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Biomedical subjects

D Kimura

Publications and source records attributed to D Kimura.

At least 19 recordsLinked to original sources
PubMed1997

A large sex difference on a two-dimensional mental rotation task.

Mental rotation tests require participants to identify rotated versions of a target stimulus. The Vandenberg Mental Rotations Test depicts rotations in 3-D space and typically yields one of the largest established cognitive sex differences favoring males. It is presently unclear whether this male advantage is related to the nature of rotations depicted in 3-D space or to the high level of difficulty of this task. The present study developed a new test depicting picture plane, or 2-D, rotations. When task difficulty within this 2-D test was varied, a male advantage as large as that seen on the Vandenberg test was found for the difficult component. These findings suggest that processing in 3 dimensions is not a necessary condition for a large sex difference on tests of mental rotation.

Adult↗
PubMed1997

Possible implications of the induction of human heme oxygenase-1 by nitric oxide donors.

To explore the involvement of nitric oxide (NO) in the induction of heme oxygenase-1, an essential enzyme in heme catabolism, we studied the effects of NO donors on the expression of heme oxygenase-1 mRNA in HeLa human cervical cancer cells. Treatment with each of three NO donors, sodium nitroprusside, 3-morpholinosydnonimine, and S-nitroso-L-glutathione, caused noticeable increases in the expression levels of heme oxygenase- mRNA, but not heme oxygenase-2 mRNA. On the other hand, nitrite or 8-bromo cGMP exerted no noticeable effect on the levels of heme oxygenase-1 mRNA. We showed that sodium nitroprusside also increased the levels of heme oxygenase-1 protein. The sodium nitroprusside-mediated increase in heme oxygenase-1 mRNA levels was abolished by treatment with actinomycin D. The expression levels of heme oxygenase-1 mRNA were also increased by NO donors in human melanoma and neuroblastoma cell lines. Thus, the observed induction of heme oxygenase-1 may represent an important response to NO or NO-related oxidative stress. The half lives of heme oxygenase-1 and heme oxygenase-2 mRNAs were estimated to be about 3.2 h and more than 5 h, respectively.

Cell Lineage↗
PubMed1996

Sex, sexual orientation and sex hormones influence human cognitive function.

Superior performance by women on a task requiring object location memory has challenged the traditional view that men excel on all spatial tasks. Sexual orientation is also associated with variation in cognitive ability pattern, but such association appears to be more consistent for a real-world targetting task than for paper-and-pencil spatial tests. Finally, there is increasing evidence that early exposure to sex hormones has lasting effects on problem-solving behaviour; moreover, current fluctuations in sex hormones in both men and women are associated with changes in cognitive pattern.

Brain↗
PubMed1996

Sex differences for speech and manual skill.

Young men and women were compared on the speeded repetition of speech (ns = 20 and 18, respectively) and manual movements (ns = 37 and 38). The repetition of a single speech or manual movement was used as a measure of baseline speed, against which to compare a sequence of movements. Males tended to be faster at repeating a single movement, but using baseline speed as a covariate resulted in a female advantage for the repetition of a sequence of movements. It was concluded that men have a basic motor-speed advantage, but that women may be faster at programming a sequence of speech or manual movements. The results are discussed with respect to sexual variation in the neural organization of motor programming systems.

Adolescent↗
PubMed1995

Estrogen replacement therapy may protect against intellectual decline in postmenopausal women.

Postmenopausal women over the age of 50, who were either on estrogen replacement therapy (N = 21) or not (N = 33), were assessed on several sexually dimorphic cognitive functions. The two groups were strictly equivalent in age, education, and vocabulary score (an abbreviated measure of past intelligence). Overall, women on therapy had better scores than those not on therapy, regardless of whether the specific function favored men or women. Previous history of reproductive surgery had no effect on scores. Estrogen may guard against some of the intellectual decline which is to be expected postmenopausally.

Affect↗
PubMed1995

Sexual orientation and performance on sexually dimorphic motor tasks.

