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NSC 503 Seminar

Shraddha Shah, Uday Chockanathan - PhD Candidate

Faculty Evaluators:  Kuan Hong Wang, Lizabeth Romanski

Student Moderator:  Allison Murphy

 Sep 20, 2021 @ 4:00 p.m.

Functional role of extrastriate corticogeniculate neurons in intact and V1-lesion animals

Matthew Adusei - PhD Candidate

Thesis Proposal - Advisor: Farran Briggs, PhD

In the visual system, geniculocortical projection neurons in the visual thalamus, the dorsal lateral geniculate nucleus (LGN), convey distinct visual information coming from the retina mainly to the primary visual cortex (V1) (Callaway 2005, Kaplan 2004, Sherman & Guillery 2006). From V1, visual information is passed on to extrastriate cortical areas along the visual cortical hierarchy (Felleman & Van Essen 1991). However, there are sparse V1-bypassing projections from the LGN to extrastriate visual cortical areas which are thought to originate primarily from cells within the koniocellular and C layers of the LGN (Dell et al 2018, Lyon & Rabideau 2012, Lysakowski et al 1988, Sherk 1986, Sincich et al 2004, Tong et al 1982). Visual perception likely involves reciprocal feedback circuits connecting the cortex with the LGN, which complement the feedforward geniculocortical projections. Using virus-mediated retrograde tracing techniques, we have identified and characterized multiple morphologically distinct corticogeniculate subtypes, predominantly in area 17 (V1) and area 18 (V2) (Briggs et al 2016, Hasse et al 2019), as well as in extrastriate visual cortical areas V4, MT and MST in macaques, and area 21a, PMLS, and PLLS, in ferrets. Physiological evidence based on axon conduction latencies and visual responses properties suggests that distinct V1 corticogeniculate subtypes align with the feedforward parallel processing streams (Briggs & Usrey 2005, Briggs & Usrey 2007, Briggs & Usrey 2009). Whether extrastriate corticogeniculate neurons are similarly functionally distinct and stream-specific is not known. Importantly, the presence of complementary, reciprocal, V1-independent connections between the LGN and extrastriate visual cortex, in ferrets and macaques, could provide a substrate for residual vision following V1 damage.
For my thesis project, I will investigate the functional role of the corticogeniculate feedback circuits that connect extrastriate visual areas with the LGN. I will investigate this by pursuing two aims using ferrets as an animal model. The first aim will investigate the functional role of extrastriate corticogeniculate neurons in regulating the activity of LGN neurons in the intact animal using a combination of virus-mediated gene delivery, optogenetics and electrophysiology. I hypothesize that extrastriate corticogeniculate neurons connect to LGN neurons in a stream-specific manner, consistent with our morphological data. I hypothesize that optogenetic activation of extrastriate corticogeniculate neurons will reduce response latencies and increase spike-timing precision among LGN neurons to which they connect. After shorter (~1 week, acute) and longer (~1 month, chronic) durations following V1 lesions, I hypothesize that there will be a progressive increase in the activity of extrastriate corticogeniculate neurons aligned with the W stream (similar to koniocellular stream) compared to intact animals. This hypothesis is supported by results from Schmid et al. (2009) suggesting that the koniocellular V1-bypassing pathway may be strengthened from a modulatory to a driving role post V1-damage. In the second aim, we will explore physiological changes among LGN, PMLS, PLLS, and area 21a neurons over time following V1 lesions. We will train ferrets to discriminate contrast, temporal frequency, spatial frequency, and direction changes among moving visual stimuli. We hypothesize that physiological changes in each area may depend on the type of visual discrimination tasks performed by the animals. Furthermore, we predict that changes in physiological properties of extrastriate corticogeniculate neurons following V1 lesions (observed in Aim 1) may dictate the changes we observe in the LGN and extrastriate areas. Altogether, these results will help us assess the functional significance of sparse extrastriate corticogeniculate projections, and

 Sep 24, 2021 @ 1:00 p.m.

Host: Univ. Rochester Med. Center: The Neuroscience Graduate Program

NSC 503 Seminars

Karl Foley, Keshov Sharma - PhD Candidate

Faculty Evaluators:  Doug Portman, Farran Briggs

Student Moderator:  Berke Karaahmet

 Sep 27, 2021 @ 4:00 p.m.

