Study of the vibrational spectrum of cuprorivaite

In this research, after tracing a history of the pigment, the preparation and analysis of samples of Egyptian blue have been reported. The main reactions taking place during its preparation are indicated. X-ray diffractions show that, starting from mixtures of precursors with stoichiometric composition, the product is practically only cuprorivaite. The kind of flux and cristallinity of silica does not seem determining factors for the pigment formation. Infrared and Raman spectra and an assignment of the bands are reported. Impurities ascertained are discussed on the basis on the data available.

Explicit and incidental facial expression processing: an fMRI study

Considerable evidence indicates that processing facial expression involves both subcortical (amygdala and basal ganglia) and cortical (occipito-temporal, orbitofrontal, and prefrontal cortex) structures. However, the specificity of these regions for single types of emotions and for the cognitive demands of expression processing, is still unclear. This functional magnetic resonance imaging (fMRI) study investigated the neural correlates of incidental and explicit processing of the emotional content of faces expressing either disgust or happiness. Subjects were examined while they were viewing neutral, disgusted, or happy faces. The incidental task required subjects to decide about face gender, the explicit task to decide about face expression. In the control task subjects were requested to detect a white square in a greyscale mosaic stimulus. Results showed that the left inferior frontal cortex and the bilateral occipito-temporal junction responded equally to all face conditions. Several cortical and subcortical regions were modulated by task type, and by facial expression. Right neostriatum and left amygdala were activated when subjects made explicit judgements of disgust, bilateral orbitofrontal cortex when they made judgement of happiness, and right frontal and insular cortex when they made judgements about any emotion.

Ipsilateral involvement of primary motor cortex during motor imagery

To investigate whether motor imagery involves ipsilateral cortical regions, we studied haemodynamic changes in portions of the motor cortex of 14 right-handed volunteers during actual motor performance (MP) and kinesthetic motor imagery (MI) of simple sequences of unilateral left or right finger movements, using functional magnetic resonance imaging (fMRI). Increases in mean normalized fMRI signal intensities over values obtained during the control (visual imagery) task were found during both MP and MI in the posterior part of the precentral gyrus and supplementary motor area, both on the contralateral and ipsilateral hemispheres. In the left lateral premotor cortex, fMRI signals were increased during imagery of either left or right finger movements. Ipsilateral cortical clusters displaying fMRI signal changes during both MP and MI were identified by correlation analyses in 10 out of 14 subjects; their extent was larger in the left hemisphere. A larger cortical population involved during both contralateral MP and MI was found in all subjects. The overall spatial extent of both the contralateral and the ipsilateral MP + MI clusters was approximately 90% of the whole cortical volume activated during MP. These results suggest that overlapping neural networks in motor and premotor cortex of the contralateral and ipsilateral hemispheres are involved during imagery and execution of simple motor tasks.

Bilateral representation of sequential finger movements in human cortical areas

The spatial distribution of cortical neural clusters activated during movement of either hand ('bilateral' population), or only of one hand, was investigated in healthy right-handed volunteers performing a sequential finger opposition task, using echo-planar functional magnetic resonance imaging. 'Bilateral' clusters were found in the mesial premotor, perirolandic and adjacent lateral premotor cortex of the two hemispheres, and in the left superior parietal lobule. In the precentral gyrus, their spatial extent was larger on the left hemisphere. Clusters activated exclusively during contralateral finger movements were equally distributed in the left and right perirolandic cortex. No cluster activated exclusively during ipsilateral finger movements was detected. These findings support a role of the motor/lateral premotor cortex of the dominant hemisphere in bilateral motor control.

