Bicuculline permits the induction of long-term depression by heterosynaptic, translaminar conditioning in the hippocampal dentate gyrus.

Using intact, urethane-anesthetized albino rats, we examine long-term depression (LTD) of the ipsilateral medial entorhinal cortical (MEC) response in the dentate gyrus (DG) that is induced by conditioning of the ipsilateral lateral entorhinal cortex (LEC). Although the LEC-DG response potentiates, conditioning the LEC induces little or no LTD of the MEC-DG response. However, bicuculline methiodide, and the correlated presence of population spikes, enable the LEC input to induce LTD of the MEC-DG response. This result suggests that inhibition can control the selectivity of translaminar interactions.