RT Journal Article SR Electronic T1 Continuous Modulation of Action Potential Firing by a Unitary GABAergic Connection in the Globus Pallidus In Vitro JF The Journal of Neuroscience JO J. Neurosci. FD Society for Neuroscience SP 12805 OP 12809 DO 10.1523/JNEUROSCI.1970-13.2013 VO 33 IS 31 A1 Jenia Bugaysen A1 Izhar Bar-Gad A1 Alon Korngreen YR 2013 UL http://www.jneurosci.org/content/33/31/12805.abstract AB The firing patterns of neurons in the globus pallidus (GP) are affected by two major sources of GABAergic inhibition: striatal afferents and local axon collaterals. Local GABAergic GP-GP synapses display short-term depression (STD) and very sparse connectivity. At the high presynaptic firing rates typical in the GP, one would expect this STD to be complete, practically canceling the postsynaptic impact of the synapse. To investigate the apparent paradox of a synapse not affecting its postsynaptic neuron, we performed dual whole-cell recordings in acute brain slices from rats and recorded, for the first time, unitary IPSPs from a GP-GP GABAergic connection. We show that at high presynaptic firing rates the unitary connection continuously modulates the postsynaptic firing rate through a combination of large chloride driving force, unitary IPSP summation, and incomplete synaptic depression. Our findings indicate that, despite substantial STD and sparse connectivity, local GABAergic axon collaterals in the GP may echo the changes in presynaptic firing frequency across postsynaptic targets.