| The appropriate functioning of cognitive processes requires the interchange of information between brain regions. To evaluate whether these mechanisms of communication are damaged by neurological conditions we have carried out a series of studies with mild cognitive impairment (MCI) and Traumatic Brain Injuri (TBI) patients. MCI represents an intermediate state between normal aging and dementia. In fact, 10-13% of MCI patients develop dementia every year. We show profiles of synchronization (based on Synchronization Likelihood; SL) between brain regions during a memory task in healthy participants and MCI patients. MCI patients show higher interhemispheric synchronization (alpha, beta and gamma) while controls show higher anterior-posterior SL values. After a follow-up of two years 7 of the MCI patients convert to dementia. We will compare synchronization values of MCI patients that subsequently develop dementia those who remain stable and healthy controls and we will discuss to what extent this analysis can help determine which patients will develop dementia. In addition to the research on MCI patients we will present data from patients with severe traumatic brain injury (TBI). In this case we test how profiles of functional connectivity change as a consequence of neuropsychological rehabilitation (NR). NR is a type of cognitive therapy where TBI patients follow a tailored cognitive training for 6 months. Before the rehabilitation process, TBI patients show increased local and long distance functional connectivity (evaluated by coherence analysis [morlet-wavelet]) in the delta band, but a reduction on the number and strength of the connections in the alpha band in comparison with a control group. After NR patients show a statistical approach to the control group in the sense of a decrease of connections in the delta band and an increase in the alpha band. All these data provides evidences about how neurological conditions affect functional connectivity and suggests that some of the profiles can be reversed after cognitive therapy. |
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