Visual Cortical Mechanisms of Perceptual Grouping: Interacting Layers, Networks, Columns, and Maps
MetadataShow full item record
The visual cortex has a laminar organintion whose circuits form functional columns in cortical maps. How this laminar architecture supports visual percepts is not well understood. A neural model proposes how the laminar circuits of Vl and V2 generate perceptual groupings that maintain sensitivity to the contrasts and spatial organization of scenic cues.The model can decisively choose which groupings cohere and survive, even while balanced excitatory and inhibitory interactions preserve contrast-sensitive measures of local boundary likelihood or strength. In the model, excitatory inputs from LGN activate layers 4 and 6 of Vl. Layer 6 activates an on-center off-surround network of inputs to layer 4. Together these layer 4 inputs preserve analog sensitivity to LGN input contrast. Layer 4 cells excite pyramidal cells in layer 2/3 which activate monosynaptic long-range horizontal excitory connections between layer 2/3 pyramidal cells, and short-range disynaptic inhibitory connections mediated by smooth stellate cells. These interactions support inward perceptual grouping between two or more boundary inducetd, but not outward grouping from a single inducer. These lJO\UHlary signals feed back to layer 4 via the layer 6-to-4 on-center off-surround network. This folded feecdback joind cells in different layers into functional columnns while selecting winning groupings. Layer G in V1 also sends top-dlown signals to LGN using an on-center off-surround network, which suppresses LGN cells that do not receive feedback, while selecting, enhaneing, and synchronizing activity of those that do. The model is used to simulate psychophysical and neurophysiological data about perceptual grouping, including various Gestalt grouping laws.
RightsCopyright 1998 Boston University. Permission to copy without fee all or part of this material is granted provided that: 1. The copies are not made or distributed for direct commercial advantage; 2. the report title, author, document number, and release date appear, and notice is given that copying is by permission of BOSTON UNIVERSITY TRUSTEES. To copy otherwise, or to republish, requires a fee and / or special permission.
Showing items related by title, author, creator and subject.
Investigating reorganization of the motor cortices following stem cell therapy in a non-human primate model of cortical ischemia Arndt, Kevin Richard (2014)Prior work demonstrated that impairments in fine motor function produced by a controlled ischemic lesion in monkey primary motor cortex were ameliorated by treatment with a cell drug product, CNTO 0007. This drug contains ...
Roche, Michael Geoffrey (Boston University, 2012)Cortical spreading depression (CoSD) is a reaction of the cerebral cortex to injury and neuropathology. It is comprised of self propagating waves of neuronal hyperexcitability, followed by a pronounced and lasting depression ...
Mayer, Charles (Boston University, 1955)Lashley has maintained that the problem of stimulus equivalence is of prime concern both to the neurophysiologist and the physiological psychologist. This stand becomes eminently justifiable when it is noted that stimulus ...