Likewise, blocking glutamate reuptake had no effect on γ power or frequency in PCD mice (TBOA 1 mM, −2.6% ± 12.5% change in γ power compared to baseline, n = 4). We conclude that MCs are necessary for generating spontaneous γ oscillations as well as for

mediating the increase in γ induced by the weakening of GABAAR inhibition or by the increase in extrasynaptic glutamatergic excitation. Odor stimulation profoundly remodels spontaneous olfactory oscillations and can lead to the emergence of beta oscillations (β; 15–40 Hz) during learning (Martin et al., 2006). We investigated whether low-γ and β oscillations reflect distinct mechanisms in awake animals. For this, we recorded LFPs in mice engaged in an olfactory Go/NoGo task (Figure 3A). After surpassing the performance criterion and maintaining stable performance (i.e., 98.0% ± 1.2% of mean correct responses on the last 200 trials, hexanol versus benzaldehyde Antidiabetic Compound Library supplier 5%), mice were recorded before and after receiving a unilateral OB injection of PTX or MK801. Each odor presentation (odor sampling time, 710 ± 33 ms, n = 8 mice) Ixazomib in vivo was preceded by a 1 s waiting period in the odor port (preodor waiting time; Figures 3A and 3B). On baseline trials, active odor sampling was systematically associated with a transient reduction in γ power (−25.2% ± 4.2% compared to preodor

time) and by the emergence of slower oscillations in the β range (mean β frequency: 32.0 ± 0.3 Hz; Figure 3B). Injection of low doses of PTX induced a strong increase in γ power during odor presentation, associated with a decrease in γ frequency (Figure 3C). The γ oscillation ratio during odor presentation compared to preodor

time was also reduced by the PTX treatment (Figure 3E). However, MK801 dramatically reduced γ power during odor presentation without changing γ frequency (Figures 3D and 3E), as observed with spontaneous oscillations. In contrast to γ oscillations, the power of odor-induced β oscillations through was strongly reduced by PTX (−66.1% ± 8.2%; Figure 3F), while the mean β frequency was slightly increased (Figure 3F). On the other hand, injection of MK801 had no effect on β oscillations (Figure 3F). Thus, PTX and MK801 treatment induced similar effects on both spontaneous and odor-evoked γ oscillations but had opposite effects on β and γ oscillations. We next evaluate the impact of increasing low-γ oscillations on single MC spiking activity in awake head-fixed mice (Figure 4A). The head-fixed condition allowed us to track the same MC before and after pharmacological treatment (Figure 4B). MCs displayed a relatively high spontaneous firing rate of 20.7 ± 2.1 Hz (n = 25 cells), as previously reported (Rinberg et al., 2006). Surprisingly, although 0.5 mM PTX treatment increased low-γ oscillations, it did not affect the spontaneous MC firing rate (+0.5 ± 0.9 Hz changes in mean firing rate, p = 0.34, paired t test, n = 25 cells; Figures 4C and 4D).