# Correlates of Theta and Gamma Activity during Visuospatial Incidental/Intentional Encoding and Retrieval Indicate Differences in Processing in Young and Elderly Healthy Participants

## TL;DR

This study shows how brain activity patterns during memory tasks differ between young and elderly people, especially when learning is intentional versus incidental.

## Contribution

The study identifies age-related differences in theta and gamma brain activity during intentional and incidental visuospatial memory encoding and retrieval.

## Key findings

- Older adults performed worse in incidental visuospatial tasks, especially with place–object associations.
- Elderly participants showed higher theta and gamma power during encoding and retrieval compared to young participants.
- Young participants had lower power during retrieval errors compared to correct responses, which was not observed in the elderly.

## Abstract

Incidental visuospatial learning acquired under incidental conditions is more vulnerable to aging than in the intentional case. The theta and gamma correlates of the coding and retrieval of episodic memory change during aging. Based on the vulnerability of incidental coding to aging, different theta and gamma correlates could occur under the incidental versus intentional coding and retrieval of visuospatial information. Theta and gamma EEG was recorded from the frontotemporal regions, and incidental/intentional visuospatial learning was evaluated in young (25–60 years old) and elderly (60–85 years old) participants. The EEG recorded during encoding and retrieval was compared between incidental low-demand, incidental high-demand, and intentional conditions through an ANCOVA considering the patient’s gender, IQ, and years of schooling as covariates. Older adults exhibited worse performances, especially in place–object associations. After the intentional study, older participants showed a further increase in false-positive errors. Higher power at the theta and gamma bands was observed for frontotemporal derivations in older participants for both encoding and retrieval. Under retrieval, only young participants had lower power in terms of errors compared with correct responses. In conclusion, the different patterns of power and coherence support incidental and intentional visuospatial encoding and retrieval in young and elderly individuals. The correlates of power with behavior are sensitive to age and performance.