(sagittal), became available to clinicians and brain scientists only in the last decade. In (a), the dotted line demarcates the temporal lobe (T); the top portion (superior surface) of the temporal lobe houses the auditory area in man. In (b), the arrows indicate the extent of the corpus callosum, the semilunar bundle of nerve fibers which connects the left and right hemispheres. In split-brain patients, the callosum is cut.

Six experiments explored hemispheric memory differences in a patient who had undergone complete corpus callosum resection The right hemisphere was better able than the left to reject new events similar to originally presented materials of several types, including abstract visual forms, faces, and categorized lists of words Although the left hemisphere is capable of mental manipulation, imagination, semantic priming, and complex language production, these functions are apparently linked to memory confusions—confusions less apparent in the more literal right hemisphere Differences between the left and right hemispheres in memory for new schematically consistent or categorically related events may provide a source of information allowing people to distinguish between what they actually witnessed and what they only inferred

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Effect of corpus callosum agenesis on the language network in children and adolescents

Brain Structure and Function ◽

10.1007/s00429-020-02203-6 ◽

2021 ◽

Author(s):

Lisa Bartha-Doering ◽

Ernst Schwartz ◽

Kathrin Kollndorfer ◽

Florian Ph. S. Fischmeister ◽

Astrid Novak ◽

...

Keyword(s):

Functional Connectivity ◽

Corpus Callosum ◽

Network Connectivity ◽

Functional Language ◽

Healthy Controls ◽

Language Abilities ◽

Verbal Abilities ◽

Left And Right ◽

Language Network

AbstractThe present study is interested in the role of the corpus callosum in the development of the language network. We, therefore, investigated language abilities and the language network using task-based fMRI in three cases of complete agenesis of the corpus callosum (ACC), three cases of partial ACC and six controls. Although the children with complete ACC revealed impaired functions in specific language domains, no child with partial ACC showed a test score below average. As a group, ACC children performed significantly worse than healthy controls in verbal fluency and naming. Furthermore, whole-brain ROI-to-ROI connectivity analyses revealed reduced intrahemispheric and right intrahemispheric functional connectivity in ACC patients as compared to controls. In addition, stronger functional connectivity between left and right temporal areas was associated with better language abilities in the ACC group. In healthy controls, no association between language abilities and connectivity was found. Our results show that ACC is associated not only with less interhemispheric, but also with less right intrahemispheric language network connectivity in line with reduced verbal abilities. The present study, thus, supports the excitatory role of the corpus callosum in functional language network connectivity and language abilities.

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M146. NEUROCHEMICAL MODULATION OF AUDITORY CORTEX FUNCTIONAL CONNECTIVITY IN PATIENTS WITH AUDITORY VERBAL HALLUCINATIONS

Schizophrenia Bulletin ◽

10.1093/schbul/sbaa030.458 ◽

2020 ◽

Vol 46 (Supplement_1) ◽

pp. S191-S191

Author(s):

Sarah Weber ◽

Helene Hjelmervik ◽

Alexander R Craven ◽

Erik Johnsen ◽

Rune Kroken ◽

...

Keyword(s):

Functional Connectivity ◽

Temporal Lobe ◽

Superior Temporal Gyrus ◽

Underlying Mechanism ◽

Auditory Hallucinations ◽

Anterior Cingulate ◽

Gamma Aminobutyric Acid ◽

Auditory Verbal Hallucinations ◽

Left And Right ◽

Neurochemical Correlates

Abstract Background Auditory hallucinations have been linked to aberrant functioning of the left superior temporal gyrus (STG) and are associated with impaired cognitive control regulated by areas in the prefrontal cortex. However, the mechanisms behind these dysfunctions are still unclear. Methods The current study combined resting state connectivity fMRI with MR spectroscopy (MRS) in a sample of 81 psychosis patients to explore how neurochemical correlates of auditory hallucinations modulate left STG functioning. The analyses were focused on glutamate (Glu) and gamma-aminobutyric acid (GABA), two neurotransmitters with excitatory and inhibitory functions, respectively, since these have previously been implicated in psychosis. Results Glu and GABA showed differential relationships with left STG connectivity in patients with and without hallucinations. Specifically, Glu concentration in the anterior cingulate cortex (ACC) was positively related to functional connectivity between the left and right temporal lobe in hallucinating patients only. In contrast, GABA concentration in the ACC was negatively related to connectivity between the left and right temporal lobe in non-hallucinating patients only. Discussion These findings support a recently proposed model of interhemispheric temporal lobe miscommunication in auditory hallucinations and indicate prefrontal neurochemical modulation as a potential underlying mechanism. The results can further be integrated with previously suggested excitatory/inhibitory imbalances as neurochemical modulators in AVH.

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The Causal Role of Left and Right Superior Temporal Gyri in Speech Perception in Noise: A Transcranial Magnetic Stimulation Study

Journal of Cognitive Neuroscience ◽

10.1162/jocn_a_01521 ◽

2020 ◽

Vol 32 (6) ◽

pp. 1092-1103 ◽

Cited By ~ 3

Author(s):

Dan Kennedy-Higgins ◽

Joseph T. Devlin ◽

Helen E. Nuttall ◽

Patti Adank

Keyword(s):

Speech Perception ◽

Side Effects ◽

Temporal Lobe ◽

Language Processing ◽

Background Noise ◽

Superior Temporal Gyrus ◽

Left Temporal Lobe ◽

Neural Organization ◽

Left And Right ◽

Listening Strategies

Successful perception of speech in everyday listening conditions requires effective listening strategies to overcome common acoustic distortions, such as background noise. Convergent evidence from neuroimaging and clinical studies identify activation within the temporal lobes as key to successful speech perception. However, current neurobiological models disagree on whether the left temporal lobe is sufficient for successful speech perception or whether bilateral processing is required. We addressed this issue using TMS to selectively disrupt processing in either the left or right superior temporal gyrus (STG) of healthy participants to test whether the left temporal lobe is sufficient or whether both left and right STG are essential. Participants repeated keywords from sentences presented in background noise in a speech reception threshold task while receiving online repetitive TMS separately to the left STG, right STG, or vertex or while receiving no TMS. Results show an equal drop in performance following application of TMS to either left or right STG during the task. A separate group of participants performed a visual discrimination threshold task to control for the confounding side effects of TMS. Results show no effect of TMS on the control task, supporting the notion that the results of Experiment 1 can be attributed to modulation of cortical functioning in STG rather than to side effects associated with online TMS. These results indicate that successful speech perception in everyday listening conditions requires both left and right STG and thus have ramifications for our understanding of the neural organization of spoken language processing.

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