Physiological and Computational-Modeling Studies of Timbre Encoding in the Inferior Colliculus

Johanna Fritzinger - PhD Candidate, Thesis Proposal - Advisor: Laurel Carney, PhD

Timbre, the quality that allows sounds to be distinguished when they are identical in pitch, level, and duration, is a critical aspect of speech comprehension and music enjoyment. My proposal will fill a gap in neural studies of timbre by investigating how underlying mechanisms of encoding lead to robust representations of suprathreshold synthetic and natural instrument timbre in the inferior colliculus (IC). To test our hypotheses, we will record single-unit IC responses from awake Dutch-belted rabbits. We will also develop a new computational IC model based on physiological responses.
The spectral envelope of a harmonic sound is correlated with the timbral perception of “brightness”. We propose two mechanisms that contribute to spectral envelope encoding in the IC: capture and off-characteristic frequency (CF) inhibition. The first mechanism, capture, refers to a reduction of neural fluctuations, or the low-frequency changes in firing rate, of auditory-nerve fibers. Capture occurs when inner-hair-cell responses saturate due to a tone presented near their CF. IC neurons are sensitive to neural fluctuations, as characterized by modulation transfer functions in response to amplitude-modulated sounds. Preliminary results indicate that spectral peaks of synthetic timbre stimuli capture peripheral responses, leading to a rate representation of salient spectral features in the midbrain. The second mechanism is off-CF inhibition, which has been proposed to explain frequency-sweep sensitivity and psychophysical forward masking. Exciting preliminary responses to wideband tone-in-noise stimuli show inhibitory sidebands consistent with off-CF inhibition. A computational model that features capture, but not off-CF inhibition, was not able to predict responses to wideband tone-in-noise, indicating the need to add complexity to the model.
We have designed a set of experiments to test the hypothesis that the timbre of synthetic and instrument sounds is robustly encoded in the midbrain via capture and off-CF inhibition. In Aim 1, we hypothesize that the influences of capture and off-CF inhibition can be teased apart by recording single-unit responses to binaural or contralateral wideband tone-in-noise stimuli. We will update our computational model of the IC by adding off-CF inhibition and fitting the model to physiological responses. Aim 2 will test the hypothesis that the spectral peak of a shaped harmonic complex, synthetic timbre, is robustly encoded in the inferior colliculus over a range of suprathreshold levels. Aim 3 bridges the gap between synthetic and natural timbre by recording physiological responses to real instrument sounds. Responses from Aim 1 and Aim 2 will be used to further test the accuracy of the off-CF inhibition model. This project will provide insight on suprathreshold encoding of timbre, and the computational models created can be used for further research into hearing loss. Currently hearing aids and cochlear implants are not able to convey timbre well, and this research could lead to the improvement of these devices.

 Sep 29, 2021 @ 11:00 a.m.

Host: Neuroscience Graduate Program

The Role of Parvalbumin-expressing Inhibitory Interneurons on Spike Synchrony Between Feature Encoding Neurons of the Somatosensory Cortex

Michael Duhain - PhD Candidate, Thesis Proposal - Advisers: Manuel Gomex-Ramirez & Kuan Wang

