Picture ordering task EEG

Daily activities like preparing a meal rely on the ability to arrange
thoughts and actions in the right order. Patients with Parkinson’s disease
(PD) have difficulties in sequencing tasks. Their deficits in sequential
working memory have been associated with basal ganglia dysfunction. Here
we demonstrate that altered parietal alpha-theta oscillations correlate
with sequential working memory in PD. We included 15 PD patients (6 women,
mean age 66.0 years), 24 healthy young (HY, 14 women, mean age 24.1
years), and 16 older participants (HO, 7 women, mean age 68.6 years).
Participants completed a picture ordering task with scalp EEG recording,
where they arranged five pictures in a specific order and memorized them
over a delay. During encoding and the delay, the baseline alpha peak
frequency for ordered trials was 10.0 Hz in HY, 10.1 Hz in HO, and 8.9 Hz
in PD. PD showed a lower baseline alpha peak frequency with higher alpha
power than HY and HO. PD with a higher baseline alpha power tended to
respond more slowly. In response to sequence manipulation, the frequency
of maximal power change between random and ordered trials (Fmax) was 10.0
Hz in HY, 11.3 Hz in HO, and 7.7 Hz in PD. PD showed a lower
Fmax than HY and HO, whereas HO showed a higher
Fmax than HY. Compared to PD with Fmax in the alpha band
(8-15 Hz, n=11), PD with Fmax in the theta band (4-7
Hz, n=4) tended to show a higher ordering-related accuracy cost
in the picture ordering task and lower accuracy and slower responses in an
independent working memory task. In conclusion, altered baseline alpha
oscillations and task-dependent modulation of alpha-theta oscillations may
be a neural marker of poor sequential working memory in PD.