The Thalamus and Hypothalamus

All incoming sensory information from periphery is relayed through the thalamus to an appropriate higher processing center. The Thalamus is segregated into several regions each pertaining to its nuclei and associated functions. The Anterior Group is part of the limbic system, the regulator of emotion. The Medial Group integrates sensory information and relays it to the frontal lobes. The Ventral Group is responsible for passing along information from the basal nuclei of the cerebrum and the cerebellum to the somatic motor areas of the cerebral cortex. It also passes along sensory information to the sensory areas of the cerebral cortex. The Posterior Group includes the Pulvinar, and the lateral and medial geniculate nuclei. The function of the Pulvinar is to process sensory information for projection to the cerebral cortex. The lateral geniculate nucleus passes along visual information to the visual cortex and the medial geniculate nuclei passes along auditory information to the auditory cortex. Lastly, the lateral group processes sensory information as well as effects emotional states.

I am particularly intrigued by mood disorders and the effect they have on the brain. I have a relative with Bi-Polar disorder and although I know what the definition is and how it is treated, I did not really understand physiologically how Bi-Polar Disorder interrupts normal brain activity. I learned that through structural imaging studies, scientist have found a decrease in overall brain volume in patients with Bi-Polar Disorder. They believe that this is in part due to the decreased number of neurons and glial cells in layers II and III (are they referring to the meninges?) in the forebrain. They also know that the frontal and temporal lobes, the pre-frontal cortex, basal ganlia and parts of the limbic system are all involved and effected by this disorder. Some scientist also believe that since the cerebral cortex is responsible for some thought process that it may also be involved in the negative thinking that are part of the negative episodes of the disorder. Some websites offered that it was an excess of neurotransmitters that causes the manic episodes and a decrease in neurotransmitters that causes the depressive episodes, while other websites claimed that it was not the amount of neurotransmitters but the "effectiveness of the cell's functioning" that was to blame.