Courtesy of Dr Joanne Park, this image shows results from mobile EEG recordings in the first study to capture known neural correlates of episodic memory in real world settings. EEG was recorded with a mobile system while study participants followed a pre-defined route around a building at the University of Stirling, stopping at unique locations to study specific objects which they were instructed to associate with the environmental context. Upon completing the route in which object-location pairs were encountered, participants then followed the same route for a second time, and at each location they were shown an object as a test stimulus and asked to indicate whether a) they had previously viewed that object at the same location, b) they had previously viewed that object at a different location, or c) that it was a new object they had not previously seen.
Over the mobile EEG event-related potential waveforms, shaded boxes highlight the time window 300-500ms after test stimulus presentation in the top row, in which an early mid-frontal old/new effect (FN400) traditionally associated with familiarity was observed, and the time window 500-800ms after test stimulus presentation in the bottom row, in which a late posterior negativity (LPN) often linked to reconstructive processes in memory retrieval was observed. The pair of topographic maps at the left illustrate these neural correlates of retrieval when the test stimulus was an object previously encountered in the same location [recognition ‘hit’ = Same Source Correct]; the pair of topographic maps at the right, when the test stimulus was an object previously encountered in a different location [recognition ‘hit’ = Different Source Correct]. Environmental context was found to influence the FN400 effect, which was sustained longer for objects shown at retrieval in a different location than where initially encountered.
This study demonstrates that event-related potentials associated with episodic memory in prior lab-based work can be detected in real word settings using mobile EEG, and that these neural correlates show sensitivity to real world environments that only mobile EEG is able to identify.
The image is taken from a recent study published in NeuroImage:
Park JL & Donaldson DI. Detecting the neural correlates of episodic memory with mobile EEG: Recollecting objects in the real world. NeuroImage 2019; 193:1-9.