Inferior Frontal Areas Research Articles

Effects of Visual Experience on the Human MT+ Functional Connectivity Networks: An fMRI Study of Motion Perception in Sighted and Congenitally Blind Individuals

Human middle temporal complex (hMT+) responds also to the perception of non-visual motion in both sighted and early blind individuals, indicating a supramodal organization. Visual experience, however, leads to a segregation of hMT+ into a more anterior subregion, involved in the supramodal representation of motion, and a posterior subregion that processes visual motion only. In contrast, in congenitally blind subjects tactile motion activates the full extent of hMT+. Here, we used fMRI to investigate brain areas functionally connected with the two hMT+ subregions (seeds) during visual and tactile motion in sighted and blind individuals. A common functional connectivity network for motion processing, including bilateral ventral and dorsal extrastriate, inferior frontal, middle and inferior temporal areas, correlated with the two hMT+ seeds both in sighted and blind individuals during either visual or tactile motion, independently from the sensory modality through which the information was acquired. Moreover, ventral premotor, somatosensory, and posterior parietal areas correlated only with the anterior but not with the posterior portion of hMT+ in sighted subjects, and with both hMT+ seeds in blind subjects. Furthermore, a correlation between middle temporal and occipital areas with primary somatosensory seeds was demonstrated across conditions in both sighted and blind individuals, suggesting a cortico-cortical pathway that conveys non-visual information from somatosensory cortex, through posterior parietal regions, to ventral extrastriate cortex. These findings expand our knowledge about the development of the functional organization within hMT+ by showing that distinct patterns of brain functional correlations originate from the anterior and posterior hMT+ subregions as a result of visual experience.

Neural activations measured by fMRI during reading novels at ordinary and rapid speeds

Event Abstract Back to Event Neural activations measured by fMRI during reading novels at ordinary and rapid speeds Norio FujiMaki1*, Shinji Munetsuna2, Toyofumi Sasaki3, Tomoe Hayakawa4, Aya Ihara1, Qiang Wei1, Yasushi Terazono1 and Tsutomu Murata1 1 National Institute of Information and Communications Technology, Japan 2 Kyushu Institute of Technology, Japan 3 OMOIGANE Co. Ltd, Japan 4 Teikyo University, Japan Human beings can read sentences at high speeds of greater than several words per second. While reading each word, readers access their lexical knowledge and execute syntactic processes to comprehend the meanings of sentences. To understand the neural processes involved in reading, it is important to investigate the dependence of neural activation on reading speed. Unlike previous neuroimaging studies with word-by-word presentation at a low rate (< 120 words per minute (wpm)), we measured neural activations during natural-style reading with multiple-sentence presentation at a high rate (> 300 wpm), using a functional magnetic resonance imaging [1]. Eight experts in a rapid-reading technique and 11 non-experts participated in the experiment. They silently read novels at ordinary and rapid speeds, and pressed a button to turn pages. The interval between turning pages was recorded to evaluate the reading speed. For each subject, we evaluated activations in 14 areas and at the 2 instructed reading speeds. Activations decreased with increasing reading speed in the left middle and posterior superior temporal area, left inferior frontal area, left precentral area, and the anterior temporal areas of both hemispheres, which have been reported to be active for linguistic processes. In contrast, activations increased with increasing reading speed in the right intraparietal sulcus, which is considered to reflect visuo-spatial processes. Despite the considerable reading speed differences (>1 order of magnitude), correlation analysis showed no significant difference in activation dependence on reading speed with respect to the subject groups and instructed reading speeds. The activation reduction with speed increase in language-related areas was opposite to the previous reports for low reading speeds. The present results suggest that subjects reduced some linguistic processes with reading speed increase from ordinary to rapid speed.

