Mechanisms of callosal input regulating primary auditory cortex sensory processing

Title: Interhemispheric Callosal Projections Sharpen Frequency Tuning and Enforce Response Fidelity in Primary Auditory Cortex

Journal: eNeuron.2020 Aug 17;7(4): ENEURON.0256-20.2020

Link: https://www.eneuro.org/content/7/4/ENEURO.0256-20.2020

Comments: Each hemifield of a sensory modality in most sensory system is primarily represented in the contralateral hemisphere of the brain. Sensory areas of a specific pattern in the two cortices are connected to each other depending on the interhemispheric projection of axons in the corpus callosum. Past studies have proven that cortical sensory representations driven by thalamic input and long-range projections including interhemispheric inputs. However, it is still unknown how does callosum pathway participate in sensory coding in vivo.

In this study, the authors applied linear silicon probe and optogenetic approaches in awake mouse to examine the mechanisms of callosal input modulating primary auditory area (A1) in sensory processing. By performing these techniques, the results led to three major discovers; first, callosal input regulates sound-evoked responses by multiplicative and subtractive effects. Second, callosal input enhances the representations of tone responses associate with spontaneous activity in A1. Third, enforcing the sharpness of frequency tuning in A1 depends largely on callosal input.

The above findings will be conducive to further clarify the mechanism between callosal input and binaural cortex sound representations and auditory-directed behavior.