Abstract
To achieve a stable visual representation of the outside world the brain has to integrate an
abundance of sensory input into a coherent and meaningful percept. During this process the brain
makes perceptual decisions we remain unaware of. Here we investigated brain activity related to
perceptual alternations, i.e. the brain’s decisions to change perception, measured with subdural
electrodes implanted in epileptic patients (for medical reasons). We compared activity related to
stimulus-induced perceptual alternations (using changing unambiguous stimuli) with activity related
to spontaneous perceptual alternations (using unchanging ambiguous stimuli). Stimulus-induced
perceptual alternations were accompanied by a profound decrease in alpha power on occipital and
parietal electrodes shortly before the perceptual alternation was reported. Spontaneous perceptual
alternations were preceded by a similar decrease in alpha power on the same electrodes, however,
compared to stimulus-induced alternations this effect appeared more gradual and much earlier (as
soon as 1500 ms before the perceptual alternation was reported). To generalize our findings across
stimuli we performed the experiment for an ambiguously rotating globe as well as binocularly
conflicting house and face stimuli. Both stimuli gave similar results. We conclude that spontaneous
perceptual decisions are the consequence of a gradual build-up of neural activity related to perceptual
decisions in occipital and parietal regions.
abundance of sensory input into a coherent and meaningful percept. During this process the brain
makes perceptual decisions we remain unaware of. Here we investigated brain activity related to
perceptual alternations, i.e. the brain’s decisions to change perception, measured with subdural
electrodes implanted in epileptic patients (for medical reasons). We compared activity related to
stimulus-induced perceptual alternations (using changing unambiguous stimuli) with activity related
to spontaneous perceptual alternations (using unchanging ambiguous stimuli). Stimulus-induced
perceptual alternations were accompanied by a profound decrease in alpha power on occipital and
parietal electrodes shortly before the perceptual alternation was reported. Spontaneous perceptual
alternations were preceded by a similar decrease in alpha power on the same electrodes, however,
compared to stimulus-induced alternations this effect appeared more gradual and much earlier (as
soon as 1500 ms before the perceptual alternation was reported). To generalize our findings across
stimuli we performed the experiment for an ambiguously rotating globe as well as binocularly
conflicting house and face stimuli. Both stimuli gave similar results. We conclude that spontaneous
perceptual decisions are the consequence of a gradual build-up of neural activity related to perceptual
decisions in occipital and parietal regions.
Original language | English |
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Publication status | Published - Nov 2010 |
Event | Society for Neuroscience Congress - Duration: 13 Nov 2010 → 17 Nov 2010 |
Conference
Conference | Society for Neuroscience Congress |
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Period | 13/11/10 → 17/11/10 |