Another oscillation that has been ubiquitously observed across cortical and subcortical structures is in the faster, gamma frequency range (30-120 Hz,Buzsáki and Wang, 2012). Due to their fast temporal dynamics, gamma oscillations provide the ideal mechanism to coordinate precise neural coding within and across structures (Buzsáki and Wang, 2012; Lisman and Jensen, 2013). Indeed, gamma oscillations are prominent in circuits underlying sensory processing and cognitive functions (Fries, 2009) and their perturbation has been noted in schizophrenia (Cho et al., 2006), underscoring their importance for neural circuit function. In HPC, discrete bands of gamma oscillations are nested within the lower frequency theta oscillation (Belluscio et al., 2012). Importantly, distinct gamma frequency bands have been implicated in differentially synchronizing CA1 with CA3 or medial entorhinal cortex (Colgin et al., 2009). These findings support the notion that theta-coupled gamma oscillations may be fundamental to synchronizing activity within and between regions.
