Conditional cross-correlation analysis of thalamocortical neurotransmission

We developed a method to quantify the probability of a target neuron discharge following synchronous or asynchronous discharges among a pair of reference neurons. To illustrate this method, we simultaneously recorded three neurons having overlapping receptive fields in the somatosensory system: two reference neurons in the thalamic ventrobasal complex and one target neuron in the secondary somatosensory (SII) cortex. Our results show that focal cutaneous stimulation elicits synchronized discharges among thalamic neurons having similar place and submodality properties. Conditional cross-correlation analysis of the reference and target spike trains indicates that thalamic synchronization increases cortical responsiveness. This result suggests that neuronal synchronization plays a critical role in transmitting sensory information from thalamus to the cerebral cortex.