Amber Zhuang

Research Mentor(s): Pierre Apostolides
Mentor Department:
Authors:
Session: Session 2 (10:00am – 10:50am)
Presentation Type: Poster 5

Abstract

Sensory cortices in the brain project information to subcortical regions using pathways that are critical for both sensory perception and behavioral outcomes. “Corticofugal” neurons in the cortex play a large role in these cortex-to-subcortex projections. Specifically for auditory signals, both corticofugal neurons in the auditory cortex, as well as neurons on the exterior of the inferior colliculus, have been shown to have an increase in activity during sound discrimination and behavioral response– the inferior colliculus (IC) being a crucial subcortical structure that auditory signals must pass through before reaching the forebrain. However, the specificities of the projection from the auditory cortex to the IC have previously only been studied in either anesthetized or passively listening mice. We sought to better understand this pathway and connections between these regions by having water-deprived and head-fixed mice actively engage in a GO/NO-GO sound discrimination task. We then used 2-photon Ca2+ imaging to record IC neuron activity in task-engaged mice and silenced auditory cortex activity using optogenetics on a subset of trials. We find that signals from the auditory cortex contribute to both auditory and non-auditory activity in the IC. Dimensionality reduction analyses further indicate that cortical silencing reduces the trial outcome-specific differences in IC population activity. Interestingly, however, cortical silencing does not fully abolish task-relevant activity patterns. This persistence of task-relevant activity in the IC despite silencing the auditory cortex implies that neurons in the IC obtain information from several sources, laying the groundwork for future research examining other potential regions that may play a role in its activation.