Performance of homosexual and heterosexual men and women on two motor tasks which reliably demonstrate sex differences in opposite directions was examined. A Throw-to-Target Task and the Purdue Pegboard were administered to undergraduate students matched for age and program of study. A two-way ANOVA (Sex x Sexual Orientation) of the Throw data showed a significant interaction, F(1, 90) = 16.22, p < or = 0.001, and a trend for an effect of sex, F(1, 90) = 3.72, p < 0.06. Heterosexual men outperformed heterosexual women, whereas gay men threw less accurately and lesbians tended to throw more accurately than their heterosexual counterparts. Differences in sports history or hand strength did not account for these effects. Analysis of the Pegboard scores found no interaction or main effect of sexual orientation, but the effect of sex was significant, F(1,63) = 7.01, p < or = 0.02. Regardless of sexual orientation, women outperformed men and this difference remained significant even when a measure of finger size was partialed out. This study provides new evidence suggesting an association between sexual orientation and motor-performance profiles. As with cognitive tasks, the motor-performance profiles of homosexuals are composites of some male-typical and some female-typical abilities. To the extent that sociological factors have been controlled, the study suggests that both sexual orientation and motor/cognitive predispositions may have early biological contributions.

Adult↗
PubMed1994

Dermatoglyphic asymmetry and sexual orientation in men.

Dermal ridges on the fingertips are formed early in fetal life and remain unchanged throughout the life span. The researchers examined dermatoglyphic characteristics (total ridge count and directional ridge asymmetry) in homosexual and heterosexual men. There was no difference between the 2 groups of men in total ridge count, but more gay men demonstrated leftward asymmetry than did nongay men. Although this effect was not accounted for by differences in hand preference, an association was observed between leftward dermatoglyphic asymmetry and an increased incidence of adextrality in homosexual men, but not in heterosexual men. These findings are consistent with a biological contribution to sexual orientation and indicate that such an influence may occur early in prenatal life.

Adult↗
PubMed1991

The relationship between testosterone levels and cognitive ability patterns.

The cognitive performance of normal men and women was studied, grouped according to whether the subjects had relatively high or low salivary testosterone (T) concentrations. Men with lower T performed better than other groups on measures of spatial/mathematical ability, tasks at which men normally excel. Women with high T scored higher than low-T women on these same measures. T concentrations did not relate significantly to scores on tests that usually favor women or that do not typically show a sex difference. These results support suggestions of a nonlinear relationship between T concentrations and spatial ability, and demonstrate some task specificity in this respect.

Adolescent↗
PubMed1989

Evidence for subgroups of adextrals based on speech lateralization and cognitive patterns.

Some non-right-handers may prefer the left hand by virtue of well-organized or high levels of spatial ability, vested primarily in the right hemisphere, rather than as a result of anomalous speech representation. This study tested the hypothesis that adextral (left-handed or ambidextrous) individuals with high spatial ability might have cerebral speech lateralization patterns similar to dextrals. Paper-and-pencil tests of various cognitive abilities, a verbal dichotic listening task, and a handedness inventory were administered to two groups (science or non-science students) of adextral and dextral subjects. The science group had predictably higher spatial ability than the non-science group. Adextral science students were as lateralized on dichotic listening, and had equal spatial ability, compared to dextral science students. Adextral non-science males were less lateralized and had (unexpectedly) poorer spatial ability than dextral non-science males. Thus in adextrals, variations in ability patterns may be related to variations in speech lateralization.

Attention↗
PubMed1989

Right-hand superiority for throwing but not for intercepting.

In humans, the organization of movements performed by both upper limbs, relies significantly on a left hemisphere "praxis" system that also subsumes speech function. Right hand preference may also be an expression of this left hemisphere dependence, arising from the preferential connections of the right hand to the left hemisphere. Consequently, a manual task that maximizes the spatial complexity of a target (presumably engaging right hemisphere mechanisms), while concurrently minimizing motor-programming demands, was expected to yield a diminished disparity in preference and performance between the hands. Left and right hand accuracy were measured independently for two motor tasks in 48 normal right-handed university students. In the first task, darts were thrown overhand at a stationary target. For the second task, subjects were asked to use the open hand to block (but not catch) projectiles launched at varying trajectories and velocities. ANOVA yielded a significant Hand x Task interaction, in which the left hand did not differ from the right hand in intercepting ability, but was significantly less accurate than the right hand for throwing. A sex difference favouring males was found for both tasks; this difference was not reducible to differences in physique or athleticism.

