Integration of retinal inputs by distinct collicular cell types

Obiettivo

Animals have a diverse set of behaviors that are triggered by specific sensory stimuli, such as motion or looming. In the visual system, this process begins in the retina where the visual scene is divided into 20 parallel information channels before reaching the brain. The superior colliculus is one of the main recipients of retinal output and it mediates tractable visually-guided behaviors such as eye movement, orienting or escaping behaviors. However, it remains unknown how visual signals from individual retinal ganglion cell types are processed by neurons in the superior colliculus to achieve specific computations relevant to behaviors.
To answer these questions, I will use transgenic mouse lines recently identified by the host laboratory, in which specific types of retino-recipient neurons of the superior colliculus are labeled with Cre recombinase. First, I will characterize the response properties of Cre-labeled individual cell types using in vivo two-photon calcium imaging during visual stimulation. Next, I will initiate calcium sensor-functionalyzed trans-synaptic viral tracing from Cre-labeled collicular cell types, and perform two-photon calcium imaging of labeled presynaptic retinal ganglion cells and starter collicular neurons. With this approach I will relate the activity of neurons to the activity of connected neuronal networks, and evaluate the degree of convergence and divergence in retino-collicular connectivity.
By linking cell types, circuits and computations, this work will provide mechanistic insight into the circuit basis for parallel processing of visual information and various visual functions in the healthy system, while possibly disclosing novel therapeutic targets for visual motor diseases.