Physiology and Biophysics

Seminars

Oct
1
Thu
2015
Alex Huk, PhD, UT-Austin @ HSB G-328
Oct 1 @ 9:30 am – 10:30 am

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.

Huk Vision / Decision Lab

host: Greg Horwitz

Oct
15
Thu
2015
Mike Manookin, PhD, University of Washington @ HSB G-328
Oct 15 @ 9:30 am – 10:30 am

Distinctive biophysical and light-encoding properties of inhibitory neurons in the macaque monkey retina.

Abstract:
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.

website

host: Stan Froehner

Oct
22
Thu
2015
Jeffrey Holt, PhD, Harvard @ HSB G-328
Oct 22 @ 9:30 am – 10:30 am

TMC function, dysfunction and the prospects for inner ear gene therapy

 

Jeffrey R. Holt, Ph.D.
Associate Professor
Department of Otolaryngology
Harvard Medical School

Holt/Geleoc Lab

abstract:

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

Nov
12
Thu
2015
Kurt Haas, UBC @ HSB G-328
Nov 12 @ 9:30 am – 10:30 am

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.

Assistant Professor
Brain Research Centre

Department of Cellular and
Physiological Sciences

University of British Columbia

lab website: http://www.haaslab.com/

Host: Andres Barria

Dec
3
Thu
2015
Henry Markram, PhD, Ecole Polytechnique Federale de Lausanne @ HSB G-328
Dec 3 @ 9:30 am – 10:30 am

Reconstruction and Simulation of Neocortical Microcircuitry

Host: Eb Fetz

Dec
17
Thu
2015
Miriam B. Goodman, PhD, Stanford @ HSB G-328
Dec 17 @ 9:30 am – 10:30 am

Miriam B. Goodman, Ph.D.

Stanford University
Associate Professor of Molecular and Cellular Physiology and, by courtesy, of Mechanical Engineering

seminar title: TBD

Lab: http://wormsense.stanford.edu/

Jan
14
Thu
2016
Rizal Hariadi, PhD, Harvard University @ HSB G-328
Jan 14 @ 9:30 am – 10:30 am

Tuning collective protein interactions using programmable DNA nanostructures

The emergence of collective movement, as in stellar streaming, flocks of birds, and ant colonies, is a widespread phenomenon across all scales. At the cellular level, the collective movement of myosins motors drives cell division, membrane trafficking, and muscle contraction. Understanding collective movements of myosin motors from whole-cell  systems is challenging because the overly-complex cellular environment obscures the underlying interactions governing the higher order functions.
To systematically dissect cellular dynamics of  motor proteins, we engineered two model systems consisting of programmable DNA nanostructures, patterned with precise numbers, types, and spatial arrangements of purified myosin motors. First, we use rectangular DNA origami nanostructures to dissect the tug-of-war in motor protein ensembles with opposite polarity myosin motors. Second, we use DNA nanotubes as platforms for engineering artificial thick filaments, the basic contractile unit of muscle, to reveal the behavior of a large number of myosin motors. Beyond controlling the spatial arrangement of myosin motors, we use DNA nanotubes as mechanical sensors for forces at short length scales and fast time scales that would be difficult to investigate by other means. These studies uncover elegant engineering principles for designing force sensors and molecular transporters on complex landscapes. Further, these DNA nanostructures can serve as platforms to reconstitute other emergent systems in molecular biology and far-from-equilibrium systems in soft condensed matter physics.
Finally, I will conclude with a discussion on the transformative potential and future directions, including the biological physics of malaria parasite invasion and mechanically active nanostructures for solving protein structures under defined tension.
Rizal F. Hariadi, Ph.D.
Wyss Institute for Biologically Inspired Engineering at Harvard University

Chalk talk, Friday, January 15th, at 9:30 in G-417.