Figure 2.

Network activity-related firing patterns of the three major parvalbumin-expressing GABAergic neurons of stratum pyramidale in areas CA1 and CA3 of rats, with or without anaesthesia. (a) Theta was recorded in the pyramidal layer of CA1, except for the CA3 bistratified cell (TV32n, bottom). In CA1, PV-positive basket cells fire on the descending phase of CA1 pyramidal layer theta. Axo-axonic cells fire just after the theta peak, earlier than basket cells, and bistratified cells later, around the trough, at the highest firing probability of pyramidal cells. Note the increase in the frequency of theta oscillations without anaesthesia, but the nearly constant phase relationships in spite of increase in firing rates. (b) During SWRs, basket and bistratified cells strongly increase their firing rate, phase locked to the local oscillation, but axo-axonic cells reduce firing either with or without anaesthesia. Theta field potential, wide band; SWRs, LFP band-pass filtered (90–140; non-anaesthetised, 90–200 or 130–230 Hz) for ripple activity. Scale bars: 0.1 s; action potentials and field potential theta, 0.2 mV; ripples, 0.1 mV. (Data from [15,33,34,40], CA3 bistratified cell without anaesthesia (TJ Viney 2013, unpublished data).)