QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

HOME  |   SEARCH  |   ARCHIVE  |   SUBSCRIBE  |   CONTACT  |   HELP

The Journal of Neuroscience, May 25, 2005, 25(21):5248-5258; doi:10.1523/JNEUROSCI.0141-05.2005

This Article Full Text Full Text (PDF) Submit an eLetter Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via ISI Web of Science (22) Citing Articles via Google Scholar Google Scholar Articles by Palva, S. Articles by Palva, J. M. Search for Related Content PubMed PubMed Citation Articles by Palva, S. Articles by Palva, J. M.

 Previous Article  |  Next Article 

Behavioral/Systems/Cognitive
Early Neural Correlates of Conscious Somatosensory Perception

Satu Palva,^1,2 Klaus Linkenkaer-Hansen,³ Risto Näätänen,^1,2 and J. Matias Palva⁴

¹BioMag Laboratory, Engineering Centre, Helsinki University Central Hospital, FIN-00029 Helsinki, Finland, ²Cognitive Brain Research Unit, Department of Psychology, University of Helsinki and Helsinki Brain Research Centre, FIN-00014 Helsinki, Finland, ³Netherlands Institute for Brain Research, 1105 Amsterdam, The Netherlands, and ⁴Department of Biological and Environmental Sciences, University of Helsinki, FIN-00014 Helsinki, Finland

The cortical processing of consciously perceived and unperceived somatosensory stimuli is thought to be identical during the first 100-120 ms after stimulus onset. Thereafter, the electrophysiological correlates of conscious perception have been shown to be reflected in the N1 component of the evoked response as well as in later (>200 ms) nonstimulus-locked -band (28-50 Hz) oscillatory activity. To evaluate more specifically the time course and correlation of neuronal oscillations with conscious perception, we recorded neuromagnetic responses to threshold-intensity somatosensory stimuli. We show here that cortical broadband activities phase locked to the subsequently perceived stimuli in somatosensory, frontal, and parietal regions as early as 30-70 ms from stimulus onset, whereas the phase locking to the unperceived stimuli was weak and primarily restricted to somatosensory regions. Such stimulus locking also preceded the perceived stimuli, indicating that the phase of ongoing cortical activities biases subsequent perception. Furthermore, the data show that the stimulus locking was present in the - (4-8 Hz), - (8-14 Hz), - (14-28 Hz), and - (28-40 Hz) frequency bands, of which the widespread -band component was dominant for the consciously perceived stimuli but virtually unobservable for the unperceived stimuli. Our results show that the neural correlates of conscious perception are already found during the earliest stages of cortical processing from 30 to 150 ms after stimulus onset and suggest that -frequency-band oscillations have a role in the neural mechanisms of sensory awareness.

Key words: oscillations; consciousness; evoked; phase locking; network; sensorimotor; somatosensory; synchrony; temporal; topography

---

Received Sep 4, 2004; revised April 13, 2005; accepted April 18, 2005.

Home  |   Search  |   Archive  |   Subscribe  |   Contact  |   Help