Dynamic Response Properties of Neurons in the Superior Colliculus

There are various forms of physical energy available allowing the brain interpret the environment.

Organisms have taken advantage of this by specializing sensory systems capable of interpreting these different forms of information. This poses an interesting problem for the brain in that it must unify these various forms of sensory input into a single neural code. This unified neural representation of our multisensory environment can then be used to produce behaviors that ultimately will benefit the organism survival.

Nowhere in the brain has this been better characterized than in the superior colliculus. This mid-brain structure receives visual, auditory and somatosensory input as well as initiates motor commands that drive the eyes, ears and head. Most interestingly is the fact that the sensory input traveling to this structure converges onto individual neurons.

Elegant electrophysiology studies examining the responses of these neurons to both modality specific and multisensory stimuli have shown these individual units are specialized such that their responses are highly modulated by the presence of multisensory cues.

These studies have also shown that various rules apply to the presentation of a multisensory stimulus in order to get the maximal modulation of response. What is still unclear is how these neurons combine this information.

The focus of this research has been to examine the underlying response properties of these neurons and to understand how these neurons combine multisensory input throughout their entire response range.

Using single-unit electrophysiology we are examining the combinatorial mechanisms employed by these neurons and determining if these particular neurons will modulate their multisensory responses in a predictable manner based on their modality-specific responses.