thresholds (WHF and CHF, respectively) were measured on the chin, forehead, and neck by using a thermostimulator. To evaluate test-retest reliability, we measured the thermal thresholds on 3 different days (days 1, 3, and 7).

RESULTS

The WHF and CHF of the right chin were 460 +/- 165 W/m(2) (mean +/- SD W/m(2)) and 589 +/- 133 W/m(2), respectively, and those of the left chin were 446 +/- 112 W/m(2) and 576 +/- 147 W/m(2), respectively. The thermal thresholds of the right and left chin were significantly correlated (R = 0.89, P < .001). Thermal-threshold measurement was more accurate in the case of the chin than in the case of the neck. The thermal thresholds measured over the 3 days varied very little (intraclass correlation coefficient, 0.80-0.81), indicating high test-retest reliability.

CONCLUSION

The heat-flux technique is accurate and highly reliable. Therefore, it may be a useful method for determining the thermal threshold of the chin.

Reliability of an infrared forehead skin thermometer for core temperature measurements

The SensorTouch thermometer performs an infrared measurement of the skin temperature above the Superficial Temporal Artery (STA). This study evaluates the validity and the accuracy of the SensorTouch thermometer. Two experiments were performed in which the body temperature was measured with a rectal sensor, with an oesophageal sensor and with the SensorTouch. After entering a warm chamber the SensorTouch underestimated the core temperature during the first 10 minutes. After that, the SensorTouch was not significantly different from the core temperature, with an average difference of 0.5 degrees C (SD 0.5 degrees C) in the first study and 0.3 degrees C (SD 0.2 degrees C) in the second study. The largest differences between the SensorTouch and the core temperature existed 15 minutes after the start of the exercise. During this period the SensorTouch was significantly higher than the core temperature. The SensorTouch did not provide reliable values of the body temperature during periods of increasing body temperature, but the SensorTouch might work under stable conditions.

Successful extension of assessment and rehabilitation intervention for an adolescent with postcoma multiple disabilities through a learning setup

Prior to the beginning of this study, the participant (an adolescent with postcoma multiple disabilities) had learned to use a forehead-skin response to access environmental stimuli. These learning data seemed to indicate a minimally conscious state (i.e., awareness of the link between response and stimuli) in spite of 1) a previous diagnosis of postcoma vegetative state; and 2) concomitant electrophysiological measurement showing no evidence of a passive P300 response and of mismatch negativity. The present study was an effort to extend the early learning investigation with two additional responses and related stimuli to broaden learning evidence and ascertain possible choice behavior. Results indicated that the participant learned the new responses and also provided evidence of choice behavior. These data were discussed in terms of the usefulness of the learning paradigm in the assessment and rehabilitation of persons with postcoma multiple disabilities and consciousness disorders.

Persons with multiple disabilities and minimal motor behavior using small forehead movements and new microswitch technology to control environmental stimuli

Persons with multiple disabilities and minimal motor behavior may be unable to use available microswitch technology to control environmental stimuli. For these persons, one may need to rely on small motor expressions (as responses) and new, matching microswitch technology to ensure a successful outcome. In the present study, a small movement of the forehead skin was selected as the response for two participants (ages 6.5 and 14.2 years) with profound multiple disabilities. The microswitch technology included (a) an optic sensor, i.e., barcode reader, (b) a small tag with horizontal bars attached to the participants' forehead, and (c) an electronic control system which activated stimuli in relation to response occurrence. Movement of the forehead skin shifted up or down the tag with bars and this shifting, if greater than a preset limit and therefore recorded as a response, led to the activation of the control system. Each participant received an ABAB sequence, in which A represented baseline and B intervention phases, and a 6-wk. postintervention check. Analysis showed both participants increased their responding during the intervention phases and maintained that responding at the postintervention check. Implications of the findings were discussed.

Effects of spinal anesthesia on the peripheral and deep core temperature in elderly diabetic patients undergoing urological surgery

PURPOSE

The effects of spinal anesthesia on temperature homeostasis have been well studied, but whether body temperature during spinal anesthesia exhibits the same characteristic changes in patients with diabetes mellitus (DM) has not been clarified. The present study measured body temperatures at the forehead and at the lower limb using a monitor of deep body temperature and compared patients with DM (n = 8) and without DM (n = 10).

METHODS

Subjects comprised 18 male patients (ASA physical status I or II) undergoing spinal anesthesia for urological surgery. Changes in deep body temperatures were measured using a Coretemp "deep-tissue" thermometer.

RESULTS

Although the forehead temperature decreased slightly in both groups after spinal anesthesia, no significant differences were noted between groups. Conversely, although the foot temperature was elevated in both groups, temperature increases were smaller in DM patients (4.0 degrees +/- 0.3 degrees C) than in controls (4.9 degrees +/- 0.6 degrees C). Moreover, longer times were required to display increases of 1 degrees C and 2 degrees C for patients with DM (1 degrees C: 19.1 +/- 4.0 min; 2 degrees C: 25.1 +/- 4.2 min) compared with controls (1 degrees C: 9.6 +/- 1.3 min; 2 degrees C: 13.1 +/- 1.5 min).

CONCLUSION

These data suggest that body temperature changes in patients with DM during spinal anesthesia are different from those of control patients, probably due to disorders of the vascular response.

