title: Attenuated frontal and sensory inputs to the basal ganglia in cannabis users.
abstract: 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.
authors.affiliation: MRI Research Unit, Hospital del Mar, Barcelona, Spain.
authors.forename: Laura
authors.initials: L
authors.lastname: Blanco-Hinojo
authors.affiliation: MRI Research Unit, Hospital del Mar, Barcelona, Spain.|Centro Investigación Biomédica en Red de Salud Mental, CIBERSAM G21, Barcelona, Spain.
authors.forename: Jesus
authors.initials: J
authors.lastname: Pujol
authors.affiliation: Melbourne Neuropsychiatry Centre, Department of Psychiatry, The University of Melbourne, Melbourne, Australia.
authors.forename: Ben J
authors.initials: BJ
authors.lastname: Harrison
authors.affiliation: MRI Research Unit, Hospital del Mar, Barcelona, Spain.
authors.forename: Dídac
authors.initials: D
authors.lastname: Macià
authors.affiliation: Department of Psychiatry and Psychology, Hospital Clínic, Institut d'Investigació Biomédica August Pi I Sunyer (IDIBAPS), CIBERSAM G25, Barcelona, Spain.|Nijmegen Institute for Scientist-Practitioners in Addiction, Nijmegen, Netherlands.
authors.forename: Albert
authors.initials: A
authors.lastname: Batalla
authors.affiliation: Section of Clinical Toxicology, Emergency Service, Hospital Clínic, IDIBAPS, University of Barcelona, Barcelona, Spain.
authors.forename: Santiago
authors.initials: S
authors.lastname: Nogué
authors.affiliation: Human Pharmacology and Clinical Neurosciences, Institute of Neuropsychiatry and Addiction, Hospital del Mar Medical Research Institute, Barcelona, Spain.|School of Medicine, Autonomous University of Barcelona, Red de Trastornos Adictivos (RETIC), Barcelona, Spain.
authors.forename: Marta
authors.initials: M
authors.lastname: Torrens
authors.affiliation: Human Pharmacology and Clinical Neurosciences, Institute of Neuropsychiatry and Addiction, Hospital del Mar Medical Research Institute, Barcelona, Spain.|School of Medicine, Autonomous University of Barcelona, Red de Trastornos Adictivos (RETIC), Barcelona, Spain.
authors.forename: Magí
authors.initials: M
authors.lastname: Farré
authors.affiliation: MRI Research Unit, Hospital del Mar, Barcelona, Spain.|Department of Clinical and Health Psychology, Autonomous University of Barcelona, Barcelona, Spain.
authors.forename: Joan
authors.initials: J
authors.lastname: Deus
authors.affiliation: Department of Psychiatry and Psychology, Hospital Clínic, Institut d'Investigació Biomédica August Pi I Sunyer (IDIBAPS), CIBERSAM G25, Barcelona, Spain.|Department of Psychiatry and Clinical Psychobiology, University of Barcelona, Barcelona, Spain.
authors.forename: Rocío
authors.initials: R
authors.lastname: Martín-Santos
mesh_terms: D000328:Adult; D001479:Basal Ganglia / Q000000981:diagnostic imaging / Q000187:drug effects* / Q000503:physiopathology; D002188:Cannabis; D005625:Frontal Lobe / Q000187:drug effects* / Q000503:physiopathology; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D002189:Marijuana Abuse / Q000150:complications*; D011930:Reaction Time / Q000187:drug effects; D013003:Somatosensory Cortex / Q000187:drug effects* / Q000503:physiopathology; D055815:Young Adult
keywords: addiction; arousal; basal ganglia; cannabis use; fMRI; motivation