(a, b) TC LTP (a) and TC LTD (b) are readily expressed in young but not mature animals. (c) LTP and LTD expression as a function of age. This graph is based on data from previous studies (Crair and Malenka, 1995; Feldman and others, 1998; Jiang and others, 2007). (d) A representative cortical map of sound frequencies in the primary ACx of mice. (e) Changes in cortical map representation in the primary (A1) area of the ACx after 2 weeks of exposure to a 7-kHz sound in neonates and mature animals (* p<0.05) [adapted from (de Villers-Sidani and others, 2007)]. (f) Cortical map plasticity as a function of age. Abbreviations: D, dorsal; EPSP, excitatory postsynaptic potential; R, rostral; TR, thalamic radiation.