Kirsten Jordan

Women and men exhibit different cortical activation patterns during mental rotation tasks

The strongest sex differences on any cognitive task, favoring men, are found for tasks that require the mental rotation of three-dimensional objects. A number of studies have explored functional brain activation during mental rotation tasks, and sex differences have been noted in some. However, in these studies there was a substantial confounding factor because male and female subjects differed in overall performance levels. In contrast, our functional brain activation study examined cortical activation patterns for males and females who did not differ in overall level of performance on three mental rotation tasks. This allowed us to eliminate any confounding influences of overall performance levels. Women exhibited significant bilateral activations in the intraparietal sulcus (IPS) and the superior and inferior parietal lobule, as well as in the inferior temporal gyrus (ITG) and the premotor areas. Men showed significant activation in the right parieto-occitpital sulcus (POS), the left intraparietal sulcus and the left superior parietal lobule (SPL). Both men and women showed activation of the premotor areas but men also showed an additional significant activation of the left motor cortex. No significant activation was found in the inferior temporal gyrus. Our results suggest that there are genuine between-sex differences in cerebral activation patterns during mental rotation activities even when performances are similar. Such differences suggest that the sexes use different strategies in solving mental rotation tasks.

The neural basis of the egocentric and allocentric spatial frame of reference

The present study examines the functional and anatomical underpinnings of egocentric and allocentric coding of spatial coordinates. For this purpose, we set up a functional magnet resonance imaging experiment using verbal descriptions of spatial relations either with respect to the listener (egocentric) or without any body-centered relations (allocentric) to induce the two different spatial coding strategies. We aimed to identify and distinguish the neuroanatomical correlates of egocentric and allocentric spatial coding without any possible influences by visual stimulation. Results from sixteen participants show a general involvement of a bilateral fronto-parietal network associated with spatial information processing. Furthermore, the egocentric and allocentric conditions gave rise to activations in primary visual areas in both hemispheres. Moreover, data show separate neural circuits mediating different spatial coding strategies. While egocentric spatial coding mainly recruits the precuneus, allocentric coding of space activates a network comprising the right superior and inferior parietal lobe and the ventrolateral occipito-temporal cortex bilaterally. Furthermore, bilateral hippocampal involvement was observed during allocentric, but not during egocentric spatial processing. Our results demonstrate that the processing of egocentric spatial relations is mediated by medial superior-posterior areas, whereas allocentric spatial coding requires an additional involvement of right parietal cortex, the ventral visual stream and the hippocampal formation. These data suggest that a hierarchically organized processing system exists in which the egocentric spatial coding requires only a subsystem of the processing resources of the allocentric condition.

Interactive effects of sex hormones and gender stereotypes on cognitive sex differences—A psychobiosocial approach.

Biological and social factors have been shown to affect cognitive sex differences. For example, several studies have found that sex hormones have activating effects on sex-sensitive tasks. On the other hand, it has been shown that gender stereotypes can influence the cognitive performance of (gender-) stereotyped individuals. However, few studies have investigated the combined effects of both factors. The present study investigated the interaction between sex hormones and gender stereotypes within a psychobiosocial approach. One hundred and fourteen participants (59 women) performed a battery of sex-sensitive cognitive tasks, including mental rotation, verbal fluency, and perceptual speed. Saliva samples were taken immediately after cognitive testing. Levels of testosterone (T) were analysed using chemiluminescence immunoassay (LIA). To activate gender stereotypes, a questionnaire was applied to the experimental group that referred to the cognitive tasks used. The control group received an identical questionnaire but with a gender-neutral content. As expected, significant sex differences favouring males and females appeared for mental rotation and verbal fluency tasks, respectively. The results revealed no sex difference in perceptual speed. The male superiority in the Revised Vandenberg and Kuse Mental Rotations Tests (MRT-3D) was mainly driven by the stereotype-active group. No significant sex difference in MRT-3D appeared in the control group. The MRT-3D was also the task in which a strong gender-stereotype favouring males was present for both males and females. Interestingly, T levels of the stereotype-activated group were 60% higher than that of male controls. The results suggest that sex hormones mediate the effects of gender stereotypes on specific cognitive abilities.

Different cortical activations for subjects using allocentric or egocentric strategies in a virtual navigation task.

