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Nicotinic receptor gene CHRNA4 interacts with processing load in attention.

Espeseth T, Sneve MH, Rootwelt H, Laeng B - PLoS ONE (2010)

Bottom Line: Two to six objects were designated as targets and the remaining objects were distracters.The same observers also performed a visual search for a target letter (i.e. X or Z) presented together with five non-targets while ignoring centrally presented distracters (i.e. X, Z, or L).Targets differed from non-targets by a unique feature in the low load condition, whereas they shared features in the high load condition.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, Center for the Study of Human Cognition, University of Oslo, Oslo, Norway.

ABSTRACT

Background: Pharmacological studies suggest that cholinergic neurotransmission mediates increases in attentional effort in response to high processing load during attention demanding tasks [1].

Methodology/principal findings: In the present study we tested whether individual variation in CHRNA4, a gene coding for a subcomponent in α4β2 nicotinic receptors in the human brain, interacted with processing load in multiple-object tracking (MOT) and visual search (VS). We hypothesized that the impact of genotype would increase with greater processing load in the MOT task. Similarly, we predicted that genotype would influence performance under high but not low load in the VS task. Two hundred and two healthy persons (age range  =  39-77, Mean  =  57.5, SD  =  9.4) performed the MOT task in which twelve identical circular objects moved about the display in an independent and unpredictable manner. Two to six objects were designated as targets and the remaining objects were distracters. The same observers also performed a visual search for a target letter (i.e. X or Z) presented together with five non-targets while ignoring centrally presented distracters (i.e. X, Z, or L). Targets differed from non-targets by a unique feature in the low load condition, whereas they shared features in the high load condition. CHRNA4 genotype interacted with processing load in both tasks. Homozygotes for the T allele (N  =  62) had better tracking capacity in the MOT task and identified targets faster in the high load trials of the VS task.

Conclusion: The results support the hypothesis that the cholinergic system modulates attentional effort, and that common genetic variation can be used to study the molecular biology of cognition.

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Related in: MedlinePlus

Estimated effect size (partial eta squared) of CHRNA4 genotype as a function of load condition in the multiple object task.
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pone-0014407-g004: Estimated effect size (partial eta squared) of CHRNA4 genotype as a function of load condition in the multiple object task.

Mentions: Mean proportional correct responses were submitted to a repeated-measures ANOVA with Load (2, 3, 4, 5, 6 objects) as within-subjects factor and Genotype (TT, CT, CC) as between-subjects factor. As expected, there was a highly significant main effect of Load, F(4, 796) = 836, P<0.0005, η2p = 0.81. There was also a significant main effect of Genotype, F(2, 199) = 4.2, P = 0.016, η2p = 0.04. Post hoc test with Tukey's HSD revealed that TT carriers had significantly higher accuracy than the two other groups, which did not differ from each other. Crucially, there was a significant Load x Genotype interaction, F(8, 796) = 3.6, P<0.0005, η2p = 0.035. Planned comparisons with one-way ANOVA shows that genotype groups did not differ from each other at the lowest tracking load (i.e. two objects, P = 0.95), but was significantly different at all the other tracking loads (P's = 0.043, 0.004, 0.01, and 0.014 for 3–6 respectively, see Figure 3. CT and CC carriers had similar accuracies at all load levels, suggesting a dominant effect of the C allele. Estimated effect size (partial eta squared) of CHRNA4 genotype on performance was dependent on processing load. Plotting partial effect size over load condition revealed a pattern of linear increase up to a load of four objects, followed by a trend towards a modest reduction (see Figure 4).


Nicotinic receptor gene CHRNA4 interacts with processing load in attention.

Espeseth T, Sneve MH, Rootwelt H, Laeng B - PLoS ONE (2010)

Estimated effect size (partial eta squared) of CHRNA4 genotype as a function of load condition in the multiple object task.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3008676&req=5

pone-0014407-g004: Estimated effect size (partial eta squared) of CHRNA4 genotype as a function of load condition in the multiple object task.
Mentions: Mean proportional correct responses were submitted to a repeated-measures ANOVA with Load (2, 3, 4, 5, 6 objects) as within-subjects factor and Genotype (TT, CT, CC) as between-subjects factor. As expected, there was a highly significant main effect of Load, F(4, 796) = 836, P<0.0005, η2p = 0.81. There was also a significant main effect of Genotype, F(2, 199) = 4.2, P = 0.016, η2p = 0.04. Post hoc test with Tukey's HSD revealed that TT carriers had significantly higher accuracy than the two other groups, which did not differ from each other. Crucially, there was a significant Load x Genotype interaction, F(8, 796) = 3.6, P<0.0005, η2p = 0.035. Planned comparisons with one-way ANOVA shows that genotype groups did not differ from each other at the lowest tracking load (i.e. two objects, P = 0.95), but was significantly different at all the other tracking loads (P's = 0.043, 0.004, 0.01, and 0.014 for 3–6 respectively, see Figure 3. CT and CC carriers had similar accuracies at all load levels, suggesting a dominant effect of the C allele. Estimated effect size (partial eta squared) of CHRNA4 genotype on performance was dependent on processing load. Plotting partial effect size over load condition revealed a pattern of linear increase up to a load of four objects, followed by a trend towards a modest reduction (see Figure 4).

Bottom Line: Two to six objects were designated as targets and the remaining objects were distracters.The same observers also performed a visual search for a target letter (i.e. X or Z) presented together with five non-targets while ignoring centrally presented distracters (i.e. X, Z, or L).Targets differed from non-targets by a unique feature in the low load condition, whereas they shared features in the high load condition.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, Center for the Study of Human Cognition, University of Oslo, Oslo, Norway.

ABSTRACT

Background: Pharmacological studies suggest that cholinergic neurotransmission mediates increases in attentional effort in response to high processing load during attention demanding tasks [1].

Methodology/principal findings: In the present study we tested whether individual variation in CHRNA4, a gene coding for a subcomponent in α4β2 nicotinic receptors in the human brain, interacted with processing load in multiple-object tracking (MOT) and visual search (VS). We hypothesized that the impact of genotype would increase with greater processing load in the MOT task. Similarly, we predicted that genotype would influence performance under high but not low load in the VS task. Two hundred and two healthy persons (age range  =  39-77, Mean  =  57.5, SD  =  9.4) performed the MOT task in which twelve identical circular objects moved about the display in an independent and unpredictable manner. Two to six objects were designated as targets and the remaining objects were distracters. The same observers also performed a visual search for a target letter (i.e. X or Z) presented together with five non-targets while ignoring centrally presented distracters (i.e. X, Z, or L). Targets differed from non-targets by a unique feature in the low load condition, whereas they shared features in the high load condition. CHRNA4 genotype interacted with processing load in both tasks. Homozygotes for the T allele (N  =  62) had better tracking capacity in the MOT task and identified targets faster in the high load trials of the VS task.

Conclusion: The results support the hypothesis that the cholinergic system modulates attentional effort, and that common genetic variation can be used to study the molecular biology of cognition.

Show MeSH
Related in: MedlinePlus