Sensitivity to cross-like figures in the cat striate neurons.

The responses and orientation tuning in 48 out of 62 (77.4%) neurons of the cat striate cortex (area 17) significantly, but with different sign, changed at stimulation by specific cross-like figure flashing in receptive field as compared with single light bar of preferred orientation. Neurons of the first group (19 units from 62, 30.6%) were found to increase the responses by 3.3 times if stimulated by a certain cross-like figure, specific for each cell configuration and orientation. Under the same conditions, neurons of the second group (29 or 46.8% revealed a three-fold decrease of responses and all tuning characteristics worsened. Among them 8% of total number of cells showed bimodal or double orientation tuning when stimulated by some configurations of crosses due to an angle specific inhibition. Dependence of the revealed effects on excitatory convergence from neurons with different orientation tuning, on inhibitory influences from end-stop and side-zones of receptive field, as well as possible functional implication of the first group neurons for an angle and line-crossing detection are discussed.