Inferior Colliculus: Aging and Plasticity

Classic views and theories of the central nervous system (CNS) emphasized that mammalian neural circuitry formed during development remained essentially invariant in adulthood. No new neurons are added, and CNS damage entails neuron loss, resulting in permanent anatomical damage and enduring functional impairments. However, advances in the study of plasticity and aging in the CNS, including the central auditory system, reveal that neural systems can reconfigure themselves with age and in response to the loss of peripheral inputs from sensory end-organs. For instance, peripheral abnormalities induce unmasking, rewiring, or changes in functional responses in the central auditory system, sometimes termed a??peripherally induced central changesa?? (Frisina et al. 2001). Alternatively, in the case of age-related changes in the central auditory system, deficits can occur independently of age-dependent alterations of the inner ear. Instances of these plastic and aging phenomena are presented in this chapter, focusing on those manifested in the inferior colliculus (IC).