Chronic smoking, but not acute nicotine administration, modulates neural correlates of working memory
Beyond the amelioration of deprivation-induced impairments, and in contrast to effects on attentional processes, the cognitive-enhancing properties of nicotine on working memory (WM) operations remain unclear.
In an effort to elucidate potential enhancing effects, we explored the impact of transdermal nicotine on neural functioning in minimally deprived smokers and, in addition, assessed differences between smokers and non-smokers using a mixed block/event-related fMRI design that attempted to isolate specific central executive operations (attentional switch events) within general WM function (task blocks).
In task blocks, participants performed a continuous counting paradigm that required the simultaneous maintenance of, and frequent switching of attentional focus between, two running tallies in WM on some trials. Cigarette smokers (n = 30) were scanned twice, once each with a nicotine and placebo patch, while non-smokers (n = 27) were scanned twice with no patch.
Across both groups, task blocks were associated with bilateral activation, notably in medial and lateral prefrontal cortex (PFC), anterior insula, and parietal regions, whereas individual attentional switch trials were associated with activation in a similar, but predominantly left-lateralized network. Within the smoker group, although nicotine increased heart rate, altered performance and mood, and reduced tobacco cravings, no acute drug (state-like) effect on brain activity was detected for either the task or switch effects. However, relative to non-smokers, smokers showed greater tonic activation in medial superior frontal cortex, right anterior insula, and bilateral anterior PFC throughout task blocks (trait-like effect).
These data suggest smokers require recruitment of additional WM and supervisory control operations during task performance.
KeywordsNicotine Central executive Working memory Anterior prefrontal cortex Medial superior frontal cortex Anterior insula
This work was supported by the National Institute on Drug Abuse—Intramural Research Program. We thank all NIDA-IRP staff members who assisted in data collection, the NIH Fellow’s Editorial Board for suggestions on this manuscript, and Hugh Garavan.
Conflict of interest
The authors declare no conflicts of interest.
- Baddeley A, Hitch G (1974) Working memory. In: Bower GA (ed) The psychology of learning and motivation. Academic, New York, pp 47–89Google Scholar
- Barr RS, Culhane MA, Jubelt LE, Mufti RS, Dyer MA, Weiss AP, Deckersbach T, Kelly JF, Freudenreich O, Goff DC, Evins AE (2008) The effects of transdermal nicotine on cognition in nonsmokers with schizophrenia and nonpsychiatric controls. Neuropsychopharmacology 33:480–490CrossRefPubMedGoogle Scholar
- Garavan H (1998) Serial attention within working memory. Mem Cogn 26:263–276Google Scholar
- R-Development-Core-Team (2009) R: a language and environment for statistical computing. R Foundation for Statistical Computing; Vienna, Austria; ISBN: 3-900051-07-0; http://www.R-project.org
- Talairach J, Tourneaux P (1988) Co-planar stereotaxic atlas of the human brain. Thieme Medical, New YorkGoogle Scholar
- Wechsler D (1999) Wechsler abbreviated scale of intelligence, 3rd edn. The Psychological Corporation, San AntonioGoogle Scholar