Electrophysiological Correlates of Gender Differences: A Review

Age and Sex Differences in Infants' Neural Sensitivity to Emotional Prosodies in Spoken Words: A Multifeature Oddball Study

PURPOSE

This study aimed to investigate infants' neural responses to changes in emotional prosody in spoken words. The focus was on understanding developmental changes and potential sex differences, aspects that were not consistently observed in previous behavioral studies.

METHOD

A modified multifeature oddball paradigm was used with emotional deviants (angry, happy, and sad) presented against neutral prosody (standard) within varying spoken words during a single electroencephalography recording session. The reported data included 34 infants (18 males, 16 females; age range: 3-12 months, average age: 7 months 26 days).

RESULTS

Infants exhibited distinct patterns of mismatch responses (MMRs) to different emotional prosodies in both early (100-200 ms) and late (300-500 ms) time windows following the speech onset. While both happy and angry prosodies elicited more negative early MMRs than the sad prosody across all infants, older infants showed more negative early MMRs than their younger counterparts. The distinction between early MMRs to angry and sad prosodies was more pronounced in younger infants. In the late time window, angry prosody elicited a more negative late MMR than the sad prosody, with younger infants showing more distinct late MMRs to sad and angry prosodies compared to older infants. Additionally, a sex effect was observed as male infants displayed more negative early MMRs compared to females.

CONCLUSIONS

These findings demonstrate the feasibility of the modified multifeature oddball protocol in studying neural sensitivities to emotional speech in infancy. The observed age and sex effects on infants' auditory neural responses to vocal emotions underscore the need for further research to distinguish between acoustic and emotional processing and to understand their roles in early socioemotional and language development.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.27914553.

Interindividual differences in brain dynamics of early visual processes: Impact on score accuracy in the mental rotation task

Interindividual variations in the ability to perform visuospatial mental transformations have been investigated extensively, in particular through mental rotation tasks. However, the impact of early visual processes on performance has been largely ignored. To clarify this issue, we explored the time-course of early visual processing (from 0 to 450 ms poststimulus) using event-related potentials topographic analyses. The main findings demonstrated a significant link between early attentional processes and accuracy scores occurring more than five seconds later, as well as a strong association between spatial covariance and microstate topographies exhibiting substantial gender differences. More specifically, the results indicated that, in a classical mental rotation task, the male brain expends more time processing visual-spatial information resulting in a longer bilateral positive potential at posterior-occipital sites. In comparison, the female brain initiates earlier processing of non-spatial information resulting in a faster transition from a bilateral positive potential of posterior-occipital sites to a negative potential at central-frontal sites. These findings illustrate how a more complete utilization of the spatiotemporal information contained in EEG recordings can provide important insights about the impact of early visual processes on interindividual differences, particularly across gender, and thus shed new light on alternate cognitive strategies.

A hybrid model for EEG-based gender recognition

The gender recognition is an important research field to study evidence regarding some personal characteristics in the information and data society. However, some current traditional methods such as vision and sound have been exposed their own security weaknesses. Recently, biometric gender recognition based on Electroencephalography (EEG) signals has been widely used in information safety and medical fields. It is necessary to explore potential of using EEG to present a more robust and accurate result with larger training data based on sophisticated machine learning approaches. In this contribution, we present an automated gender recognition system by a hybrid model based on EEG data of resting state from twenty-eight subjects. These data are useful and handy to get insights into assessing the differences in personal gender. For achieving a good performance and a strong robustness, the system develops a hybrid model of combining random forest and logistic regression, and employs four common entropy measures to analyze the non-stationary EEG signals. Result also suggests that the recognition performance achieve an improved progress with an accuracy of 0.9982 and AUC of 0.9926 based on a nested tenfold cross-validation loop, implying that show a significant potential applicability of the proposed approach and is capable of recognizing personal gender.

Gender differences in event-related potentials during visual-spatial attention

The aim of present work is to test possible gender differences in the ERPs to the standards during the performance of a visual-spatial attention task. The sample: 20 subjects (10 women) aged 18-24. Electrodes: F3, F4, C3, C4, P3, P4, T5, T6, O1, O2. ANOVA tests were computed with the following factors: attention, gender, visual field, hemisphere, and electrodes. Results showed that men presented higher amplitudes in P1 and in P3b than did women, and women presented higher amplitudes in the temporal N1 than did men. For the P3, the amplitude in frontal-central regions for the attended condition was higher in men than in women, and men presented a gender-specific right frontal functional asymmetry that was not present in women. Since these components are related with the modulation of visual processing by the effect of spatial attention, the intra- and inter-gender differences obtained suggest possible differences in the processing of visual information in both genders. However, the fact that the brain generators could have a different orientation is also a possible explanation for the differences obtained in the ERPs in both genders.