Object sensing and manipulation (i.e. haptics) requires discriminating a myriad of tactile features through the sense of touch. Key to this process are mechanisms of feature-based attention, which provide preferential processing of attended sensory features, while filtering out sensory information encoding non-relevant features. A previous study showed that selection of behaviorally relevant features is represented in the synchronized spiking between neurons tuned for the attended feature. The study further showed that increases in synchronized spiking were associated with enhanced performance. Yet, although this study showed how the brain enables selection of neural signals encoding the relevant features in the somatosensory system, the underlying circuit mechanism generating this feature-specific spike synchrony effect is yet to be elucidated. Fast scale coordinated spiking in neuronal populations is thought to be mediated by the activity of parvalbumin (PV) expressing inhibitory interneurons. Furthermore, in visual cortex, PV neurons are known to selectively respond to visual features (e.g., orientation and spatial frequency). Based on these findings, I propose that feature-specific spike synchrony in the somatosensory system is generated by a parvalbumin (PV) and pyramidal microcircuit (PvPy), whose cells are tuned for the same tactile feature. In this circuit, feature tuned PV interneurons generate inhibition of similarly tuned excitatory cells that is followed by a short window of high spiking probability between feature tuned pyramidal ensembles. I hypothesize that feature selection controls the coordinated spiking dynamics within a PvPy circuit to enhance representations of selected features in local neuronal populations, and facilitate interareal communication between functional subgroups in primary (S1) and secondary (S2) somatosensory cortex. To test the validity of this circuit and its dynamics, I trained mice to perform a 2-alternative forced-choice task that requires a response to a change in vibration frequency of a tactile stimulus delivered to the forepaws. Animals are visually cued to discriminate stimuli at one paw, while ignoring all stimuli at the uncued paw. In aim 1 of this project, I systematically test that the proposed PvPy circuit generates feature-specific spike synchrony effects in S1. In aim 2, I test how feature-specific spike synchrony drives interareal communication between functional subgroups of neurons. These aims will be accomplished in behaving animals through a series of experiments consisting of electrophysiological recordings with multi-laminar electrode arrays, in vivo 2-photon calcium imaging of specific neuronal populations, and optogenetics. Overall, this project aims to critically evaluate the presence of a novel functional circuit (PvPy) within somatosensory cortex that implements feature-based attention to enable preferential processing of selected features within local and across cortical areas.

 Sep 29, 2021 @ 2:00 p.m.

Host: Neuroscience Graduate Program

NSC 503 Seminars

Berke Karaahmet, Anjali Sinha - PhD Candidate

Faculty Evaluators:  Julian Meeks, Jesse Schallek

Student Moderator:  Karl Foley

 Oct 04, 2021 @ 4:00 p.m.

NSC 503 Seminars

Kate Andersh, Allison Murphy - PhD Candidate

Faculty Evaluators:  Pat White, Ross Maddox

Student Moderator:  Keshov Sharma

 Oct 11, 2021 @ 4:00 p.m.

NSC 503 Seminars

Kathryn Toffolo, Greg Reilly - PhD Candidate

Faculty Evaluators:  J. Chris Holt, Hohui Xia

Student Moderator:  Fara Zakusilo

 Oct 18, 2021 @ 4:00 p.m.

NSC 503 Seminars

Cody McKee, Luke Shaw - PhD Candidate

Faculty Evaluators:  Kerry O'Banion, Jon Mink

Student Moderator:  Greg Reilly

 Oct 25, 2021 @ 4:00 p.m.

NSC 503 Guest Speaker: Dr. Adriana DiPolo

Dr. Adriana DiPolo - Professor

Department of Neuroscience, University of Montreal
Axe neurosciences, CRCHUM

Dr. Adriana Di Polo's laboratory focuses on the pathobiology of retinal ganglion cells, the neurons that convey visual information from the retina to the brain via their axons in the optic nerve. Loss of vision in glaucoma, the leading cause of irreversible blindness worldwide, is caused by the death of retinal ganglion cells. At present, there is no cure for glaucoma and current treatments are often insufficient to stop disease progression. We seek to understand the mechanisms underlying retinal ganglion cell death and to develop novel therapeutics to preserve and restore vision.

Student Moderator:  Kate Andersh

 Nov 01, 2021 @ 4:00 p.m.

NSC 503 Seminars

Jingyi Yang, Mark Stoessel - PhD Candidate

Faculty Evaluators:  Andrew Wojtovich, Gail Johnson

Student Moderator:  Alesha Usuki

 Nov 08, 2021 @ 4:00 p.m.

NSC 503 Seminars

Fei Shang, Silei Zhu - PhD Candidate

Faculty Evaluators:  Ania Majewska, Adam Snyder

Student Moderator:  Cody McKee

 Nov 22, 2021 @ 4:00 p.m.

NSC 503 Seminars

Estephanie Balbuena, Julia Granato - PhD Candidate

Faculty Evaluators:  Dave MacLean, John Olschowka

Student Moderator:  Anjali Sinha

 Nov 29, 2021 @ 4:00 p.m.

