Activation of a Temporal Memory in Purkinje Cells by the mGluR7 Receptor

Cerebellar Purkinje cells can learn to respond to a conditioned stimulus with an adaptively timed pause in firing. This response was usually ascribed to long-term depression of parallel fiber to Purkinje cell synapses but has recently been shown to be due to a previously unknown form of learning involving an intrinsic cellular timing mechanism. Here, we investigate how these responses are elicited. They are resistant to blockade of GABAergic inhibition, suggesting that they are caused by glutamate release rather than by a changed balance between GABA and glutamate. We show that the responses are abolished by antagonists of the mGlu7 receptor but not significantly affected by other glutamate antagonists. These results support the existence of a distinct learning mechanism, different from changes in synaptic strength. They also demonstrate in vivo post-synaptic inhibition mediated by glutamate and show that the mGlu7 receptor is involved in activating intrinsic temporal memory. [Display omitted] •Cerebellar cortical mGluR7 mediates an adaptively timed, learned response•mGluR7 can activate cellular memories of temporal intervals•mGluR7 mediates an inhibitory action of glutamate tied to a behavioral response•Temporally modulated firing rates can be regulated by post-synaptic mechanisms Johansson et al. show that a recently discovered temporal memory in cerebellar Purkinje cells, which takes the form of an adaptively timed inhibitory response to glutamate, can be tied to a specific metabotropic receptor subtype.