Nicotine alters flash-evoked potentials in Long–Evans rats

This experiment examined the effects of nicotine on flash-evoked potentials (FEPs) recorded from both the visual cortex (VC) and the superior colliculus (SC) of chronically implanted male Long-Evans rats. FEPs were recorded at 5, 20, 40, and 60 min following subcutaneous injections of saline, and of 0.4, 0.7, and 1.0 mg/kg nicotine on separate days. In the VC, the amplitude of components N(39), N(53), N(67), and P(88) increased, while the amplitude of components N(30) and P(235) decreased following nicotine administration. P(22), P(47), and N(153) were unchanged. In the SC, components P(27), N(48), and N(53) were reduced in amplitude, while P(37) and N(57) were unaffected by nicotine. Many peak latencies in the VC and SC were increased by nicotine, often at all three doses. However, effects of nicotine on FEPs were both dose- and time-dependent. When body temperature was recorded 65 min after drug administration, significant hypothermia was found with both the 0.7- and 1.0-mg/kg nicotine doses. The 1.0-mg/kg dose of nicotine resulted in a significant increase in movement during the recording sessions, but not in subsequent open-field observations. The results demonstrate that nicotinic acetylcholine receptors (nAChRs) play a differential role in the production/modulation of the various components of FEPs.

Carbamazepine and cocaine-cue reactivity

Subjective and electroencephalographic reactions to cocaine cues were evaluated in 33 cocaine-dependent out-patients and 17 non-cocaine-dependent controls. Subjective, EEG, and autonomic reactions to three 5-min videos (cocaine-associated, erotic, neutral) were evaluated twice with an interpolated 1-week interval. Between evaluations, cocaine-dependent patients received carbamazepine 400 mg daily or matching placebo in double-blind fashion. In all three groups the cocaine-associated and erotic videos produced a comparable increase in the self-rated desire for cocaine and reduction in total EG power. Carbamazepine treatment increased EEG fast alpha power and self-rated fatigue, and decreased self-rated concentration and vigor. However, it had no specific effect on subjective or physiological reactivity to either the cocaine-associated or erotic videos. This negative finding is consistent with recent clinical trials of carbamazepine for cocaine dependence.

EEG spectral findings in healthy, elderly men and women--sex differences

Computerized spectral analysis of the EEG was performed in 119 healthy, elderly men and women, ranging in age from 60 to 87 years with an x age of 70.4 years, to evaluate gender-related variance. The groups did not differ in age, education levels or Folstein score. We compared the parasagittal derivations in men (n = 53) to women (n = 66), controlling for the effect of age by decade. Compared to men, women had a significant (usually P < 0.01) increase in the parasagittal mean frequency (1-30 Hz and 4-20 Hz), beta 1 and beta 2, while alpha 2 and theta-beta were decreased. Mean frequency did not differ significantly by decade, nor were there significant sex-age interactions. Our results extend previous EEG spectral findings to older, healthy, elderly subjects. Although the basis for the gender-related differences is uncertain, we suggest that quantitative EEGs establish gender-based norms in elderly adults.

Pattern reversal evoked potentials: gender differences and age-related changes in amplitude and latency

This report is intended to complement the current body of literature by describing pattern reversal evoked potential (PREP) component amplitudes and latencies in a larger sample than has been previously studied and providing comparisons of males and females across the lifespan. Binocular PREPs were measured from 406 normal subjects, 6-80 years of age. In general, latencies were found to decrease during maturation, stabilize across early adulthood, then begin to increase sometime after the late 20s. There were minimal gender differences in latencies during development but males tended to have longer latencies than females during adulthood. Across the lifespan, amplitudes were larger for females. Results of regression analyses using the entire data set were compared to results of separate regression analyses for developmental years (6-20) and adulthood (21-80). Separate analyses appear to provide more useful descriptions of PREP latency and amplitude changes across the lifespan. It is clear that predicted normal values can vary depending on age range and relative proportion of males and females comprising a reference sample. Appropriate clinical values should be based on age- and sex-matched normal subjects and should be specific with regard to technical and methodological variables.

Variation in evoked potential measures over the menstrual cycle: a pilot study

The P3 component of a visual event related potential (ERP) was studied for five consecutive weeks in six women with normal menstrual cycles. Serum concentrations of luteinizing hormone (LH), estradiol (E2) and progesterone were studied during the same period. Increases in P3 amplitude, although nonsignificant, were noted in the week preceding onset of menses. No significant changes in reaction times to target/nontarget stimuli were noted over the same time period.

Maturation of prestimulation-induced startle modulation in girls

This study of the maturation of prestimulation-induced modulation of startle in 4- to 8-year-old girls and young women demonstrated significant effects of age on both startle amplitude and onset latency modulation. Prestimulation with nonstartling tones resulted in strong inhibition of both amplitude and latency of the startle blink reflex in adults when 25-ms tones preceded the startling stimuli by 120 ms or 250 ms. Following sustained prestimulation for 2000 ms, the adults showed weak nonsignificant response facilitation. Eight-year-old girls showed mature inhibitory startle amplitude modulation, but significantly less inhibition of onset latency compared to adults. Preschool girls showed significantly less amplitude and latency inhibition and more facilitation than 8-year-olds and adult women. These findings in female subjects were very similar to those obtained by Ornitz, Guthrie, Kaplan, Lane, and Norman (1986) in male subjects. Gender differences were limited to the 8-year-old age group. The 8-year-old girls showed significantly less startle amplitude inhibition than 8-year-old boys following the 120-ms and 250-ms prestimulation intervals and less latency facilitation following 2000 ms of sustained prestimulation. In general, these findings suggest that brainstem mechanisms that mediate startle response modulation undergo development during early childhood and do not mature until about 8 years of age in both male and female subjects. The results are discussed in relation to studies of gender effects on development of other neurophysiological variables and to maturation of the nervous system.

