2012 Symposia

Pulvinar and Vision: New insights into circuitry and function

Organizer: Vivien A. Casagrande, Department of Cell & Developmental Biology, Vanderbilt Medical School
Time/Room: Friday, May 11, 1:00 – 3:00 pm, Royal Ballroom 1-3

The most mysterious nucleus of the visual thalamus is the pulvinar. In most mammals the pulvinar is the largest thalamic nucleus, and it has progressively enlarged in primate evolution so that it dwarfs the remainder of the thalamus in humans. Despite the large size of the pulvinar, relatively little is known regarding its function, and consequently its potential influence on cortical activity patterns is unappreciated. This symposium will outline new insights regarding the role of the pulvinar nucleus in vision, and should provide the VSS audience with a new appreciation of the interactions between the pulvinar nucleus and cortex. More…

What does fMRI tell us about brain homologies?

Organizer: Reza Rajimehr, McGovern Institute for Brain Research, Massachusetts Institute of Technology
Time/Room: Friday, May 11, 1:00 – 3:00 pm, Royal Ballroom 4-5

Over the past 20 years, the functional magnetic resonance imaging (fMRI) has provided a great deal of knowledge about the functional organization of human visual cortex. In recent years, the development of the fMRI technique in non-human primates has enabled neuroscientists to directly compare visual cortical areas across species. These comparative studies have shown striking similarities (‘homologies’) between human and monkey visual cortex. Comparing cortical structures in human versus monkey provides a framework for generalizing results from invasive neurobiological studies in monkeys to humans. It also provides important clues for understanding the evolution of cerebral cortex in primates. More…

Part-whole relationships in visual cortex

Organizer: Johan Wagemans, Laboratory of Experimental Psychology, University of Leuven
Time/Room: Friday, May 11, 1:00 – 3:00 pm, Royal Ballroom 6-8

In 1912 Wertheimer launched Gestalt psychology, arguing that the whole is different from the sum of the parts. Wholes were considered primary in perceptual experience, even determining what the parts are. How to reconcile this position with what we now know about the visual brain, in terms of a hierarchy of processing layers from low-level features to integrated object representations at the higher level? What exactly are the relationships between parts and wholes then? A century later, we will take stock and provide an answer from a diversity of approaches, including single-cell recordings, human fMRI, human psychophysics, and computational modeling. More…

Distinguishing perceptual shifts from response biases

Organizer: Joshua Solomon, City University London
Time/Room: Friday, May 11, 3:30 – 5:30 pm, Royal Ballroom 1-3

Our general topic will be the measurement of perceptual biases. These are changes in appearance that cannot be attributed to changes in the visual stimulus. One perceptual bias that has received a lot of attention lately is the change in apparent contrast that observers report when they attend (or remove attention from) a visual target. We will discuss how to distinguish reports of truly perceptual changes from changes in response strategies. More…

Human visual cortex: from receptive fields to maps to clusters to perception

Organizer: Serge O. Dumoulin, Experimental Psychology, Helmholtz Institute, Utrecht University, Utrecht, Netherlands
Time/Room: Friday, May 11, 3:30 – 5:30 pm, Royal Ballroom 4-5

This symposium will introduce current concepts of the visual cortex’ organization at different spatial scales and their relation to perception. At the smallest scale, the receptive field is a property of individual neurons and summarizes the visual field region where visual stimulation elicits a response. These receptive fields are organized into visual field maps, which in turn are organized in clusters that share a common fovea. We will relate these principles to notions of population receptive fields (pRF), cortico-cortical pRFs, extra-classical contextual effects, detailed foveal organization, visual deprivation, prism-adaptation and plasticity. More…

Neuromodulation of Visual Perception

Organizer: Jutta Billino, Justus-Liebig-University Giessen, and Ulrich Ettinger, Rheinische Friedrich-Wilhelms-Universität Bonn
Time/Room: Friday, May 11, 3:30 – 5:30 pm, Royal Ballroom 6-8

Although the neuronal bases of vision have been extensively explored over the last decades we are just beginning to understand how visual perception is modulated by neurochemical processes in our brain. Recent research provides first insights into regulation of signal processing by different neurotransmitters. This symposium is devoted to the questions (1) by which mechanisms neurotransmitters influence perception and (2) how individual differences in neurotransmitter activity could explain normal variation and altered visual processing in mental disease and during ageing. Presentations will provide an overview of state-of-the-art methods and findings concerning the complexity of neuromodulation of visual perception. More…