How does the retina take part in the brainwide complex feedback circuits?
As we have learned more about local circuit functions of individual brain areas, it becomes increasingly important to understand (a) how these areas interact with each other to modulate the local circuit functions; and (b) how such interactions help process sensory and motor signals to organize an animal's behavior. In the visual system, for example, while sensory afferents form the basic response properties of the visual cortex, it receives modulatory inputs from the motor cortex under different behavioral conditions and sends efferent signals to modulate the thalamic responses. Such complex feedback loops often omit the retina, the first stage of the visual processing; however, it should be considered part of such brain-wide loops because there is an anatomical substrate of efferent inputs from distinct brain areas to the retina across species. In fact, the mouse retina is an excellent model system to study the role of long-range neural interactions and their effects on local circuit functions. First, we can functionally analyze the role of the retinal efferents and their impact on the retinal afferents from the view point of visual computation. The retina is one of the best understood circuits in the central nervous system, and the physiological functions are known in detail from the molecular to the cellular circuit level. Second, various tools are available in mice to label, monitor, and manipulate specific cell types and circuits. My research will thus focus on the bidirectional interactions between the retina and the brain, and aim to address the following questions:
How is retinal visual processing modulated by efferent inputs from the brain under different behavioral states of an animal?
How does retinal processing contribute to computation in the successive stages of the afferent visual pathway?
A key to address these questions is to clarify a causal relationship, not just correlation, among visual stimuli, behavioral states, and neuronal activities. I will achieve this by using electrophysiological and optogenetic tools in mice. The experimental results will then be integrated to build a quantitative model that better describes retinal circuit functions and visual processing.
