Sensory Deprevation - Serotonin system is effected through means of fasting and other related activities. The levels of serotonin in the thalamus are shifted causing the thalamus to loose some of its ability to control the flow of information coming in from the senses. Serotonin is synthesized from the amino acid L-tryptophan. This substance may also be important in eliciting local tissue reactions resembling inflammation. At this point, where the relationship of the two neurons is one of contact only, the impulse traveling in the first neuron initiates an impulse in the second neuron.
Synapses are polarized, i.e., the impulses pass in one direction only.
They are susceptible to fatigue, offer a resistance to the passage of impulses, and are markedly susceptible to the effects of oxygen deficiency, anesthetics, and other agents, including therapeutic drugs and toxic chemicals. Thalamus - A large ovoid mass of gray matter at the base of the brain, the chief center for transmission of sensory impulses to the cerebral cortex.