Aaron Schurger (Laboratory of Cognitive Neuroscience & Center for Neuroprosthetics École Polytechnique Fédérale de Lausanne and NeuroSpin Research Center, CEA-Saclay, France)
"Cortical activity is more stable when sensory stimuli are consciously perceived" / Tuesday, February 10, 2015 17:15 h
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Bernstein Center Freiburg
Bernstein Seminar
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Aaron Schurger
Laboratory of Cognitive Neuroscience & Center for Neuroprosthetics
École Polytechnique Fédérale de Lausanne (EPFL) and INSERM Cognitive Neuroimaging Lab NeuroSpin Research Center, CEA-Saclay FRANCE Cortical activity is more stable when
sensory stimuli are consciously perceived |
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Tuesday, February 10, 2015 17:15 h |
Lecture Hall (ground floor) Bernstein Center Freiburg Hansastraße 9a 79104 Freiburg |
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Abstract:
According to recent evidence, stimulus-tuned neurons in the
cerebral cortex exhibit reduced variability in firing-rate across
trials, after the onset of a stimulus. However, in order for a
reduction in variability to be directly relevant to perception and
behavior, it must be realized within trial – the pattern of activity
must be relatively stable. Stability is characteristic of decision
states in recurrent attractor networks, and its possible relevance to
conscious perception has been suggested by theorists. However, it is
difficult to measure on the within-trial time scales and broadly
distributed spatial scales relevant to perception. We recorded
simultaneous magneto- and electro-encephalography (MEG and EEG) data
while subjects observed threshold-level visual stimuli.
Pattern-similarity analyses applied to the data from MEG gradiometers
uncovered a pronounced decrease in variability across trials after
stimulus onset, consistent with previous single-unit data. This was
followed by a significant divergence in variability depending upon
subjective report (seen / unseen), with seen trials exhibiting less
variability. Applying the same analysis across time, within trial, we
found that the latter effect coincided in time with a difference in
the stability of the pattern of activity. Stability alone could be
used to classify data from individual trials as ‘seen’ or ‘unseen’.
The same metric applied to EEG data from patients with
disorders-of-consciousness exposed to auditory stimuli diverged
parametrically according to clinically diagnosed
level-of-consciousness. Differences in signal strength could not
account for these results. Conscious perception may involve the
transient stabilization of distributed cortical networks,
corresponding to a global brain-scale decision.
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Host: Carsten Mehring
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The talk is open to the public. Guests are cordially invited!
www.bcf.uni-freiburg.de |
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abgelegt unter:
Bernstein Seminar