Neuroimaging of marijuana smokers during inhibitory processing: a pilot investigation.
Staci A Gruber, Deborah A Yurgelun-Todd
Brain research. Cognitive brain research April 2005 DOI: 10.1016/j.cogbrainres.2005.02.016 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Pilot investigation, case-control neuroimaging study Pilot study Peer reviewed |
|---|---|
| Population | Heavy cannabis smokers and matched control subjects |
| Measures | fMRI, diffusion tensor imaging (DTI), Stroop task, errors of commission, fractional anisotropy (FA), trace |
| Topics | Cannabis |
| Key findings | Chronic marijuana smokers showed different patterns of brain activation and more errors of commission than controls during the Stroop interference condition, despite similar task performance. Diffusion tensor imaging revealed no fractional anisotropy differences but higher trace values in smokers. The authors suggest these findings indicate altered frontal neural function during inhibition and performance monitoring in substance abusers. |
Abstract
Neuropsychological investigations of substance abusers have reported impairments on tasks mediated by the frontal executive system, including functions associated with behavioral inhibition and decision making. The higher order or executive components which are involved in decision making include selective attention and short term storage of information, inhibition of response to irrelevant information, initiation of response to relevant information, self-monitoring of performance, and changing internal and external contingencies in order to "stay the course" towards the ultimate goal. Given the hypothesized role of frontal systems in decision making and the previous evidence that executive dysfunctions and structural brain changes exist in subjects who use illicit drugs, we applied fMRI and diffusion tensor imaging (DTI) techniques in a pilot investigation of heavy cannabis smokers and matched control subjects while performing a modification of the classic Stroop task. Marijuana smokers demonstrated significantly lower anterior cingulate activity in focal areas of the anterior cingulate cortex and higher midcingulate activity relative to controls, although both groups were able to perform the task within normal limits. Normal controls also demonstrated increased activity within the right dorsolateral prefrontal cortex (DLPFC) during the interference condition, while marijuana smokers demonstrated a more diffuse, bilateral pattern of DLPFC activation. Similarly, although both groups performed the task well, marijuana smokers made more errors of commission than controls during the interference condition, which were associated with different brain regions than control subjects. These findings suggest that marijuana smokers exhibit different patterns of BOLD response and error response during the Stroop interference condition compared to normal controls despite similar task performance. Furthermore, DTI measures in frontal regions, which include the genu and splenium of the corpus callosum and bilateral anterior cingulate white matter regions, showed no between group differences in fractional anisotropy (FA), a measure of directional coherence within white matter fiber tracts, but a notable increase in trace, a measure of overall isotropic diffusivity in marijuana smokers compared to controls. Overall, results from the present study indicate significant differences in the magnitude and pattern of signal intensity change within the anterior cingulate and the DLPFC during the Stroop interference subtest in chronic marijuana smokers compared to normal controls. Furthermore, although chronic marijuana smokers were able to perform the task reasonably well, the functional activation findings suggest they utilize different cortical processes from the control subjects in order to do so. Findings from this study are consistent with the notion that substance abusers demonstrate evidence of altered frontal neural function during the performance of tasks that involve inhibition and performance monitoring, which may affect the ability to make decisions.
Comparable studies
Other experimental studies on cannabis, most cited first.
| Study | Year | Design | Participants |
|---|---|---|---|
| Smoked Cannabis' Psychomotor and Neurocognitive Effects in Occasional and Frequent Smokers Occasional (<2x/week) and frequent (≥4x/week) cannabis smokers | 2015 | Controlled within-subjects study | n = 25 |
| Dissociable effects of cannabis with and without cannabidiol on the human brain’s resting-state functional connectivity Healthy volunteers experienced with cannabis but not regular users | 2019 | Within-subjects experimental design | n = 17 |
| Which biological and self-report measures of cannabis use predict cannabis dependency and acute psychotic-like effects? Young cannabis users | 2018 | Observational study (naturalistic, within-subject counterbalanced design) | n = 410 |
| Cannabis Essential Oil: A Preliminary Study for the Evaluation of the Brain Effects Healthy volunteers | 2018 | Experimental study | n = 5 |
| Coming off cannabis: a cognitive and magnetic resonance imaging study in patients with multiple sclerosis Patients with multiple sclerosis who began using cannabis after disease onset, used it... | 2019 | Quasi-experimental study with odd-even allocation | n = 40 |
Citations in the library
Cited by 51
- Modulation of Mediotemporal and Ventrostriatal Function in Humans by Δ9-Tetrahydrocannabinol Archives of General Psychiatry April 1, 2009
- The neuropsychopharmacology of cannabis: A review of human imaging studies Pharmacology & Therapeutics October 20, 2018
- Neuroimaging in cannabis use: a systematic review of the literature Psychological Medicine July 23, 2009
- Effects of Cannabis on Impulsivity: A Systematic Review of Neuroimaging Findings Current Pharmaceutical Design May 10, 2014
- The effect of cannabis on the brain: can it cause brain anomalies that lead to increased risk for schizophrenia? Current Opinion in Psychiatry March 1, 2008
and 46 more in the library