Biology subjects

Wiegand, I.

Publications and source records attributed to Wiegand, I..

4 recordsLinked to original sources

bioRxiv2024

Electrophysiological correlates of visual memory search

In everyday life, we frequently engage in hybrid search, where we look for multiple items stored in memory (e.g., a mental shopping list) in our visual environment. Across three experiments, we used event-related potentials to better understand the contributions of visual working memory (VWM) and long-term memory (LTM) during the memory search component of hybrid search. Experiments 1 and 2 demonstrated that the FN400 - an index of LTM recognition - and the CDA - an index of VWM - increased with memory set size (target load), suggesting that both VWM and LTM are involved in memory search, even when memory load exceeds capacity limitations of VWM. In Experiment 3, we used these electrophysiological indices to test how categorical similarity of targets and distractors affects memory search. The CDA and FN400 were modulated by memory set size only if items resembled targets. This suggests that dissimilar distractor items can be rejected before eliciting a memory search. Together, our findings demonstrate the interplay of VWM and LTM processes during memory search for multiple targets.

neuroscience↗

bioRxiv2023

Category-based attention facilitates memory search

We often need to decide whether the object we look at is also the object we look for. When we look for one specific object, this process can be facilitated by preparatory feature-based attention. However, when we look for multiple objects at the same time (e.g., the products on our shopping list) such a strategy may no longer be possible, as research has shown that we can actively prepare to detect only one object at a time. Therefore, looking for multiple objects may additionally involve search in long-term memory, slowing down decision making. Interestingly, however, previous research has shown that memory search can be very efficient when distractor objects are from a different category than the items in the memory set. Here, using EEG, we show that this efficiency is supported by top-down attention at the category level. In Experiment 1, human participants (both sexes) performed a memory search task on individually presented objects of the same or different category as the objects in the memory set. We observed category-level attentional modulation of distractor processing from [~]150 ms after stimulus onset, expressed both as an evoked response modulation and as an increase in decoding accuracy of same-category distractors. In Experiment 2, memory search was performed on two concurrently presented objects. When both objects were distractors, spatial attention (indexed by the N2pc component) was directed to the object that was of the same category as the objects in the memory set. Together, these results demonstrate how attention can facilitate memory search. Significance statementWhen we are in the supermarket, we repeatedly decide whether a product we look at (e.g., a banana) is on our memorized shopping list (e.g., apples, oranges, kiwis). This requires searching our memory, which takes time. However, when the product is of an entirely different category (e.g., dairy instead of fruit), the decision can be made quickly. Here, we used EEG to show that this between-category advantage in memory search tasks is supported by top-down attentional modulation of visual processing: The visual response evoked by distractor objects was modulated by category membership, and spatial attention was quickly directed to the location of within-category (vs. between-category) distractors. These results demonstrate a close link between attention and memory.

neuroscience↗

bioRxiv2019

Age Differences in Hemispheric Lateralization in Spatial and Verbal Visual Working Memory

Due to hemispheric specialization of the human brain, neural signatures of visual working memory (WM) performance are expected to differ between tasks involving verbal versus spatial memoranda. Theories of cognitive aging suggest a reduction of hemispheric specialization in older adults. Using behavioral and neural WM capacity markers, we assessed hemispheric lateralization in younger and older adults performing a spatial or verbal visual WM task. Participants encoded information presented in the left or right hemifield. We observed behavioral advantages for spatial stimuli processed in the right hemisphere and for verbal stimuli processed in the left hemisphere. While younger adults showed lateralization in both tasks, older adults showed lateralization only in the verbal task. Lateralization was assessed by the contralateral delay activity (CDA) on the neural level. CDA amplitudes displayed hemispheric lateralization for verbal versus spatial material, but this effect was age-invariant. While our findings support right-hemispheric specialization for spatial information maintenance, and left-hemispheric specialization for verbal information maintenance, we could not confirm a generalized reduction in hemispheric lateralization at older ages.

neuroscience↗

bioRxiv2018

Cue-related phase reset accounts for age differences in phasic alerting

Alertness is fundamental for the efficiency of information processing. A persons level of alertness refers to the systems state of general responsiveness, and can be temporarily increased by presenting a neutral warning cue shortly before an event occurs (Posner & Petersen, 1990). However, effects of alerts on subsequent stimulus processing are less consistent in older than in younger individuals. In this study, we investigated the neural underpinnings of age differences in processing of auditory alerting cues. We measured electroencephalographic power and phase locking in response to alerting cues in a visual letter report task, in which younger but not older adults showed a cue-related behavioral advantage.\n\nAlerting cues evoked a significant increase in power as well as in inter-trial phase locking, with a maximum effect in the alpha frequency (8-12 Hz) in both age groups. Importantly, these cue-related increases in phase locking and power were stronger in older than in younger adults and were negatively correlated with the behavioral alerting effect in the older sample.\n\nOur results are in accordance with the assumption that older adults neural responses may be more strongly driven by external input and less variable than younger adults. A stronger resetting of the system in response to the auditory cue may have hindered older adults effective use of the warning signal to foster processing of the following visual stimulus.

neuroscience↗