Women in the midluteal phase of the menstrual cycle have difficulty suppressing the processing of negative emotional stimuli: An event-related potential study

Emotion regulation deficits have been implicated in anxiety and depressive disorders, and these internalising disorders are more prevalent in women than men. Few electrophysiological studies have investigated sex differences in emotional reactivity and emotion regulation controlling for menstrual phase. Event-related potentials (ERPs) were recorded from 28 early follicular women, 29 midluteal women, and 27 men who completed an emotion regulation task. A novel finding of increased N2 amplitude during suppression was found for midluteal women compared with men. These findings suggest midluteal women may be significantly less able to suppress cortical processing of negative stimuli compared to men. This ERP finding was complemented by behavioral ratings data which revealed that while both early follicular and midluteal women reported more distress than men, midluteal women also reported greater effort when suppressing their responses than men. P1 and N1 components were increased in midluteal women compared to men regardless of instructional set, suggesting greater early attentional processing. No sex or menstrual phase differences were apparent in P3 or LPP. This study underscores the importance of considering menstrual phase when examining sex differences in the cortical processing of emotion regulation and demonstrates that midluteal women may have deficits in down-regulating their neural and behavioural responses.     

Sex differences and handedness in hemispheric lateralization of tactile-spatial functions

Sex differences in spatial processing and handedness were studied with a tactile-spatial task in 27 male and 29 female right-handed undergraduate students in psychology. Subjects were asked to identify amorphous shapes to investigate possible male right-hemisphere specialization for spatial functions and bilateral representation among the women. The Annett handedness questionnaire estimated extent of right-handedness. Subjects were classified by major, and women by phase of menstrual cycle. Analysis shows significantly more right-handedness in women and ambidexterity in men. Over-all, men do not perform significantly better than women, although men outperform women with their left hands when handedness is covaried. Within sex, no difference is seen between left and right hand scores for men, but women perform significantly better with right than left hands. Further analyses suggest men appear right-hemisphere dominant for this task whereas women show left-hemisphere dominance. Analyses of hormonal data support recent research, in that for women on the pill there is a trend to perform worse than all other groups. Engineering students perform significantly better than all other majors.     

Spatial stimulus-response compatibility and coding of tactile motor events: influence of distance between stimulated and responding body parts, spatial complexity of the task and sex of subject

We studied spatial stimulus response compatibility in the somatosensory modality by instructing 16 men and 16 women to press a key using the left or the right thumb in response to a nonnoxious electric stimulation delivered either to the left or to the right little finger or, in different blocks, to the left or to the right malleolar region. The task was performed in compatible (stimulus and key-response on the same side of the corporeal midline) and in incompatible conditions (stimulus and key-response on opposite sides of the corporeal midline). In Exp. 1 subjects were tested while keeping their limbs in anatomic position; in Exp. 2 subjects performed the task while keeping the left upper and lower limbs on the right side and the right limbs on the left side of the bodily midline (crossed position). The compatibility effect was observed in both experiments and was higher for stimuli delivered to the little finger than to the malleolar region. This suggests that the cost of inhibiting compatible responses is maximal when stimulated and responding body parts are contiguous. Moreover, in the spatially most demanding task (Exp. 2) men outperformed women for both speed and accuracy suggesting a sex related specialisation in the spatial processing of somatosensory information.     

ERP correlates of language-specific processing of auditory pitch feedback during self-vocalization

The present study investigated whether the neural correlates for auditory feedback control of vocal pitch can be shaped by tone language experience. Event-related potentials (P2/N1) were recorded from adult native speakers of Mandarin and Cantonese who heard their voice auditory feedback shifted in pitch by −50, −100, −200, or −500 cents when they sustained the vowel sound /u/. Cantonese speakers produced larger P2 amplitudes to −200 or −500 cents stimuli than Mandarin speakers, but this language effect failed to reach significance in the case of −50 or −100 cents. Moreover, Mandarin speakers produced shorter N1 latencies over the left hemisphere than the right hemisphere, whereas Cantonese speakers did not. These findings demonstrate that neural processing of auditory pitch feedback in vocal motor control is subject to language-dependent neural plasticity, suggesting that cortical mechanisms of auditory-vocal integration can be shaped by tone language experience.     

