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Smoking withdrawal shifts the spatiotemporal dynamics of neurocognition.

ABSTRACT: Smoking withdrawal is associated with significant deficits in the ability to initiate and maintain attention for extended periods of time (i.e. sustained attention; SA). However, the effects of smoking abstinence on the temporal dynamics of neurocognition during SA have not been evaluated. Twenty adult smokers underwent functional magnetic resonance imaging scans following smoking as usual and after 24-hours abstinence. During scanning they completed a SA task with two levels of task difficulty, designed to measure both sustained (i.e. over the duration of the task) and transient (i.e. event-related) activation. Smoking abstinence significantly decreased task accuracy regardless of task difficulty. Compared to smoking as usual, abstinence resulted in decreased sustained activation in right inferior and middle frontal gyri but increased transient activation across dispersed cortical areas including precuneus and right superior frontal gyrus. Greater task difficulty was associated with even greater transient activation during abstinence in mostly right hemisphere regions including right inferior frontal gyrus. These findings suggest smoking withdrawal shifts the temporal and spatial dynamics of neurocognition from sustained, right prefrontal activation reflecting proactive cognitive control (Braver, Gray & Burgess 2009) to more dispersed and transient activation reflecting reactive control.

SUBMITTER: Kozink RV

PROVIDER: S-EPMC2996612 | biostudies-literature | 2010 Oct

REPOSITORIES: biostudies-literature

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Smoking withdrawal shifts the spatiotemporal dynamics of neurocognition.

Kozink Rachel V RV Lutz Avery M AM Rose Jed E JE Froeliger Brett B McClernon F Joseph FJ

Addiction biology 20101001 4

Smoking withdrawal is associated with significant deficits in the ability to initiate and maintain attention for extended periods of time (i.e. sustained attention; SA). However, the effects of smoking abstinence on the temporal dynamics of neurocognition during SA have not been evaluated. Twenty adult smokers underwent functional magnetic resonance imaging scans following smoking as usual and after 24-hours abstinence. During scanning they completed a SA task with two levels of task difficulty, ...[more]

PMID: 21040240

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Project description:Rhodamine-phalloidin-labeled actin filaments were visualized gliding over a skeletal heavy meromyosin (HMM)-coated surface. Experiments at low filament densities showed that when two filaments collided, their paths were affected in a manner that depended on collision angle. Some collisions resulted in complete alignment of the filament paths; in others, the filaments crossed over one another. Filament crossover or alignment was equally probable at ?40° contact angle. Filaments often underwent significant bending during collision and analysis of filament shape indicated an energy requirement of ?13 kBT. Experiments were performed over a wide range of HMM surface density and actin filament bulk concentration. Actin filament gliding speed and path persistence plateaued above a critical HMM surface density, and at high (micromolar) actin filament concentrations, filament motion became dramatically aligned in a common direction. Spatiotemporal features of alignment behavior were determined by correlation analysis, supported by simulations. The thermal drift of individual filament tracks was suppressed as the population became more oriented. Spatial correlation analysis revealed that long-range alignment was due to incremental recruitment rather than fusion of locally ordered seed domains. The global alignment of filament movement, described by an "order parameter," peaked at optimal actin concentrations and myosin surface densities, in contrast to previous predictions of a critical phase transition. Either hydrodynamic coupling or exchange of filaments between the surface bound and adjacent bulk phase layers might degrade order at high actin filament concentration, and high HMM surface densities might decrease alignment probability during collisions. Our results are compatible with generation of long-range order from mechanical interaction between individual actin filaments. Furthermore, we show that randomly oriented myosin motors align relatively short, submicrometer actin filaments into motile surface domains that extend over many tens of micrometers and these patterns persist for several minutes.

Dataset Information

Smoking withdrawal shifts the spatiotemporal dynamics of neurocognition.

Publications

Smoking withdrawal shifts the spatiotemporal dynamics of neurocognition.

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