Interhemispheric interzonal connections in the parietal cortex

Area of Science:

• Neuroscience
• Comparative Physiology

Background:

• The parietal associative cortex plays a crucial role in integrating sensory information.
• Transcallosal responses (TCRs) provide insights into interhemispheric communication between cortical regions.

Purpose of the Study:

• To investigate transcallosal responses (TCRs) in the parietal associative cortex of cats following stimulation of the visual or auditory cortex.
• To characterize the forms, pathways, and interhemispheric asymmetries of these responses.

Main Methods:

• Acute experiments on immobilized cats.
• Stimulation of the visual or auditory cortex and recording of transcallosal responses in the parietal associative region.
• Surgical section of the corpus callosum and intracortical pathways to assess response origins.

Main Results:

• Two forms of heterotopical TCRs were identified: positive-negative and negative-positive.
• Negative-positive TCRs relied on the corpus callosum and intracortical pathways, while positive-negative responses were more resilient to sectioning.
• Significant interhemispheric asymmetries were found in both visual-parietal and audioparietal TCRs, with variations based on stimulus modality, response component, sex, and hemisphere.

Conclusions:

• The parietal associative cortex exhibits distinct response patterns and interhemispheric asymmetries in processing visual and auditory information via TCRs.
• These findings suggest a potential symmetricizing function of the parietal associative cortex in integrating sensory information across hemispheres.