Speed of phonological and orthographic processing as factors in dyslexia: electrophysiological evidence

The author investigated the hypothesis that speed of processing in the phonological and orthographic systems is one of the underlying variables of word-reading effectiveness. Speed of processing was assessed using measures of behavioral reaction time and electrophysiological latencies during phonological and orthographic task performance. Participants were 20 dyslexic and 20 normal-reading, male college students. An electrophysiological component complex (N1-P2-N2), as well as 2 other components (P3 and N4), was identified in both groups on each of the experimental tasks. Significant group differences were obtained only on the phonological tasks. Speed of processing during phonological judgment tasks was significantly prolonged among the dyslexic readers compared with the controls as reflected by P2, P3, and N4 latencies and reaction time. Between-task comparisons revealed significantly prolonged P2, P3, and N4 latencies on phonological compared with orthographic tasks in both dyslexic and normal readers, indicating that phonological classification of words may demand more time than orthographic classification. However, the gap score between speed of processing on the phonological and orthographic tasks was larger among the dyslexic readers and was observed mainly in P3 latency and reaction time. The highest correlation between word-reading accuracy score and the experimental measures was obtained in the dyslexic group with P3 latency gap score and in the control group with P2 latency gap score. The author proposes that slow phonological processing may cause "asynchrony" between the processing speeds within and between phonological and orthographic systems and may lead to a lack of efficient integration among the various subprocesses activated in reading, may slow down reading rate, and may impair word-reading effectiveness.     

Covariation of sex differences in mental rotation with body size

Sex difference in mental rotation ability was reconsidered. The Vandenberg-Kuse figures were administered to 120 male and 76 female students from the Medical School of BlackSea Technical University in Trabzon, Turkey to assess the mental rotation ability. Students' height and weight were measured. As expected, men outperformed women on this test and had greater height and weight. Number correct on mental rotation test significantly correlated with height and weight for the total sample and for men, but only with weight for women. Using weight as covariate, the sex difference was no longer significant. The mean mental rotation score was significantly higher for heavy women than for light men. There was a positive correlation between weight and mental rotation test scores for heavy women, but height and weight were negatively correlated with mental rotation test scores for light men. These results suggest that there is no sex difference in mental rotation ability as measured.     

Self-rated right–left confusability and performance on the Money Road-Map Test

This study assessed the relationship between self-rated right–left confusability and performance on the Money Road-Map Test (MRMT). Eighty-six undergraduate university students (44 women and 42 men) rated right–left subjective confusability using a questionnaire, and then completed the MRMT. Low- and high-confusability groups were determined using self-rated confusability scores. The high-confusability participants were less accurate and slower than the low-confusability participants in completing the MRMT. Self-confusability ratings significantly correlated with both accuracy scores and completion times on the MRMT. Although, women showed a significantly greater inclination than men to judge themselves as being more prone to confusion in right–left discrimination, the male advantage was not observed in terms of accuracy of response: there was a significant difference only in the completion time on the MRMT.     

Association of height and weight with second to fourth digit ratio (2D:4D) and sex differences

Sex difference in 2D:46 digit ratio was studied in 386 right-handed students. The lengths of index (2D) and ring (4D) fingers were measured using a caliper. Height and weight of participants were recorded. Body height correlated negatively with right- and left-hand digit ratios in the total sample (N = 386); correlations were significant for the left-hand digit ratio of men and for the right-hand digit ratio of women (no significant correlations with weight). Males had a significantly lower 2D:4D ratio than females. After controlling for height, sex differences in right- and left-hand digit ratios completely disappeared. The results suggest that height of adults reflecting prenatal hormone status may play a role in differences between men and women in 2D:4D digit ratio for right-handers.     

Are 2D:4D finger-length ratios related to sexual orientation? Yes for men,no for women

The ratio of index and ring finger lengths (2D:4D) is thought to be a marker of prenatal androgen exposure. In a sample of over 2,000 participants, men had significantly lower 2D:4D ratios than women (d = .36 and .23 for right and left hands, respectively), and these results were consistent across ethnic groups. Heterosexual men had significantly lower (more male typical) 2D:4D ratios than gay men (d = .32 and .31 for right and left hands, respectively), and these results tended to be consistent across ethnic groups. Heterosexual and lesbian women showed no significant differences in 2D:4D ratios, after ethnicity was taken into account. The current findings add to evidence that prenatal hormonal factors may be linked to men's sexual orientation.     

