![]() Right panel, examples of auditory stimuli. Left panel, illustration of “cloud-of-tones” task, a two-alternative forced-choice frequency-discrimination task. Bicuculine (20 μM) was added in the bath solution to block local GABAergic activity. EPSCs on MSN was elicited by local electrical stimulation on axon fibers, with CNO (10 µM, red) and without CNO (black) application. Right lower panel, one example of whole-cell recordings (average EPSCs) on striatal slice showing CNO-mediated terminal inhibition. Right upper panel, example image of labeled thalamostriatal fibers. Left panel, schematic diagram of viral injection and CNO infusion setup. b CNO/DREADD-mediated inhibition of thalamostriatal projection. Images are taken at the auditory striatum. AAV expressing GFP was injected into MGB, and AAV-expressing dTomato was injected into auditory cortex. Right panel, Example images of thalamic projections (green) and cortical projection (red) to the auditory striatum. ![]() a Left panel, illustration of the projections from the MGB and primary ACx to the auditory striatum. Inhibition of the MGB projection to the auditory striatum impaired animals’ performance in “cloud-of-tones” task. Our results indicate that the projections from the MGB and primary ACx differentially modulate striatal auditory information and that these effects are essential for making an auditory frequency-discrimination decision. Upon demonstrating the behavioral relevance of this connection, we used in vivo tetrode recordings to characterize striatal sound responses to the stimuli used in the behavioral task, and then optogenetically dissected the MGB and primary ACx contributions to the striatal sound representation. To understand how the MGB projection to the auditory striatum contribute to auditory decision-making, we used chemogenetic tools to assess the effects of the MGB projection inhibition on performance of an auditory frequency-discrimination task. Two recent studies have found that projections from ACx to the auditory striatum drives decision-making in rodents, and that selective plasticity of these synapses may underlie the establishment of this behavioral association 20, 21. ![]() The sensory subdivision, especially the auditory striatal region which receives projections from the medial geniculate body (MGB, the main auditory thalamus) and the auditory cortex (ACx), remains largely elusive. Moreover, the majority of previous studies have focused on the motor subdivision of the dorsal striatum 16, 17, 18, 19. However, the mechanisms underlying this function remain unclear. Previous studies suggest that thalamostriatal projections may be important for alertness and behavioral switching 15. How these two projections coordinate to regulate striatal activities and striatal-dependent behaviors remain largely unknown. The axon terminals of cortical and thalamic projections converge with comparable densities onto individual striatal neurons, forming functional glutamatergic synapses (i.e., thalamostriatal and corticostriatal synapses) 12, 13, 14. The dorsal striatum receives topographically organized projections from nearly the entire neocortex 9, and from most thalamic nuclei 10, 11. Striatal neurons can respond to visual, auditory, or somatosensory stimulation 8, consistent with anatomically demonstrated sensory inputs. ![]() The neostriatum, the main input structure of the basal ganglia, has been widely implicated in habitual and social behaviors 1, 2, 3, decision-making 4, 5, 6, and reinforcement learning 7. Together, our findings reveal that the MGB projection mainly functions as a gain controller, whereas the primary ACx projection provides tuning information for striatal sound representations. In contrast, transiently silencing the primary ACx projection diminish sound responses preferentially at the best frequencies in striatal medium spiny neurons. While recording striatal sound responses, we find that transiently silencing the MGB projection reduced sound responses across a wide-range of frequencies in striatal medium spiny neurons. Here we show that chemogenetic inhibition of the projections from either the medial geniculate body (MGB) or primary auditory cortex (ACx) to auditory striatum in mice impairs performance in an auditory frequency discrimination task. ![]() How these pathways contribute to auditory striatal activity and function remains largely unknown. A posterior sub-region of the dorsal striatum, the auditory striatum, receives convergent projections from both auditory thalamus and auditory cortex. The dorsal striatum has emerged as a key region in sensory-guided, reward-driven decision making. ![]()
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