Serotonin Involvement in Plasticity of the Visual Cortex
Serotonin (5-hydroxytryptamine, 5-HT) is widely distributed in the nervous system, and has been implicated in many aspects of behavioral and physiological regulation, including the control of blood pressure, body temperature, sleep, pain perception, sensory processing, anxiety, impulsivity, aggression, depression, sex and feeding behaviors, learning, and memory (Curzon, 1988; Wilkinson and Dourish, 1991; Lucki, 1992; Westenberg et al., 1996). A number of studies over the past decades provided evidence that serotonin also is involved in structural and functional remodeling of cortical circuits. Neurons in cortical areas that process sensory information such as vision, audition, and somatic sensation can modify their response properties following prolonged alterations in input activity, especially during early postnatal life. For instance, visual experience plays a pivotal role in shaping visual cortex structure and function during postnatal development. In addition, it has been also shown that nonvisual inputs to the visual cortex are important regulators for visual cortex plasticity (Gu, 2002, 2003). Neurotransmission of serotonin in the visual cortex is considered one of the nonvisual inputs that may serve as the neurochemical basis of attention, arousal, and motivation. In the following sections, serotonininduced neuronal responses in the visual cortex will be briefly described. The contribution of serotonin to ocular dominance plasticity in the visual cortex and possible underlying mechanisms will then be discussed.
KeywordsVisual Cortex Primary Visual Cortex Ocular Dominance Cortical Plasticity Monocular Deprivation
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