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Modelle neuronaler Systeme

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The Contribution of Feedback and Horizontal Connections to Center-Surround Interaction in Macaque V1: A Recurrent Network Model
Zitatschlüssel schwabe05g
Autor Schwabe, L. and Angelucci, A. and Obermayer, K. and Bressloff, P.
Buchtitel Soc. Neurosci. Abs. 31
Jahr 2005
Notiz CD-ROM
Zusammenfassung Neuronal responses in the macaque striate cortex (V1) are suppressed when both the receptive field (RF) center and surround are stimulated. Long-range lateral connections within V1 have long been thought of as the sole anatomical substrate of these effects, but recently it has been shown [1,2,3] that suppression can be evoked by stimuli far beyond the range of lateral connections. Moreover, the short temporal latency of suppression arising from the far surround cannot be accounted for by their slow conduction velocity. Extrastriate feedback projections to V1 are commensurate with these suppressive effects in terms of spatial scale and conduction velocity, and could thus represent their anatomical substrate. We set up a network model whose architecture is constrained to fit with recent anatomical/physiological studies [2], and is consistent with the observation that feedback contacts predominantly (95%) excitatory cells in V1 [4]. The feedback connections from extrastriate cortex exert their suppressive influence arising from the far surround by targeting excitatory neurons in the near surround, which in turn send horizontal connections to local inhibitory neurons in the RF center. The model reproduces suppression from the far surround in a way consistent with the currently available data regarding the static and dynamic effects of surround suppression. The circuit model is also used to make easily testable predictions. One such prediction is that stimulation of the far surround with high contrast gratings can facilitate the center response to low contrast gratings. This prediction is consistent with our recent physiological data [5], which thus support the model and reveal that the suppressive surround of V1 neurons is not always suppressive. [1] Levitt and Lund 2002 [2] Angelucci et al. 2002 [3] Bair et al. 2003 [4] Johnson and Burkhalter 1996 [5] Ichida et al. 2005.
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