CNS pattern of metabolic activity during tonic pain: evidence for modulation by beta-endorphin

CNS correlates of acute prolonged pain, and the effects of partial blockade of the central beta-endorphin system, were investigated by the quantitative 2-deoxyglucose technique in unanaesthetized, freely moving rats. Experiments were performed during the second, tonic phase of the behavioural response to a prolonged chemical noxious stimulus (s.c. injection of dilute formalin into a forepaw), or after minor tissue injury (s.c. saline injection). During formalin-induced pain, local glucose utilization rates in the CNS were bilaterally increased in the grey matter of the cervical spinal cord, in spinal white matter tracts and in several supraspinal structures, including portions of the medullary reticular formation, locus coeruleus, lateral parabrachial region, anterior pretectal nucleus, the medial, lateral and posterior thalamic regions, basal ganglia, and the parietal, cingulate, frontal, insular and orbital cortical areas. Pretreatment with anti-beta-endorphin antibodies, injected i.c.v., led to increased metabolism in the tegmental nuclei, locus coeruleus, hypothalamic and thalamic structures, putamen, nucleus accumbens, diagonal band nuclei and dentate gyrus, and in portions of the parietal, cingulate, insular, frontal and orbital cortex. In formalin-injected rats, pretreated with anti-beta-endorphin, behavioural changes indicative of hyperalgesia (increased licking response) were found, which were paralleled by a significant enhancement of functional activity in the anterior pretectal nucleus and in thalamo-cortical systems. A positive correlation was found between the duration of the licking response and metabolic activity of several forebrain regions. These results provide a map of the CNS pattern of metabolic activity during tonic somatic pain, and demonstrate a modulatory role for beta-endorphin in central networks that process somatosensory inputs.

High impedance low energy pacing leads: long-term results with a very small surface area steroid-eluting lead compared to three conventional electrodes

We evaluated the handling performance at implant, and the long-term atrial and ventricular electrical performance of a new generation using a very small surface area (1.2 mm2) steroid-eluting electrode (Medtronic CapSure Z). We compared the performance of CapSure Z to that of traditional passive fixation leads, with and without steroid elution. The study was conducted during 2 years of follow-up. We studied 188 patients (105 males and 83 females; mean age 71 +/- 7 years). All of the patients were implanted with a dual chamber pacemaker and the same type of lead in both chambers. Forty-one patients received CapSure Z leads, 25 patients received Target Tip leads (8-mm2 surface area; no steroid elution), 63 patients received CapSure leads (8-mm2 surface area; steroid elution), and 59 patients received CapSure SP leads (5.8-mm2 surface area; steroid elution). The four groups were homogeneous in regards to sex, age, cardiac disease, and reason for implant. At follow-up, the CapSure Z lead showed sensing values comparable to the other leads, with lower pacing thresholds and higher pacing impedance in both chambers. We evaluated the mean current drained from the pacemaker by the different types of leads when using safe, low energy output settings. We found that by using CapSure Z leads, the mean current was significantly lower than that of the other types of leads (0.42 microA for CapSure Z ventricular lead vs 0.85 for CapSure SP, 1.42 for CapSure, and 1.54 for Target Tip). Thus, the use of the CapSure Z lead, combined with low energy output programming, will increase pacemaker longevity compared to the use of traditional leads and standard output programming.

Neural circuits underlying ketamine-induced oculomotor behavior in the rat: 2-deoxyglucose studies

Time-related changes in oculomotor function and of metabolic activity patterns in selected brain networks, as assessed by the quantitative 2-deoxyglucose technique, were investigated in Long-Evans rats following intraperitoneal administration of a ketamine anesthetic dose. During ketamine-induced anesthesia a nystagmic-like behavior was present, characterized by uni-directional slow ocular drifts with superimposed paroxystic bursts of quick (saccadic-like) eye movements; all quick movements were executed in the horizontal direction, were strictly confined to an ocular hemifield of vision, and were followed by a backward (centripetal) drift. A metabolic hyperactivity was found in the dorso-medial shoulder region of the frontal cortex, corresponding to the rat saccadic cortical generator area, whereas functional activity levels were decreased in cerebellum and in several brainstem regions, including portions of the reticular formation and medial vestibular nuclei, putatively indicated as the locus of the oculomotor neural integrator. Starting 2 h after drug injection, a gradual recovery of oculomotor function occurred, with the disappearance of slow ocular drifts. However, an almost uninterrupted sequence of individual saccades was still present. Significant metabolic increases were found at this time in the cingulate and frontal cortex, basal ganglia, superior colliculus, paramedian reticular formation and oculomotor nuclei, the cerebellar vermis and paraflocculus. In medial vestibular nuclei, metabolic levels were undistinguishable from controls. These results suggest different concentration-dependent actions of ketamine on cortical and subcortical circuits involved in saccade generation and gaze holding. These effects are likely to be related at least in part to antagonism of N-methyl-D-aspartate receptor-mediated functions.

