neither prenatal nor adolescent exposure. Intact cortical cholinergic transmission is required for normal attentional performance198. Enhanced cholinergic neurotransmission improves the selectivity of perceptual processing and improves the efficacy of brain regions supporting higher cortical function, an effect associated with reduced activation of regions mediating higher cortical processing199. Therefore, these results suggested to the authors a loss of efficiency in cortical regions supporting auditory attention; visualized as areas with greater fMRI activation. The small sample size of the group undergoing fMRI did not allow for conclusions on gender specific fMRI effects. Greater vulnerability of the neurocircuitry supporting auditory attention in males, and both auditory and visual attention in females, following nicotine exposure during prenatal and adolescent development was evident. The authors hypothesize that these gender specific effects on auditory attention may not stem from the global male-female differences in nicotinic receptor binding sites, but may be attributable to gender differences in the downstream effects of nAChR activation by nicotine or in the hormonal regulation of these downstream effects. Further studies of sub-regions specifically involved in auditory tasks may demonstrate sex related differences in receptor expression or functioning.
