Fig. 2: Polysynaptic inhibition between ChINs is a ubiquitous intrastriatal inhibitory pathway.
a In multi-neuron patch clamp configuration polysynaptic responses can be observed in multiple postsynaptic ChINs simultaneously (n = 30 cases of divergent connectivity), elicited by neighboring presynaptic ChINs (gray traces), as well as feedback inhibition onto the same ChIN (black traces, n = 846 observed examples). Scale bar: 40 µm. b Probability of feed-forward inhibition (32%) is slightly lower than feedback inhibition (39%). In pairs of ChINs exhibiting feed-forward inhibition, reciprocal connectivity probability increases to 49%. c Venn diagrams showing the probabilities for recording feedback and feed-forward polysynaptic inhibition between ChINs. The majority of ChINs (64%) initiating feed-forward inhibition also initiate feedback inhibition, though ChINs receiving feed-forward inhibition exhibit only marginally more feedback inhibition (42% versus 37%). d Relative spatial distribution of 620 tested pairs. Polysynaptic inhibition does not exhibit a significant directional preference within the dorso-ventral and rostro-caudal axes in parasagittal slices. e Connection probability (black/gray bars) ranges from 24 to 43% for 496 potential connections tested within 300 µm (numbers above bars denote tested connections per bin). Feed-forward response amplitude (red trace, mean amplitude per bin ± s.e.m.) shows a weak distance-dependent decrease (rS(183) = −0.15, p = 0.048).
