Neuroscience 2004 Abstract
| Presentation Number: | 175.6 |
|---|---|
| Abstract Title: | Determining the biophysical requirements for dendritic computation of visual stimulus competition and attentional modulation. |
| Authors: |
Archie, K. A.*1,2
; Mel, B. W.2,3
1Dept of Physics, Washington Univ, St. Louis, MO 2CA, 1 Brookings Dr Campus Box 1105, 63130, 3USA, 1 Brookings Dr Campus Box 1105, 63130, |
| Primary Theme and Topics |
Sensory Systems - Vision -- Visual cortex: Attention and cognition |
| Secondary Theme and Topics | Sensory Systems<br />- Vision<br />-- Visual cortex: Functional organization and circuitry |
| Session: |
175. Visual Cortex: Attentional Modulation Poster |
| Presentation Time: | Sunday, October 24, 2004 9:00 AM-10:00 AM |
| Location: | San Diego Convention Center - Hall A-H, Board # P26 |
| Keywords: | DENDRITE, NMDA RECEPTOR, MODEL, SIMULATION |
Reynolds, Chelazzi, and Desimone (J. Neurosci. 19:1736, 1999) showed that neurons in areas V2 and V4 of macaque visual cortex exhibit stimulus competition: the response when two stimuli are presented simultaneously is a weighted average of the response to each stimulus presented alone. Attention directed to one stimulus changes the response to the combined image towards the response for the attended stimulus alone.
We previously proposed a model for the mechanisms underlying both phenomena (Archie and Mel, SFN Abstracts 25, 1999). The receptive field (RF) of a V2/V4 neuron is divided into individually attendable subregions. Sensory input to a subregion drives excitatory projections directed to one dendritic branch of the V2/V4 cell and inhibitory projections scattered over the entire cell. Each branch, therefore, corresponds to a single RF subregion. Attention is directed to a particular RF subregion through increased excitation of the corresponding dendritic branch and increased inhibition across the entire cell.
Using biophysically detailed compartmental simulations and simplified algebraic models, we have determined the biophysical properties needed for this model to account for stimulus competition and attentional modulation: (1) Individual dendritic branches must be sufficiently electrotonically isolated from each other. (2) Each branch must have a suitable nonlinear input/output function, of a form that could be generated by voltage-sensitive Na+ or Ca2+ channels or NMDA synapses. Both of these requirements are consistent with physiological properties observed in neocortical pyramidal neurons. We conclude that an individual pyramidal cell could perform stimulus competition and attentional modulation via nonlinear dendritic processing.
We previously proposed a model for the mechanisms underlying both phenomena (Archie and Mel, SFN Abstracts 25, 1999). The receptive field (RF) of a V2/V4 neuron is divided into individually attendable subregions. Sensory input to a subregion drives excitatory projections directed to one dendritic branch of the V2/V4 cell and inhibitory projections scattered over the entire cell. Each branch, therefore, corresponds to a single RF subregion. Attention is directed to a particular RF subregion through increased excitation of the corresponding dendritic branch and increased inhibition across the entire cell.
Using biophysically detailed compartmental simulations and simplified algebraic models, we have determined the biophysical properties needed for this model to account for stimulus competition and attentional modulation: (1) Individual dendritic branches must be sufficiently electrotonically isolated from each other. (2) Each branch must have a suitable nonlinear input/output function, of a form that could be generated by voltage-sensitive Na+ or Ca2+ channels or NMDA synapses. Both of these requirements are consistent with physiological properties observed in neocortical pyramidal neurons. We conclude that an individual pyramidal cell could perform stimulus competition and attentional modulation via nonlinear dendritic processing.
Supported by NSF
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2004 Neuroscience Meeting Planner. San Diego, CA: Society for Neuroscience, 2004. Online.
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