Persistent firing supported by an intrinsic cellular mechanism in hippocampal CA3 pyramidal cells.

Short-term information retention is crucial for information processing in the brain. It has long been suggested that the hippocampal CA3 region is able to support short-term information retention through persistent neural firing. Theoretical studies have shown that this persistent firing can be supported by abundant excitatory recurrent connections in CA3. However, it remains unclear whether individual cells can support persistent firing. In this study, using in vitro whole-cell patch-clamp recordings in a rat hippocampal slice preparation, we show that hippocampal CA3 pyramidal cells support persistent firing under perfusion of the cholinergic agonist carbachol (10 μm). Furthermore, in contrast to earlier theoretical studies, this persistent firing is independent of ionotropic glutamatergic synaptic transmission and is supported by the calcium-activated non-selective cationic current. Because cholinergic receptor activation is crucial for short-term memory tasks, persistent firing in individual cells may support short-term information retention in the hippocampal CA3 region.