Electrical coupling mediates tunable low-frequency oscillations and resonance in the cerebellar Golgi cell network.

Tonic motor control involves oscillatory synchronization of activity at low frequency (5-30 Hz) throughout the sensorimotor system, including cerebellar areas. We investigated the mechanisms underpinning cerebellar oscillations. We found that Golgi interneurons, which gate information transfer in the cerebellar cortex input layer, are extensively coupled through electrical synapses.

Enhancement of GABA release through endogenous activation of axonal GABA(A) receptors in juvenile cerebellum.

Recent evidence indicates the presence of presynaptic GABA(A) receptors (GABA(A)Rs) in the axon domain of several classes of central neurons, including cerebellar basket and stellate cells. Here, we investigate the possibility that these receptors could be activated in the absence of electrical or chemical stimulation. We find that low concentrations of GABA increase the frequency of miniature GABAergic synaptic currents.

T-type and L-type Ca2+ conductances define and encode the bimodal firing pattern of vestibulocerebellar unipolar brush cells.

Cerebellar unipolar brush cells (UBCs) are glutamatergic interneurons that receive direct input from vestibular afferents in the form of a unique excitatory synapse on their dendritic brush. UBCs constitute independent relay lines for vestibular signals, and their inherent properties most likely determine how vestibular activity is encoded by the cerebellar cortex. We now demonstrate that UBCs are bimodal cells; they can either fire high-frequency bursts of action potentials when stimulated from hyperpolarized potentials or discharge tonically during sustained depolarizations.

Developmental changes in parvalbumin regulate presynaptic Ca2+ signaling.

Certain interneurons contain large concentrations of specific Ca2+-binding proteins (CBPs), but consequences on presynaptic Ca2+ signaling are poorly understood. Here we show that expression of the slow CBP parvalbumin (PV) in cerebellar interneurons is cell specific and developmentally regulated, leading to characteristic changes in presynaptic Ca2+ dynamics (Ca(i)). Using whole-cell recording and fluorescence imaging, we studied action potential-evoked Ca(i) transients in axons of GABA-releasing interneurons from mouse cerebellum.