The role of inferior frontal and parietal areas in differentiating meaningful and meaningless object-directed actions

Over the past two decades single cell recordings in primates and neuroimaging experiments in humans have uncovered the key properties of visuo-motor mirror neurons located in monkey premotor cortex and parietal cortices as well as homologous areas in the human inferior frontal and inferior parietal cortices which presumably house neurons with similar response properties. One of the most interesting claims regarding the human mirror neuron system (MNS) is that its activity reflects high-level action understanding. If this was the case, one would expect signal in the MNS to differentiate between meaningful and meaningless actions. In the current experiment we tested this prediction using a novel paradigm. Functional magnetic resonance images were collected while participants viewed (i) short films of object-directed actions (ODAs) which were either semantically meaningful, i.e. a hand pressed a stapler or semantically meaningless, i.e. a foot pressed a stapler, (ii) short films of pantomimed actions and (iii) static pictures of objects. Consistent with the notion that the MNS represents high-level action understanding, meaningful and meaningless actions elicited BOLD signal differences at bilateral sites in the supramarginal gyrus (SMG) of the inferior parietal lobule (IPL) where we observed a double dissociation between BOLD response and meaningfullness of actions. Comparison of superadditive responses in the inferior frontal gyrus (IFG) and IPL (supramarginal) regions revealed differential contributions to action understanding. These data further specify the role of specific components of the MNS in understanding object-directed actions.

Gray and white matter brain volumes in older adults with bipolar disorder

Structural magnetic resonance imaging (MRI) studies have been inconsistent in demonstrating volumetric differences in subjects with bipolar disorder. Most studies have not found difference in total gray or white matter in bipolar patients compared with controls, but there have been several studies suggesting that regional abnormalities are present. These have predominately been located in the frontal and temporal lobes. Since age has been inversely correlated with total gray matter in patients, analyses of gray matter changes in older adults or in studies that have included older subjects have been difficult. This study assessed the presence of gray matter volume, and the potential for regional volumetric differences in older adults with bipolar disorder. Fifty-six older adults with DSM-IV bipolar disorder (mean age 60.5) and 43 non-psychiatrically ill controls (mean age 58.1) had structured interviews and MRI scanning on a 1.5T GE Scanner. Image parcellation divided the cerebrum into 16 units. Volumetric differences were examined using the multivariate linear regression models with alpha = 0.05. Relative to controls, the older adults with bipolar disorder had significantly smaller gray matter volumes bilaterally in the inferior frontal areas. White matter volume was also reduced in these same areas but did not reach statistical significance when controlled for gender and age. No significant difference was noted in total gray or white matter volumes. Older adults with bipolar disorder showed gray matter volumetric deficits in inferior frontal lobe regions which include structures identified as contributing to the anterior limbic network.

Musical and verbal semantic memory: Two distinct neural networks?

Semantic memory has been investigated in numerous neuroimaging and clinical studies, most of which have used verbal or visual, but only very seldom, musical material. Clinical studies have suggested that there is a relative neural independence between verbal and musical semantic memory. In the present study, “musical semantic memory” is defined as memory for “well-known” melodies without any knowledge of the spatial or temporal circumstances of learning, while “verbal semantic memory” corresponds to general knowledge about concepts, again without any knowledge of the spatial or temporal circumstances of learning. Our aim was to compare the neural substrates of musical and verbal semantic memory by administering the same type of task in each modality. We used high-resolution PET H2O15 to observe 11 young subjects performing two main tasks: (1) a musical semantic memory task, where the subjects heard the first part of familiar melodies and had to decide whether the second part they heard matched the first, and (2) a verbal semantic memory task with the same design, but where the material consisted of well-known expressions or proverbs. The musical semantic memory condition activated the superior temporal area and inferior and middle frontal areas in the left hemisphere and the inferior frontal area in the right hemisphere. The verbal semantic memory condition activated the middle temporal region in the left hemisphere and the cerebellum in the right hemisphere. We found that the verbal and musical semantic processes activated a common network extending throughout the left temporal neocortex. In addition, there was a material-dependent topographical preference within this network, with predominantly anterior activation during musical tasks and predominantly posterior activation during semantic verbal tasks.