In vivo time-resolved reflectance spectroscopy of the human forehead

We present an in vivo broadband spectroscopic characterization of the human forehead. Absorption and scattering properties are measured on five healthy volunteers at five different interfiber distances, using time-resolved diffuse spectroscopy and interpreting data with a model of the diffusion equation for a homogeneous semi-infinite medium. A wavelength-tunable mode-locked laser and time-correlated single-photon counting detection are employed, enabling fully spectroscopic measurements in the range of 700-1000 nm. The results show a large variation in the absorption and scattering properties of the head depending on the subject, whereas intrasubject variations, assessed at different interfiber distances, appear less relevant, particularly for what concerns the absorption coefficient. The high intersubject variability observed indicates that a unique set of optical properties for modeling the human head cannot be used correctly. To better interpret the results of the analysis of in vivo measurements, we performed a set of four-layer model Monte Carlo simulations based on different data sets for the optical properties of the human head, partially derived from the literature. The analysis indicated that, when simulated time-resolved curves are fitted with a homogeneous model for the photon migration, the retrieved absorption and reduced scattering coefficients are much closer to superficial layer values (i.e., scalp and skull) than to deeper layer ones (white and gray matter). In particular, for the shorter interfiber distances, the recovered values can be assumed as a good estimate of the optical properties of the first layer.

Effects of a Color Filter Used in Auriculomedicine on Ultraweak Photon Emission of the Human Body

CONTEXT

The human body emits ultraweak photons. It has been demonstrated that feedback regulation of ultraweak photon emission from the hand is detectable utilizing gelatin color filters in complete darkness. Color filters are commonly utilized in auriculomedicine diagnostic procedures based on the radial artery vascular autonomic signal.

OBJECTIVE

To evaluate the possibility of an effect by a dark-adapted red filter on (1) local ultraweak human photon emission using different anatomic locations, and (2) on systemic photon emission using one location for red filter exposure and another for photon emission recording.

DESIGN

Photon emission of abdomen, forehead, palm, and dorsum of the hand was recorded before and after the presence of a red filter. In addition, photon emission of forehead and dorsum of the hand was recorded before, during, and after the presence of the red filter close to the palm. In both instances, the filter was dark-adapted and placed in close proximity to, but not touching the skin of the dark-adapted subject. A low-noise, end window photomultiplier for recording ultraviolet and visible (200-650 nm) photon emission (with a very low background count rate) and designed for manipulation in three directions was situated in a dark room. The technology was utilized to record spontaneous photon emission of the abdomen, forehead, palm, and dorsum of the hand of one human male subject.

RESULTS

Data demonstrate that a dark-adapted subject responds in the total absence of light with a temporary increase in photon emission from the anatomic locations that had been exposed for 200 s at a distance of 3 cm to a dark-adapted red filter. Data from sequential time series suggest red filter initiation of a refractory emission reaction. Exposure of the palm to the red filter also evokes photon emission from the dorsum of the same hand and from the forehead. This response could be registered immediately after the beginning of the exposure. The stimulated emission is followed by a slow decrease of emission in the period after exposure to the filter.

CONCLUSION

Data suggest that red filter-stimulated photon emission response is systemic and rapid. Data imply an exchange of information vis-à-vis light from both hand and red filter. The mechanism of such interaction is currently speculation only.

[Bone conduction auditory brainstem responses in normal hearing individuals]

BACKGROUND

bone conduction auditory brainstem responses (ABR) in normal hearing individuals.

AIM

to evaluate the clinical applicability of bone conduction ABR, characterizing normality and determining an assessment protocol.

METHOD

participants of this study were 22 individuals with normal hearing (20dB NA), with ages between 20 and 30 years, 14 female and 8 male. All individuals were assessed using air and bone (vibrator positioned on the forehead and mastoid) conduction ABR. EP25 equipment, Interacoustic; 3A insertion phone; B-71 bone vibrator; click stimulus.

RESULTS

it was possible to evaluate the bone conduction ABR in all individuals. The results demonstrate that the electrophysiological threshold obtained when the vibrator was positioned on the forehead (32.69+/-5.63 and 32.5+/-7.07dB nHL) was higher than that obtained when the vibrator was positioned on the mastoid (25.00+/-7.33 and 30.00+/-5.34dB nHL) for both genders respectively. For this reason the vibrator was positioned on the mastoid. The electrophysiological threshold obtained by bone conduction was higher than that obtained by air conduction for both genders and also when all individuals were grouped together. Thus it is necessary to use a correction factor, according to the results, of 10dB nHL. The latency-intensity values of the V wave in the ipsilateral and contralateral recordings differed statistically according to gender, and should be considered separately. The value of 26.81+/-6.99dB nHL was adopted as being the normal threshold for bone conduction ABR.

CONCLUSION

it is possible to evaluate bone conduction ABR in the clinical environment. These results, when considered along with the air conduction ABR, increase the chances of a more precise diagnosis regarding the type of hearing loss.

Hostility and sex differences in the magnitude, duration, and determinants of heart rate response to forehead cold pressor: Parasympathetic aspects of risk

Recent models hypothesize that hostility confers increased risk of CHD through weaker parasympathetic dampening of cardiovascular reactivity (CVR). We tested this possibility using the forehead cold pressor task, a common maneuver which elicits the "dive reflex" characterized by a reflexive decrease in HR presumably through cardiac-parasympathetic stimulation. Participants were initially chosen from the outer quartiles of a sample of 670 undergraduates screened using the hostility subscale of the Aggression Questionnaire ([Buss, A.H., Perry, M., 1992. The Aggression Questionnaire. Journal of Personality and Social Psychology, 63, 452-459.]). The final sample of 80 participants was evenly divided between men and women and high and low hostility. Following a 10-min baseline, participants underwent a 3-min forehead cold pressor task. The task evoked a significant HR deceleration that was mediated by PNS activation, as assessed by respiratory sinus arrhythmia (RSA). Replicating prior research, men displayed greater decrease in HR. More important, low hostiles maintained larger HR deceleration over time compared to high hostiles although the autonomic basis for this effect was unclear. The findings broaden understanding of hostility and sex-related cardiovascular functioning and support the task as a method for evoking PNS-cardiac stimulation.

