Bidirectional Connectivity between Hemispheres Occurs at Multiple Levels in Language Processing But Depends on Sex
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Our aim was to determine the direction of interhemispheric communication in a phonological task in regions involved in different levels of processing. Effective connectivity analysis was conducted on functional magnetic resonance imaging data from 39 children (ages 9-15 years) performing rhyming judgment on spoken words. The results show interaction between hemispheres at multiple levels. First, there is unidirectional transfer of information from right to left at the sensory level of primary auditory cortex. Second, bidirectional connections between superior temporal gyri (STGs) suggest a reciprocal cooperation between hemispheres at the level of phonological and prosodic processing. Third, a direct connection from right STG to left inferior frontal gyrus suggest that information processed in the right STG is integrated into the final stages of phonological segmentation required for the rhyming decision. Intrahemispheric connectivity from primary auditory cortex to STG was stronger in the left compared to the right hemisphere. These results support a model of cooperation between hemispheres, with asymmetric interhemispheric and intrahemispheric connectivity consistent with the left hemisphere specialization for phonological processing. Finally, we found greater interhemispheric connectivity in girls compared to boys, consistent with the hypothesis of a more bilateral representation of language in females than males. However, interhemispheric communication was associated with slow performance and low verbal intelligent quotient within girls. We suggest that females may have the potential for greater interhemispheric cooperation, which may be an advantage in certain tasks. However, in other tasks too much communication between hemispheres may interfere with task performance.Keywords:
Inferior frontal gyrus
Right hemisphere
Superior temporal gyrus
Gyrus
Right hemisphere
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Modality (human–computer interaction)
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There are two well-known hypotheses regarding hemispheric lateralization of emotions. The Right Hemisphere Hypothesis (RHH) postulates that emotions and associated display behaviors are a dominant and lateralized function of the right hemisphere. The Valence Hypothesis (VH) posits that negative emotions and related display behaviors are modulated by the right hemisphere and positive emotions and related display behaviors are modulated by the left hemisphere. Although both the RHH and VH are supported by extensive research data, they are mutually exclusive, suggesting that there may be a missing factor in play that may provide a more accurate description of how emotions are lateralization in the brain. Evidence will be presented that provides a much broader perspective of emotions by embracing the concept that emotions can be classified into primary and social types and that hemispheric lateralization is better explained by the Emotion-type Hypothesis (ETH). The ETH posits that primary emotions and related display behaviors are modulated by the right hemisphere and social emotions and related display behaviors are modulated by the left hemisphere.
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Right hemisphere
Depression
Cortical Spreading Depression
Cerebral hemisphere
Expression (computer science)
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Cerebral lateralization of global-local processing of 70 left-handed and 70 right-handed students was compared using a computerized global-local task in a half-visual field paradigm. Analysis showed that left-handed individuals were slower than right-handed individuals in processing Globally Directed stimuli presented to the left visual field (right hemisphere). In addition, left-handed individuals showed smaller local superiority in the left hemisphere to the right-handed individuals. These findings are more consistent with Levy's prediction of spatial inferiority of left-handed individuals than Geschwind and Galaburda's or Annett's hypotheses.
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Objective To explore the role of thalamus in analgesia induced by transcutaneous acupoint electrical stimulation(TAES).Methods 14(7 male,7 female) healthy right-handed volunteers received functional magnetic resonance imaging(fMRI) scan before and after TAES respectively.Thalamus was as the region of interest(ROI).All the processing works were carried out using the Statistical Parametric Mapping.Results Compared with the basic state,significantly weaker functional connectivity was mainly found in the region of bilateral precuneus gyrus,bilateral superior gyrus of parietal lobe,the inferior gyrus of left temporal,the middle gyrus of right temporal and the middle gyrus of right frontal;while significantly greater functional connectivity was found in bilateral cerebellum,bilateral insula,the basal ganglia,inferior gyrus of bilateral frontal,the orbital gyrus of left frontal,the superior gyrus of left temporal(P0.005,cluster10 mm3) after TAES.Conclusion Thalamus plays a key role in the central analgesia induced by TAES,which may associate with the functonal connectivity between thalamus and the regions of cerebellum,precuneus gyrus,insula,the basal ganglia,superior gyrus of parietal lobe,the orbital,middle and inferior gyrus of frontal lobe and the temporal lobe.
Limbic lobe
Inferior frontal gyrus
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Superior temporal gyrus
Middle frontal gyrus
Middle temporal gyrus
Inferior temporal gyrus
Angular gyrus
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Cerebral hemisphere
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