The Thalamus

The thalamus is a structure at the center of each cerebral hemisphere which is a relay for sensory pathways, and for brain stem, cerebellar, and subcortical pathways to the cortex, as well as a relay between different cortical areas. In addition to the anatomy defined by these inputs, the thalamus is characterized by a well-defined arrangement of neurons and their connections. The related physiology leads to neuronal firing, as either trains of single spikes versus trains bursts of spikes, which may be related to wakefulness and drowsiness or sleep. These firing patterns may also influence sensory transmission or represent pathological activity related to chronic pain or abnormal movement. The thalamus has long been a target of surgical approaches to the treatment of these conditions by lesioning or stimulating thalamic nuclei; the basic problem with this type of surgery is that small functionally distinct and therapeutically important structures are located in a small area. These challenges have been met with translational advances in surgery based upon the neuroscience of the thalamus, as well as imaging, electrophysiology, and databases combining these types of data.