Anatomic characterization of human ultra-weak photon emission in practitioners of transcendental meditation(TM) and control subjects

BACKGROUND

Research on human ultra-weak photon emission (UPE, biophoton emission) has raised the question whether a typical human emission anatomic percentage distribution pattern exists in addition to individual subject overall anatomic summation intensity differences. The lowest UPE intensities were observed in two subjects who regularly meditate. Spectral analysis of human UPE has suggested that ultra-weak emission is probably, at least in part, a reflection of free radical reactions in a living system. It has been documented that various physiologic and biochemical shifts follow the long-term practice of meditation and it is inferred that meditation may impact free radical activity.

OBJECTIVE

To systematically quantify, in subjects with long-term transcendental meditation (TM) experience and subjects without this experience, the UPE emission of the anterior torso, head and neck plus the hands in an attempt to document the differences by the two groups.

SUBJECTS

Subjects were 20 men reported to be healthy and nonsmokers. Each of the subjects in the meditation group had practiced TM twice daily for at least the past 10 years.

METHODS

UPE in 20 subjects was recorded in a dark room using a highly sensitive, cooled photomultiplier system designed for manipulation in three directions. The protocol for multisite registration of spontaneous emission includes recording of 12 anatomic locations of anterior torso, head, and hands.

RESULTS

Data demonstrate emission intensities that are lower in TM practitioners as compared to control subjects. The percent contribution of emission from most anatomic locations was not significantly different for TM practitioners and control subjects. Exceptions are the contributions of throat and palm.

CONCLUSION

In subjects with long-term TM experience, the UPE emission is different from control subjects. Data support the hypothesis that free radical reactions can be influenced by TM.

Mental strain in medical students during simulator training measured by forehead sweating

Forehead sweating developed in 78% of medical students when they attempted tracheal intubation on a simulator, and increased during subsequent attempts if the first attempt was not successful. Thus, forehead sweating may be a useful index of mental strain.

Left-right asymmetry of the facial microvascular control

Facial blood flow and temperature were significantly higher on the right side of the forehead compared to the left. This asymmetry implies that the hemispheric autonomic control of the face differs and could influence the expression of emotion.

Long-term effects of hormone therapy on skin rigidity and wrinkles

OBJECTIVE

To evaluate the effects of long-term hormone therapy (HT) on skin rigidity and wrinkling.

DESIGN

Single blinded cross-sectional analysis.

SETTING

Academic medical center.

PATIENT(S)

Sixty-five long-term HT users who underwent menopause at least 5 years before evaluation and who have either consistently used HT or have never used HT.

INTERVENTION(S)

Visual assessment of severity of wrinkles at 11 facial locations using the Lemperle scale by a plastic surgeon blinded to HT use. Measurement of skin rigidity at the cheek and forehead with a durometer.

MAIN OUTCOME MEASURE(S)

Lemperle wrinkle score and skin rigidity.

RESULT(S)

Twenty women met inclusion criteria. Eleven women who had not used HT were compared to nine long-term HT users. Demographics including age, race, sun exposure, sunscreen use, tobacco use, and skin type were similar. Rigidity was significantly decreased in HT users compared to nonusers at both the cheek (1.1 vs. 2.7) and forehead (20 vs. 29). Average wrinkle scores were lower in hormone users than in nonhormone users (1.5 vs. 2.2).

CONCLUSION(S)

Long-term postmenopausal HT users have more elastic skin and less severe wrinkling than women who never used HT, suggesting that hormone therapy may have cosmetic benefits.

The occipitofrontalis muscle is composed of two physiologically and anatomically different muscles separately affecting the positions of the eyebrow and hairline

After the surgical correction of aponeurotic blepharoptosis or blepharoplasty, the positions of the eyebrow and hairline change as if the frontal belly is independent from the occipital belly of the occipitofrontalis muscle. Therefore, the occipitofrontalis muscle was studied physiologically with electromyographic evaluation in healthy subjects and anatomically with cadaver dissections. Along with contraction of the levator muscle to maintain an adequate visual field, at a less upward gaze position, contraction of only the frontal belly was induced, and at a more upward gaze position, contraction of both the frontal and the occipital bellies was always induced to lift the eyebrow with the upper eyelid skin. The superficial fascia overlying the occipital belly becomes the temporoparietal fascia and ends at the superior end of the frontal belly, thus creating a superficial musculoaponeurotic system that lifts the eyebrow and pulls the scalp forwards. Beneath the superficial musculoaponeurotic system, the occipital belly of the occipitofrontalis muscle becomes the galea aponeurotica and inserts into the underside of the frontal belly, thus creating a deep musculoaponeurotic system that pulls the superficial musculoaponeurotic system with the scalp backwards. Thus, the occipitofrontalis muscle appears to be composed of two physiologically and anatomically different muscles.

