Long-Term Potentiation in the Recurrent Inhibitory Circuit of the Dentate Gyrus

The question of whether long-term potentiation occurs in the inhibitory circuits of the hippocampus remains controversial. Buszaki and Eidelberg (1982), recording extracellularly from putative interneurones (basket cells) in the dentate gyrus and area CAl of the anaesthetized rat, found a prolonged increase in probability of cell firing to afferent stimulation after high-frequency stimulation of Schaffer-commissural fibres, and concluded that LTP occurs at excitatory feedforward synapses onto interneurones. Similarly, Kairis et al (1987) have presented field potential evidence for LTP in feedforward synapses onto inhibitory neurones in the dentate gyrus of the anaesthetized rat. In the hipp…