Adult↗
PubMed1989

The relation between oral movement control and speech.

A large series of neurological patients, selected solely on the basis that they had damage restricted to one hemisphere of the brain, was given a variety of tests of basic speech and praxic function. Within the left-damaged group, patients were further identified as aphasic or nonaphasic, based on preexisting standard tests of aphasia. Subgroups of aphasics were studied on the basis of lesion location, rather than on the basis of aphasia type. The focus of the study was the relation between the production of speech and nonspeech oral movements, particularly across anterior and posterior lesions. Reproduction of single nonverbal oral movements and of single isolated speech sounds was found to be very highly correlated, and both depended selectively on the left anterior region of the brain. This same region was critically important for rapid repeated articulation of a syllable, suggesting that it mediates control at some "unit" level of movement, in a phenomenological sense, for both speech and nonspeech movements. Other "speech" regions in the left hemisphere appeared to be dispensable for the production of single oral movements, whether these were verbal or nonverbal movements. However, for most aphasic patients, an area in the left posterior region was inferred to be essential for production of multiple oral movements, whether nonverbal or verbal, suggesting a critical role in the accurate selection of movements. Within the posterior region, there was further differentiation for multisyllabic speech into a parietal system, which appeared to mediate primarily praxic function, and a temporal system, which appeared to mediate verbal-echolalic function. Aphasias from anterior and posterior lesions resembled "Broca's" and "Wernicke's" aphasia only insofar as they differed in fluency, with anterior aphasics clearly less fluent. Tests of speech comprehension did not differentiate the groups. It is suggested that classifying aphasic patients via lesion location rather than aphasic typology might yield a view of functional subsystems different from those commonly accepted.

Adult↗
PubMed1989

Neuropsychological improvement versus practice effect following unilateral carotid endarterectomy in patients without stroke.

Patients who were admitted to hospital for a recent transient ischemic attack were entered into one of three groups based on medical and surgical characteristics; those with an abnormal neurological examination or a focal abnormality on CT Scan were omitted from the study. The two surgical groups (12 patients each) underwent either a left or right endarterectomy for a symptomatic atheroma of the ipsilateral carotid artery. The control group consisted of 12 patients who either demonstrated minor or nonexistent carotid abnormalities or a TIA distribution that was contralateral to what would otherwise have been a surgically treatable lesion. Patients were tested before surgery and again 6-8 weeks later with the WAIS, WMS, and other neuropsychological measures. Significant improvement on some measures at follow-up was strictly equivalent across all groups and was attributed to practice effects.

Aged↗
PubMed1988

Reciprocal effects of hormonal fluctuations on human motor and perceptual-spatial skills.

Normal adult women showed systematic performance fluctuations across the menstrual cycle on several motor and perceptual tests that typically yield sex differences in performance. The midluteal phase, characterized by high levels of estradiol and progesterone, was associated with improved performance on tests of speeded motor coordination and impaired performance on a perceptual-spatial test, relative to performance during menses. Variations in gonadal steroid levels may contribute substantially to the sex differences reported in human cognitive and motor skills.

Adult↗
PubMed1987

Hand movement asymmetry during speech: no effect of speaking topic.

Right-handed subjects were videotaped as they spoke on verbal, spatial and neutral topics and the frequencies of their spontaneous hand movements were analyzed. Although subjects made more free movement gestures during the spatial topics than during the other topics, there was a consistent level of right hand preference for free movements across topics. Self-touching movements showed no hand preference in any topic. The results suggest that free movements are generated by a left-hemisphere motor control system which exerts consistently greater influence over the right than the left hand regardless of the source of processing preceding activation of this system.

Adolescent↗
PubMed1987

Attentional and perseverative impairment in two cases of familial fatal parkinsonism with cortical sparing.

The neuropsychological findings in twin brothers with familial fatal Parkinsonism are reported. Post-mortem examination had shown extensive pathology in basal ganglia and brainstem, but not in the cerebral cortex. Although both showed average intelligence three months prior to death, they had impairment on a sorting task and in serial attention span. Some possible neural mechanisms are discussed.

Attention↗