Cerebral effects of nicotine during cognition in smokers and non-smokers.

For the smoker, nicotine has a positive effect on attention, cognition and mood. Conversely, nicotine abstinence is characterized by uncomfortable psychological effects such as impaired attention, but also irritability. We postulated that nicotine exerts an effect on cerebral areas important for attention and mood. Regional cerebral blood flow (rCBF), as an index for cerebral activity, was measured in both smokers and non-smokers. They were scanned during performance of a psychometric task with and without i.v. infusion of nicotine (1-methyl-2-[3-pyridyll] pyrrolidine). Nicotine induced rCBF decreases in the anterior cingulate cortex and the cerebellum, and concomitant increases in the occipital cortex. The changes were similar in nature and magnitude in smokers and non-smokers. Thus, specific changes were induced in areas pertaining to the anterior attention system and to higher order visual cortex. We conclude that these effects on cerebral activity provide insights into the desired positive effects of nicotine on cognition as well as the negative effects experienced during nicotine abstinence.

Signed and spoken language perception studied by positron emission tomography.

Sign and spoken language seem to be localized in the same brain areas. They elicit similar regional cerebral blood flow (rCBF) patterns, even though sign language is dependent on spatial information. We investigated sign and spoken language perception in a group of healthy bilingual subjects. Four videotaped activation conditions were used during PET imaging: (1) sign language, (2) spoken language, (3) spoken language with mouth covered, and (4) spoken language on a sound track while showing a motionless face. Spoken language (condition 4) activated significantly the perisylvian cortex (Brodmann areas 22 and 43) bilaterally. Sign language activated the visual association areas (Brodmann areas 37 and 19) but did not selectively activate parietal regions. A reciprocal relationship was observed between the level of activation in visual language perception areas and that in auditory perception areas. We conclude that when healthy bilingual subjects use the visual route for sign language perception, the functional anatomy overlaps that of language processing containing both auditory and visual components.