Seminar Series

Population activity in the cerebellar cortex that mediates behavior and learning

Court Hull

Associate Professor, Department of Neurobiology, Duke University

host: Greg Horwitz

Abstract: The cerebellum is a key brain region involved in associative learning, and in particular for generating predictive sensorimotor associations.  To mediate such learning, convergent input from two main pathways is thought to be required; the climbing fiber and granule cell pathways.  Using multiphoton imaging in awake behaving mice, we have investigated how each of these pathways encodes the sensory and motor information necessary for learning.  These studies have revealed surprising results that extend current views of cerebellar learning.  Specifically, we have found that cerebellar climbing fibers can exhibit reward-related responses that are consistent with many of the predictions of reinforcement learning, in contrast with the long-held view that the cerebellum operates exclusively according to supervised learning principles.  In addition, we have found that granule cells generate sparse population codes that rely on local synaptic inhibition to enable pattern separation and learned sensorimotor discriminations.  I will discuss the implications of these results in the context of cerebellar associative learning.

Awake perception is associated with dedicated neuronal assemblies in cerebral cortex

Alain Destexhe

Saclay Paris and European Institute for Theoretical Neuroscience

Host: Adrienne Fairhall

Spiking codes for skilled motor control

Sam Sober, PhD

Director of the Simons-Emory International Consortium on Motor Control

Emory University

Abstract: Neurons coordinate patterns of muscle activity to produce an astonishing variety of behaviors. However, the biological and computational bases of sensorimotor control remain mysterious, in part due to a lack of experimental hardware and computational frameworks for examining motor signals. To address these challenges, my group combines physiological, computational, and engineering approaches to understand motor control across species and behaviors. My talk will provide an overview of three projects. First, physiological and computational studies of vocal production in songbirds reveal that neurons in the motor system employ millisecond-resolution spike timing codes to regulate vocal behavior, highlighting the need to examine spiking codes across cortical, basal ganglia, and spinal motor circuits. Second, to examine spiking codes across motor circuits, we have developed electrode arrays for examining spiking patterns in muscle tissue during natural behaviors. These “Myomatrix” arrays reveal the spatiotemporal structure of muscle activity at motor-unit resolution across effectors (forelimb, trunk, orofacial, respiratory, and vocal muscles) and species – including humans – during unconstrained behavior. Third, in-progress studies examining muscle spike trains in mice (locomotion) and monkeys (reaching movements) reveal how complex patterns of motor unit activity shape skilled forelimb control. https://scholarblogs.emory.edu/soberlab/  

Probing and manipulating the hippocampus-accumbens-VTA circuit in drug addiction

Luke Sjulson

Assistant Professor of Psychiatry and Neuroscience

Albert Einstein College of Medicine

Abstract: It has long been known that exposure to contextual cues previously paired with drug use is likely to trigger relapse. In the first part of the talk, I will discuss progress we have made toward understanding the role of selective plasticity in the hippocampus to nucleus accumbens pathway in storing drug-context associations. In the second half, I will discuss translational applications, including the development of a therapeutic strategy for opioid use disorder based on a novel chemogenetic opioid receptor mutant. website:  https://sjulsonlab.org/

“Properties of robust, flexible, and state-dependent respiratory control”

Nathan A Baertsch, Ph.D.

Seattle Children’s Research Institute, Center for Integrative Brain Research

Abstract: Despite the deceptive simplicity of breathing, the underlying neural control of this vital physiological process is complex. Breathing is regulated automatically by neural circuits in the medulla to ensure breathing continues without interruption during wakefulness, sleep, and even anesthesia. To do so, the respiratory rhythm produced by these circuits must be robust, but also flexible to adapt breathing to changes in metabolic or environmental demands. In addition to this automatic control, breathing is conditionally modified by behavior and emotion in the awake state. This seminar will provide an overview of our recent work to understand the brainstem circuits and neural properties that mediate the robust, flexible, and state-dependent properties of breathing.    

Calcium Signaling, Chemotherapy, and the Prevention of Treatment Side Effects

Barbara Ehrlich, Ph.D.

Departments of Pharmacology and Cellular & Molecular Physiology, Yale University School of Medicine

Abstract:

website: https://medicine.yale.edu/pharm/profile/barbara-ehrlich/

“How neurons ‘count’ their eggs: intrinsic and cell-type specific properties of pyramidal neurons that shape the input-output computations they perform”

Nikolai Dembrow, Ph.D.