Temporal and intensity coding of pain in human cortex

Temporal and intensity coding of pain in human cortex. J. Neurophysiol. 80:3312-3320, 1998. We used a high-resolution functional magnetic resonance imaging (fMRI) technique in healthy right-handed volunteers to demonstrate cortical areas displaying changes of activity significantly related to the time profile of the perceived intensity of experimental somatic pain over the course of several minutes. Twenty-four subjects (ascorbic acid group) received a subcutaneous injection of a dilute ascorbic acid solution into the dorsum of one foot, inducing prolonged burning pain (peak pain intensity on a 0-100 scale: 48 +/- 3, mean +/- SE; duration: 11.9 +/- 0.8 min). fMRI data sets were continuously acquired for approximately 20 min, beginning 5 min before and lasting 15 min after the onset of stimulation, from two sagittal planes on the medial hemispheric wall contralateral to the stimulated site, including the cingulate cortex and the putative foot representation area of the primary somatosensory cortex (SI). Neural clusters whose fMRI signal time courses were positively or negatively correlated (P < 0.0005) with the individual pain intensity curve were identified by cross-correlation statistics in all 24 volunteers. The spatial extent of the identified clusters was linearly related (P < 0.0001) to peak pain intensity. Regional analyses showed that positively correlated clusters were present in the majority of subjects in SI, cingulate, motor, and premotor cortex. Negative correlations were found predominantly in medial parietal, perigenual cingulate, and medial prefrontal regions. To test whether these neural changes were due to aspecific arousal or emotional reactions, related either to anticipation or presence of pain, fMRI experiments were performed with the same protocol in two additional groups of volunteers, subjected either to subcutaneous saline injection (saline: n = 16), inducing mild short-lasting pain (peak pain intensity 23 +/- 4; duration 2.8 +/- 0.6 min) or to nonnoxious mechanical stimulation of the skin (controls: n = 16) at the same body site. Subjects did not know in advance which stimulus would occur. The spatial extent of neural clusters whose signal time courses were positively or negatively correlated with the mean pain intensity curve of subjects injected with ascorbic acid was significantly larger (P < 0.001) in the ascorbic acid group than both saline and controls, suggesting that the observed responses were specifically related to pain intensity and duration. These findings reveal distributed cortical systems, including parietal areas as well as cingulate and frontal regions, involved in dynamic encoding of pain intensity over time, a process of great biological and clinical relevance.

Primary motor and sensory cortex activation during motor performance and motor imagery: a functional magnetic resonance imaging study

The intensity and spatial distribution of functional activation in the left precentral and postcentral gyri during actual motor performance (MP) and mental representation [motor imagery (MI)] of self-paced finger-to-thumb opposition movements of the dominant hand were investigated in fourteen right-handed volunteers by functional magnetic resonance imaging (fMRI) techniques. Significant increases in mean normalized fMRI signal intensities over values obtained during the control (visual imagery) tasks were found in a region including the anterior bank and crown of the central sulcus, the presumed site of the primary motor cortex, during both MP (mean percentage increase, 2.1%) and MI (0.8%). In the anterior portion of the precentral gyrus and the postcentral gyrus, mean functional activity levels were also increased during both conditions (MP, 1.7 and 1.2%; MI, 0.6 and 0.4%, respectively). To locate activated foci during MI, MP, or both conditions, the time course of the signal intensities of pixels lying in the precentral or postcentral gyrus was plotted against single-step or double-step waveforms, where the steps of the waveform corresponded to different tasks. Pixels significantly (r > 0.7) activated during both MP and MI were identified in each region in the majority of subjects; percentage increases in signal intensity during MI were on average 30% as great as increases during MP. The pixels activated during both MP and MI appear to represent a large fraction of the whole population activated during MP. These results support the hypothesis that MI and MP involve overlapping neural networks in perirolandic cortical areas.