Effect of meditation on ultraweak photon emission from hands and forehead

BACKGROUND

Various physiologic and biochemical shifts can follow meditation. Meditation has been implicated in impacting free radical activity. Ultraweak photon emission (UPE, biophoton emission) is a constituent of the metabolic processes in a living system. Spectral analysis showed the characteristics of radical reactions.

OBJECTIVES

Recording and analysing photon emission in 5 subjects before, during and after meditation.

METHODS

UPE in 5 subjects who meditated in sitting or supine positions was recorded in a darkroom utilising a photomultiplier designed for manipulation in three directions.

RESULTS

Data indicated that UPE changes after meditation. In 1 subject with high pre-meditation values, UPE decreased during meditation and remained low in the postmeditation phase. In the other subjects, only a slight decrease in photon emission was found, but commonly a decrease was observed in the kurtosis and skewness values of the photon count distribution. A second set of data on photon emission from the hands before and after meditation was collected from 2 subjects. These data were characterised by the Fano factor, F(T), i.e. variance over mean of the number of photoelectrons observed within observation time T. All data were compared to surrogate data sets which were constructed by random shuffling of the data sets. In the pre-meditation period, F(T) increased with observation time, significantly at time windows >6 s. No such effect was found after meditation, when F(T) was in the range of the surrogate data set.

CONCLUSIONS

The data support the hypothesis that human photon emission can be influenced by meditation. Data from time series recordings suggest that this non-invasive tool for monitoring radical reactions during meditation is useful to characterise the effect of meditation. Fano factor analysis demonstrated that the time series before meditation do not represent a simple Poisson process. Instead, UPE has characteristics of a fractal process, showing long-range correlations. The effect of meditation waives out this coherence phenomenon, suggesting a weaker and less ordered structure of UPE. In general, meditation seems to influence the complex interactions of oxidative and anti-oxidative reactions which regulate photon emission. The reason for the statistical changes between pre- and post-meditation measurements remains unclear and demands further examination.

Stress influences the level of negative affectivity after forehead cold pressor pain

The purpose of this study was to investigate simultaneously a stress manipulation and an experimental pain manipulation to determine how stress and pain interact to influence negative affectivity. One hundred healthy subjects completed a counterbalanced repeated measure crossover design in which stress (speech task) versus a nonstress control condition (magazine reading) was manipulated. Each session was immediately followed by a 2-minute forehead cold pressor task. Measures of affectivity (Positive Affect Negative Affect Schedule), pain ratings, cardiovascular measures (systolic blood pressure, diastolic blood pressure, heart rate), and salivary cortisol were obtained during each session. Regression analysis showed that the stress manipulation influenced the level of anger and that change in anger predicted post-pain negative affectivity independently of the contribution of maximum pain (model R(2) =.31), with 45% of the total model variance accounted for by change in anger and 17% of the total model variance accounted for by maximum pain intensity. In the nonstress condition only level of pain intensity was an independent predictor of negative affectivity (model R(2) =.16), with 69% of the total model variance accounted for by maximum pain intensity. These results show that stress significantly amplifies post-pain negative mood beyond that accounted for by the level of pain intensity alone.

[Usefulness of monitoring forehead deep-tissue temperature as an index of core temperature in adult patients undergoing laparotomies under general anesthesia--investigation in operating rooms with air-movement control system using vertical flow]

BACKGROUND

Acute changes in air temperature in the vicinity of the patents' forehead may impair clinical usefulness of the forehead deep-tissue thermometry. We thus investigated usefulness of monitoring the forehead deep-tissue temperature as an index of core temperature in 12 adult patients undergoing laparotomies in operating rooms with air-movement control system using vertical flow.

METHODS

Nasopharyngeal, forehead deep-tissue, palm deep-tissue, and fingertip skin-surface temperatures were recorded during surgery every 5 minutes in operating rooms where room temperature was thermostatically controlled at approximately 25 degrees C. The patients were not actively warmed with forced-air warmers, but covered with cotton blankets where possible. The deep-tissue and fingertip skin-surface temperatures were compared with the nasopharyngeal temperature using regression and Bland and Altman's analyses.

RESULTS

The four temperatures continued decreasing during surgery, and the nasopharyngeal temperature decreased to below 36 degrees C 2 hours after induction of anesthesia. Only the forehead deep-tissue temperature satisfactorily correlated with the nasopharyngeal temperature (r = 0.76, n = 300, P < 0.0001). The difference between nasopharyngeal and forehead temperatures was +0.26 degree C, and its standard deviation was 0.34 degree C.

CONCLUSIONS

The forehead deep-tissue temperature has sufficient accuracy and precision for clinical use in operating rooms with air-movement control system using vertical flow. However, the core temperature appears to be slightly underestimated with the forehead deep-tissue thermometry.

Pressure pain threshold of the posterior aspect of the temporomandibular joint measured with a semi-spherical probe

AIMS

To develop and test a probe for measurement of the pressure pain threshold (PPT) over the posterior aspect of the temporomandibular joint (TMJ) in healthy individuals, including determination of PPT levels, reliability, and the smallest detectable difference (SDD) between measurements.

METHODS

A semi-spherical probe was designed to measure PPT levels over the posterior aspect of the TMJ through the external auditory meatus. The probe was connected to an electronic algometer. Three consecutive measurements were performed with this probe over the posterior and lateral aspects of the left and right TMJs as well as over a reference point on the forehead (glabella) in 31 healthy subjects: 10 male and 21 female. Measurements were also performed for comparison with a conventional flat probe with a 1 cm2 area over the lateral aspect of the TMJ and the reference point.