Where syntax meets math: Right intraparietal sulcus activation in response to grammatical number agreement violations

Previous research has shown that the processing of words referring to actions activated motor areas. Here, we show activation of the right intraparietal sulcus, an area that has been associated with quantity processing, when participants are asked to read pairs of words with number agreement violations as opposed to phrases with gender agreement violations or with no violation. In addition, we show activation in the left premotor and left inferior frontal areas when either gender or number agreement is violated. We argue that number violation automatically activates processes linked to quantity processing which are not directly related to language mechanisms.

How Are ‘Barack Obama’ and ‘President Elect’ Differentially Stored in the Brain? An ERP Investigation on the Processing of Proper and Common Noun Pairs

BackgroundOne of the most debated issues in the cognitive neuroscience of language is whether distinct semantic domains are differentially represented in the brain. Clinical studies described several anomic dissociations with no clear neuroanatomical correlate. Neuroimaging studies have shown that memory retrieval is more demanding for proper than common nouns in that the former are purely arbitrary referential expressions. In this study a semantic relatedness paradigm was devised to investigate neural processing of proper and common nouns.Methodology/Principal Findings780 words (arranged in pairs of Italian nouns/adjectives and the first/last names of well known persons) were presented. Half pairs were semantically related (“Woody Allen” or “social security”), while the others were not (“Sigmund Parodi” or “judicial cream”). All items were balanced for length, frequency, familiarity and semantic relatedness. Participants were to decide about the semantic relatedness of the two items in a pair. RTs and N400 data suggest that the task was more demanding for common nouns. The LORETA neural generators for the related-unrelated contrast (for proper names) included the left fusiform gyrus, right medial temporal gyrus, limbic and parahippocampal regions, inferior parietal and inferior frontal areas, which are thought to be involved in the conjoined processing a familiar face with the relevant episodic information. Person name was more emotional and sensory vivid than common noun semantic access.Conclusions/SignificanceWhen memory retrieval is not required, proper name access (conspecifics knowledge) is not more demanding. The neural generators of N400 to unrelated items (unknown persons and things) did not differ as a function of lexical class, thus suggesting that proper and common nouns are not treated differently as belonging to different grammatical classes.

Cerebellum, language, and cognition in autism and specific language impairment.

We performed cerebellum segmentation and parcellation on magnetic resonance images from right-handed boys, aged 6-13 years, including 22 boys with autism [16 with language impairment (ALI)], 9 boys with Specific Language Impairment (SLI), and 11 normal controls. Language-impaired groups had reversed asymmetry relative to unimpaired groups in posterior-lateral cerebellar lobule VIIIA (right side larger in unimpaired groups, left side larger in ALI and SLI), contralateral to previous findings in inferior frontal cortex language areas. Lobule VIIA Crus I was smaller in SLI than in ALI. Vermis volume, particularly anterior I-V, was decreased in language-impaired groups. Language performance test scores correlated with lobule VIIIA asymmetry and with anterior vermis volume. These findings suggest ALI and SLI subjects show abnormalities in neurodevelopment of fronto-corticocerebellar circuits that manage motor control and the processing of language, cognition, working memory, and attention.

Neural activations correlated with reading speed during reading novels

Functional magnetic resonance imaging was used to measure neural activations in subjects instructed to silently read novels at ordinary and rapid speeds. Among the 19 subjects, 8 were experts in a rapid reading technique. Subjects pressed a button to turn pages during reading, and the interval between turning pages was recorded to evaluate the reading speed. For each subject, we evaluated activations in 14 areas and at 2 instructed reading speeds. Neural activations decreased with increasing reading speed in the left middle and posterior superior temporal area, left inferior frontal area, left precentral area, and the anterior temporal areas of both hemispheres, which have been reported to be active for linguistic processes, while neural activation increased with increasing reading speed in the right intraparietal sulcus, which is considered to reflect visuo-spatial processes. Despite the considerable reading speed differences, correlation analysis showed no significant difference in activation dependence on reading speed with respect to the subject groups and instructed reading speeds. The activation reduction with speed increase in language-related areas was opposite to the previous reports for low reading speeds. The present results suggest that subjects reduced linguistic processes with reading speed increase from ordinary to rapid speed.

