Figure 8

A working hypothesis for the generation of behavioral preferences for olfactory- and tactile-cue-directed options. (A, B) Olfactory and whisker sensory pathways in WT mice project to the dorsal striatum, which contains mGluR1, mGluR3, NMDA receptors, AC5, and CaMKIIα as key components of the decision making system (A). Whisker trimming in WT mice (B) increases the corticostriatal synaptic input from the barrel cortex, which activates mGluR1 and its down-stream signaling cascade including CaMKIIα. Consequently whisker trimming modulates behavioral outputs in choosing olfactory- and tactile-cue-directed options. (C, D) The AC5 deficiency disrupts the mGluR3-mediated suppression of mGluR1, resulting in the activation of mGluR1 and a down-stream signaling cascade including CaMKIIα, and consequently behavioral outputs (C). Whisker trimming in AC5 KO mice (D) increases the corticostriatal synaptic input from the barrel cortex, which activates mGluR1 and a down-stream signaling cascade including CaMKIIα; whereas the AC5 KO lead to the activation of mGluR1 and a down-stream signaling cascade. It is possible that whisker trimming in AC5 KO mice activates secondary signaling systems in the dorsal striatum, which are not switched on singly by AC5 KO or whisker trimming alone. Although it is unknown whether mGluR3 is colocalized with mGluR1 in the same post-synaptic neurons, whether mGluR3 and mGluR1 are located in different cells in the dorsal striatum, or whether mGluR3 is located in the presynaptic terminals of corticostriatal inputs, this model envisions that mGluR3 antagonistically suppresses the function of mGluR1 (pathways ① and ②).