Task demands modulate the effects of perceptual expectations in early visual cortex
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1
Radboud University Nijmegen, Donders Centre for Cognitive Neuroimaging, The Netherlands
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2
Columbia University, Psychology, United States
Predicted stimuli often lead to a reduced neural response (Summerfield et al., 2008; Todorovic et al., 2011; Kok et al., 2012); however, it is unclear whether this suppressive effect of expectation is automatic (Den Ouden et al., 2009; Alink et al., 2010), or rather requires attention (Larsson & Smith, 2012). To investigate this, we orthogonally manipulated spatial attention and perceptual expectation. To investigate whether the effects of expectation depend on perceptual and working memory (WM) resources, we included two different types of distracting tasks.
We acquired fMRI data in 23 healthy human subjects. On each trial, a grating annulus surrounding a noisy, coloured letter at fixation was presented following a tone. Tones predicted the orientation of the upcoming grating with either 100% or 50% validity. Attention was manipulated per scanner run: participants responded to the spatial-frequency of the gratings (grating task) or performed one of two fixation tasks: a 1-back task on letter (perceptual task) or 2-back task on colour (WM task).
The grating-evoked response in early visual cortex was strongest during the grating task, weakest during the perceptual task, and intermediate during the WM task (F(2,22) = 35.4, p < .001). Task set determined whether predictions led to a suppression or enhancement of grating activity (F(1,22) = 5.03, p = .035). During the perceptual task, activity was reduced when perceptual expectations about the grating were strong (100% blocks) versus weak (50% blocks). However, during the grating task, activity was increased with strong expectations. There was no effect of expectation during the WM task.
Our results suggest that task demands modulate the effect of perceptual expectations on the response. The neural response to predicted stimuli is facilitated when stimuli are task relevant; suppressed when they compete with task resources (perceptual task); and unaffected when they do not (WM task).
Keywords:
Attention,
Perception,
functional MRI,
prediction,
expectation,
early visual processing,
top-down modulation
Conference:
XII International Conference on Cognitive Neuroscience (ICON-XII), Brisbane, Queensland, Australia, 27 Jul - 31 Jul, 2014.
Presentation Type:
Oral Presentation
Topic:
Attention
Citation:
St. John-Saaltink
E,
Utzerath
C,
Kok
P,
Lau
H and
De Lange
F
(2015). Task demands modulate the effects of perceptual expectations in early visual cortex.
Conference Abstract:
XII International Conference on Cognitive Neuroscience (ICON-XII).
doi: 10.3389/conf.fnhum.2015.217.00088
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Received:
19 Feb 2015;
Published Online:
24 Apr 2015.
*
Correspondence:
Ms. Elexa St. John-Saaltink, Radboud University Nijmegen, Donders Centre for Cognitive Neuroimaging, Nijmegen, The Netherlands, e.st.john-saaltink@donders.ru.nl