Microelectrode studies of normal organization and plasticity of human somatosensory thalamus

Microelectrode studies of single units in the human thalamus during stereot actic surgery offer a unique opportunity to study the organization and plas ticity of the sensory thalamus. In this review the authors present results using single-unit microelectrode recording in the mapping of human sensory thalamus in a variety of patients. First they outline the overall organizat ion of the human sensory thalamus, including both somatosensory and pain pa thways. They also show that the sensory maps for receptive and projection f ields can be altered during pathologic states such as amputation and spinal transection. Additionally, the sensory maps show plasticity during states with abnormal patterns of motor activity, like dystonia. Lastly, they discu ss the processing of painful and emotionally laden sensory experiences thro ugh the thalamus. The physiologic results of thalamic pain processing are d iscussed in relation to the sensory-limbic model of pain. The studies revie wed demonstrate the spectrum of stimulus processing and plasticity of both painful and nonpainful signals by the human thalamus.