Diego Cavallotti
Drug addiction as a disorder of associative learning. Role of nucleus accumbens shell/extended amygdala dopamine
DI CHIARA, GAETANO;BASSAREO, VALENTINA;ACQUAS, ELIO MARIA GIOACHINO;FENU, SANDRO;CARBONI, EZIO
1999-01-01
Abstract
Conventional reinforcers phasically stimulate dopamine transmission in the nucleus accumbens shell. This property undergoes one-trial habituation consistent with a role of nucleus accumbens shell dopamine in associative learning. Experimental studies with place- and taste-conditioning paradigms confirm this role. Addictive drugs share with conventional reinforcers the property of stimulating dopamine transmission in the nucleus accumbens shell. This response, however, undergoes one-trial habituation in the case of conventional reinforcers but not of drugs. Resistance to habituation allows drugs to repetitively activate dopamine transmission in the shell upon repeated self-administration. This process abnormally facilitates associative learning, leading: to the attribution of excessive motivational value to discrete stimuli or contexts predictive of drug availability. Addiction Is therefore the expression of the excessive control over behavior acquired by drug-related stimuli as a result of abnormal strenghtening of stimulus-drug contingencies by nondecremental drug-induced stimulation of dopamine transmission in the nucleus accumbens shell.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.