Upcoming Boynton Colloquia

January 25, 2021
12:00 p.m., Zoom Meeting
Carla Shatz, Stanford University
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Synapses Lost and Found: Critical periods, Amblyopia and Alzheimer's disease
The brain is the most incredible computational machine imaginable, with trillions of synaptic connections. How are connections wired up in development? Wiring happens sequentially first by forming a basic scaffold of connectivity according to genetic blueprints that define strict molecular guidance cues. Then the exact details of each circuit emerge by pruning and sculpting synapses from the immature pattern of connections. The decision-making process that determines which synaptic connections remain and which are pruned is also genetically specified and requires neural function. Even before birth, the brain generates its own internal neural activity to jump-start the sculpting process. After birth sensory systems mature and experience of the external world takes over to influence brain wiring during developmental critical periods. Neural activity and sensory experience regulate expression of sets of genes including several previously thought to act only in the immune system. These activity-regulated genes- including Major Histocompatibility Class I family members and Paired immunoglobulin-like receptor B- are required in neurons for pruning and sculpting synapses during development. Unexpectedly PirB signaling may also contribute to excessive synapse pruning in Alzheimer?s disease and PirB blockade can restore visual function in a mouse model of Amblyopia. Thus, the baby's brain is not a miniature version of the adult, but rather is a dynamically changing structure in which neural activity and experience ultimately select and stabilize essential details of neural circuitry that make each of us different from one another.

February 8, 2021
12:00 p.m., Zoom Meeting
Alessandra Angelucci, U. of Utah
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Organization and function of feedback connections in early visual processing
In the primate visual cortex, information travels along feedforward connections through a hierarchy of areas. Neuronal receptive fields in higher areas become tuned to increasingly complex stimulus features, via convergent feedforward inputs from lower areas.
In turn, anatomically prominent feedback connections send information from higher to lower areas. Feedback connections have been implicated in many important functions for vision, including attention, expectation, and visual context, yet their anatomy and function have remained unknown. This is partly due technical difficulties in previous studies of selectively labeling and manipulating the activity of feedback neurons. To overcome these technical limitations, we have used novel viral labeling and optogenetic approaches to investigate the anatomy and function of feedback connections between the secondary (V2) and the primary (V1) visual areas of primates. Anatomically, we find evidence for multiple distinct feedback channels, and for direct, monosynaptic feedback-feedforward loops. Functionally, our results point to a fundamental role of feedback in early visual processing, controlling the spatial resolution of visual signals, by modulating receptive field size, the perceptual sensitivity to image features, by modulating response gain, and contributing to contextual modulation and correlated variability in V1.

May 24, 2021
12:00 p.m., Zoom Meeting
Ziad Hafed, Center for Intergrated Neuroscience, Tuebingen
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Title TBA
Abstract: TBA
Past Boynton Colloquia
2020

November 23, 2020
Melchi Michel, Rutgers University
Visual Memory and Information Integration across Saccadic Eye Movements
Download MP4 video (112 MB)

December 7, 2020
EJ Chichilnisky, Stanford University
Toward a High-fidelity Artificial Retina
Download MP4 video (70 MB)
2019

April 23, 2019
Greg Horwitz, University of Washington
Signals and noise in the primate early visual system

May 7, 2019
Preeti Verghese, Smith-Kettlewell Eye Research Institute
The role of the visual periphery in depth perception

May 14, 2019
Janneke Jehee, Donders Institute for Brain, Cognition and Behavior
Uncertainty in perceptual decision making


December 4, 2019
Anitha Pasupathy, U of Washington
Mid-level cortical representations for object recognition
2018

February 12, 2018
Randolph Blake, Centennial Professor of Psychology, Vanderbilt University
Visual competition and perceptual inference

April 16, 2018
Joseph Carroll, Medical College Wisconsin
Challenges and Opportunities Regarding Imaging-Based Biomarkers for Studying Retinal Disease

May 7, 2018
Rick Born, Professor of Neurobiology, Harvard Medical School
Does cortical feedback convey learned priors?

May 14, 2018
Holly Bridge, University of Oxford
Understanding the pathways underlying residual visual function after damage to primary visual cortex
co-sponsored by Neurology, Neuroscience, Neurosurgery


October 30, 2018
King-Wai Yau, Johns Hopkins University
Light Detection in the Eye - The Big Picture
2017
January 9, 2017
Jose Sahel, University of Pittsburgh
Maintaining or Restoring Central Vision in Retinal Degenerations
March 20, 2017
Miguel Eckstein, UC Santa Barbara
Rapidly Looking at Faces: A Sensory Optimization Theory
April 10, 2017
Beth Buffalo, University of Washington
Bridging the gap between the spatial and mnemonic views of the hippocampus
May 1, 2017
David Fitzpatrick, Max Planck Institute
Functional Synaptic Architecture of Neurons in Visual Cortex
May 15, 2017
Adam Kohn, Albert Einstein University
Corticocortical signaling in the primate visual cortex
co-sponsored by Neuroscience