V1-origin Bidirectional Plasticity in Visual Thalamo-ventral Pathway and Its Contribution to Saliency Detection of Dynamic Visual Inputs.

Visual neural plasticity and V1 saliency-detection are vital for efficient-coding of dynamically changing visual inputs. However, how does neural plasticity contribute to saliency-detection of temporal-statistically distributed visual stream remains unclear. Therefore, we adopted randomly presented but unevenly distributed stimuli with multiple orientations, and examined the single-unit responses evoked by this biased orientation-adaptation protocol, by single-unit recordings in the visual thalamo-ventral pathway of cats (of either sex). We found neuronal responses potentiated when the probability of biased orientation was slightly higher than other non-biased ones, and suppressed when the probability became much higher. This single-neuronal short-term bidirectional-plasticity is selectively induced by optimal stimuli, but inter-ocularly transferable. It is inducible in LGN, Area 17 and Area 21a with distinct and hierarchically progressive patterns. With the results of latency-analysis, receptive-field structural test, cortical lesion and simulations, we suggest this bidirectional-plasticity may principally originate from the adaptation-competition between excitatory and inhibitory components of V1 neuronal receptive-field. In our simulation, above bidirectional-plasticity could achieve saliency-detection of dynamic visual inputs. These findings demonstrate a rapid probability-dependant plasticity on the neural coding of visual stream, and suggest its functional role in the efficient-coding and saliency-detection of dynamic environment.SIGNIFICANCE STATEMENTNovel elements within a dynamic visual stream can "pop-up" from the context, vital for rapid response to dynamically changing world. "Saliency-detection" is a promising bottom-up mechanism contributing to efficient selection of visual inputs, wherein visual adaptation also plays a significant role. However, the saliency-detection of dynamic visual stream is poorly understood. Here we found a novel form of visual short-term bidirectional-plasticity in multi-stages of visual system that contributes to saliency-detection of dynamic visual inputs. This bidirectional-plasticity may principally originate from the local balance of excitation-inhibition in primary visual cortex, and propagates to lower and higher visual areas with progressive pattern-change. Our findings suggest the excitation-inhibition balance within visual system contributing to visual efficient-coding.