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NMDA receptor antagonist ketamine impairs feature integration in visual perception.

Meuwese JD, van Loon AM, Scholte HS, Lirk PB, Vulink NC, Hollmann MW, Lamme VA - PLoS ONE (2013)

Bottom Line: Therefore, we tested whether ketamine, a non-competitive NMDA receptor antagonist, reduces feature integration in humans.This effect is not merely due to task difficulty or a difference in sedation levels.We are the first to show a behavioral effect on feature integration by manipulating the NMDA receptor in humans.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, University of Amsterdam, Amsterdam, The Netherlands ; Cognitive Science Center Amsterdam, University of Amsterdam, Amsterdam, The Netherlands.

ABSTRACT
Recurrent interactions between neurons in the visual cortex are crucial for the integration of image elements into coherent objects, such as in figure-ground segregation of textured images. Blocking N-methyl-D-aspartate (NMDA) receptors in monkeys can abolish neural signals related to figure-ground segregation and feature integration. However, it is unknown whether this also affects perceptual integration itself. Therefore, we tested whether ketamine, a non-competitive NMDA receptor antagonist, reduces feature integration in humans. We administered a subanesthetic dose of ketamine to healthy subjects who performed a texture discrimination task in a placebo-controlled double blind within-subject design. We found that ketamine significantly impaired performance on the texture discrimination task compared to the placebo condition, while performance on a control fixation task was much less impaired. This effect is not merely due to task difficulty or a difference in sedation levels. We are the first to show a behavioral effect on feature integration by manipulating the NMDA receptor in humans.

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Related in: MedlinePlus

Reaction times.Reaction times on the texture discrimination task and on the fixation task were not affected during ketamine administration, indicating that ketamine-induced performance impairments were not caused by sedation (A). Ketamine administration did not slow down responses to the texture discrimination task (compared to the fixation task) any further than the placebo condition (B).
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pone-0079326-g006: Reaction times.Reaction times on the texture discrimination task and on the fixation task were not affected during ketamine administration, indicating that ketamine-induced performance impairments were not caused by sedation (A). Ketamine administration did not slow down responses to the texture discrimination task (compared to the fixation task) any further than the placebo condition (B).

Mentions: Reaction times on the texture discrimination task were not affected during ketamine administration, further supporting the notion that performance impairments were not due to the sedative effect of ketamine (F(1,13) = .767, p = .40). The same applies for the fixation task (F(1,13) = 1.153, p = .30). There was an overall effect of SOA, subjects became faster as SOA’s decreased (texture discrimination task: F(8,6) = 20.260, p = .001; fixation task: F(8,6) = 4.897, p = .034), but no interactions of drug condition and SOA were observed (texture discrimination task: F(8,6) = 1.744, p = .26; fixation task: F(8,6) = .426, p = .87) (see Figure 6A). When reaction time differences between the texture discrimination task and the fixation task were compared, it turned out that subjects in the ketamine condition were not slowed down by the texture discrimination task any further than in the placebo condition (F(1,13) = .227, p = .64) (see Figure 6B). This was the case throughout the task, as there were no interactions of drug condition with SOA (F(8,6) = .455, p = .85), and no main effect of SOA either (F(8,6) = 2.314, p = .16). The fact that reaction times and reaction time differences between tasks are not affected by ketamine, further supports the idea that ketamine administration does not simply affect texture discrimination performance due to task difficulty or enhanced dual task interference.


NMDA receptor antagonist ketamine impairs feature integration in visual perception.

Meuwese JD, van Loon AM, Scholte HS, Lirk PB, Vulink NC, Hollmann MW, Lamme VA - PLoS ONE (2013)

Reaction times.Reaction times on the texture discrimination task and on the fixation task were not affected during ketamine administration, indicating that ketamine-induced performance impairments were not caused by sedation (A). Ketamine administration did not slow down responses to the texture discrimination task (compared to the fixation task) any further than the placebo condition (B).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3815103&req=5

pone-0079326-g006: Reaction times.Reaction times on the texture discrimination task and on the fixation task were not affected during ketamine administration, indicating that ketamine-induced performance impairments were not caused by sedation (A). Ketamine administration did not slow down responses to the texture discrimination task (compared to the fixation task) any further than the placebo condition (B).
Mentions: Reaction times on the texture discrimination task were not affected during ketamine administration, further supporting the notion that performance impairments were not due to the sedative effect of ketamine (F(1,13) = .767, p = .40). The same applies for the fixation task (F(1,13) = 1.153, p = .30). There was an overall effect of SOA, subjects became faster as SOA’s decreased (texture discrimination task: F(8,6) = 20.260, p = .001; fixation task: F(8,6) = 4.897, p = .034), but no interactions of drug condition and SOA were observed (texture discrimination task: F(8,6) = 1.744, p = .26; fixation task: F(8,6) = .426, p = .87) (see Figure 6A). When reaction time differences between the texture discrimination task and the fixation task were compared, it turned out that subjects in the ketamine condition were not slowed down by the texture discrimination task any further than in the placebo condition (F(1,13) = .227, p = .64) (see Figure 6B). This was the case throughout the task, as there were no interactions of drug condition with SOA (F(8,6) = .455, p = .85), and no main effect of SOA either (F(8,6) = 2.314, p = .16). The fact that reaction times and reaction time differences between tasks are not affected by ketamine, further supports the idea that ketamine administration does not simply affect texture discrimination performance due to task difficulty or enhanced dual task interference.

Bottom Line: Therefore, we tested whether ketamine, a non-competitive NMDA receptor antagonist, reduces feature integration in humans.This effect is not merely due to task difficulty or a difference in sedation levels.We are the first to show a behavioral effect on feature integration by manipulating the NMDA receptor in humans.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, University of Amsterdam, Amsterdam, The Netherlands ; Cognitive Science Center Amsterdam, University of Amsterdam, Amsterdam, The Netherlands.

ABSTRACT
Recurrent interactions between neurons in the visual cortex are crucial for the integration of image elements into coherent objects, such as in figure-ground segregation of textured images. Blocking N-methyl-D-aspartate (NMDA) receptors in monkeys can abolish neural signals related to figure-ground segregation and feature integration. However, it is unknown whether this also affects perceptual integration itself. Therefore, we tested whether ketamine, a non-competitive NMDA receptor antagonist, reduces feature integration in humans. We administered a subanesthetic dose of ketamine to healthy subjects who performed a texture discrimination task in a placebo-controlled double blind within-subject design. We found that ketamine significantly impaired performance on the texture discrimination task compared to the placebo condition, while performance on a control fixation task was much less impaired. This effect is not merely due to task difficulty or a difference in sedation levels. We are the first to show a behavioral effect on feature integration by manipulating the NMDA receptor in humans.

Show MeSH
Related in: MedlinePlus