RESULTS

The PPT measured with the semi-spherical probe and the conventional probe showed similar degrees of interindividual variation and reproducibility. The relative SDD, expressed as the percentage of the mean PPT for 2 measurements, showed similar levels for the flat and semi-spherical probes, i.e., 28% to 32% of the mean PPT at the TMJ.

CONCLUSION

The semi-spherical probe shows similar reliability and relative SDD for measurement of PPT levels over the posterior aspect of the TMJ in healthy individuals as measurement over the lateral aspect with a flat probe. Measurement of the posterior PPT with a semi-spherical probe may be a useful adjunct to conventional lateral PPT measurements.

Representation of different trigeminal divisions within the primary and secondary human somatosensory cortex

Clinical, neurophysiological, and neuroimaging studies have yielded controversial results about the representation of the face in the somatosensory cortex. To clarify this issue we mechanically stimulated the left forehead (ophthalmic trigeminal division, V1) and left lower lip (mandibular trigeminal division, V3) in 14 healthy volunteers during acquisition of whole-brain fMRI images. During V1 and V3 stimulation the fMRI signal in the primary (SI) and secondary (SII) somatosensory cortices in the contralateral hemisphere increased. Within both SI and SII, the foci activated by stimulation of the two trigeminal divisions largely overlapped. In contrast, the ipsilateral representation differed. Whereas V3 stimulation activated the contralateral somatosensory cortex alone, V1 stimulation activated SI and SII bilaterally. These results to some extent contrast with electrophysiological data in monkeys and disclose distinct cortical representations within facial territories in humans.

Intra- and interactive touch on the face

Experiments were performed in which the subjective size of steel balls was judged by the method of absolute magnitude estimation (AME). The balls were rolled actively ("scripting") by the right index finger pad of the subject over the passively receiving areas of the face, namely the forehead, cheek and the vermilion border of the lower lip. These areas were stimulated on the subject's own person (intra-active touch), on another person's face (interactive touch) and by another person upon the face of the subject (interactive touch). Results indicate that size perception appears to be governed primarily by the mechanical characteristics of the stimuli, including the balls and the sites on the face. When the subject's finger was used to script upon another's face, there were significant differences among or between the sites. When another person scripted upon the subject's face there were no significant differences among any of the sites. The results are discussed considering mode of stimulation and tissue mechanics.

Vestibular evoked myogenic potentials in response to laterally directed skull taps

In recent years it has been demonstrated that loud clicks generate short latency vestibular evoked myogenic potentials (VEMP). It has also been demonstrated that midline forehead skull tap stimulation evokes similar VEMP. In the present study, the influence of skull tap direction on VEMP was studied in 13 normal subjects and in five patients with unilateral vestibular loss. Gentle skull taps were delivered manually above each ear on the side of the skull. The muscular responses were recorded over both sternocleidomastoid muscles using skin electrodes. Among the normals, laterally directed skull taps evoked "coordinated contraction-relaxation responses", i.e. skull taps on one side evoked a negative-positive "inverted" VEMP on that side and a positive-negative "normal" VEMP on the other side. Among patients with unilateral vestibular function loss, skull taps above the lesioned ear evoked similar coordinated contraction-relaxation responses. However, skull taps above the healthy ear did not evoke that type of response. These findings suggest that laterally directed skull taps activate mainly the contralateral labyrinth.

Impact of anatomical location on barrier recovery, surface pH and stratum corneum hydration after acute barrier disruption

BACKGROUND

It is not known whether distinct anatomical locations will respond with different recovery rates following acute barrier challenges.

OBJECTIVES

To investigate whether barrier parameters differ at five body sites during recovery from acute disruption.

METHODS

Acute barrier disruption was achieved by tape stripping and by acetone extraction of stratum corneum lipids. Transepidermal water loss (to assess barrier function), capacitance (for stratum corneum hydration) and skin surface pH were measured at each of five different body sites in 14 human volunteers. Individual measurements were obtained every 24 h for 96 h.

RESULTS

Lipid-rich skin areas (e.g. the forehead) were the most vulnerable to barrier disruption by either method. While acetone treatment affected barrier function and decreased stratum corneum hydration, tape stripping similarly altered barrier function but increased capacitance values. Although the effect of barrier disruption on surface pH appeared to vary with location, no significant pattern of variation emerged. Independent of the method used for barrier disruption, the pH normalized within 96 h.

CONCLUSIONS

Skin at different body sites shows distinct patterns of barrier recovery that are likely to be related to structural and physiological differences. Therefore, 'anatomically specific' regimens appear possible and relevant for the treatment of cutaneous disorders. In addition, adequate statistical analyses are essential to detect real differences in barrier recovery parameters.

Skin reflectance-spectra and colour-value dependency on measuring-head aperture area in ordinary reflectance spectrophotometry and tristimulus colourimetry

BACKGROUND/AIMS

Measurement of skin colour has become increasingly popular in the study of dermatology with the increased availability of portable instruments. However, different instruments have been reported as giving different results from measurement of the same skin region. The aim of this study was to examine the effects of differences in measuring-head aperture area on skin reflectance spectra and colour values.

METHODS

We measured both reflectance spectra and CIE-L*a*b* values of the skin in five different anatomical regions on 10 subjects using two MINOLTA reflectance spectrometers that were identical apart from the aperture area of the measuring heads (diameters: 5 and 11 mm). For comparison, data were also obtained from a skin-coloured tile.

