Symmetry in frontal but not motor and somatosensory corticocortical and corticostriatal circuitry.

Neocortex and striatum are topographically organized by cortical areas representing sensory and motor functions, where primary cortical areas are generally used as models for other cortical regions. But different cortical areas are specialized for distinct purposes, with sensory and motor areas lateralized for touch and motor control, respectively. Frontal areas are involved in decision making, where lateralization of function may be less important. This study contrasted the topographic precision of ipsilateral and contralateral projections from cortex based on the injection site location. While sensory cortical areas had strongly topographic outputs to ipsilateral cortex and striatum, they were weaker and not as topographically strong to contralateral targets. Motor cortex had somewhat stronger projections, but still relatively weak contralateral topography. In contrast, frontal cortical areas had high degrees of topographic similarity for both ipsilateral and contralateral projections to cortex and striatum. This contralateral connectivity reflects on the pathways in which corticostriatal computations might integrate input outside closed basal ganglia loops, enabling the two hemispheres to act as a single unit and converge on one result in motor planning and decision making.

Transcript Expression of Vesicular Glutamate Transporters in Rat Dorsal Root Ganglion and Spinal Cord Neurons: Impact of Spinal Blockade during Hindpaw Inflammation.

Studies in mouse, and to a lesser extent in rat, have revealed the neuroanatomical distribution of vesicular glutamate transporters (VGLUTs) and begun exposing the critical role of VGLUT2 and VGLUT3 in pain transmission. In the present study in rat, we used specific riboprobes to characterize the transcript expression of all three VGLUTs in lumbar dorsal root ganglia (DRGs) and in the thoracolumbar, lumbar, and sacral spinal cord. We show for the first time in rat a very discrete VGLUT3 expression in DRGs and in deep layers of the dorsal horn. We confirm the abundant expression of VGLUT2, in both DRGs and the spinal cord, including presumable motorneurons in the latter. As expected, VGLUT1 was present in many DRG neuron profiles, and in the spinal cord it was mostly localized to neurons in the dorsal nucleus of Clarke. In rats with a 10 day long hindpaw inflammation, increased spinal expression of VGLUT2 transcript was detected by qRT-PCR, and intrathecal administration of the nonselective VGLUT inhibitor Chicago Sky Blue 6B resulted in reduced mechanical and thermal allodynia for up to 24 h. In conclusion, our results provide a collective characterization of VGLUTs in rat DRGs and the spinal cord, demonstrate increased spinal expression of VGLUT2 during chronic peripheral inflammation, and support the use of spinal VGLUT blockade as a strategy for attenuating inflammatory pain.