One of the central questions in neuroscience is how the brain represents an object in space. We hope to understand the neural mechanism of visual perception at the single-cell level in the brain. Our studies have shown that in the visual area of the brain, responses of many neurons increase when local patterns are part of an extended contour, while responses decrease with a disrupted pattern. When stimulated with an extended pattern, response facilitation often occurs when the contrast of the target pattern is low, but responses are often suppressed at high target contrasts. We want to characterize these basic physiological findings in relation to the known anatomical structure and pharmacology of lateral connections in the visual brain.

Visual experience early in life determines how nerve cells in the visual brain respond to stimuli encountered in adult life. What underlies this experience-dependent plasticity is unclear. We have accumulated evidence to strengthen the general hypothesis that the norepinephrinebeta-adrenoreceptor system in the brain is one neurochemical mechanism regulating plasticity of neural connections.

Extending the idea beyond the usual age limit, we have shown that neural plasticity is partially restored to the adult brain by experimental application of drugs. In addition to studying the involvement of beta-adrenergic receptors, we have evaluated the roles of neurotrophins, molecules which promote growth and survival of immature nerve cells. Our long-term goal is to provide a sound neurochemical basis for the visual rehabilitation of individuals, particularly amblyopes, who suffer from inadequate or abnormal visual stimulation during development.

For more information, visit Takuji Kasamatsu's lab web pages.

Collaborators: Michael Chang, Richard Miller, Zhao Zhu, Yoshiyuki Ishida. Erich Sutter, Chien-Chung Chen.