RESULTS

Skin reflectance values measured with the wider-aperture instrument were higher than those measured with the other, irrespective of anatomical location. The differences between the two were near zero at an incident light wavelength of 400 nm, but increased to around 10% of the reflectance value at 700 nm, increasing exponentially with incident light of increasing wavelength. Skin colour was observed to be brighter, redder and yellower, in CIE-L*a*b* expression, when measured with the wider-aperture instrument. The differences between measurements obtained from the skin-coloured tile were much smaller.

CONCLUSION

Skin reflectance and colour values measured with reflectance instruments are not absolute data but depend on the aperture area of the measuring head. This is probably due to variations in the proportion of longer-wavelength light reflected from the skin and collected by the instrument.

Bone conduction hearing on the teeth of the lower jaw

Bone conduction stimulation of the teeth of the lower jaw initiates auditory sensations. However the lower jaw is only loosely coupled to the skull by the temporo-mandibular joint. Therefore the 'classical' bone conduction pathway involving skull vibration transmission entirely along bone to the temporal-petrous bone requires further consideration. Bone conduction hearing thresholds to stimulation at the forehead and at the teeth of the upper and lower jaw were determined in human subjects. Thresholds on the teeth were better than those on the forehead and there was no difference between the thresholds measured following stimulation of the upper and lower teeth. Experiments in guinea-pigs provided evidence that vibration of the teeth leads to transmission of the audio-frequency vibrations by means of soft tissue, through skull foramina, into the skull cavity (brain and CSF) and from there by fluid channels directly into inner ear fluids, exciting the cochlea.

Emotion in criminal offenders with psychopathy and borderline personality disorder

BACKGROUND

Criminal offenders with a diagnosis of psychopathy or borderline personality disorder (BPD) share an impulsive nature but tend to differ in their style of emotional response. This study aims to use multiple psychophysiologic measures to compare emotional responses to unpleasant and pleasant stimuli.

METHODS

Twenty-five psychopaths as defined by the Hare Psychopathy Checklist and 18 subjects with BPD from 2 high-security forensic treatment facilities were included in the study along with 24 control subjects. Electrodermal response was used as an indicator of emotional arousal, modulation of the startle reflex as a measure of valence, and electromyographic activity of the corrugator muscle as an index of emotional expression.

RESULTS

Compared with controls, psychopaths were characterized by decreased electrodermal responsiveness, less facial expression, and the absence of affective startle modulation. A higher percentage of psychopaths showed no startle reflex. Subjects with BPD showed a response pattern very similar to that of controls, ie, they showed comparable autonomic arousal, and their startle responses were strongest to unpleasant slides and weakest to pleasant slides. However, corrugator electromyographic activity in subjects with BPD demonstrated little facial modulation when they viewed either pleasant or unpleasant slides.

CONCLUSIONS

The results support the theory that psychopaths are characterized by a pronounced lack of fear in response to aversive events. Furthermore, the results suggest a general deficit in processing affective information, regardless of whether stimuli are negative or positive. Emotional hyporesponsiveness was specific to psychopaths, since results for offenders with BPD indicate a widely adequate processing of emotional stimuli.

In vivo optical characterization of human tissues from 610 to 1010 nm by time-resolved reflectance spectroscopy

A fully automated system for time-resolved reflectance spectroscopy based on tunable mode-locked laser sources and on time-correlated single-photon counting for the detection of time-resolved reflectance data was applied to the evaluation of the optical properties of biological tissues (arm, abdomen and forehead) in vivo from 610 to 1010 nm. The scattering decreases progressively with increasing wavelength, while the absorption line shapes show the typical spectral features of the principal tissue components (haemoglobin, water and lipid), with different weights depending on the tissue type. The best fit of the absorption spectra measured in vivo with the spectra of the pure constituents yielded information on the percentage composition of the different tissues. The interpretation of transport scattering spectra with Mie theory provided information on tissue structure.

Postural reflexes evoked by tapping forehead and chest

We investigated whether a tap with a reflex hammer to the forehead can elicit responses in the leg muscles and whether vestibular stimulation is the crucial prerequisite for eliciting these responses. We also measured the postural changes caused by the tap and by the compensatory, presumably reflex-like reactions of the subject. Tap-evoked activity of leg muscles was easily elicited during upright stance in normal subjects and was also seen in two subjects without vestibular function. The pattern of muscle activation clearly showed a counteraction to the tap-evoked perturbation of stance. Taps applied to the chest elicited similar reflexes. Since these two conditions imply a different activation of the vestibular apparatus, the vestibular input alone cannot account for the observed leg muscle reflexes. We suggest that multisensory reflex pathways that integrate vestibular and proprioceptive inputs account for these reflexes.

Innervation of sweat glands in the forehead. A study in patients with Horner's syndrome

The amount of sweating in lateral and medial sites in the forehead was investigated with quantitative evaporimetry in 18 patients with Horner's syndrome: eight cases with a central (1st), five with a preganglionic (2nd), and five with a postganglionic (3rd) neurone lesion. The amount of sweating was measured after body heating, and, at another occasion, after intracutaneous injection of the cholinergic drug pilocarpine. The two sites were at the root of the nose (medial position) and at the lateral angle of the eye (lateral position). Generally, there was a reduced level of sweating on the symptomatic versus the non-symptomatic side in both positions during body heating, except in the lateral part of the forehead in the 3rd neurone lesions, where sweating was greater on the symptomatic than on the non-symptomatic side. There was a nearly symmetrical sweating response after pilocarpine injection at all sites. There was one exception to this rule; the lateral position in the preganglionic neurone lesion group where pilocarpine induced more sweating on the non-symptomatic side. Thus, the results suggest a relative supersensitivity to pilocarpine in the medial position for all patients and in the lateral position for the central neurone lesion group. The findings suggest that the innervation of sweat glands in the medial and lateral parts of the forehead is different, the medial part being supplied by nerve fibres from the sympathetic plexus of the internal carotid artery, while the sweat glands in the lateral part is furnished from the plexus surrounding the external carotid artery.