Spatiotemporal and frequency signatures of noun and verb processing: A wavelet-based beamformer study

A total of 8 participants were tested using magnetoencephalography for investigating the spatial, temporal, and frequency signatures of noun and verb processing in the brain. Visually presented nouns and verbs both activated the occipital, left posterior temporal, and left inferior frontal cortices at a latency range of 106–329 ms in a frequency range of 24–98 Hz. Nouns activated the left posterior temporal area while verbs activated the inferior left frontal area at a latency range of 411–430 ms in a frequency range of 116–137 Hz. Nouns and verbs were processed in similar brain areas during early latency and relatively low frequency, but were processed in different brain areas during late latency and high frequency. The results indicate that there are distinct neural substrates underlying different aspects of the language system. This finding sheds light on the cerebral mechanisms of impairments of selective word categories in patients with brain damage in clinical neuropsychology.

Altered error-related activity in patients with schizophrenia

Deficits in working memory (WM) and executive cognitive control are core features of schizophrenia. However, findings regarding functional activation strengths are heterogeneous, partly due to differences in task demands and behavioral performance. Previous investigators proposed integrating these heterogeneous findings into a comprehensive model of cortical inefficiency assuming the inverted U-shaped relationship between performance and neuronal activation to be shifted in patients. The present study pursued a novel approach of precise performance balancing potentially resolving a number of discrepancies with regard to performance related cognitive activation patterns in schizophrenia. Error-related WM activity was examined in 55 patients and 55 controls by balancing the mean number of incorrect responses between the groups and analyzing remaining incorrect trials. A modified Sternberg Item Recognition task (SIRT) allowing for the segregation of encoding, executive maintenance and retrieval-related activation was applied. Relative to healthy controls, patients showed extended hypoactivations in inferior temporal, superior parietal, inferior, middle and superior frontal as well as cerebellar regions during encoding of incorrectly remembered items. During erroneous retrieval of information patients exhibited a significantly decreased activation in an executive control network comprising inferior and middle frontal areas, precuneus and cerebellum. Present data suggest that in patients with schizophrenia encoding of erroneously retrieved items as well as erroneous retrieval itself is associated with extended activation abnormalities in task-relevant regions even after balancing performance. Thus, present results clearly indicate that disorder-characteristic activation abnormalities become manifest during dysfunctional executive processing even when the moderating effect of performance is largely eliminated.

The neural correlates of verbal short-term memory in Alzheimer's disease: an fMRI study

Although many studies have shown diminished performance in verbal short-term memory tasks in Alzheimer's disease, few studies have explored the neural correlates of impaired verbal short-term memory in Alzheimer's disease patients. In this fMRI study, we examined alterations in brain activation patterns during a verbal short-term memory recognition task, by differentiating encoding and retrieval phases. Sixteen mild Alzheimer's disease patients and 16 elderly controls were presented with lists of four words followed, after a few seconds, by a probe word. Participants had to judge whether the probe matched one of the items of the memory list. In both groups, the short-term memory task elicited a distributed fronto-parieto-temporal activation that encompassed bilateral inferior frontal, insular, supplementary motor, precentral and postcentral areas, consistent with previous studies of verbal short-term memory in young subjects. Most notably, Alzheimer's disease patients showed reduced activation in several regions during the encoding phase, including the bilateral middle frontal and the left inferior frontal gyri (associated with executive control processes) as well as the transverse temporal gyri (associated with phonological processing). During the recognition phase, we found decreased activation in the left supramarginal gyrus and the right middle frontal gyrus in Alzheimer's disease patients compared with healthy seniors, possibly related to deficits in manipulation and decision processes for phonological information. At the same time, Alzheimer's disease patients showed increased activation in several brain areas, including the left parahippocampus and hippocampus, suggesting that Alzheimer's disease patients may recruit alternative recognition mechanisms when performing a short-term memory task. Overall, our results indicate that Alzheimer's disease patients show differences in the functional networks underlying memory over short delays, mostly in brain areas known to support phonological processing or executive functioning.

