Fig. 7.

Astrocyte-specific TeNT expression in vivo provoked a task-specific cognitive decline, manifested as a significant deficit in recognition memory. Y-maze–evaluated (A) and FC-evaluated memories (B) showed no gamma oscillation-dependent impairments. (A, Left) No group differences in general exploratory levels were observed as assessed by the number of arm entries (ANOVA: F_(4,17) = 2.5, P = 0.07). (A, Right) Bars represent the percentage of spontaneous alternations (unique triplets) ± SEM. The TeNT-expressing mice (3×TG-T) showed no changes compared with the control groups (ANOVA: F_(4,17) = 2.3, P = 0.10). (B) Bars represent the time (in seconds) freezing for animals trained to associate a context or a tone cue with an aversive stimulus (foot shock) ± SEM. The 3×TG-T mice showed similar freezing levels to the control groups in both the contextual (ANOVA: F_(4,17) = 1.0, P = 0.41) and conditioned stimulus tests (ANOVA: F_(4,17) = 1.5, P = 0.24). (C) Gamma-oscillation–defective mice suffered a significant memory deficit in a NOR test. Bars represent the discrimination index value [DI = (T_NOVEL-T_FAMILIAR)/(T_NOVEL+T_FAMILIAR)] ± SEM (ANOVA: F_(4,17) = 4.03, P = 0.01). Although the control mice (2×TG, n_control = 5, n_2xTG-T = 3, n_2xTG-TD = 3) showed significant preference for the novel object, the 3xTG-T mice (n = 5) did not discriminate between the familiar and the novel object, and therefore these groups were different [Fisher’s protected least significant difference (PLSD), P = 0.02, labeled with an asterisk]. Such defect was restored in mice with suppression of the TeNT by doxycycline (3xTG-T+D. n = 6; Fisher’s PLSD, P = 0.003, labeled with “#”), suggesting the need for a normal expression of gamma oscillations for the regular processing of recognition memory.