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Attenuated frontal and sensory inputs to the basal ganglia in cannabis users
Author(s) -
BlancoHinojo Laura,
Pujol Jesus,
Harrison Ben J,
Macià Dídac,
Batalla Albert,
Nogué Santiago,
Torrens Marta,
Farré Magí,
Deus Joan,
MartínSantos Rocío
Publication year - 2017
Publication title -
addiction biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.445
H-Index - 78
eISSN - 1369-1600
pISSN - 1355-6215
DOI - 10.1111/adb.12370
Subject(s) - basal ganglia , frontal lobe , inferior frontal gyrus , psychology , neuroscience , sensory system , striatum , cannabis , go/no go , context (archaeology) , audiology , functional magnetic resonance imaging , central nervous system , dopamine , medicine , biology , psychiatry , paleontology , machine learning , computer science
Heavy cannabis use is associated with reduced motivation. The basal ganglia, central in the motivation system, have the brain's highest cannabinoid receptor density. The frontal lobe is functionally coupled to the basal ganglia via segregated frontal–subcortical circuits conveying information from internal, self‐generated activity. The basal ganglia, however, receive additional influence from the sensory system to further modulate purposeful behaviors according to the context. We postulated that cannabis use would impact functional connectivity between the basal ganglia and both internal (frontal cortex) and external (sensory cortices) sources of influence. Resting‐state functional connectivity was measured in 28 chronic cannabis users and 29 controls. Selected behavioral tests included reaction time, verbal fluency and exposition to affective pictures. Assessments were repeated after one month of abstinence. Cannabis exposure was associated with (1) attenuation of the positive correlation between the striatum and areas pertaining to the ‘limbic’ frontal–basal ganglia circuit, and (2) attenuation of the negative correlation between the striatum and the fusiform gyrus, which is critical in recognizing significant visual features. Connectivity alterations were associated with lower arousal in response to affective pictures. Functional connectivity changes had a tendency to normalize after abstinence. The results overall indicate that frontal and sensory inputs to the basal ganglia are attenuated after chronic exposure to cannabis. This effect is consistent with the common behavioral consequences of chronic cannabis use concerning diminished responsiveness to both internal and external motivation signals. Such an impairment of the fine‐tuning in the motivation system notably reverts after abstinence.