Upcoming Boynton Colloquia

Carla Shatz

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.

Alessandra Angelucci

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.

Ziad Hafed

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

Melchi Michel

November 23, 2020

Melchi Michel, Rutgers University

Visual Memory and Information Integration across Saccadic Eye Movements

Download MP4 video (112 MB)


EJ Chichilnisky

December 7, 2020

EJ Chichilnisky, Stanford University

Toward a High-fidelity Artificial Retina

Download MP4 video (70 MB)


2019

Greg Horwitz

April 23, 2019

Greg Horwitz, University of Washington

Signals and noise in the primate early visual system


Preeti Verghese

May 7, 2019

Preeti Verghese, Smith-Kettlewell Eye Research Institute

The role of the visual periphery in depth perception


Janneke Jehee

May 14, 2019

Janneke Jehee, Donders Institute for Brain, Cognition and Behavior

Uncertainty in perceptual decision making


Dennis Levi

October 16, 2019

Dennis Levi, UC Berkeley

Learning to see in depth


Anitha Pasupathy

December 4, 2019

Anitha Pasupathy, U of Washington

Mid-level cortical representations for object recognition


2018

Randolph Blake

February 12, 2018

Randolph Blake, Centennial Professor of Psychology, Vanderbilt University

Visual competition and perceptual inference


Joseph Carroll

April 16, 2018

Joseph Carroll, Medical College Wisconsin

Challenges and Opportunities Regarding Imaging-Based Biomarkers for Studying Retinal Disease


Rick Born

May 7, 2018

Rick Born, Professor of Neurobiology, Harvard Medical School

Does cortical feedback convey learned priors?


Holly Bridge

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


Alex Huk

October 23, 2018

Alex Huk, UT-Austin

New perspectives in visual motion processing


King-Wai Yau

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