[Functional mapping of the motor and primary sensorial cortex using magnetic resonance techniques. II. Image analysis techniques]

Functional Magnetic Resonance Imaging (fMRI) techniques to investigate brain function are now available on clinical MR systems. However, the software packages provided with the MR equipment to analyze the functional images are often inadequate. In the present study, two registration algorithms for correcting motion artifacts and three procedures of statistical analysis (t-test, correlation analysis, Kolmogorov-Smirnov test) were compared using programs implemented on a graphic workstation. For both registration algorithms, transformation parameters for in plane translations and rotation of images were significantly affected by the task, being higher during sequential finger movements than during the control (visual imagery) condition. Regions of interest were identified on the anatomical images and their boundaries automatically projected on functional images. The number of significantly activated pixels in the pre- and postcentral areas was not significantly different after the registration with the two procedures. The percentage of pixels of the pre- and postcentral areas whose signal intensity was significantly different between the two tasks decreased with respect to the adopted threshold of significance as a power function. For an area identified outside the brain, the same relation was linear: no activated pixel was found for p < 0.001. The application of the t-test or of the correlation analysis yielded similar results. The analysis of the profile of mean normalized signal intensity showed higher increases in signal intensities during the motor task in the precentral gyrus than in the postcentral gyrus. This appears to be due to a greater number of activated pixels during motor performance. The application of registration procedures, the identification of the regions of interest on the basis of the anatomical images and appropriate statistical analyses allow a more detailed characterization of task-related activation.

Evaluation of differential optical flow techniques on synthesized echo images

The performance of three methods for evaluation of motion on synthesized 2-D echo image sequences with features similar to real ones are examined. The selected techniques based on the computation of optical flow are of the differential type and assume that the image brightness pattern is constant over time. They differ in the choice of the smoothing term and in the local or global treatment of the domain. The images were synthesized by simulating the process of echo formation, considering the interaction between ultrasonic fields and human tissues. Moreover, two different approaches were followed to generate the sequences: 1) a known motion field was applied to the intensity distribution of the synthesized images; 2) a known motion field was applied directly to the point scatterer distribution of the tissue. Favorable results were obtained by applying Lucas-Kanade and Horn-Schunck techniques to the sequences of the first type, while all the techniques produced large errors when applied to the other type of sequences. A discussion about the suitability of the above-mentioned techniques for evaluation of motion on real echocardiographic images is also presented together with some results.

Evaluation of the effectiveness of isradipine SRO in the treatment of hypertensive patients with left ventricular hypertrophy

Myocardial hypertrophy is a response to many diseases, above all hypertension, that involves morphological and functional damage and may be the basis for the development of myocardial dysfunction. We attempted to verify the effectiveness of a new calcium antagonist, isradipine 5 mg SRO, on the reversal of left ventricular hypertrophy. For this purpose 13 hypertensive patients (pts) were treated for 12 weeks, which is the minimum period described in the literature for the regression of hypertrophy. At the end of the study, blood pressure in all patients returned to normal levels (mean blood pressure from 120.15 +/- 4.4 to 108 +/- 6.4 mmHg, p < 0.001); end-systolic stress (from 128 +/- 30 to 65 +/- 14 g/cm2, p < 0.001), and left ventricular mass index (from 142 +/- 31 to 97 +/- 23 g/m2, p < 0.001) showed significant reduction. Moreover, Doppler-derived indexes of left ventricular filling improved, particularly early to late peak velocity of the mitral valve (E/A ratio) and deceleration time (from 235 +/- 37 to 198 +/- 17 msec, p < 0.001), which were normalized after 12 weeks. In conclusion isradipine shows rapid effects in the reversal of morphofunctional damage in hypertension. For this reason it also appears to be useful for the treatment of myocardial hypertrophy in the absence of chronic hypertension.

