Basolateral amygdala neurons encode cocaine self-administration and cocaine-associated cues.
Electrophysiological recording procedures were used to examine basolateral amygdala (BLA) cell firing during cocaine self-administration and relative to response-independent presentations of cocaine-associated stimuli. Of 72 neurons (n = 10 rats), 31 cells (43%) were classified as phasically active, exhibiting one of three types of patterned discharges relative to the drug-reinforced response, similar to that previously described for nucleus accumbens (Acb) neurons (Carelli, 2002). Briefly, neurons exhibited increased firing rates within seconds preceding the response [termed preresponse (PR)], increased activity within seconds after the response [termed reinforcement excitation (RFe)] or an inhibition in cell firing before and/or after the response for intravenous cocaine [termed reinforcement inhibition (RFi)]. To examine the responsiveness of these same neurons to cocaine-associated stimuli, the stimulus "probe" procedure was used. Specifically, probe trials (18-20) were presented in which the audiovisual (tone-house light) stimulus associated with intravenous cocaine delivery during self-administration was randomly presented by the computer, interspersed between reinforced lever press responses. Neurons classified as type PR or type RFi were not activated by the stimulus. In contrast, neurons that exhibited increased firing immediately after the response (type RFe neurons) were significantly activated by the audiovisual cue. These findings are discussed with respect to the role of the BLA in cocaine addiction as well as previous studies characterizing Acb cell firing during cocaine self-administration.
Carelli
Regina M
RM
Department of Psychology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3270, USA. rcarelli@unc.edu
Williams
Jefferson G
JG
Hollander
Jonathan A
JA
D000161:Acoustic Stimulation; D000679:Amygdala / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D003042:Cocaine / Q000008:administration & dosage*; D019970:Cocaine-Related Disorders / Q000503:physiopathology*; D003216:Conditioning, Operant; D003463:Cues; D004567:Electrodes, Implanted; D004594:Electrophysiology; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D010775:Photic Stimulation; D051381:Rats; D012054:Reinforcement, Psychology; D012646:Self Administration
D003042:Cocaine