Reorganization of functional connectivity as a correlate of cognitive recovery in acquired brain injury -- Castellanos et al. 133 (8): 2365 -- Brain

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Reorganization of functional connectivity as a correlate of cognitive recovery in acquired brain injury
Nazareth P. Castellanos1, Nuria Paúl2, Victoria E. Ordóñez1, Olivier Demuynck3, Ricardo Bajo1, Pablo Campo1, Alvaro Bilbao4, Tomás Ortiz2, Francisco del-Pozo1 and Fernando Maestú1,5
1 Laboratory of Cognitive and Computational Neuroscience, Centre for Biomedical Technology (CTB), Universidad Politécnica de Madrid, Madrid, 28660, Spain 2 Department of Psychiatric and Medical Psychology, Medicine School, Universidad Complutense de Madrid, 28040, Spain 3 Department of Signals, Systems and Radiocomunications, Universidad Politécnica de Madrid, 28040, Spain 4 National Centre for Brain Injury Treatment (CEADAC) Madrid, 28034, Spain 5 Department of Basic Psychology II – Cognitive Process, Universidad Complutense de Madrid, 28223, Spain

Correspondence to: Nazareth P. Castellanos, Laboratory of Cognitive and Computational Neuroscience, Centre for Biomedical Technology, Campus de Montegancedo 28660, Universidad Politécnica de Madrid, Spain E-mail: nazareth@pluri.ucm.es

Cognitive processes require a functional interaction between specialized multiple, local and remote brain regions. Although these interactions can be strongly altered by an acquired brain injury, brain plasticity allows network reorganization to be principally responsible for recovery. The present work evaluates the impact of brain injury on functional connectivity patterns. Networks were calculated from resting-state magnetoencephalographic recordings from 15 brain injured patients and 14 healthy controls by means of wavelet coherence in standard frequency bands. We compared the parameters defining the network, such as number and strength of interactions as well as their topology, in controls and patients for two conditions: following a traumatic brain injury and after a rehabilitation treatment. A loss of delta- and theta-based connectivity and conversely an increase in alpha- and beta-band-based connectivity were found. Furthermore, connectivity parameters approached controls in all frequency bands, especially in slow-wave bands. A correlation between network reorganization and cognitive recovery was found: the reduction of delta-band-based connections and the increment of those based on alpha band correlated with Verbal Fluency scores, as well as Perceptual Organization and Working Memory Indexes, respectively. Additionally, changes in connectivity values based on theta and beta bands correlated with the Patient Competency Rating Scale. The current study provides new evidence of the neurophysiological mechanisms underlying neuronal plasticity processes after brain injury, and suggests that these changes are related with observed changes at the behavioural level.


Key Words: brain injury; functional connectivity; magnetoencephalography; plasticity


Abbreviations: MEG , magnetoencephalograhy; PCRS , Patient Competency Rating Scale; WAIS , Wechsler Adult Intelligence Scale III

Received March 9, 2010. Revised May 19, 2010. Accepted May 20, 2010.

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Reorganization of functional connectivity as a correlate of cognitive recovery in acquired brain injury -- Castellanos et al. 133 (8): 2365 -- Brain