NSC 503 Seminars

Leslie Gonzalez, Lia Calcinez Rodruiguez, Alexis Fiedler - PhD Candidate

Faculty Evaluators:  Rock Libby, Laurel Carney

Student Moderator:  Luke Shaw

 Dec 06, 2021 @ 4:00 p.m.

NSC 503 Seminars

Catalina Guzman, Mark Osabutey, Sean Lydon - PhD Candidate

Faculty Evaluators:  Harris Gelbard, Krystel Huxlin

Student Moderator:  Jingyi Yang

 Dec 13, 2021 @ 4:00 p.m.

NSC 503 Seminars

Fara Zakusilo, Alesha Usuki - PhD Candidate

Faculty Evaluators:  Ken Henry, Manual Gomez-Ramirez

Student Moderator:  Emily Przysinda

 Jan 10, 2022 @ 4:00 p.m.

NSC 503 Seminars

Dennis Jung, Bingyu Sun - PhD Candidate

Faculty Evaluators:  Paul Kammermeier, Amy Kiernan

Student Moderator:  Fei Shang

 Jan 24, 2022 @ 4:00 p.m.

NSC 503 Seminars

Lelo Shamambo, Tori Popov - PhD Candidate

Faculty Evaluators:  Anne Luebke, Chris Pröschel

Student Moderator:  Silei Zhu

 Jan 31, 2022 @ 4:00 p.m.

NSC 503 Seminars

Jay Gonzalez-Amoretti, Amy Bucklaew - PhD Candidate

Faculty Evaluators:  Keith Nehrke, Jennifer Hunter

Student Moderator:  Dennis Jung

 Feb 07, 2022 @ 4:00 p.m.

NSC 503 Guest Speaker: Dr. Andre Fenton

Andre Fenton, PhD - Professor, NYU

Professor of Neural Science

I study how brains store experiences as memories, and how the expression of knowledge activates information that is relevant without activating what is irrelevant. My laboratory uses molecular, electrophysiological, behavioral, engineering, and theoretical methods to investigate these fundamental and interrelated issues in neuroscience.

In work with Todd Sacktor's laboratory, we identified protein kinase M zeta (PKMzeta) as a key molecular component of long term memory. PKMζ is a persistently active kinase that maintains enhanced electrical communication at the synapses between neurons. We discovered PKMζ's role in long-term memory storage by infusing ZIP, a selective inhibitor of PKMζ, into specific brain areas. Long-term memory for a particular place was erased after infusing ZIP into hippocampus a day, even a month after rats learned a place avoidance task. Importantly, ZIP did not alter baseline synaptic activity nor did it impair the rat's ability to relearn and remember the same information if it was retrained after the erasure. Subsequent work has shown that PKMζ is involved in memory storage in many parts of the brain. Our initial work on PKMζ and memory was selected as one of the ten "Breakthroughs of the Year 2006" by the editors of Science, and received substantial attention in the popular media, including the New York Times. We are continuing to study PKMζ's role in the synaptic organization of memory and in maintaining memory-related brain activity.

Neural coordination
We are investigating the role of the hippocampus in controlling how we choose relevant information to process, by studying the interaction of memories and neural activity in signaling information from multiple spatial frames. While rats and mice solve problems that require using relevant information and ignoring distractions, we make recordings from multiple sites and use computational tools to decode information from these recordings about cognitive variables like current location, memory, attention, and cognitive control. Evidence from this work suggests that neural activity is exquisitely coordinated on multiple time scales from milliseconds to minutes, so that neurons that represent the same information discharge together in time, but are desynchronized when representing conflicting information. We are studying specific disturbances of this neural coordination in rat and mouse models of schizophrenia, intellectual disability, autism, depression, epilepsy, and traumatic brain injury.

Recording electrical brain activity
We have developed an inexpensive, miniature, wireless digital device for recording electrical brain activity from rats that have spontaneous seizures and abnormalities of neural coordination. By making recordings that last days to weeks, we can characterize abnormalities in the coordinated electrical activity that leads up to seizures. Our goal is to learn whether this activity underlies cognitive impairments, and whether behavioral and pharmacological interventions can attenuate the neural and cognitive abnormalities. Together with business and engineering partners, we have developed our brain-recording technology for medical applications.

