Dear fellow neuroscientists,
We would like to invite you to join us on Tuesday, January 18 at 1:00 pm EST (UTC-5) for the next edition of E.A.R.S. (Electronic Auditory
Research Seminars), a monthly auditory seminar series with the focus on central auditory processing and circuits. Please pre-register (for free) and tune in via Crowdcast (enter your email to receive the link for the talk): https://www.crowdcast.io/e/ears/14
(Note: for optimal performance, we recommend using Google Chrome as your browser).
Dr. Kerry Walker (University of Oxford):
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"Hearing in an acoustically varied world"
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In order for animals to thrive in their complex environments, their sensory systems must form representations of objects that are invariant to changes in some dimensions of their physical cues. For example, we can recognize a
friend’s speech in a forest, a small office, and a cathedral, even though the sound reaching our ears will be very different in these three environments. I will discuss our recent experiments into how neurons in auditory cortex can form stable representations
of sounds in this acoustically varied world. We began by using a normative computational model of hearing to examine how the brain may recognize a sound source across rooms with different levels of reverberation. The model predicted that reverberations can
be removed from the original sound by delaying the inhibitory component of spectrotemporal receptive fields in the presence of stronger reverberation. Our electrophysiological recordings then confirmed that neurons in ferret auditory cortex apply this algorithm
to adapt to different room sizes. Our results demonstrate that this neural process is dynamic and adaptive. These studies provide new insights into how we can recognize auditory objects even in highly reverberant environments, and direct further research questions
about how reverb adaptation is implemented in the cortical circuit.
Dr. Lizabeth Romanski (University of Rochester):
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“Investigation of Identity and _expression_ Processing in Ventrolateral Prefrontal Cortex”
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Previous studies have demonstrated that the ventrolateral prefrontal cortex (VLPFC) processes and integrates social communication information including faces and vocalizations. Features embedded within audiovisual stimuli, including
emotional _expression_ and caller identity, provide abundant information about an individual’s intention, emotional state, motivation, and social status, which are important to encode in a social exchange. However, it is unknown to what extent the VLPFC encodes
such features. We examined the responses of VLPFC neurons to face and vocal stimuli which differed by either identity or _expression_. First, we recorded single-unit activity while macaques performed a discrimination task using species-specific face+vocalization
stimuli. We found that a large proportion of VLPFC cells demonstrated a significant change in activity during the sample, delay, or nonmatch task periods of the task while a subset of neurons was modulated by the identity, emotional _expression_, or both features,
within the face-vocalization stimuli. In further recordings, we explored the population coding of identity and _expression_ in response to naturalistic vocalization movie stimuli by VLPFC neurons. Linear Discriminant Analysis of single cell firings rates revealed
greater than chance decoding of _expression_ and identity. Time binned decoding of the pseudo-population resulted in early and sustained identity decoding accuracy compared to _expression_. Analysis of the locations of identity and _expression_ related cells in
recorded VLPFC neurons indicated that fewer neurons showed significant responses related to _expression_ and these cells were concentrated in the most anterolateral quadrant of the recording area, approximately area 12vl, whereas identity related cells were
more widespread in VLPFC. These findings indicate a role for VLPFC in the processing of identity and _expression_ in social communication stimuli and suggest differences between anterolateral and posterior regions of VLPFC.
Additional upcoming E.A.R.S. seminars (1:00 pm ET):
February 15:
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Ioana Carcea (Rutgers University)
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Liberty Hamilton (University of Texas at Austin)
March 15:
April 19:
May 10:
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Diego Elgueda (University of Chile)
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Narayan Sankaran (University of California San Francisco)
With kind wishes,
Maria Geffen
Yale Cohen
Steve Eliades
Stephen David
Alexandria Lesicko
Nathan Vogler
Jean-Hugues Lestang
Huaizhen Cai
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