Motion processing in the primate dorsal stream
Short summary: In this talk I will present the dorsal stream of primates as a model system for understanding rich aspects of sensorimotor integration and neural coding. Building off classic work that has characterized the encoding of frontoparallel visual motion underlying the perception of simple forms off motion, I will describe our work attempting to learn more about how the brain extracts 3-dimentional velocities, forms perceptual decisions, and how it functions in free-viewing contexts that do not require training or conventional threshold-level tasks.
host: Greg Horwitz
Distinctive biophysical and light-encoding properties of inhibitory neurons in the macaque monkey retina.
The retina is the only part of the brain that is visible to the naked eye. It’s natural isolation from the rest of the brain makes the retina an ideal model for studying the biophysical properties of neurons and the computational properties of neural circuits in an intact experimental preparation. In this talk, I will discuss the biophysical and light-encoding properties of an inhibitory neuron—the wiry-type amacrine cell. These cells have been identified morphologically in the macaque and human retina. They exhibit long, thin dendritic processes that exhibit regenerative potentials likely arising from NMDA spikes. In addition, these cells show asymmetrical responses to visual motion, suggesting that they contribute to motion processing in the primate visual stream.
host: Stan Froehner
TMC function, dysfunction and the prospects for inner ear gene therapy
Jeffrey R. Holt, Ph.D.
Department of Otolaryngology
Harvard Medical School
TMC proteins are of considerable interest for basic inner ear biologists and for translational and clinical neuroscientists because they cause deafness in mice and humans when mutated. Our research group has proposed they may be components of the elusive mechanotransduction channel in sensory hair cells. Evidence for and against this hypothesis will be presented. In addition, a potential gene therapy approach to restore hair cell and auditory function in mice and humans with Tmc1 mutations will be discussed.
host: Ed Rubel
Experience-driven brain circuit remodeling
The spatial arrangement of a neuron’s synapses determines how inputs interact to perform computations, such as through recruitment of nonlinear conductances by spatially clustered activity. However, it remains poorly understood how such functional arrangements arise. We developed a random access microscope able to simultaneously record activity of every excitatory synapse, somatic firing, and dendrite morphology of an individual neuron throughout plasticity-inducing visual training in awake animals. We find that dendrite growth and pruning in the developing retinotectal system of transparent Xenopus tadpoles is regulated by sensory experience in a manner strongly dependent on each neuron’s evoked responses. We identify rules based on local dendritic activity patterns that promote clustering of synaptic inputs with shared tuning and promote processing of the specific stimuli experienced.
Kurt Haas, Ph.D.
Brain Research Centre
Department of Cellular and
University of British Columbia
lab website: http://www.haaslab.com/
Host: Andres Barria
Reconstruction and Simulation of Neocortical Microcircuitry
Host: Eb Fetz
Tuning collective protein interactions using programmable DNA nanostructures
Chalk talk, Friday, January 15th, at 9:30 in G-417.