Switching between neural modes at sequential fixations in free viewing predicts successful episodic memory
Nikolaev, Andrey LU
; Bramao, Ines
LU
; Johansson, Roger
LU
and Johansson, Mikael
LU
(2022)
International Conference of Cognitive Neuroscience
- Abstract
- Objectives
The formation of episodic memories is critically determined by how we visually sample the world over time via sequences of eye movements. Nonetheless, in the neuroscience of human memory, memory encoding has almost exclusively been studied in experimental paradigms where the study material is presented in a single fixed location on the screen, and where eye movements are treated as artifacts. Thus, the neural mechanisms subserving memory construction across eye movements are virtually unknown.
Research question
What are the neural correlates of episodic memory formation during eye movements in natural visual behavior?
Materials and methods
We developed an associative memory task in which participants encoded... (More) - Objectives
The formation of episodic memories is critically determined by how we visually sample the world over time via sequences of eye movements. Nonetheless, in the neuroscience of human memory, memory encoding has almost exclusively been studied in experimental paradigms where the study material is presented in a single fixed location on the screen, and where eye movements are treated as artifacts. Thus, the neural mechanisms subserving memory construction across eye movements are virtually unknown.
Research question
What are the neural correlates of episodic memory formation during eye movements in natural visual behavior?
Materials and methods
We developed an associative memory task in which participants encoded multiple events, each comprising distinct elements from three categories (faces, places, objects) in different locations of the screen. The spatial configuration of the element locations allowed us to separate relevant and irrelevant saccades for integrating them into a coherent event. Participants memorized the event, while their EEG and eye movements were simultaneously recorded. Episodic memory was thereafter assessed by testing retrieval of the element associations specifying each event. In the EEG analysis, we overcame the problem of overlapping EEG responses to sequential saccades in free viewing using a deconvolution approach. We segmented EEG relative to the fixation onset and examined the power of EEG signals in the theta and alpha frequency bands.
Results
High subsequent memory performance was predicted by theta synchronization over the centro-parietal areas during fixation intervals after saccades relevant to event integration. This may reflect the binding of elements into coherent event representation. High memory performance was also predicted by alpha desynchronization during fixations after task-irrelevant saccades. This may reflect discrimination of elements from the same category, which is necessary for successful memory encoding. Finally, high frontal theta power during fixations after scrutinizing, within-element saccades predicted high memory. This may reflect increased visual sampling of elements leading to better memory.
Conclusion
Thus, memory formation across eye movements is characterized by three neural mechanisms that rapidly turned on and off in a saccadic sequence during event encoding. These mechanisms provide essential building blocks for the construction of episodic memory during naturalistic viewing. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/e150665b-08f2-41be-8233-0502ecb82134
- author
- Nikolaev, Andrey
LU
; Bramao, Ines
LU
; Johansson, Roger
LU
and Johansson, Mikael
LU
- organization
- publishing date
- 2022
- type
- Contribution to conference
- publication status
- published
- subject
- conference name
- International Conference of Cognitive Neuroscience
- conference location
- Helsinki, Finland
- conference dates
- 2022-05-18 - 2022-05-22
- project
- Learning and remembering: The cognitive neuroscience of memory for real-world events
- language
- Swedish
- LU publication?
- yes
- id
- e150665b-08f2-41be-8233-0502ecb82134
- alternative location
- https://www2.helsinki.fi/sites/default/files/atoms/files/icon2022_poster_abstracts.pdf
- date added to LUP
- 2022-05-29 18:09:46
- date last changed
- 2022-05-30 08:50:49
@misc{e150665b-08f2-41be-8233-0502ecb82134,
abstract = {{Objectives<br/>The formation of episodic memories is critically determined by how we visually sample the world over time via sequences of eye movements. Nonetheless, in the neuroscience of human memory, memory encoding has almost exclusively been studied in experimental paradigms where the study material is presented in a single fixed location on the screen, and where eye movements are treated as artifacts. Thus, the neural mechanisms subserving memory construction across eye movements are virtually unknown.<br/>Research question<br/>What are the neural correlates of episodic memory formation during eye movements in natural visual behavior?<br/>Materials and methods<br/>We developed an associative memory task in which participants encoded multiple events, each comprising distinct elements from three categories (faces, places, objects) in different locations of the screen. The spatial configuration of the element locations allowed us to separate relevant and irrelevant saccades for integrating them into a coherent event. Participants memorized the event, while their EEG and eye movements were simultaneously recorded. Episodic memory was thereafter assessed by testing retrieval of the element associations specifying each event. In the EEG analysis, we overcame the problem of overlapping EEG responses to sequential saccades in free viewing using a deconvolution approach. We segmented EEG relative to the fixation onset and examined the power of EEG signals in the theta and alpha frequency bands.<br/>Results<br/>High subsequent memory performance was predicted by theta synchronization over the centro-parietal areas during fixation intervals after saccades relevant to event integration. This may reflect the binding of elements into coherent event representation. High memory performance was also predicted by alpha desynchronization during fixations after task-irrelevant saccades. This may reflect discrimination of elements from the same category, which is necessary for successful memory encoding. Finally, high frontal theta power during fixations after scrutinizing, within-element saccades predicted high memory. This may reflect increased visual sampling of elements leading to better memory.<br/>Conclusion<br/>Thus, memory formation across eye movements is characterized by three neural mechanisms that rapidly turned on and off in a saccadic sequence during event encoding. These mechanisms provide essential building blocks for the construction of episodic memory during naturalistic viewing.}},
author = {{Nikolaev, Andrey and Bramao, Ines and Johansson, Roger and Johansson, Mikael}},
language = {{swe}},
title = {{Switching between neural modes at sequential fixations in free viewing predicts successful episodic memory}},
url = {{https://www2.helsinki.fi/sites/default/files/atoms/files/icon2022_poster_abstracts.pdf}},
year = {{2022}},
}