Corticostriatal responses from striatal interneurons. A: Voltage responses (top) to intracellular current steps (bottom) from a fast-spiking (FS) interneuron. B: Corticostriatal responses of the same FS interneuron to field stimulus of increasing strength. Suprathreshold responses (blue) elicit a high frequency discharge and last hundreds of milliseconds. C: Voltage responses (top) to current steps (bottom) from a persistent low-threshold spike (PLTS) interneuron. Time scale was compressed as compared to A in order to observe the off-response (spikes are clipped). PLTS (arrow) elicits high frequency trains followed by slowly adapting action potentials. D: Corticostriatal responses of the same PLTS interneuron. Holding potential (−80 mV) used for comparing responses is not the resting potential of these neurons so that action potentials on top of synaptic response appear partially inactivated. Still, synaptic depolarizations last hundreds of milliseconds after a single stimulus and some exhibit auto regenerative events (arrow). E: Voltage responses (top) to current steps (bottom) from a tonically active neuron (TAN) at −80 mV holding potential. Note voltage sags after depolarizing and hyperpolarizing current steps. Evoked discharge is slowly adapting. F: Corticostriatal responses of the same TAN interneuron evoked with field cortical stimuli. Synaptic responses last hundreds of milliseconds and even seconds (inset). Evoked discharge is of low frequency. G: Histogram comparing frequency discharge (mean ± SEM in this and similar graphs) during corticostriatal responses in different interneurons: FS interneurons attain the highest frequencies while TAN interneurons attain the lowest ones. H: Duration at half amplitudes is compared. Lengthier responses belong to TAN interneurons. I: Areas under corticostriatal responses: largest areas correspond to TANs and dSPNs.
Vizcarra-Chacón et al. BMC Neuroscience 2013 14:60 doi:10.1186/1471-2202-14-60