Cortical synchrony changes detected by scalp electrode electroencephalograph as traumatic brain injury patients emerge from coma.

BACKGROUND Recent studies show conscious perception is correlated with firing rate synchronization across multiple neuronal assemblies. This study explores the synchrony between multiple cortical surface sites as brain injury patients emerge from coma. METHODS Scalp electrode EEG recordings were collected and analyzed from 13 traumatic brain injury patients during their stay in a neurosurgical intensive care unit. Neuronal synchrony was calculated between various electrode pairs during comatose and conscious periods defined by the GCS. Frequency bands from 1 to 30 Hz were evaluated in each patient. RESULTS As patients emerged from coma at GCS 3 to GCS scores > or =8, synchrony values from all electrode pairs revealed a global decrease in synchrony at higher GCS scores. No significant effects were detected relative to the amount of sedation given, but at higher GCS scores significantly increased neuronal synchrony was observed between occipital lobes and right parietal and temporal lobe sites. Synchrony was decreased between frontal-occipital, frontal-parietal, and parietal-occipital electrodes. CONCLUSIONS In frequencies from 1 to 30 Hz, synchrony between right parietal and temporal lobes, as well as bilateral occipital lobes, tends to be increased as patients emerge from comatose states. However, synchrony between most intrahemispheric cortical sites is decreased at higher GCS scores in most of the above frequency bands. Thus, brain injury patients demonstrate both increased and decreased cortical surface synchrony between different lobes during emergence from coma.

[1]  F. Varela,et al.  Guiding the study of brain dynamics by using first-person data: Synchrony patterns correlate with ongoing conscious states during a simple visual task , 2002, Proceedings of the National Academy of Sciences of the United States of America.

[2]  E. John The neurophysics of consciousness , 2002, Brain Research Reviews.

[3]  G. Edelman,et al.  A Universe Of Consciousness: How Matter Becomes Imagination , 2000 .

[4]  J. Desmedt,et al.  Transient phase-locking of 40 Hz electrical oscillations in prefrontal and parietal human cortex reflects the process of conscious somatic perception , 1994, Neuroscience Letters.

[5]  F. Varela,et al.  Perception's shadow: long-distance synchronization of human brain activity , 1999, Nature.

[6]  H Petsche,et al.  Synchronization between temporal and parietal cortex during multimodal object processing in man. , 1999, Cerebral cortex.

[7]  E R John,et al.  Switchboard versus statistical theories of learning and memory. , 1972, Science.

[8]  Stephane A. Roy,et al.  Coincidence Detection or Temporal Integration? What the Neurons in Somatosensory Cortex Are Doing , 2001, The Journal of Neuroscience.

[9]  G. Ojemann,et al.  Changes in power and coherence of brain activity in human sensorimotor cortex during performance of visuomotor tasks. , 2001, Bio Systems.

[10]  K. Thornton,et al.  Exploratory investigation into mild brain injury and discriminant analysis with high frequency bands (32-64 Hz). , 1999, Brain injury.

[11]  Troels W. Kjær,et al.  Reflective Self-Awareness and Conscious States: PET Evidence for a Common Midline Parietofrontal Core , 2002, NeuroImage.

[12]  A. Okumura,et al.  Cognitive impairment after traumatic brain injury: a functional magnetic resonance imaging study using the Stroop task , 2005, Neuroradiology.

[13]  S. Tobimatsu,et al.  Interhemispheric functional synchronization at the first step of visual information processing in humans , 2004, Clinical Neurophysiology.

[14]  Ernst Niebur,et al.  Electrophysiological correlates of synchronous neural activity and attention: a short review. , 2002, Bio Systems.

[15]  S. Slewa-Younan,et al.  Is ‘gamma’ (40 Hz) synchronous activity disturbed in patients with traumatic brain injury? , 2002, Clinical Neurophysiology.

[16]  J. Martinerie,et al.  The brainweb: Phase synchronization and large-scale integration , 2001, Nature Reviews Neuroscience.

[17]  J. Martinerie,et al.  Comparison of Hilbert transform and wavelet methods for the analysis of neuronal synchrony , 2001, Journal of Neuroscience Methods.

[18]  G J Vachtsevanos,et al.  Gamma coherence and conscious perception , 2002, Neurology.

[19]  P. Cariani Anesthesia, Neural Information Processing, and Conscious Awareness , 2000, Consciousness and Cognition.

[20]  Gustave Moonen,et al.  Cortical Processing of Noxious Somatosensory Stimuli in the Persistent Vegetative State , 2002, NeuroImage.

[21]  J. Martinerie,et al.  Preictal state identification by synchronization changes in long-term intracranial EEG recordings , 2005, Clinical Neurophysiology.