Topographic mapping of EEG and evoked potentials in psychiatry: delusions, illusions, and realities

This paper reviews the utility of topographic mapping of EEG and evoked potentials in psychiatry. Further, a wide variety of caveats related to this technique are reviewed including cerebral and extracerebral sources of artifact. Moreover, both questionable and legitimate uses of mapping in psychiatry are addressed and possible future applications of this technique are considered. Finally, multidisciplinary approaches to the study of the brain are discussed.

Interhemispheric asymmetry of homotopic transcallosal responses of the auditory cortex in the cat

In acute experiments on 29 d-tubocurarine immobilized cats, with topographical pick-up of potentials from 150-170 symmetrical points of the auditory cortex, the interhemispheric asymmetry of homotopic transcallosal responses were studied. It was established that in the majority of the animals the potentials in the right hemisphere had a greater amplitude and shorter latent periods as compared with the responses of the left hemisphere. A dependence of the properties of the interhemispheric asymmetry on the sex of the animal was noted. In females the asymmetry was characterized by a right hemispheric tendency and by a greater magnitude as compared with males. The maximal magnitude of the asymmetry was detected in the group of pregnant females. The hypothesis is proposed to the effect that the established polarity of transcallosal influenced in the auditory cortex is associated with the dominance of the right hemisphere in the organization of spatial audition.

Amplitudes of visually evoked potentials to patterned stimuli: age and sex comparisons

Electrophysiological age and sex differences in visual pattern responsivity were investigated. Pattern reversal evoked potentials (PREPs) and visual evoked potentials (VEPs) to patterned and unpatterned flashes were recorded from 20 normal subjects in each of 4 groups: young females and males aged 25-35 years and older females and males aged 55-70 years. PREP waves N70-P100 and P100-N150 from the older women were significantly larger than those from subjects in the other groups; mean amplitudes for the young females, young males and older males were not different. A similar effect, unusually large potentials for the older women, was obtained for VEPs, but only for VEPs elicited by patterned flashes and recorded from occipital scalp, i.e., an area overlying visual cortex which is sensitive to lines and edges. Our findings suggest that the visual system of older females is unusually responsive to patterned stimuli.

Power spectral analysis and cortical coupling of EEG for young and old normal adults

Power spectral analysis and cortical coupling were computed on eyes closed EEG recorded from 80 normal volunteers: 20 females and 20 males aged 25-35 years and 20 females and 20 males aged 55-70 years. Recordings were from Fz, Cz, C3, Pz and Oz areas. The results indicate that with increased age there was a greater uniformity of EEG activity across the brain. Magnitude of EEG power was significantly less variable across recording sites for the old than for the young. In addition, cortical coupling values were reliably higher for the older subjects indicating a greater congruity among EEG patterns. The EEG power and cortical coupling measures were significantly correlated and thus may indicate an underlying mechanism common to both. The results support a theory of decreased central inhibitory function in old age and may reflect an age-related breakdown of functional autonomy of cortical areas. Gender had no significant effect on either EEG power or cortical coupling.

The effect of age, sex and interstimulus interval on augmenting and reducing of occipital VEPs

Three intensities of patterned and unpatterned flashes were used to elicit occipital visually evoked potentials (VEPs) from 4 groups of 15 subjects: boys and girls aged 7-9 years and boys and 15 girls aged 13-15 years. Interstimulus intervals (ISIs) of 1, 2 and 4 sec were used. Amplitude/intensity (A/I) slope was computed for each ISI and flash type condition and an estimate was made of the ability to differentiate patterned from unpatterned stimuli. The latter was inferred from coefficients of correlation which reflected the degree of similarity between VEP wave forms elicited by the two types of flashes. Responses of younger children attenuated to increasing stimulus intensity (negative A/I slope), while VEP amplitude of older subjects augmented to brighter flashes. VEP amplitude reduction may be the response of an immature brain to overstimulation. Amplitude reducing by 7-9-year-old children does not appear to be related to insufficient time between flashes for visual system recovery, since ISI did not differentially affect A/I slope of the younger and older subjects. Longer ISIs did, however, tend to produce more positive A/I slopes for all subjects, but only for patterned stimuli, suggesting that pattern detectors do not fully recover with ISIs of 1 and 2 sec. The visual system of young children was relatively less efficient than that of older children at differentiating patterned from unpatterned stimuli, indicating a differential sensitivity of pattern detectors as a function of age. Gender was not a factor in either magnitude of A/I slope or similarity of VEP wave forms.