Associate Professor, Department of Psychology
Ph.D. California Institute of Technology
Sc.B. Brown University
Research Interests: How local circuits in the auditory cortex encode and transform sensory information
Overview: We study how local circuits in the cerebral cortex encode and transform sensory information. We use the rodent auditory cortex as a model system to investigate how cellular and network properties shape cortical responses to a continuous and temporally complex stream of sensory data. Research in my laboratory combines aspects of both cellular, systems, and computational neuroscience, by using the tools of molecular biology and cellular physiology to address systems-level questions. By using a variety of electrophysiological approaches, in particular in vivo whole cell recording methods in combination with molecular manipulations, we are trying to identify the cellular and synaptic mechanisms with which cortical circuits process auditory information, leading ultimately to our perceptual experiences of acoustic streams, such as music and speech.
Auditory Cortex Contributes to Discrimination of Pure Tones.
eNeuro. 2019 Sep/Oct;6(5):
Authors: O'Sullivan C, Weible AP, Wehr M
The auditory cortex is topographically organized for sound frequency and contains highly selective frequency-tuned neurons, yet the role of auditory cortex in the perception of sound frequency remains unclear. Lesion studies have shown that auditory cortex is not essential for frequency discrimination of pure tones. However, transient pharmacological inactivation has been reported to impair frequency discrimination. This suggests the possibility that successful tone discrimination after recovery from lesion surgery could arise from long-term reorganization or plasticity of compensatory pathways. Here, we compared the effects of lesions and optogenetic suppression of auditory cortex on frequency discrimination in mice. We found that transient bilateral optogenetic suppression partially but significantly impaired discrimination performance. In contrast, bilateral electrolytic lesions of auditory cortex had no effect on performance of the identical task, even when tested only 4 h after lesion. This suggests that when auditory cortex is destroyed, an alternative pathway is almost immediately adequate for mediating frequency discrimination. Yet this alternative pathway is insufficient for task performance when auditory cortex is intact but has its activity suppressed. These results indicate a fundamental difference between the effects of brain lesions and optogenetic suppression, and suggest the existence of a rapid compensatory process possibly induced by injury.
PMID: 31591138 [PubMed - indexed for MEDLINE]
A Cortico-Collicular Amplification Mechanism for Gap Detection.
Cereb Cortex. 2020 Feb 14;:
Authors: Weible AP, Yavorska I, Wehr M
Auditory cortex (AC) is necessary for the detection of brief gaps in ongoing sounds, but not for the detection of longer gaps or other stimuli such as tones or noise. It remains unclear why this is so, and what is special about brief gaps in particular. Here, we used both optogenetic suppression and conventional lesions to show that the cortical dependence of brief gap detection hinges specifically on gap termination. We then identified a cortico-collicular gap detection circuit that amplifies cortical gap termination responses before projecting to inferior colliculus (IC) to impact behavior. We found that gaps evoked off-responses and on-responses in cortical neurons, which temporally overlapped for brief gaps, but not long gaps. This overlap specifically enhanced cortical responses to brief gaps, whereas IC neurons preferred longer gaps. Optogenetic suppression of AC reduced collicular responses specifically to brief gaps, indicating that under normal conditions, the enhanced cortical representation of brief gaps amplifies collicular gap responses. Together these mechanisms explain how and why AC contributes to the behavioral detection of brief gaps, which are critical cues for speech perception, perceptual grouping, and auditory scene analysis.
PMID: 32055848 [PubMed - as supplied by publisher]