During quiet wakefulness, the average spontaneous firing rates of PV neurons are highest, SST neurons are intermediate, and 5HT3AR-expressing neurons are lowest, with all three classes of GABAergic neurons on average firing at considerably higher rates than excitatory L2/3 neurons (Gentet et al., 2010, 2012) (Figures 3C and 3D). However, it is important to note that there is a wide distribution of AP firing rates within each genetically defined class, which include both high and low firing rate individual neurons. Dual whole-cell recordings in awake head-restrained mice have revealed that the slow, large-amplitude membrane

potential fluctuations that characterize quiet wakefulness in L2/3 mouse barrel cortex (Crochet and Petersen, 2006; Poulet and Petersen,

2008) are highly synchronous in PV, 5HT3AR, and excitatory neurons, whereas these fluctuations selleck screening library are strongly reduced and negatively correlated in SST neurons (Gentet et al., 2010, 2012) (Figure 3C). The SST neurons therefore have different spontaneous membrane potential dynamics compared to all the other classes of nearby neurons. SST neurons are also unique in being hyperpolarized and inhibited by sensory whisker input (either passively applied by the experimenter or actively acquired by the mouse palpating objects), whereas PV, 5HT3AR, and excitatory neurons learn more are depolarized and excited by sensory stimulation (Gentet et al., 2010, 2012) (Figures 3E and 3F). PV neurons have the strongest increase in firing rates evoked by whisker stimulation, closely followed by 5HT3AR neurons, and both of these types of GABAergic neurons fire approximately an order of magnitude more sensory-evoked APs than the excitatory neurons. There are therefore strong differences comparing the activity of excitatory neurons and different

types of inhibitory neurons in L2/3 mouse barrel cortex. In particular, the SST neurons have a radically different behavior from the other cell types, probably indicating that they receive different synaptic inputs. Several mechanisms might contribute to the unusual inhibitory responses in SST neurons. The SST cells Parvulin might receive stronger inhibition than other nearby cells types or they might lack excitatory input that the other cell types receive (Adesnik et al., 2012). Also, the need for repetitive AP firing in presynaptic excitatory neurons to evoke facilitated synaptic input may contribute to the functional differences observed for SST neurons (Reyes et al., 1998; Silberberg and Markram, 2007; Kapfer et al., 2007; Fanselow et al., 2008; Gentet et al., 2012). Cell type-specific firing of different types of GABAergic neurons has also been reported in L2/3 mouse primary visual cortex.