Fig. 3.

Average percent decrease in dentate nucleus (DN) stimulation-evoked dopamine responses following kynurenate infusion into the ventral tegmental area (VTA), mediodorsal thalamus (ThN md), or the ventrolateral thalamus (ThN vl), as well as the summed average percent decrease of each drug infused across sites. In Lurcher and Fmr1 wildtype mice infusions of kynurenate into the VTA reduced dopamine responses by ∼50%, while kynurenate infusions into the thalamus (md and vl combined) also reduced the dopamine response by a total of ∼50% (md = ∼35% and vl = ∼15%). In contrast, the reduction in the dopamine response following kynurenate into the VTA in Lurcher mutant (∼30%) and Fmr1 mutant (∼20%) mice was significantly less, indicating a reduction in the modulatory strength of this pathway. This reduction in strength in mutant mice was coupled to an increase in signal strength of the pathway through the thalamus, specifically the ThN vl. Thus, kynurenate infused into this nucleus reduced dopamine responses by ∼15 % in wildtype mice of both strains and ∼40% in mutant mice of both strains. Regardless of strain or genotype kynurenate infused into the ThN md reduced the dopamine signal between 30 to 40%. The inset figure shows the two independent pathways by which cerebellar output through the DN modulates dopamine release in the mPFC. See text for additional description.