Exploring the neural correlates of naturalistic hybrid search tasks: Concurrent magnetoencephalography and eye-tracking recordings

GONZALEZ J; CARE D; RIES AJ; KAMIENKOWSKI JE; ISON MJ

Congreso; XXXVIII Sociedad Argentina de Neurociencias; 2023

In hybrid visual and memory search (HS) tasks, observers are asked to search for any item of a previously memorized set of items. One of the main signatures of HS is a robust linear relationship between response time and visual set size and a logarithmic relationship between RT and memory set size. However, little is known about the underlying neural mechanisms in HS. One reason is that eye movements produce artifacts in M-EEG signals, which are much larger than the signals of interest.  Here, we aim to start uncovering the neurophysiological mechanisms underlying HS. To that end, we combined MEG and eye tracking recordings while participants performed a “new mapping” naturalistic search task, where the memory set changes in each trial, as in most real life scenarios, where the search targets rarely repeat. After identifying and characterizing robust markers of neural and saccadic spike artifacts in the signal, we implemented a deconvolution analysis approach and found a P300m component in the fixation-related fields from targets when compared to distractors. Moreover, we found significant task effects in low-frequency oscillations, such as parieto-occipital Alpha activity suppression during memorization of the items. Altogether, our approach provides a way to study the role of specific neurophysiological signals in complex scenarios that include eye movements, such as HS, to get a deeper understanding of the brain mechanisms of memory encoding and search in natural tasks.