Figure 4. Neurophysiological properties of naive, sham and therapy rats.

a, c, e, g, i, Noise exposure caused a significant map distortion (a), decreased frequency selectivity (c), increased the tone-evoked response (e), increased the spontaneous rate (g) and increased the degree of cortical synchronization (i). VNS/multiple tone pairing returned each of these parameters, except spontaneous activity, to normal levels. b,d,f, Map organization (b), frequency selectivity (d) and tone-evoked response strength (f) were all correlated with the degree of gap impairment in individual rats. h, j, Spontaneous activity (h) and synchronization (j) were not significantly correlated with gap impairment. Each rat's gap detection ability was quantified as the average gap detection at the putative tinnitus frequency of each rat, averaged across the four time points collected after the beginning of therapy (Fig. 2). Error bars, s.e.m. Asterisks represent significant differences compared with naive rats (P values as indicated). Triangles and circles represent rats from the sham and therapy groups, respectively.