The Neuron and Regions of the Brain 5. The Brain's Immune System , Wolfgang J. Streit and Carol A. Kincaid-Colton, Scientific American , November 1995. Since the brain may be inaccessible to immune cells in the blood, it is believed to lack an immune defense mechanism. However, recent studies show that microglia may serve as its immune system. Structures in Motion Seen at Synapses , Carl T. Hall, San Francisco Chronicle , January 5, 1999.
Neurons make connections with other neurons via a complex known as the synapse.
The dendrites of the receiving neuron possess a unique structure called dendritic spines, and modern video imaging techniques demonstrate that these spines are not rigid structures at all. It has been thought that the cerebellum's major, if not sole, function is the regulation of fine, highly coordinated movement. Recent studies reveal that this highly evolved structure is significantly involved in the regulation of sophisticated cognitive functions as well as of emotions. Integration of Information between the Cerebral Hemispheres , Marie T. Banich, Current Directions in Psychological Science , February 1998. The right and left cerebral hemispheres are physically connected by a bundle of brain tissue called the corpus callosum.