Methylphenidate alters selective attention by amplifying salience.
BACKGROUND
Methylphenidate, the most common treatment of attention deficit hyperactivity disorder (ADHD), is increasingly used by healthy individuals as a "smart drug" to enhance cognitive abilities like attention. A key feature of (selective) attention is the ability to ignore irrelevant but salient information in the environment (distractors). Although crucial for cognitive performance, until now, it is not known how the use of methylphenidate affects resistance to attentional capture by distractors.


OBJECTIVE
The present study aims to clarify how methylphenidate affects distractor suppression in healthy individuals.


METHODS
The effect of methylphenidate (20 mg) on distractor suppression was assessed in healthy subjects (N = 20), in a within-subject double-blind placebo-controlled crossover design. We used a visuospatial attention task with target faces flanked by strong (faces) or weak distractors (scrambled faces).


RESULTS
Methylphenidate increased accuracy on trials that required gender identification of target face stimuli (methylphenidate 88.9 ± 1.4 [mean ± SEM], placebo 86.0 ± 1.2 %; p = .003), suggesting increased processing of the faces. At the same time, however, methylphenidate increased reaction time when the target face was flanked by a face distractor relative to a scrambled face distractor (methylphenidate 34.9 ± 3.73, placebo 26.7 ± 2.84 ms; p = .027), suggesting enhanced attentional capture by distractors with task-relevant features.


CONCLUSIONS
We conclude that methylphenidate amplifies salience of task-relevant information at the level of the stimulus category. This leads to enhanced processing of the target (faces) but also increased attentional capture by distractors drawn from the same category as the target.
Karakter Child and Adolescent Psychiatry University Centre, Reinier Postlaan 12, 6526 GC, Nijmegen, Netherlands. nielsterhuurne@gmail.com.|Centre for Cognitive Neuroimaging, Donders Institute for Brain, Cognition and Behaviour, Radboud University, Kapittelweg 29, 6525 EN, Nijmegen, Netherlands. nielsterhuurne@gmail.com.
Niels
N
ter Huurne
Department of Cognitive Neuroscience, Radboudumc, Donders Institute for Brain, Cognition and Behaviour, Radboud University, P.O. Box 9101 (204), 6500 HB, Nijmegen, Netherlands. s.fallon@psy.ox.ac.uk.|Department of Experimental Psychology, Oxford, OX13UD, UK. s.fallon@psy.ox.ac.uk.
Sean James
SJ
Fallon
Department of Neurology, University of California, San Francisco, San Francisco, CA, USA. martine.vanschouwenburg@ucsf.edu.|Department of Physiology, University of California, San Francisco, San Francisco, CA, USA. martine.vanschouwenburg@ucsf.edu.|Department of Psychiatry, University of California, San Francisco, San Francisco, CA, USA. martine.vanschouwenburg@ucsf.edu.
Martine
M
van Schouwenburg
Centre for Cognitive Neuroimaging, Donders Institute for Brain, Cognition and Behaviour, Radboud University, Kapittelweg 29, 6525 EN, Nijmegen, Netherlands. m.vanderschaaf@donders.ru.nl.
Marieke
M
van der Schaaf
Karakter Child and Adolescent Psychiatry University Centre, Reinier Postlaan 12, 6526 GC, Nijmegen, Netherlands. Jan.Buitelaar@radboudumc.nl.|Department of Cognitive Neuroscience, Radboudumc, Donders Institute for Brain, Cognition and Behaviour, Radboud University, P.O. Box 9101 (204), 6500 HB, Nijmegen, Netherlands. Jan.Buitelaar@radboudumc.nl.
Jan
J
Buitelaar
Centre for Cognitive Neuroimaging, Donders Institute for Brain, Cognition and Behaviour, Radboud University, Kapittelweg 29, 6525 EN, Nijmegen, Netherlands. o.jensen@donders.ru.nl.
Ole
O
Jensen
Centre for Cognitive Neuroimaging, Donders Institute for Brain, Cognition and Behaviour, Radboud University, Kapittelweg 29, 6525 EN, Nijmegen, Netherlands. roshan.cools@gmail.com.
Roshan
R
Cools
D000328:Adult; D001288:Attention / Q000187:drug effects* / Q000502:physiology; D000697:Central Nervous System Stimulants / Q000494:pharmacology; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D008774:Methylphenidate / Q000494:pharmacology*; D010775:Photic Stimulation / Q000379:methods; D011597:Psychomotor Performance / Q000187:drug effects* / Q000502:physiology; D011930:Reaction Time / Q000187:drug effects* / Q000502:physiology; D055815:Young Adult
D000697:Central Nervous System Stimulants; D008774:Methylphenidate
ADHD; Attention; Cognitive enhancer; Distractor; Dopamine; Methylphenidate; Resistance; Salience; Smart drug; Suppression