Ratio of fourth to second fingertip extensions in relation to serum estradiol and testosterone levels in men and women

Sex differences in second (2D) and fourth (4D) fingertip extensions relative to the middle fingertip and 4D:2D fingertip extension ratios were studied in men and women. Body height positively correlated with index fingertip extensions, not with ring fingertip extensions, nor with their ratio. Mean 2D extension (both hands) was smaller in women than men; mean 4D extension (right hand) was smaller in men than women; 4D:2D fingertip extension ratios from both hands were larger in women than men. Serum estradiol concentration negatively correlated with 2D extensions for both hands (no significant correlation with 4D extensions), but positively correlated with 4D:2D extension ratios for both hands. Serum testosterone concentration positively correlated with 2D extensions of both hands (no significant correlation with 4D extension), but negatively correlated with 4D:2D extension ratios for both hands. These relations were also studied in men and women separately. It was concluded that the 4D:2D extension ratio was greater in women than in men; 2D and 4D extensions and 4D:2D extension ratios may be determined prenatally by sex hormones; fingertip extensions may be predictive of adult and prenatal sex hormone levels.     

Grip strength of Texas Special Olympians

Little is known about the physical fitness parameters of individuals who participate in the Special Olympics. The purpose of this study was to assess the grip strength of 104 Special Olympians participating in the winter Olympic Games. Men were significantly stronger than women across age groups 20 to 59 yr. Women's right hands were stronger than their left, while the opposite was true for men, despite the fact that 78.8% of the subjects reported right hand dominance. Mean right and left grip strengths were 25-40% less than the 1985 normative data of Mathiowetz, et al. by age groups. Special Olympian men and women have grip strengths comparable to elderly people rather than age-matched men and women.     

The mental number line electrified: brain potentials in a numerical flanker task

It has been suggested that the mental representation of numbers is spatial in nature such that numbers are ordered on a mental number line. In the present investigation we use a variant of the Eriksen flanker task requiring a magnitude decision (smaller or larger than 5) for a central target number by pressing a response button with the right or left hand. The target number is flanked by irrelevant distracters that are either identical to the target, different from the target but biasing the same response, or different from the target and biasing a different response. Response latencies and event-related brain potentials were obtained in a group of healthy adults. Besides the typical response congruency effects on response latency and the N2 component of the ERP, we observed several other effects. First, numerical distance of the target to the standard 5 influenced decision latencies and amplitude and latency of the P3 component with smaller distances leading to longer decision latencies, longer P3 latencies and smaller P3 amplitudes. Second, smaller numerical distance between target and distracters led to faster decisions for response congruent and to slower decisions for response-incongruent trials. For response-incongruent trials P3 amplitude was small/large and P3 latency was long/short for small/large distances. These findings underscore the spatial character of number representation and further show that the relation between targets and distracters, although task irrelevant, is assessed automatically with facilitatory and inhibitory effects driven by spatial distance on the mental number line.     

A somatosensory latency between the thalamus and cortex also correlates with level of intelligence

As part of a study on speed of information processing and intelligence, 205 young adult postsecondary students were tested for somatosensory evoked potential (SEP) latencies and intelligence. Following stimulation at the wrist, latencies of three SEPs were determined: N13, generated in the cervical spinal cord/medulla region; N19, generated in the thalamus; P22, generated in the arm region of the somatosensory (parietal) cortex. These latencies and two latency differences, N19 - N13 and P22 - N19, were tested for correlation with a nonverbal measure of intelligence; only P22 - N19 significantly correlated (r = −.217; P = .013, two-tailed). Comparing this latency difference in students in the first IQ quartile (mean IQ = 103.4) with that of students in the fourth quartile (M = 131.2) showed mean differences of 4.13 ms versus 3.21 ms, respectively (p = .0034, two-tailed).P22 - N19 measures time for signal transmission from the thalamus to the sensory cortex. These results agree with considerably more extensive data on visually evoked potentials showing a negative correlation between IQ and the latency for a visual stimulus of the retina to produce a signal at the visual cortex (most of this latency is between the thalamus and the cortex; Reed & Jensen, 1992). The findings here agree with the visual results and strongly suggest that the IQ-latency correlation occurs because the latency indexes cortical nerve conduction velocity, an important component of information processing speed.     

The cortical representation of centrally presented words: A magnetic stimulation study

The right and left visual fields each project to the contralateral cerebral hemispheres. The current study aimed to investigate the extent of the functional overlap of the two hemifields along the vertical meridian. We applied repetitive transcranial magnetic stimulation (rTMS) over the left and right occipital cortex to investigate whether the foveal representation of words is bilaterally represented or is split between the two hemispheres. Employing a lateralized lexical decision task, we first showed a double dissociation between the stimulated cortical site and performance; right visual field (RVF) but not left visual field (LVF) performance was impaired when the left visual cortex was stimulated, and LVF but not RVF performance was impairred when the right visual cortex was stimulated. Unilateral stimulation also significantly impaired lexical decision latencies to centrally presented words. These findings support the suggestion that foveal representation of words is split. We discuss future strategies for the use of TMS in further tests of the split representation account.     

