Nonlinear processing of shape information in rat lateral extrastriate cortex

Abstract

34We previously reported that the progression of rat extrastriate areas located laterally to

Causal adaptation to visual input dynamics governs the development of complex cells in V1

“…2a, which shows a representative complex cell from the control group (left: blue lines) and representative simple cell from the experimental group (right: orange lines). Both units displayed sharp orientation tuning (polar plots), but the STA method successfully recovered a sharp, Gabor-like RF only for the simple cell (as expected, given the nonlinear stimulus-response relationship of complex cells 23 ). Consistently, the response of the complex cell was only weakly modulated at the temporal frequency (4 Hz) of its preferred grating (middle plots), with the highest power spectral density concentrated at frequencies < 4 Hz (bottom plot).…”

“…To estimate the amount of signal contained in a given STA image, we used the contrast index (CI) metric that we have introduced in a previous study 23 . The CI is a robust measure of maximal local contrast in a z-scored STA image.…”

“…1). During a recording session, each animal was presented with drifting gratings spanning 12 directions, and with contrastmodulated movies of spatially and temporally correlated noise 23,24 . Responses to the noise movies allowed inferring the linear RF structure of the recorded units using the spiketriggered average (STA) analysis (see Methods).…”

“…This allowed isolating the pure contribution of temporal contiguity to the postnatal development of V1 simple and complex cells. The latter were studied by performing multi-channel extracellular recordings from V1 of each rat under fentanyl/medetomidin anesthesia 23 , shortly after the end of the controlledrearing period. Our recordings mainly targeted layer 5, which is known to contain the largest fraction of complex cells in rodents 24 as well as layer 4, with the distributions of recorded units across the cortical depth and the cortical laminae being statistically the same for the control and experimental groups (Extended Data Fig.…”

“…Responses to the drifting gratings were used to estimate the tuning of the neurons with standard orientation and direction selectivity indexes (OSI and DSI; defined in Fig. 2), as well as to probe their sensitivity to phase-shifts of their preferred gratings, thus measuring their position tolerance 23,24 . This is illustrated in Fig.…”