Patients with Mild Cognitive Impairment Display Reduced Auditory Event-Related Delta Oscillatory Responses

Abstract

Background. Event-related oscillations (ERO) may provide a useful tool for the identification of cognitive deficits in mild cognitive impairment (MCI) and Alzheimer's disease (AD). In the present study, we investigate peak-to-peak amplitude of auditory event-related delta oscillations of MCI subjects. Method. The study included twenty-two consecutive patients with MCI recruited in neurology clinic and 21 age- and education-matched normal elderly controls. A classical auditory oddball paradigm was used in the experiments. EEG was recorded from F3, Fz, F4, C3, Cz, C4, P3, Pz, P4, O1, Oz, and O2 locations. The maximum peak-to-peak amplitudes for each subject's averaged delta response (0.5–2.2 Hz) were measured. Results. The amplitudes between groups differed significantly at the frontal and mid-centroparietal locations. ANOVA on delta responses revealed a significant effect for groups (F(1.41) = 4.84, P = 0.033), indicating a larger delta response for healthy controls than MCI subjects. Post hoc comparisons revealed that peak-to-peak delta response was significantly larger for healthy controls than for MCI over electrode sites F3, Fz, F4, Cz, C4, and Pz. Discussion. Event-related delta frequency band seems to be the most affected oscillatory response in cognitive impairment due to AD. Therefore, it deserves to be investigated as a candidate electrophysiological biomarker in further studies.

A novel biomarker of amnestic MCI based on dynamic cross-frequency coupling patterns during cognitive brain responses

“…The frequency pairs that showed significant higher PAC value for MCI compared to NI group are the δ−α 2 , θ−α 2 , θ−β 1 , θ−γ, β 1 −γ and β 2 −γ (Figure 7 ). Previous studies demonstrated a decreased of δ amplitude in auditory tasks for MCI compared to the control group (Yener et al, 2012 ; Başar et al, 2013 ; Yener and Basar, 2013 ; Kurt et al, 2014 ). In this context, the higher coupling of δ phase with θ amplitude in MCI subjects can be interpreted as an increased attention (Dimitriadis et al, 2010a ; Başar et al, 2013 ; Kurt et al, 2014 ).…”

Decrease of delta oscillatory responses is associated with increased age in healthy elderly

“…We analyzed delta, theta, beta and alpha oscillatory responses of some of these subjects as control groups for our studies on mild cognitive impairment Kurt et al, 2014;Yener et al, 2013).…”

“…At this stage, the delta frequency range (0.5-3 Hz) was chosen for investigating the age effect on ERO, since marked differences were observed in delta range in previous studies of our group Kurt et al, 2014;Yener et al, 2008Yener et al, , 2013. Peak-to-peak amplitude of delta target ERO responses during the post-stimulus 0-800 ms time window of two groups of elderly was measured.…”

“…Previous studies related to brain pathological states indicate that the amplitude of event-related delta oscillations decreases in Alzheimer's disease (Yener et al, 2008), mild cognitive impairment (Kurt et al, 2014;Yener et al, 2013), schizophrenia (Ergen et al, 2008;Ford et al, 2008), bipolar disorder (Atagün et al, 2014) and alcoholism (Kamarajan et al, 2004). However, there are few studies in the literature investigating delta ERO in healthy elderly (Schmiedt-Fehr and .…”

A gustatory stimulator

“…ERPs have been largely applied for scientific purpose in cognitive neuroscience but also in clinical application (Niedermeyer and Lopes da Silva, 2005, Kurt et al, 2014, Polak et al, 2014). An excellent example of this are the olfactory ERPs now widely used for assessment of olfactory functions, e.g.…”