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.
Gap encoding by parvalbumin-expressing interneurons in auditory cortex.
J Neurophysiol. 2018 Mar 28;:
Authors: Keller CH, Kaylegian K, Wehr M
Synaptic inhibition shapes the temporal processing of sounds in auditory cortex, but the contribution of specific inhibitory cell types to temporal processing remains unclear. Here we recorded from parvalbumin-expressing (PV+) interneurons in auditory cortex to determine how they encode gaps in noise, a model of temporal processing more generally. We found that PV+ cells had stronger and more prevalent on-responses, off-responses, and post-response suppression compared to presumed pyramidal cells. We summarize this pattern of differences as "deeper modulation" of gap responses in PV+ cells. Response latencies were also markedly faster for PV+ cells. We found a similar pattern of deeper modulation and faster latencies for responses to white noise bursts, suggesting that these are general properties of on- and off-responses in PV+ cells rather than specific features of gap encoding. These findings are consistent with a role for PV+ cells in providing dynamic gain control by pooling local activity.
PMID: 29589814 [PubMed - as supplied by publisher]
Rapid Rebalancing of Excitation and Inhibition by Cortical Circuitry.
Neuron. 2018 Feb 16;:
Authors: Moore AK, Weible AP, Balmer TS, Trussell LO, Wehr M
Excitation is balanced by inhibition to cortical neurons across a wide range of conditions. To understand how this relationship is maintained, we broadly suppressed the activity of parvalbumin-expressing (PV+) inhibitory neurons and asked how this affected the balance of excitation and inhibition throughout auditory cortex. Activating archaerhodopsin in PV+ neurons effectively suppressed them in layer 4. However, the resulting increase in excitation outweighed Arch suppression and produced a net increase in PV+ activity in downstream layers. Consequently, suppressing PV+ neurons did not reduce inhibition to principal neurons (PNs) but instead resulted in a tightly coordinated increase in both excitation and inhibition. The increase in inhibition constrained the magnitude of PN spiking responses to the increase in excitation and produced nonlinear changes in spike tuning. Excitatory-inhibitory rebalancing is mediated by strong PN-PV+ connectivity within and between layers and is likely engaged during normal cortical operation to ensure balance in downstream neurons.
PMID: 29503186 [PubMed - as supplied by publisher]
Vision Drives Accurate Approach Behavior during Prey Capture in Laboratory Mice.
Curr Biol. 2016 Nov 21;26(22):3046-3052
Authors: Hoy JL, Yavorska I, Wehr M, Niell CM
The ability to genetically identify and manipulate neural circuits in the mouse is rapidly advancing our understanding of visual processing in the mammalian brain [1, 2]. However, studies investigating the circuitry that underlies complex ethologically relevant visual behaviors in the mouse have been primarily restricted to fear responses [3-5]. Here, we show that a laboratory strain of mouse (Mus musculus, C57BL/6J) robustly pursues, captures, and consumes live insect prey and that vision is necessary for mice to perform the accurate orienting and approach behaviors leading to capture. Specifically, we differentially perturbed visual or auditory input in mice and determined that visual input is required for accurate approach, allowing maintenance of bearing to within 11° of the target on average during pursuit. While mice were able to capture prey without vision, the accuracy of their approaches and capture rate dramatically declined. To better explore the contribution of vision to this behavior, we developed a simple assay that isolated visual cues and simplified analysis of the visually guided approach. Together, our results demonstrate that laboratory mice are capable of exhibiting dynamic and accurate visually guided approach behaviors and provide a means to estimate the visual features that drive behavior within an ethological context.
PMID: 27773567 [PubMed - indexed for MEDLINE]