Opaque for the reader but transparent for the brain: Neural signatures of morphological complexity

Within linguistics, words with a complex internal structure are commonly assumed to be decomposed into their constituent morphemes (e.g., un-help-ful). Nevertheless, an ongoing debate concerns the brain structures that subserve this process. Using functional magnetic resonance imaging, the present study varied the internal complexity of derived words while keeping the external surface structure constant as well as controlling relevant parameters that could affect word recognition. This allowed us to tease apart brain activations specifically related to morphological processing from those related to possible confounds of perceptual cues like word length or affix type. Increased task-related activity in left inferior frontal, bilateral temporo-occipital and right parietal areas was specifically related to the processing of derivations with high complex internal structure relative to those with low complex internal structure. Our results show, that morphologically complex words are decomposed and that the brain processes the degree of internal complexity of word derivations.

Spontaneous Periodic Hypothermia and Hyperhidrosis

We present a patient diagnosed with Shapiro syndrome without corpus callosum agenesis. A 4-year-old-girl was admitted to the hospital with complaints of sweating, cooling, and drowsiness that continued during the last week of her admission. Attacks occurred almost daily, and lasted for about 1 hour. All laboratory findings, as well as Holter and echocardiography results, were normal. Cranial magnetic resonance imaging demonstrated an intact corpus callosum, and electroencephalography obtained during an attack revealed normal findings. However, technetium 99m-labeled hexamethylpropylene amine oxime brain single-photon emission computed tomography indicated increased perfusion in the right thalamus, basal ganglia, and inferior frontal areas during a hypothermic period. Although oxcarbazepine reduced the frequency of attacks, they were not halted completely. The patient responded better to carbamazepine.

Early neural activation for lexico-semantic access in the left anterior temporal area analyzed by an fMRI-assisted MEG multidipole method

To determine the time and location of lexico-semantic access, we measured neural activations by magnetoencephalography (MEG) and functional magnetic resonance imaging (fMRI) and estimated the neural sources by fMRI-assisted MEG multidipole analysis. Since the activations for phonological processing and lexico-semantic access were reported to overlap in many brain areas, we compared the activations in lexical and phonological decision tasks. The former task required visual form processing, phonological processing, and lexico-semantic access, while the latter task required only visual form and phonological processing, with similar phonological task demands for both tasks. The activation areas observed among 9 or 10 subjects out of 10 were the superior temporal and inferior parietal areas, anterior temporal area, and inferior frontal area of both hemispheres, and the left ventral occipitotemporal area. The activations showed a significant difference between the 2 tasks in the left anterior temporal area in all 50-ms time windows between 200–400 ms from the onset of visual stimulus presentation. Previous studies on semantic dementia and neuroimaging studies on normal subjects have shown that this area plays a key role in accessing semantic knowledge. The difference between the tasks appeared in common to all areas in the time windows of 100–150 ms and 400–450 ms, suggesting early differences in visual form processing and late differences in the decision process, respectively. The present results demonstrate that the activations for lexico-semantic access in the left anterior temporal area start in the time window of 200–250 ms, after early visual form processing.

