Biomedical subjects

Alan Pickering

Publications and source records attributed to Alan Pickering.

3 recordsLinked to original sources

PubMed2007

A double-blind placebo-controlled experimental study of nicotine: II--Effects on response inhibition and executive functioning.

RATIONALE: Smokers may show abnormal functioning in prefrontal cortex during acute abstinence, reflecting deficient activity in mesocorticolimbic circuitry. Cognitive correlates of this putatively include impaired response inhibition and other aspects of executive functioning. OBJECTIVES: To investigate whether inhibitory control and other executive functions in smokers are impaired during acute abstinence relative to post-nicotine. METHODS: 145 smokers were tested twice after overnight abstinence-once after nicotine and once after placebo lozenges (order counterbalanced, double-blind)-on an antisaccade task, a continuous performance task (CPT), a delayed response spatial working memory task and a verbal fluency test. RESULTS: Compared with placebo, nicotine was associated with better inhibitory control on the antisaccade task and fewer impulsive responses to filler stimuli (motor errors) on the CPT; at the first assessment only, nicotine also reduced impulsive responses to 'catch' stimuli on the CPT. However, it did not affect CPT response bias (an index of impulsive vs cautious decision-making), spatial working memory, or verbal fluency. CONCLUSIONS: Smoking abstinence appears to be associated with a difficulty in inhibiting prepotent motor responses, and with nicotine to attenuate this difficulty. However, more 'cognitive' forms of inhibitory control (e.g. decision-making) and the other aspects of executive function tested here appear to be unaffected.

Adult↗

PubMed2006

A double-blind placebo controlled experimental study of nicotine: I--effects on incentive motivation.

RATIONALE: Brain reward pathways implicated in addiction appear to be less reactive in regular drug users; behavioural manifestations may include decreased sensitivity to natural reinforcers. OBJECTIVES: This study aimed to replicate earlier findings of abstinence-associated incentive motivation deficits in smokers and to determine whether these can be reversed with nicotine in the form of lozenge. METHODS: One hundred forty-five smokers were each tested twice, once after receiving nicotine, and once after receiving placebo lozenge in counterbalanced order. Participants completed various tests of incentive motivational functioning: a measure of subjective enjoyment, the Snaith-Hamilton pleasure scale (SHAPS); a simple card sorting task, the card arranging reward responsivity objective test (CARROT) with and without financial incentive; the modified emotional Stroop test; a cue-reactivity task; and a novel reaction time task to explore effects of signals of reward, the incentive motivational enhancement of response speed task. RESULTS: Compared with performance during abstinence (placebo condition), nicotine was associated with: higher self-reported pleasure expectations on the SHAPS; enhanced responsiveness to financial reward on the CARROT in smokers who smoked 15 or more cigarettes a day; and greater interference from appetitive words on the Stroop task. CONCLUSIONS: These results are generally consistent with contemporary neurobiological theories of addiction and suggest that short-term smoking abstinence is associated with impaired reward motivation which can be reversed with nicotine.

Adult↗

PubMed2006

Cross-species differences in color categorization.

Berlin and Kay (1969) found systematic restrictions in the color terms of the world's languages and were inclined to look to the primate visual system for their origin. Because the visual system does not provide adequate neurophysiological discontinuities to supply natural color category boundaries, and because recent evidence points to a linguistic origin (Davidoff, Davies, & Roberson, 1999), a new approach was used to investigate the controversial issue of the origin of color categories. Baboons and humans were given the same task of matching-to-sample colors that crossed the blue/green boundary. The data and consequent modeling were remarkably clear-cut. All human subjects matched our generalization probe stimuli as if to a sharp boundary close to the midpoint between their training items. Despite good color discrimination, none of the baboons showed any inclination to match to a single boundary but rather responded with two boundaries close to the training stimuli. The data give no support to the claim that color categories are explicitly instantiated in the primate color vision system.

Adult↗