Student Moderator:  Uday Chockanathan

 Feb 14, 2022 @ 4:00 p.m.

NSC 503 Seminars

Bryan Crum, Mike Gianetto - PhD Candidate

Faculty Evaluators:  Krishnan Padmanabhan, Mark Noble

Student Moderator:  Mark Stossel

 Feb 21, 2022 @ 4:00 p.m.

NSC 503 Seminars

Dennisha King, Evan Newbold - PhD Candidate

Faculty Evaluators:  Ed Freedman, Marc Schieber

Student Moderator:  Michael Duhain

 Feb 28, 2022 @ 4:00 p.m.

NSC 503 Guest Speaker: Dr. Shane Liddlelow

Shane Liddlelow, PhD - Asst. Professor

Neuroscience Institute @ NYU
Assistant Professor, Department of Neuroscience and Physiology
Assistant Professor, Department of Ophthalmology

Our work focuses on the mechanisms that induce different forms of reactive astrocytes, and how these reactive cells interact with other cells in the CNS in a positive or negative way. We use high throughput single cell and bulk RNA sequencing, and spatial transcriptomics to investigate the heterogeneity of astrocytes in multiple species. We also take advantage of genetic engineering and modern in vitro modeling to interrogate disease mechanisms and interaction with other CNS cells that change between health and disease.

Student Moderator:  Linh Le

 Mar 14, 2022 @ 4:00 p.m.

NSC 503 Seminars

Paige Nicklas, Abigail Sawicki - PhD Candidate

Faculty Evaluators:  Duje Tadin, Benjamin Suarez-Jimenez

Student Moderator:  Jo Fritzinger

 Mar 21, 2022 @ 4:00 p.m.

NSC 503 Seminars

Ari Seldowitz, Yanya Ding - PhD Candidate

Faculty Evaluators:  Margot Mayer-Pröschel, Jean Bidlack

Student Moderator:  Sarah Yablonski

 Mar 28, 2022 @ 4:00 p.m.

NSC 503 Guest Speaker: Dr. Emily Corderre

Emily Coderre, PhD - Asst. Professor

Assistant Professor
Dept. of Communication Sciences and Disorder
Univ. Vermont

Dr. Coderre studies the cognitive neuroscience of language using neuroimaging techniques such as electroencephalography (EEG) and functional magnetic resonance imaging (fMRI). Her research examines the cognitive processes underlying language in both typically-developing populations and in special population such as bilinguals and individuals with autism. She is particularly interested in how we understand the meaning of language during word, sentence, and narrative comprehension, and in how such understanding is impaired in autism. Her work aims to better understand the mechanisms of language deficits in autism in order to design more effective treatment interventions.

Student Moderator:  Kathryn Toffolo

 Apr 04, 2022 @ 4:00 p.m.

NSC 503 Seminars

Bryan Redmond, Thomas Delgado - PhD Candidate

Faculty Evaluators:  Vera Gorbunova, Suzanne Haber

Student Moderator:  MaKenna Cealie

 Apr 11, 2022 @ 4:00 p.m.

NSC 503 Seminars

Sean Lydon, Estephanie Balbuena - PhD Candidate

Faculty Evaluators:  Dragony Fu, David Dodell-Feder

Student Moderator:  Caitlin Sharp

 Apr 18, 2022 @ 4:00 p.m.

NSC 503 Seminars

Catalina Guzman, Leslie Gonzalez - PhD Candidate

Faculty Evaluators:  Ian Fiebelkorn, Greg DeAngelis

Student Moderator:  Matt Adusei

 Apr 25, 2022 @ 4:00 p.m.

NSC 503 Seminars

Lia Calcinez Rodruiguez, Julia Granato - PhD Candidate

Faculty Evaluators:  Ruchira Singh, Marissa Sobolewski

Student Moderator:  Jay Gonzalez-Amoretti

 May 02, 2022 @ 4:00 p.m.

NSC 503 Seminars

Alexis Fiedler, Mark Osabutey - PhD Candidate

Faculty Evaluators:  Martina Poletti, Jude Mitchell

Student Moderator:  Amy Bucklaew

 May 09, 2022 @ 4:00 p.m.