Interactions of cognitive reserve with regional brain anatomy and brain function during a working memory task in healthy elders

Cognitive reserve (CR) defines the capacity of the adult brain to cope with pathology in order to minimize symptomatology. Relevant lifetime social, cognitive and leisure activities represent measurable proxies of cognitive CR but its underlying structural and functional brain mechanisms remain poorly understood. We investigated the relationship between CR and regional gray matter volumes and brain activity (fMRI) during a working memory task in a sample of healthy elders. Participants with higher CR had larger gray matter volumes in frontal and parietal regions. Conversely, a negative correlation was observed between CR and fMRI signal in the right inferior frontal cortex, suggesting increased neural efficiency for higher CR individuals. This latter association however disappeared after adjusting for gray matter images in a voxel-based manner. Altogether, present results may reflect both general and specific anatomofunctional correlates of CR in the healthy elders. Thus, whereas heteromodal anterior and posterior gray matter regions correspond to passive (i.e. morphological) correlates of CR unrelated to functional brain activation during this particular cognitive task, the right inferior frontal area reveals interactions between active and passive components of CR related to the cognitive functions tested in the fMRI study.

Auditory verbal hallucinations predominantly activate the right inferior frontal area

The pathophysiology of auditory verbal hallucinations (AVH) is largely unknown. Several functional imaging studies have measured cerebral activation during these hallucinations, but sample sizes were relatively small (one to eight subjects) and findings inconsistent. In this study cerebral activation was measured using fMRI in 24 psychotic patients while they experienced AVH in the scanner and, in another session, while they silently generated words. All patients were right handed and diagnosed with schizophrenia, schizo-affective disorder or psychotic disorder not otherwise specified. Group analysis for AVH revealed activation in the right homologue of Broca's area, bilateral insula, bilateral supramarginal gyri and right superior temporal gyrus. Broca's area and left superior temporal gyrus were not activated. Group analysis for word generation in these patients yielded activation in Broca's and Wernicke's areas and to a lesser degree their right-sided homologues, bilateral insula and anterior cingulate gyri. Lateralization of activity during AVH was not correlated with language lateralization, but rather with the degree to which the content of the hallucinations had a negative emotional valence. The main difference between cerebral activity during AVH and activity during normal inner speech appears to be the lateralization. The predominant engagement of the right inferior frontal area during AVH may be related to the typical low semantic complexity and negative emotional content.

Le cerveau aux limites du vieillissement: à propos des nonagénaires et centenaires

The elderly population represents the fastest growing age group worldwide and there is a growing awareness of age-related diseases such as dementia. By 2020 it is estimated that at least 1 billion people will be older than 60 years representing more than 20% of the total population. However, recent epidemiological studies of very old individuals have shown that prevalence rates of dementia vary from 27 to 62% pointing to the fact that dementia is not inevitable in very old individuals and that the risk of Alzheimer's disease (AD) decreases significantly after age 90, suggesting a relative resistance of centenarians to the degenerative process. Normal brain aging is characterised by the formation of neurofibrillary tangles (NFT) and senile plaques (SP), as well as neuronal and synaptic loss in both cognitively intact individuals and patients with AD. In non-demented cases neurofibrillary tangles are usually restricted to the hippocampal formation, whereas the progressive involvement of the association areas in the temporal neocortex parallels the development of overt clinical signs of dementia. In contrast, there is no correlation between the quantitative distribution of senile plaques and severity of AD. The pattern of lesion distribution and neuronal loss changes in extreme aging. Several neuropathologic analyses postulated that in contrast to younger cases where dementia is mainly related to severe NFT formation within adjacent components of the medial and inferior aspects of the temporal cortex, oldest-old individuals display a preferential involvement of the anterior part of the CA1 field of the hippocampus whereas the inferior temporal and frontal association areas are relatively spared, supposing that the extent of NFT development in the hippocampus is the key determinant of dementia in the very old. In our first series of 12 patients older than 90 years with sterological analysis we found a significant difference in NFT densities, in the anterior CA1 field, but not in the posterior CA1 field and entorhinal cortex (EC), between demented and non-demented very old patients and suggested that nonagenarians and centenarians may show a displacement of subregional distribution of NFT within the CA field. Cortical association areas were relatively preserved. The progression of NFT formation across the different CDR groups was significantly slower in nonagenarians and centenarians compared to younger cases in the CA1 field and EC; even cases with moderate dementia display only mild NFT formation in this area with more than 80% of preserved neurons. The total amyloid and the neuronal loss in the entorhinal cortex and CA1 field in these cases were also significantly lower than that reported in younger AD cases. In a second stereologic study of 19 very old individuals with various degrees of cognitive impairment we also assessed total capillary length, number and length-weighted mean diameters in the CA1 and entorhinal cortex. Both mean diameters and total capillary numbers, but no capillary length, were strongly related to total neuron numbers in the CA1 field and entorhinal cortex. In conclusion, the most intriguing results of these studies were the relative paucity of correlations between AD pathological hallmarks in the hippocampal formation and clinical status after 90 years and the clear dissociation between total neuron numbers and AD-related lesions in the hippocampal formation. Microvascular parameters such as mean capillary diameters may be a key factor to consider for the prediction of cognitive decline in the oldest-old.