Subjects were required to navigate through a virtual 3D labyrinth presented on a screen while fMRI images were obtained. Contrasting the fMRI images obtained during the navigation trials with appropriate control conditions revealed a bilateral network comprising the parietal lobe (including the intraparietal sulcus) and various lateral and medial premotor areas. The subjects using an allocentric strategy showed stronger activation in the medial temporal areas including the parahippocampal region, the hippocampus, and the thalamus. In addition, the cerebellum was also active in those subjects. We believe that this activation pattern is related to visually guided memory retrieval based on generalized spatial maps. The stronger activation in the thalamic–basal ganglia–cerebellar–loop points to a more automatic support of memory and attentional processes possibly supporting memorization of spatial maps.

Mental Rotation Test Performance in Four Cross-Cultural Samples (N = 3367): Overall Sex Differences and the Role of Academic Program in Performance

Two meta-analyses (Linn and Petersen, 1985; Voyer et al., 1995) discuss variables that affect mental rotation performance but they do not mention a potentially important variable, the Academic Program in which students are enrolled. Sex differences in brain size have been related to sex differences in spatial performance (e.g., Falk et al., 1999) and thus it is important to know whether mental rotation performance shows a significant interaction between Sex and Academic Program. To put our understanding of the Academic Program effect on a firmer empirical footing, we conducted a large scale multicultural study, with samples from Canada, Germany and Japan, using identical test procedures in all studies. Significant main effects for Sex and Academic Program were found in all four studies, with large effect sizes for Sex and medium to large effect sizes for Academic Program (based on Cohens d). No significant interactions between these variables were found in the four samples. Our demonstration of a reliable Academic Program effect has clear and important pragmatic implications for a broad range of work on spatial ability and its interpretation.

The Role of Testosterone in Sexuality and Paraphilia—A Neurobiological Approach. Part II: Testosterone and Paraphilia

INTRODUCTION Antiandrogen therapy has been used for 30 years to treat paraphilic patients and sexual offenders. Yet the therapeutic success of antiandrogens is uncertain. Furthermore, there is still a lack of comprehensive knowledge about the effects of androgen-lowering therapy in paraphilic patients. AIM We discuss endocrinological, neurobiological, and therapeutic aspects of paraphilia with the aim of integrating these on the basis of the current neurobiological and clinical knowledge on testosterone that was set out in Part I of this review. METHODS Our review of the human literature comprises the current knowledge about the neurobiology of paraphilia and the known endocrinological, pathophysiological, and genetic aspects of this disorder. The role of testosterone is discussed. A survey of antiandrogen therapy and its outcome in paraphilic patients and sex offenders is provided. RESULTS Although not all data are consistent, current imaging research suggests that structural and functional changes in pedophilia appear for the most part in brain regions also involved in sexual functions. Not exclusively testosterone but also some other endocrinological and neurochemical parameters could be disturbed in pedophilic patients and child molesters; these include changes in hypothalamic-pituitary function, prolactin levels, and dopaminergic or serotonergic functions. There appears to be a sex-steroid-related genetic influence on antisocial traits, externalizing behavior, and sexual behavior. Most of the studies in which antiandrogen therapy in paraphilic patients and sex offenders have been examined were case reports, or observational or open-label studies, and many did not include adequate control groups. Only a few placebo-controlled double-blind studies have been published with inconsistent results concerning treatment effects. Outcome measures differ between the studies and do not seem ideally suited to their purpose. CONCLUSIONS On the basis of the current knowledge about testosterone and its effects on brain and behavior as described in Part I, and of available results on the relationship between testosterone and paraphilia as well as antiandrogen therapy, we present from a neurobiological perspective an extended scientific proposal for design features to investigate the effects of antiandrogen treatment in large clinical trials.

