In vivo and in vitro patch-clamp recording analysis of the process of sensory transmission in the spinal cord and sensory cortex

Following the integration and modification of the sensory inputs in the spinal cord, the information is transmitted to the primary sensory cortex where the integrated information is further processed and perceived. Processing of the sensory information in the spinal cord has been intensively investigated. However, the mechanisms of how the inputs are processed in the cortex are still unclear. To know the correlation of the sensory processing in the dorsal horn and cortex, in vivo and in vitro patch-clamp recordings were made from rat dorsal horn and sensory cortex. Although dorsal horn neurons showed spontaneous and evoked EPSCs by noxious and non-noxious stimuli, most somatosensory neurons located at 100 to 1000 microm from the surface of the cortex exhibited an oscillatory activity and received synaptic inputs from non-noxious but not noxious receptors. These observations suggest that the synaptic responses in cortical neurons are processed in a more complex manner; and this may be due to the reciprocal synaptic connection between thalamus and cortex.