Spontaneous neural activity during human slow wave sleep.

Slow wave sleep (SWS) is associated with spontaneous brain oscillations that are thought to participate in sleep homeostasis and to support the processing of information related to the experiences of the previous awake period. At the cellular level, during SWS, a slow oscillation (<1 Hz) synchronizes firing patterns in large neuronal populations and is reflected on electroencephalography (EEG) recordings as large-amplitude, low-frequency waves. By using simultaneous EEG and event-related functional magnetic resonance imaging (fMRI), we characterized the transient changes in brain activity consistently associated with slow waves (>140 microV) and delta waves (75-140 microV) during SWS in 14 non-sleep-deprived normal human volunteers. Significant increases in activity were associated with these waves in several cortical areas, including the inferior frontal, medial prefrontal, precuneus, and posterior cingulate areas. Compared with baseline activity, slow waves are associated with significant activity in the parahippocampal gyrus, cerebellum, and brainstem, whereas delta waves are related to frontal responses. No decrease in activity was observed. This study demonstrates that SWS is not a state of brain quiescence, but rather is an active state during which brain activity is consistently synchronized to the slow oscillation in specific cerebral regions. The partial overlap between the response pattern related to SWS waves and the waking default mode network is consistent with the fascinating hypothesis that brain responses synchronized by the slow oscillation restore microwake-like activity patterns that facilitate neuronal interactions.

Gender-specific strategy use and neural correlates in a spatial perspective taking task

In the context of the present study spatial perspective taking refers to the ability to translocate one's own egocentric viewpoint to somebody else's viewpoint in space. We adopted a spatial perspective taking paradigm and performed a functional magnetic resonance imaging study to assess gender differences of neural activity during perspective taking. 24 healthy subjects (12 male/12 female) were asked to systematically either take their own (first-person-perspective, 1PP) or another person's perspective (third-person-perspective, 3PP). Presented stimuli consisted of a virtual scenery with an avatar and red balls around him that had to be counted, if visible, from 1PP or 3PP. Reaction time was increased and correctness scores were decreased during the cognitively more effortful 3PP condition. Correctness scores showed a trend towards a more pronounced decline of performance during 3PP as compared to 1PP in female subjects. Female subjects correctness scores declined by 6.7% from 1PP to 3PP, while in male subjects this performance decline was only 2.7%. Debriefings after the experiment, reaction times depending on angle of rotation and error rates suggest that males are more likely to employ an object-based strategy in contrast to a consistently employed egocentric perspective transformation in females. In the whole group, neural activity was increased in the parieto-occipital, right inferior frontal and supplementary motor areas, confirming previous studies. With respect to gender, male subjects showed stronger activation in the precuneus and the right inferior frontal gyrus than female subjects in a region-of-interest approach. In a subgroup of male subjects whose strategy reports suggest object-based strategies these differences seem to be more pronounced. In conclusion, the differential recruitment of brain regions most likely reflects different strategies in solving this spatial perspective taking task.