Orientation of the body response to galvanic stimulation as a function of the inter-vestibular imbalance

We proposed to study and quantify the anteroposterior component, on top of the lateral one, of the body sway induced by different configurations of galvanic vestibular stimulation (GVS) in order to advance the understanding of the orientation of the response. Four stimulation configurations were used in two separate experiments: monaural, binaural, and opposite double monaural in the first experiment (11 subjects); monaural and double monaural in the second (13 subjects). The postural response of the subjects, standing with their eyes closed, to the stimulus (0.6 mA, 4 s) was assessed by measuring the displacement of the center of pressure (CoP) using a force platform. As usual, binaural GVS induced a strictly lateral deviation of the center of pressure. The opposite double monaural condition induced a similar lateral sway to that obtained in the binaural mode, although with a very different stimulation configuration. Monaural GVS induced an oblique, stereotyped deviation in each subject. The anteroposterior component comprised a forward deviation when the anode was on the forehead and a backward deviation when the anode was on the mastoid. The lateral component, directed towards the anode as in the binaural design, was twice as large in the binaural than in the monaural mode. The second experiment showed that double monaural stimulation elicited an anteroposterior deviation (backwards when the anode was on the mastoids and forwards when it was on the forehead) that was equivalent to the addition of two complementary monaural configurations. The present results show that monaural stimulation activates one side of the vestibular apparatus and induces reproducible, stereotyped deviations of the CoP in both the anteroposterior and lateral plane. Secondly, binaural GVS appears to result from the addition of two complementary monaural stimulations. Lateral components of the response to each stimulation, being in the same direction, are summed, whilst anteroposterior components, being in opposite directions, cancel each other out. The opposite happens when both labyrinths are polarized in the same way, as in the double monaural configuration. We suggest that the orientation of the response to GVS is a function of the imbalance between right and left vestibular polarization, rather than a function of the actual position of the electrodes.

Odor distinctiveness between enantiomers of linalool: difference in perception and responses elicited by sensory test and forehead surface potential wave measurement

The effects on humans of inhalation of optically active linalools were examined in terms of sensory tests and portable forehead surface electroencephalographic (IBVA-EEG) measurements in order to assess their odor distinctiveness by chiral isomers. (R)-(-)-Linalools with specific rotation of [alpha](D) = -15.1 degrees were isolated by repeated flash column chromatography from lavender oil, while (S)-(+)-linalools with [alpha](D) = +17.4 degrees and (RS)-(+/-)-linalools with [alpha](D) = 0 degrees and content of (R)-form 50.9% and (S)-form 49.1% were obtained from coriander oil and commercial linalool, respectively, by using the same method. With the use of an inhalator, each was administered to subjects both before and after 10 min of work. It was found that administration after work evoked different subjective impressions when compared with that before work depending on the configuration of the isomers and the type of work employed. For instance, inhalation of (R)-(-)-linalool after hearing environmental sounds not only produced a much more favorable impression in the sensory test but was also accompanied by a greater decrease in beta waves after work in comparison with that before work. This is in contrast to the case of mental work, which resulted in a tendency for agitation accompanied by an increase in beta waves. These findings led us to conclude that enantiomeric stereospecificity of linalool evoked different odor perception and responses not only with chiral dependence but also with task dependence. In addition, in comparing these sensory profiling features and IBVA-EEG tendencies between hearing environmental sound and mental work, a tendency was observed for (R)-(-)-linalool to coincide with (RS)-(+/-)-linalool but not with (S)-(+)-linalool.

[Utility of an infrared ear thermometer as an intraoperative core temperature monitor]

We investigated the utility of an infrared ear thermometer (M 10, Terumo) as an intraoperative core temperature monitor. Temperatures of the axilla and inner ear were measured before and after anesthesia. Bladder, rectal, and forehead deep temperatures were continuously measured using a core temperature monitor (CTM-205, Terumo) during anesthesia. At the same time, the temperature of the inner ear was measured 4 times every 15 minutes (twice from cephalad and twice from caudal directions). There were no significant differences in the measured inner ear temperatures, either between directions of measurement or between the 1st and 2nd measurements. The inner ear temperature showed a close correlation with rectal, bladder, forehead deep, and axillary temperatures (r = 0.72-0.79, P < 0.01). The smallest temperature difference in this study was found to be that between the inner ear and forehead deep temperatures (-0.10), and the limit of agreement between these temperatures was also the smallest (0.81). In conclusion, we recommended the use of an infrared ear thermometer as an intraoperative core temperature monitor, especially in lower abdominal surgery, in which neither rectal nor bladder temperature monitoring is reliable.

