Online Lecture by Jennifer Hoy
Age and context-dependent processing of novel visual stimuli in the mouse.
Abstract: Understanding how the brain detects salient information in the environment and decides how to respond, is an important goal in neuroscience. The study of prey-capture behavior in many species has long advanced our progress towards this goal. In classical models, it has been discovered the specific sizes, shapes and types of stimulus motion innately evoke approach and striking behaviors, yet the circuitry mediating these visuomotor transformations remain unclear. To begin to identify their specific neural circuit basis in a mammalian system, we study visually-guided insect predation and object pursuit in the mouse model. As I will show in my seminar, our work has identified for the first time which specific cell types in the superficial superior colliculus (sSC) are required for prey detection and successful prey-capture. While we found that these cell types encoded a wide range of visual stimulus features potentially relevant to approach and pursuit behavior, it remained unclear which specific visual features of the prey mice utilized to make approach decisions and under which context. We recently found that mice readily orient to simple two-dimensional stimuli presented on a computer screen with properties similar to stimuli used in visual physiology studies of the superior colliculus. Indeed, mice do naturally prefer to approach specific combinations of object size and speed of motion presented in the middle to lower visual field when freely moving. Surprisingly, they also exhibited robust freezing responses that increased in frequency as stimulus speed increased and as relative object size decreased. Moreover, when mice are given prey capture experience and expect insects in the environment prior to exposure to our stimuli, the frequency of approach responses specifically increases. Our studies therefore show which specific combinations of object size, speed and visual field location bias behavioral choice between a freeze and approach type orienting response. We also reveal rapid alteration of these biases with relatively brief interventions of natural hunting experience. Our future work will now seek to understand how the specific representations of stimuli that we found evoke approach or freezing change in the sSC in an age and experience-dependent manner.