Neuroscience 2003 Abstract
| Presentation Number: | 910.18 |
|---|---|
| Abstract Title: | Computational prediction about localization of functions in primary visual cortex. |
| Authors: |
Okamoto, T.*1
; Watanabe, M.1
; Kondo, S.1
1Kondo Lab., Quantum Eng & Sys Sci, Grad. Sch. Eng, Univ. Tokyo, Bunkyo-ku, Tokyo, Japan |
| Primary Theme and Topics |
Sensory Systems - Vision -- Visual cortex: Functional organization and circuitry |
| Session: |
910. Striate Cortex: Neuronal Properties Poster |
| Presentation Time: | Wednesday, November 12, 2003 2:00 PM-3:00 PM |
| Location: | Morial Convention Center - Hall F-I, Board # E62 |
| Keywords: | orientation tuning, contextual modulation, computational model, lateral interaction |
In recent years, optical imaging studies gave the comprehensive description of orientation map in primary visual cortex (V1). The optical orientation map contains nonuniform distribution of orientation selectivity, such as pinwheels, fractures and linear zones. This means that each neuron in V1 is placed in different cortical surroundings. Although it is natural to think that different surroundings evoke different functions, little is known about the differences in functions. In the previous study, we have suggested that orientation tuning is sharper and contextual modulation is stronger in the middle of an iso-orientation domain than at the neighborhood of a pinwheel center singularity (Okamoto et al. SFN 2002). In the present study, we examined the localization of orientation tuning and contextual modulation in more detail by simulation of a computational model. The model for layer 2/3 of V1 contains excitatory and inhibitory orientation modules and geometric orientation map. The orientation module is equivalent to 'mini-column', and connections between modules are isotropic as a function of horizontal distance between them. Afferent input to each module is tuned broadly and afferent selectivity is determined by geometric orientation map. Geometric orientation map is modeled based on the honeycomb-like arrangement of singularities, which reflects the typical properties of orientation arrangement such as pinwheels and linear zones. Our model reproduces that the strength of orientation tuning is proportional to the distance from proximal singularity seen as an optical polar map, and predicts that the strength of contextual modulation is also proportional to the distance from proximal singularity. Furthermore, the model demonstrates that the effect of lateral interaction between modules and the population of iso- and cross-orientation modules show the similar spatial periodicity. The amplitude of periodicity is proportional to the distance from proximal singularity.
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2003 Neuroscience Meeting Planner. New Orleans, LA: Society for Neuroscience, 2003. Online.
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