Diagnostic Accuracy of Eye Movements in Assessing Pedophilia

INTRODUCTION Given that recurrent sexual interest in prepubescent children is one of the strongest single predictors for pedosexual offense recidivism, valid and reliable diagnosis of pedophilia is of particular importance. Nevertheless, current assessment methods still fail to fulfill psychometric quality criteria. AIMS The aim of the study was to evaluate the diagnostic accuracy of eye-movement parameters in regard to pedophilic sexual preferences. METHOD Eye movements were measured while 22 pedophiles (according to ICD-10 F65.4 diagnosis), 8 non-pedophilic forensic controls, and 52 healthy controls simultaneously viewed the picture of a child and the picture of an adult. Fixation latency was assessed as a parameter for automatic attentional processes and relative fixation time to account for controlled attentional processes. MAIN OUTCOME MEASURES Receiver operating characteristic (ROC) analyses, which are based on calculated age-preference indices, were carried out to determine the classifier performance. Cross-validation using the leave-one-out method was used to test the validity of classifiers. RESULTS Pedophiles showed significantly shorter fixation latencies and significantly longer relative fixation times for child stimuli than either of the control groups. Classifier performance analysis revealed an area under the curve (AUC) = 0.902 for fixation latency and an AUC = 0.828 for relative fixation time. The eye-tracking method based on fixation latency discriminated between pedophiles and non-pedophiles with a sensitivity of 86.4% and a specificity of 90.0%. Cross-validation demonstrated good validity of eye-movement parameters. CONCLUSIONS Despite some methodological limitations, measuring eye movements seems to be a promising approach to assess deviant pedophilic interests. Eye movements, which represent automatic attentional processes, demonstrated high diagnostic accuracy.

Mental rotation of letters, pictures, and three-dimensional objects in German dyslexic children

This study examines mental rotation ability in children with developmental dyslexia. Prior investigations have yielded equivocal results that might be due to differences in stimulus material and testing formats employed. Whereas some investigators found dyslexic readers to be impaired in mental rotation, others did not report any performance differences or even superior spatial performance for dyslexia. Here, we report a comparison of mental rotation for letters, three-dimensional figures sensu Shepard and Metzler, and colored pictures of animals or humans in second-grade German dyslexic readers. Findings indicate that dyslexic readers are impaired in mental rotation for all three kinds of stimuli. Effects of general intelligence were controlled. Furthermore, dyslexic children were deficient in other spatial abilities like identifying letters or forms among distracters. These results are discussed with respect to the hypotheses of a developmental dysfunction of the parietal cortex or a subtle anomaly in cerebellar function in dyslexic readers.

Sex hormones and mental rotation: an intensive longitudinal investigation.

The present study used an intensive longitudinal design to examine whether mental rotation performance varies according to a monthly cycle in both males and females and whether these variations are related to variations in progesterone, estradiol, and testosterone levels. We collected reaction time and accuracy data for 10 males and seven females each workday over eight weeks using 136 pairs of mental rotation stimuli/day, and measured sexual hormones concentrations in the saliva twice a week. A mixed linear model statistical analysis revealed that all females and seven males showed significant cycle effects in mental rotation performance. The female cycle showed an amplitude that was twice as large compared with the amplitude found in males. For males and females, estradiol and testosterone were significantly linearly and quadratically related to interindividual variation in performance at the beginning of the study (progesterone was linearly related to performance for females). The association between testosterone and performance differed across sexes: for males, it had an inverse U-shape, for females it was U-shaped. Towards the end of the study, none of the hormones were significantly related to performance anymore. Thus, the relationship between hormones and mental rotation performance disappeared with repeated testing. Only estradiol levels were significantly elevated at the lowest point of the cycle in mental rotation performance in females. In conclusion, in this intensive longitudinal study spanning two months, a monthly cycle in mental rotation performance was found among both males and females, with a larger cycles amplitude for females.

Sex Differences in Left/Right Confusion

In agreement with the literature, females (n=269) gave themselves significantly poorer ratings than males (n=164) in evaluating their ability to make fast and accurate left/right judgments. In order to evaluate the ecological validity of the self-ratings, subjects were tested on a task that required fast and accurate left/right judgments, on a mental rotation task, and on a task that required navigation of a virtual maze. The correlations between the performances and self-ratings were computed. Both males and females who gave themselves very poor LRC (left/right confusion) ratings had significantly lower accuracy scores on the left/right judgement task than males and females with average ratings, but there was no sex-specific relation between LRC ratings and left/right judgements that would explain why females give themselves lower LRC ratings. For females only, a weak correlation between LRC scores and the learning of the virtual maze was observed, but no significant correlations were observed between LRC scores and mental rotation performance. We conclude that self-ratings on left/right confusion questions, although they yield reliable sex differences, are poor predictors of actual performance on spatial tasks that involve left/right judgements. Thus, and in support of earlier speculations (Sholl and Egeth, 1981; Teng and Lee, 1982; Williams et al., 1993), the principal cause of the marked sex differences in LRC self-ratings likely lies in a greater willingness of females to rate themselves more poorly on questions of this type than is the case for men.