THE ROLE OF THE THALAMUS IN MODULATING PAIN

The thalamus is one of the structures that receives projections from multiple ascending pain pathways. The structure is not merely a relay centre but is involved in processing nociceptive information before transmitting the information to various parts of the cortex. The thalamic nuclei are involved in the sensory discriminative and affective motivational components of pain. Generally each group of nucleus has prominent functions in one component for example ventrobasal complex in sensory discriminative component and intralaminar nuclei in affective- motivational component. The thalamus is also part of a network that projects to the spinal cord dorsal horn and modulates ascending nociceptive information. In the animal models of neuropathic pain, changes in the biochemistry, gene expression, thalamic blood flow and response properties of thalamic neurons have been shown. These studies suggest the important contribution of the thalamus in modulating pain in normal and neuropathic pain condition.