Near-infrared monitoring of tissue oxygenation during application of lower body pressure at rest and during dynamical exercise in humans

During the application of a wide range of graded lower body pressures (LBP) (-50 to 50 mmHg), we examined how (1) the tissue oxygenation in the lower and upper parts of the body changes at rest, and (2) how tissue oxygenation changes in the lower extremities during dynamical leg exercise. We used near-infrared spectroscopy (NIRS) to measure the changes induced by LBP in total Hb content and Hb oxygenation in seven subjects. At rest, total Hb increased and Hb oxygenation decreased in the thigh muscles during -25 and -50 mmHg LBP, while both decreased during +25 and +50 mmHg LBP. However, in the forearm muscles during graded LBP, the pattern of change in total Hb was the reverse of that in the thigh. Measurements from the forehead showed changes only during +50 mmHg LBP. These results demonstrated that the pattern of change in total Hb and Hb oxygenation differed between upper and lower parts with graded LBP at rest. During dynamical leg exercise, total Hb and Hb oxygenation in the thigh muscles decreased during stepwise increases in LBP above -25 mmHg, Hb oxygenation decreasing markedly during +50 mmHg LBP. These results suggest that during dynamical exercise (i) LBP at +25 mmHg or more causes a graded decline in blood volume and/or flow in the thigh muscles, and (ii) especially at +50 mmHg LBP, the O2 content may decrease markedly in active muscles. Our results suggest that NIRS can be used to monitor in a non-invasive and continuous fashion the changes in oxygenation occurring in human skeletal muscles and head during the graded changes in blood flow and/or volume caused by changes in external pressure and secondary reflexes both at rest and during dynamical exercise.

[The forehead cutaneo-musculo-aponeurotic unit and aging of the forehead. Anatomo-physiological considerations and surgical implications]

The occipitofrontalis muscle, as it is described in classical anatomy text books, does not exist. The epicranial aponeurosis or galea aponeurotica receives the occipitalis muscle on its deep surface and the frontalis muscle on its superficial surface. The frontalis muscle plays a fundamental role not only in forehead expression, but also in the support and elevation of the eyelids. This revised and corrected anatomy gives rise to the concept of the forehead cutaneomusculoaponeurotic unit, composed of skin, galea and frontalis muscle (forehead CMAU), resulting in a new forehead facelift which corrects forehead ageing, essentially related to recession of the forehead and relaxation of the galea.

Can short-latency vestibulospinal reflexes in lower leg muscles be elicited by tapping the head?

A gentle tap on the forehead evoked short-latency motor responses in the sternocleidomastoid muscle, which may be vestibulocollic reflexes with characteristics similar to those elicited by clicks. We tested this paradigm in subjects standing upright, in order to determine the differential effects of taps on the forehead on the patterns and latencies of spinal stretch and vestibulospinal reflexes, which are important for postural control. Taps on the forehead elicited short-latency inhibitory electromyographic responses in both gastrocnemius muscles with a mean latency of 48.3 +/- 3.1 ms (onset) to 98.3 +/- 6.3 ms (end). Taps on the sternum elicited similar responses from the gastrocnemius muscles, indicating that vestibular stimulation is not essential for eliciting these responses. Both responses may play a role in predetermining the strategy for correcting body perturbations. The actual reflex is probably elicited by somatosensory input from the neck, which converges with vestibular input for the multisensory control of posture.

Propagation of various tooth impacts in the human body

The purpose of this study was to investigate how far tooth impacts were propagated in the body and whether the propagation would be influenced by posture. The impacts were propagated to all recording sites on the head and neck of the 10 examinees tested. In the recordings on the limbs, even at the most distal site, the number of examinees detecting the vibration was seven out of nine examinees. These results showed that the impacts exerted on the tooth were propagated to distal sites of limbs through the bones and soft tissues and implied that the propagated vibration would influence the whole of the body. On the other hand, as the amplitude of propagated vibration was influenced by posture and recording site, the posture during jaw functioning appears to be important.

Effects of static forehead and forearm muscle tension on total respiratory resistance in healthy and asthmatic participants

The impact of static muscle tension on total respiratory resistance (TRR) was examined. Participants (24 healthy, 24 asthmatic) performed biofeedback-assisted sequences of tensing (15 s) and relaxing (20 s) forehead and forearm muscles. Muscle tension levels were 40% or 80% of the maximum individual force. Oscillatory TRR, electromyograms, ventilation, heart period, and respiratory sinus arrhythmia were recorded. Baseline TRR did not change over the session as a whole. Decreases in TRR during forehead tension in both groups were accompanied by increases in end-expiratory volume, which could have mediated TRR changes. During forearm tension, decreases in TRR with minimal ventilation changes were only observed in healthy participants, whereas asthmatic patients revealed marked increases in respiratory volume and flow. These results indicate that static muscle activity and TRR are negatively related. Ventilatory changes can exaggerate or diminish evidence for this relationship.

The effect of adrenergic blockade on blushing and facial flushing

The effect of adrenergic blockade on vascular responses in the forehead was assessed during stressful mental arithmetic, singing, and moderate exercise in 21 frequent blushers and 21 infrequent blushers. Adrenergic antagonists were introduced into a small site on the forehead by iontophoresis, and vascular responses were monitored bilaterally with laser Doppler flowmetry. Beta blockade prevented increases in blood flow in infrequent blushers during mental arithmetic and partially inhibited vasodilatation during singing, indicating minor participation of beta-adrenoceptors in blushing. Alpha blockade did not affect blushing but augmented vasodilatation during exercise. Despite higher ratings of self-consciousness in frequent than in infrequent blushers, vascular responses were similar in both groups. Thus, blushing propensity does not appear to be related to the density of alpha- or beta-adrenoceptors in facial vessels and may have a psychological basis.