PT - JOURNAL ARTICLE AU - Hull, Court AU - Adesnik, Hillel AU - Scanziani, Massimo TI - Neocortical Disynaptic Inhibition Requires Somatodendritic Integration in Interneurons AID - 10.1523/JNEUROSCI.5717-08.2009 DP - 2009 Jul 15 TA - The Journal of Neuroscience PG - 8991--8995 VI - 29 IP - 28 4099 - http://www.jneurosci.org/content/29/28/8991.short 4100 - http://www.jneurosci.org/content/29/28/8991.full SO - J. Neurosci.2009 Jul 15; 29 AB - In his theory of functional polarity, Ramon y Cajal first identified the soma and dendrites as the principal recipient compartments of a neuron and the axon as its main output structure. Despite notable exceptions in other parts of the nervous system (Schoppa and Urban, 2003; Wässle, 2004; Howard et al., 2005), this route of signal propagation has been shown to underlie the functional properties of most neocortical circuits studied so far. Recent evidence, however, suggests that neocortical excitatory cells may trigger the release of the inhibitory neurotransmitter GABA by directly depolarizing the axon terminals of inhibitory interneurons, thus bypassing their somatodendritic compartments (Ren et al., 2007). By using a combination of optical and electrophysiological approaches, we find that synaptically released glutamate fails to trigger GABA release through a direct action on GABAergic terminals under physiological conditions. Rather, our evidence suggests that glutamate triggers GABA release only after somatodendritic depolarization and action potential generation at GABAergic interneurons. These data indicate that neocortical inhibition is recruited by classical somatodendritic integration rather than direct activation of interneuron axon terminals.