A human cortical adaptive mutual inhibition circuit underlying competition for perceptual decision and repetition suppression reversal
A model based on inhibitory coupling has been proposed to explain perceptual oscillations. This adapting reciprocal inhibition model postulates that it is the strength of inhibitory coupling that determines the fate of competition between percepts. Here, we used an fMRI-based adaptation technique to reveal the influence of neighboring neuronal populations, such as reciprocal inhibition, in motion-selective hMT+/V5. If reciprocal inhibition exists in this region, the following predictions should hold: 1. stimulus-driven response would not simply decrease, as predicted by simple repetition-suppression of neuronal populations, but instead increase due to the activity from adjacent populations; 2. perceptual decision involving competing representations, should reflect decreased reciprocal inhibition by adaptation; 3. neural activity for the competing percept should also later on increase upon adaptation. Our results confirm these three predictions, showing that a model of perceptual decision based on adapting reciprocal inhibition holds true. Finally, they also show that the well-known repetition suppression phenomenon can be reversed by this mechanism. Significance StatementfMRI-based adaptation has been developed as a tool to identify functional selectivity in the human brain. This is based on the notion that stimulus-selective adaptation leads to direct response suppression. In this study, we go a step further by showing that adaptation can also reveal the influence of neighboring neuronal populations. Our data reveals neural evidence for a disinhibition effect as a result of the adaptation of adjacent populations, which is in line with the adapting reciprocal inhibition model. Reciprocal inhibition can, thus, be tracked in the human brain using fMRI, adding to the understanding of human multistable perception and the neural coding of visual information. Moreover, our results also provide a mechanism for reversal of repetition suppression.