Gilad Silberberg (Department of Neuroscience, Karolinska Institute, Stockholm, Sweden) | Bilateral and multimodal sensory integration in the striatal microcircuit

Abstract

The basal ganglia have been extensively studied within the context of motor and reward-related functions, whereas their involvement in sensory processing is largely unknown. The high degree of corticostriatal convergence suggests that individual striatal neurons receive inputs originating from different cortical areas and from both cortical hemispheres, thus supporting the integration of multiple sensory input pathways. In order to determine whether and how the striatum integrates such sensory inputs we obtained whole-cell patch-clamp recordings from neurons in the mouse dorsal striatum during presentation of brief deflections of ipsi- and contralateral whiskers as well as visual stimuli. All recorded projection neurons and interneurons responded to bilateral whisker stimulation and almost one third also responded to visual stimulation. Using anatomical tracing and TTX injections we showed that whereas responses to contralateral whisker stimulation are mediated via ipsilateral corticostriatal projections from the barrel cortex to dorsolateral striatum, responses to ipsilateral whisker stimulation involve an additional cortico-cortical projection from the barrel cortex to motor cortex and contralateral barrel cortex. Direct pathway projection neurons had longer latency differences between ipsi- and contralateral responses than indirect pathway neurons, suggesting different functional roles in bilateral sensory integration. Our results show that all neurons in dorsal striatum receive bilateral tactile input from the whiskers and a large proportion of them also perform multisensory integration, suggesting that the striatum acts as a sensory “hub” with specialized functional roles for the different neuron types.