Data from: Presynaptic GABAB receptors functionally uncouple somatostatin interneurons from the active hippocampal network

Information processing in cortical neuronal networks relies on properly
balanced excitatory and inhibitory neurotransmission. A ubiquitous motif
for maintaining this balance is the somatostatin interneuron (SOM-IN)
feedback microcircuit. Here, we investigate the modulation of this
microcircuit by presynaptic GABAB receptors (GABABRs) in the rat
hippocampus. Whole-cell recordings from SOM-INs reveal that both
excitatory and inhibitory synaptic inputs are strongly inhibited by
GABABRs, while optogenetic activation of the interneurons shows that their
inhibitory output is also strongly suppressed. Electron microscopic
analysis of immunogold-labelled freeze-fracture replicas confirms that
GABABRs are highly expressed presynaptically at both input and output
synapses of SOM-INs. Activation of GABABRs selectively suppresses the
recruitment of SOM-INs during gamma oscillations induced in vitro. Thus,
axonal GABABRs are positioned to efficiently control the input and output
synapses of SOM-INs and can functionally uncouple them from local network
with implications for rhythmogenesis and the balance of entorhinal versus
intrahippocampal afferents.