Purchase this article with an account.
Alexandre Reynaud, Guillaume Masson, Frédéric Chavane; Cortical origin of contrast response function contextual modulation in V1 population activity measured with voltage-sensitive dye imaging. Journal of Vision 2009;9(8):749. doi: 10.1167/9.8.749.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
In psychophysics and physiology, it is well established that the contrast gain control is context-dependent. In both human and monkey ocular following studies, it has been shown that modulations of the contrast response functions (CRF) induced by a peripheral stimulus are delayed. We investigated the role of cortico-cortical interactions on this delayed contextual modulations using recording of population activity with voltage sensitive dye imaging (VSDI) in area V1 of behaving monkeys.
Dynamics of contrast response functions to a local stimulus were found to be very similar in V1 cortical activity and ocular following responses (OFR). At both levels, contrast gains increase over time in response to a single grating motion. However, adding a dynamical surround both clamps the contrast gains to their initial value and maintains larger dynamical ranges. Using an ideal observer model, we show that these results can match the behavioral observation (see Perrinet et al. VSS 2009).
To investigate the cortical origin of this modulation, the visual input was manipulated while measuring V1 activity using VSDI. In order to test whether the peripheral modulation originated from V1 horizontal intracortical connectivity (slow connectivity between small receptive fields, sensitive to slow motion and static stimuli, with precise retinotopic organization) and/or feedback from MT (fast connectivity from large receptive fields, sensitive to fast motion, with gross retinotopic organization), bipartite stimuli with different properties were used: (i) different spatio-temporal scales, (ii) surround containing or not motion signal and (iii) varying center-surround distance.
Our experiments show that non-linear interactions between and within cortical areas lead to the modulation of the CRF. Depending on stimulus characteristics, we observed a dynamical balance between fast facilitation and slower suppression that results from a strong interplay between horizontal and feedback connectivity.
This PDF is available to Subscribers Only