W. Martin Usrey

Our laboratory uses anatomical and physiological tools to study the functional organization of the mammalian visual system. In particular, we are interested in how visual information is processed and transmitted from one level of the visual pathway to the next. Along the visual pathway, from retina to extrastriate cortex, neurons become increasingly selective to the patterns of light - the visual stimulus - that are excitatory. The goal of our laboratory is to understand the neural circuitry responsible for generating these selective responses. In addition, we are investigating the dynamics of these neural circuits to determine what role activity patterns play in influencing neuronal responses.

Traditionally, systems neuroscience has relied on single electrodes to characterize the activity of individual neurons in the brain. For researchers studying the visual system, the activity of individual neurons is recorded while animals are presented with various visual stimuli. By correlating neural responses with visual stimuli, one can ascertain the optimal visual stimulus for any given neuron. While this approach has proven extremely successful over the years and has provided the foundation for our understanding of the neural mechanisms of vision, the single- electrode approach is limited in the extent that we can only infer how populations of neurons behave together in a neural network. With recent progress in multielectrode technology, visual neuroscience is now primed and ready for the next major conceptual advancement: discovering how populations of neurons interact to code and communicate information. In particular, we need to determine the patterns of synaptic activity that convey information within each brain region as well as from one region to the next.

In an ongoing study, we are investigating the relationship between ascending and descending connections made between the thalamus and visual cortex. In an effort to determine the functional role(s) of these connections, we are using multielectrode arrays to record the responses of neurons that are synaptically connected. By recording simultaneously the responses of synaptically connected neurons, in vivo, we can relate neural connection to neural function. In other words, we can discover the rules that govern the connections from one level to the next, and how these connections determine new visual response properties.

Our research is funded by the NIH, the NSF, the McKnight Foundation, the Esther A. and Joseph Klingenstein Foundation, and the Alfred P. Sloan Foundation.

Teaching Interests: Systems Neuroscience, Neurobiology of Vision, Neuroanatomy, Human Physiology. Courses Taught: NSC 201 Neuroanatomy - Term(s): Fall NSC 222 Systems Neuroscience - Term(s): Winter NPB 101 Human Physiology - Term(s): Winter NSC 261B Visual Neuroscience - Term(s): Winter