Neural Correlates of True and False Memory in Mild Cognitive Impairment

Abstract

The goal of this research was to investigate the changes in neural processing in mild cognitive impairment. We measured phase synchrony, amplitudes, and event-related potentials in veridical and false memory to determine whether these differed in participants with mild cognitive impairment compared with typical, age-matched controls. Empirical mode decomposition phase locking analysis was used to assess synchrony, which is the first time this analysis technique has been applied in a complex cognitive task such as memory processing. The technique allowed assessment of changes in frontal and parietal cortex connectivity over time during a memory task, without a priori selection of frequency ranges, which has been shown previously to influence synchrony detection. Phase synchrony differed significantly in its timing and degree between participant groups in the theta and alpha frequency ranges. Timing differences suggested greater dependence on gist memory in the presence of mild cognitive impairment. The group with mild cognitive impairment had significantly more frontal theta phase locking than the controls in the absence of a significant behavioural difference in the task, providing new evidence for compensatory processing in the former group. Both groups showed greater frontal phase locking during false than true memory, suggesting increased searching when no actual memory trace was found. Significant inter-group differences in frontal alpha phase locking provided support for a role for lower and upper alpha oscillations in memory processing. Finally, fronto-parietal interaction was significantly reduced in the group with mild cognitive impairment, supporting the notion that mild cognitive impairment could represent an early stage in Alzheimer’s disease, which has been described as a ‘disconnection syndrome’.

Corticothalamic phase synchrony and cross-frequency coupling predict human memory formation

“…The limited available scalp electrode coverage in our participants, however, precludes drawing strong conclusions in this regard. We note also, though, that both frontal and parietal cortices are well-recognized as being involved in memory processing ( Weiss and Rappelsberger, 2000 ; Otten et al, 2002 ; Sauseng et al, 2005 ; Uncapher and Wagner, 2009 ; Friese et al, 2012 ; Sweeney-Reed et al, 2012 ).…”

Exploration of the neural correlates of cerebral palsy for sensorimotor BCI control

“…We then extracted the instantaneous phase from each trial using the Hilbert transform and calculated the PLV pair-wise for all possible channel combinations according to the following formula (Lachaux et al, 1999) ${\text{PLV}}_{\text{t}}=\frac{1}{\text{N}}\left|true{\sum }_{\text{n} = 1}^{\text{N}}\text{exp}false(\text{j}\theta false(\text{t},\text{n}false)false)\right|,$ where N denotes the number of trials to average, t denotes the time point in the time series, and θ(t,n) denotes the phase difference between the two time series. The PLVs for all possible pairwise combinations were then averaged as per the approach taken in Sweeney-Reed et al (2012). …”

Chiropractic management using a brain-based model of care for a 15-year-old adolescent boy with migraine headaches and behavioral and learning difficulties: a case report

“…It can also be mathematically described as the temporal coherence or statistical dependence of activity between different nerve cells or their circuits. 30 Functional disconnections have been hypothesized in mild cognitive impairment, 31 schizophrenia, 32 Parkinson disease, 33 multiple sclerosis, 34 neglect, 35 autism, 36 Alzheimer disease, 37 behavioral changes, 38 alexia, 39 and more. The common trait between these conditions is the altered function of the nervous system that creates a functional loss of capacity in a patient's health or behavior.…”