Differences in EEG power in young and mature healthy adults during an incidental/spatial learning task are related to age and execution efficiency

Abstract

The differential characteristics of absolute power in the EEG theta (4-8 Hz) and gamma (30-45 Hz) frequency bands have been analysed in young (18-25 years old, n = 14) and mature adults (45-65 years old, n = 12) during the incidental or intentional behavioural conditions of learning and recalling in a visuospatial task. A printed drawing of a maze including eight figures of common objects in specific placements, solved by connecting its entrance and exit points, allowed the subject's performance efficiency to be measured based on the number, position accuracy and/or identity of incidentally or intentionally learned and remembered objects. Meanwhile, EEG recordings from frontal, parietal and temporal derivations were obtained to determine the power values of the theta (4-8 Hz) and gamma (30-45 Hz) bands for each behavioural condition and derivation. Relative to the young adults, the mature adults generally showed lower absolute theta power values, mainly due to their low theta powers under the basal and incidental learning conditions, and higher absolute gamma power values in the frontal and temporal regions. Furthermore, higher theta band power in the frontal regions was related to higher performance efficiency in both incidental and intentional learning, regardless of the subjects' age. A significant negative correlation between the parameters of individual incidental or intentional learning performance and age was also found. Indeed, a differential accuracy of remembered information seems to be associated with age and incidental or intentional learning/memory testing conditions. These data support an increasing vulnerability of visuospatial learning abilities at mature ages and as ageing progresses.

No effect of transcranial direct current stimulation of the dorsolateral prefrontal cortex on short‐term memory

“…The online effects of tDCS on visual short-term memory were shown in Figure 5. HIT showed no significant difference between sham and anodal tDCS (t (1,6) = 0.46, P = 0. 6) ( Figure 5A).…”

“…Memory span and visual short‐term memory task were usually used to measure the capability of short‐term memory. Poor recognition performance in short‐term memory has been observed in elderly people and in patients with neurological and psychiatric disorders such as Alzheimer's disease, Parkinson's disease, and mild cognitive impairment.…”

Age Differences in Learning-Related Neurophysiological Changes

“…The findings on theta power suggest that although older participants had a generally lower theta power, the power in this frequency band increases more strongly during learning. As EEG theta and gamma power have both been implicated to play a role in the encoding and retrieval of visuospatial information and visuospatial learning specifically (Lopez-Loeza et al, 2016;Sato & Yamaguchi, 2007), the current findings indicate these processes develop differently over time during learning in younger compared to older adults. Even when behavioral performance is about equal in younger and older adults, different networks of brain regions can be employed by both age groups as demonstrated by studies using functional neuroimaging (Grady & Craik, 2000; Reuter-Lorenz,…”

“…The number of participants was estimated based on previous studies, as well as on a power analysis. The number of participants in the experimental studies of Alain and Snyder (2008), Eppinger et al (2008), Eppinger and Kray (2011), Lopez-Loeza et al (2016), and Pietschmann et al (2008, 2011) discussed above ranged between 12 and 18 participants per group. Using the lowest effect size (partial eta squared, η p 2 ) for reported effects regarding interactions between time and age on neurophysiological outcome measures in these experimental studies (namely a η p 2 of .06) and a priori power analyses for repeated measures, within-between interaction F tests in G*Power 3 (Faul et al, 2007), with an error probability of 0.05 and a power of 0.95, indicated that a total sample size of 10 for 2 different groups would ensure sufficient power.…”

“…However, they did not find any difference between these two age groups. A study examining general changes in power bands in the EEG signal by Lopez-Loeza and colleagues (2016) tested younger ( M age = 21.50) and older adults ( M age = 52.75 years) on a visuospatial learning task. The older adults showed a pattern of generally lower theta power and higher gamma power in frontal and temporal brain areas.…”