University of Washington

Abstract: It has long been appreciated since the seminal work of Ramon y Cajal that neurons fall into distinct categories based upon their morphology. Over the last few decades, we have come to learn that this is also true for the complement and distribution of ion channels a neuron expresses. The combination of morphology and ion channel expression makes a neurons’ intrinsic electrophysiological properties and shape how they transform synaptic input into spiking output. These intrinsic properties do not fall into a ‘one size fits all’ category, but rather can be separated into distinct neuron types. With advances in single-cell sequencing of expressed genes and the ability to target and selectively manipulate these various neuron types, it has become evident that neuron types have separable functional contributions to network activity and even behavior. A key feature of pyramidal neurons across many species is their extensively branched processes called dendrites that receive thousands of excitatory synaptic contacts. Although all pyramidal neurons have dendritic arbors, the pattern and distribution of these structures can vary greatly depending upon cell type, brain region and species. Dendrites are critical for understanding the computations neuron types perform. My long-term research goal is to provide meaningful insights in how the intrinsic dendritic properties of the different neuron types contribute to functional (and sometimes tragically dysfunctional) network activity in health and disease. website: https://pbio.uw.edu/directories/faculty/entry/ndembrow/

“Development of ultrafast camera-based single fluorescent-molecule imaging, and discovery of metastable nano-liquid signaling platforms on the cell membrane”

Speaker: Akihiro Kusumi

Okinawa Institute of Science & Technologies

website: https://groups.oist.jp/mcu/akihiro-kusumi

“The curious role of the amygdala in reinforcement learning”

Vincent Costa, Ph.D

Assistant Professor, Dept Behavioral Neuroscience OHSU and ONPRC

Abstract: website: https://www.fullcolorbrain.com/

2023 Crill Lecture

“Resilience to Perturbation in Degenerate Neurons and Circuits: Relevance to Climate Change”

Eve Marder, Ph.D.

Professor of Biology, Brandeis University

 

Inside the fly eye: adventures in understanding structure & function

Michael Reiser, PhD

Sr Group Leader, HHMI Janelia Research Campus

 

Many animals navigate through their environment by using the pattern of changes in the visual scene, called optic flow, that is both caused by and serves as a signal of self-motion. Recent research in the Drosophila visual system is providing an increasingly complete explanation for how the fly brain computes optic flow (and other forms of motion vision). I will discuss my group’s progress on three aspects of this beautiful puzzle:

1.     How small, Directionally Selective (DS) neurons compute the direction of local motion. This long-standing mystery has been recently clarified by EM connectomics, electrophysiology, and biophysical modeling.

2.     Since a visual system cannot be arbitrarily sensitive to all directions of motion at all retinal positions, we’ve described the precise organization of the DS neuron array, revealing an unexpectedly strong connection between the eye’s peripheral structure, function of neurons deep in the brain, and body movement control.

3.     A diverse group of neuron types integrate input signals from DS neurons to generate a broad range of motion-pattern selectivities. By using computational neuroanatomy, neurophysiology, quantitative behavior, and genetic manipulation of neural activity, we identified cell types that detect visual looming, wide-field visual motion, and translatory optic flow.

    website: https://www.janelia.org/people/michael-reiser host: John Tuthill

“Optic flow circuits and the visual guidance of avian flight”

Douglas L. Altshuler, Ph.D.

Professor, Department of Zoology, University of British Columbia

Abstract: As an animal moves through the world, surfaces and edges in the environment appear to move along the retina, a visual signal known as optic flow. All vertebrates have a rapid pathway for optic flow encoding. From the retina, ganglion cell axons project to two regions in the midbrain, the lentiformis mesencephali and the nucleus of the basal optic root, which respond only to optic flow signals. In mammals, these regions are called the nucleus of the optic tract and the terminal nuclei, respectively. The optic flow information is transmitted to several pre-motor regions in the hindbrain including the inferior olive, the vestibulocerebellum, and the oculomotor cerebellum. The circuit has a well-known role in stabilizing eye movements, and has been thought be highly conserved in its anatomy, neural response properties, and visually-mediated behavior. My collaborators and I have found evidence that this optic flow pathway has a much larger role, also controlling stabilization of the whole body, and the inverse function, maneuverability in response to salient visual signals. I will present evidence that the anatomy of this midbrain optic flow circuit, its neural response properties, and visual guidance strategies are all tuned to differences in species visual ecology and mode of locomotion. website