Perceptual distortion of intrapersonal and near-personal space sensed by proprioception

It is known that the illusory displacement of a vibrated limb can be transferred to a nonvibrated contacted limb. The purpose of this study was to quantify and compare the transferred illusory displacements occurring in the intrapersonal and near-personal space. In two tasks, 8 male and 8 female blindfolded subjects estimated (1) the height of the left elbow and (2) the height of an external object located at the same height as the left elbow, by the proprioception of the right arm which was Subject to illusory displacement. If the internal representation of the left elbow in one's body schema could provide precise information of its static position independently of the proprioception of the right arm, the perceived displacement of the right arm might be smaller when influenced by proprioceptive information from the static left arm, than when in contrast instead with an object which is not a body part. There was no difference in the estimation of illusory displacement between male and female subjects and between right and left arms. No significant difference was observed between transferred displacements of the left elbow and the object. This means that the perception of limb position sensed by the proprioception of another limb can be distorted as easily as the perception of location of an external object. This suggests that the internal representation of static limb position is not enough to provide the correct information of current limb position in the absence of vision.     

Asymmetrical Body Perception: A Possible Role for Neural Body Representations

ABSTRACT— Perception of one's body is related not only to the physical appearance of the body, but also to the neural representation of the body. The brain contains many body maps that systematically differ between right- and left-handed people. In general, the cortical representations of the right arm and right hand tend to be of greater area in the left hemisphere than in the right hemisphere for right-handed people, whereas these cortical representations tend to be symmetrical across hemispheres for left-handers. We took advantage of these naturally occurring differences and examined perceived arm length in right- and left-handed people. When looking at each arm and hand individually, right-handed participants perceived their right arms and right hands to be longer than their left arms and left hands, whereas left-handed participants perceived both arms accurately. These experiments reveal a possible relationship between implicit body maps in the brain and conscious perception of the body.     

Hemisphericity style, sex, and torque: an exploratory study

A sample of 139 male and 218 female college students were given the Preference Questionnaire and a torque test to assess (a) whether subjects who prefer a left hemisphericity style would show a higher incidence of torque than those who prefer a right hemisphericity style and (b) whether men would yield a higher incidence of torque than women. The first hypothesis received limited support. Men with a left hemisphericity style yielded a higher incidence of torque than men with a right style, however, the difference was only marginally significant.     

Evening and morning EEG differences between young men and women adults

Evening and morning waking EEG (eyes closed) was recorded in 16 women and 13 men aged 18-26 years old. Participants were fitted with a 13-electrode montage (Fp1, Fp2, FZ, F7, F8, C3, C4, T3, T4, P3, P4, O1, and O2) referred to linked ears. For each recording electrode, EEG total spectral amplitude power (microV/Hz, 0.75-19.75 Hz) was compared using 2 (Gender) x 2 (Moments) analyses of variance for repeated measures and LSD post-hoc tests. We found significant simple Gender effects, with women displaying higher EEG values for Central, Frontal, Parietal, and left Temporal leads. Simple Moment effects were also found, with lower morning values in Temporal and left Frontal recording sites. A Gender x Moment interaction was found at the right Frontal recording site. No significant effects were found for Prefrontal and Occipital recording sites, whatsoever. These results bring new understandings of gender and time of day effects in waking EEG and point to different sensitivity in different cortical areas. The present results could explain some of the observations related to gender differences in cognitive performance.     

Smoking,personality, and imagery preference in Relation to spontaneous bilateral electrodermal activity

Effects of smoking on spontaneous bilateral skin conductance were studied as a consequence of interactions with set and setting. Bilateral skin conductance was recorded in six men and six women who smoked and an equal number of nonsmokers on two different days. On the first day, spontaneous electrodermal activity was recorded before and after a 10-minute rest period during which half the smokers smoked a cigarette. On the second day, one week later, spontaneous activity was again recorded before and after a 10-minute rest period during which the remaining smokers smoked a cigarette. Nonsmokers did not smoke at any time. Following smoking there was a significant negative correlation between a preference for visual over nonvisual imagery and spontaneous skin conductance responsivity in the left as compared to the right hand. Correlations were significantly different in smokers and nonsmokers. Smokers showed significantly greater preferences for either visual or nonvisual imagery than nonsmokers. Nonresponding nonsmokers were higher on the psychoticism (P) scale of the Eysenck Personality Questionnaire (EPQ) than responding nonsmokers. Smokers scored higher on P than nonsmokers. Interactions between personality, cognitive style, and the experimental situation, set, and setting were discussed in relation to the arousing effects of nicotine.