Abstract
It has been hypothesized that mutual inhibition circuit underlies bi-stable perception. It is possible that this circuit functions to resolve ambiguity of input image by quickly shifting the balance of competing signals in response to conflicting features. Furthermore, it is possible that feedback signals influence this "biased competition" to reflect global properties of the image. I developed a system to record from two pyramidal cells in primary visual cortex in vitro by double patch clamp recording technique combined with so-called "dynamic clamp" system. In this system, two neurons can be connected by modeled synapses. When a connection between the two neurons are established by mutually inhibiting model synapses, simultaneous activation of the two neurons caused bi-stable activities: dominance of neural activities alternated between the two neurons in about 1~2 seconds interval. Next, I ran paradigms analogous to various experimental paradigms used for behavioral studies of bi-stable perception. Levelt's 4th law states that increasing the strength of input contrast causes increase of switching frequency. Similarly, increasing the depolarizing current injected to both neurons showed increase of switching frequencies at the higher range of injected current. Flash suppression paradigm was modeled by injecting depolarizing current to one neuron for few seconds followed by simultaneous injections of the current to the two neurons. The simultaneous injection evoked bi-stability that mostly started with the dominant activity of the non-adapted neuron. Intermittent presentation of bi-stable figure is known to prolong the percept duration. When this paradigm was modeled by injecting depolarizing current intermittently, the prolongation effect was not observed. Finally, by placing a stimulus electrode to V2, feedback excitation was evoked. The stimulation often caused the switch of dominance. Hence, feedback signals can influence the outcome of the competition. With this system, the details of neural processes that undergo bi-stable activities can be investigated.
Meeting abstract presented at VSS 2017