Medical treatment of senile cataract: clinical investigation of bendazac-lysine using objective and subjective methods

A modified Zeiss slit lamp coupled with a digital image-processing system was used to evaluate objectively changes in lens transparency over 1 year at 4-month intervals in 150 eyes of 92 patients affected by early senile cataract. A total of 59 patients were treated daily with 1.5 g bendazac-lysine, and 33 patients constituted the control group. At follow-up, visual acuity was also tested using Snellen letter charts at variable contrast to provide an additional parameter closer to traditional methods. Results indicate that the minimal angle of resolution at 10% contrast (MAR10) and the mean gray-level value of the lens image obtained by retroillumination (MLR) are sensitive to early changes in lens transparency. Using MAR10 as a parameter, the control group showed a significant, progressive worsening of the lens status over 12 months, whereas the treated group exhibited no significant changes. MRL indicated the same behaviour as MAR10, although lens damage was detected later in the control group. The results show that bendazac-lysine may delay the formation of lens opacities.

Measurement of metamorphopsia in the presence of ocular media opacities

Opacities in the cornea, crystalline lens, and vitreous may make conventional measurements of retinal/visual function of little value. Here, we present two psychophysical hyperacuity tests that are designed to detect and quantify retinal distortions even in the presence of substantial opacities. One test makes use of a two-dot vernier display in which directional bias as well as vernier acuity can be estimated. The second test is a multi-dot hyperacuity bisection task, which resembles a simplified Amsler grid test. By varying the spatial parameters of these stimuli, metamorphopsia may be quantified. The method is applicable both in clear and occluded ocular media.

Incremental binocular amplitude of the pattern visual evoked potential during the first five months of life: electrophysiological evidence of the development of binocularity

The amplitude of the pattern visual evoked potential (VEP) of a binocular stimulus has been shown to be generally larger than the VEP obtained monocularly. There is evidence that this effect can be considered an electrophysiological index of fusion. To study how binocular vision develops in infancy we evaluated the incremental binocular amplitude (IBA) in three infants in a longitudinal investigation during the first five months of life. The stimuli were phase-alternating square-wave gratings with spatial and temporal parameters chosen to be appropriate for neonates. IBA was defined as the percentage increment of the largest binocular response compared with the monocular response. In the first two months of life IBA values were near zero, that is, no summation occurred. Between the second and third month IBA values rose markedly and after the third month its value was greater than 100%, demonstrating binocular facilitation. Thus in the first two months of life the eyes do not seem to cooperate as in adults. By the second and third month the binocular pattern VEP reflects an increasing binocular interaction. Other studies of the development of stereopsis have also found evidence of binocularity at similar ages.

Experimental errors in digital image processing for the determination of geometrical parameters of the human eye

A new method is presented for measuring geometrical parameters of the anterior segment of human eye. A digital imaging technique is employed in conjunction with a slit lamp and TV camera. A method was developed to analyze images and the problem of minimizing measuring errors was studied. The method was tested using a contact lens to simulate the anterior corneal surface.

Modifications of the slit lamp for digital image processing of the anterior segment of the eye

The Zeiss slit lamp has been modified in order to extend its use to measurements of lens transparency. Two major modifications have been introduced: (1) a support for a high-sensitivity TV camera that is connected to an image processing system; (2) two potentiometers for recording electrical signals proportional to the rotation angle of the slit-supporting arm with respect to the visual axis and the slit tilting angle. As a result, the slit lamp output consists of three signals; one TV signal for the images and two analog signals for measurement of the angles. With the aid of an image-processing system connected to a minicomputer, software has been developed to enable the operator to acquire reliable digital images of the anterior segment of the eye in real time. The software provides the user with an easy-to-follow menu.