Reward center is located in -

Ans. D. HypothalamusMotivation &Addiction: -a. Addiction, defined as the repeated compulsive use of a substance despite negative health consequences, can be produced by various drugs.b. According to the World Health Organization, over 76 million people worldwide suffer from alcohol abuse and over 15 million suffer from drug abuse. Addictive drugs include opioids (eg, morphine and heroin), cocaine, amphetamine, alcohol, cannabinoids, and nicotine.c. Each of these drugs increase the amount of dopamine available to act on D3 receptors in the nucleus accumbens to stimulate the brain's reward system, which is comprised of the main dopamine pathways of the brain (mesolimbic pathway), the ventral tegmental area, and nucleus accumbens.d. The major reward centers have been found to be located along the course of the medial forebrain bundle, especially in the lateral and ventromedial nuclei of the hypothalamus. Long-term addiction involves the development of tolerance or the need for increasing amounts of a drug to produce a high.e. Withdrawal produces psychological and physical symptoms. For opioid addicts, the relapse rate in the first year is about 80%.f. Relapse often occurs on exposure to sights, sounds, and situations that were previously associated with drug use. Even a single dose of an addictive drug facilitates release of excitatory neurotransmitters in brain areas concerned with memory. The medial frontal cortex, hippocampus, and amygdala are concerned with memory, and they all project via excitatory glutamatergic pathways to the nucleus accumbens. Absence of b-arrestin-2 blocks tolerance but has no effect on dependence; b-arrestin-2 is a member of a family of proteins that inhibit heterotrimeric G- proteins by phosphorylating them.