Biology subjects

Dede, A. J. O.

Publications and source records attributed to Dede, A. J. O..

5 recordsLinked to original sources

bioRxiv2025

Distinct neurophysiological features and memory representations along the long axis of the developing medial temporal lobe

The medial temporal lobe (MTL) is crucial for episodic memory, whereby posterior MTL preferentially represents visuospatial information, and anterior MTL is involved in the representation of semantic or conceptual information. The neurophysiological underpinnings of content-preferential organization in the developing MTL are largely unknown. Here we utilized rare electrocorticography (ECoG) recordings from 23 pediatric epilepsy patients who completed a visual scene recognition memory task to systematically examine the neurophysiological underpinnings of memory formation along the MTL long axis. The timing of high-frequency activity (HFA, [~]70-150 Hz) differed between the posterior and anterior MTL, peaking after scene onset in the posterior MTL and around scene category response (indoor/outdoor scene categorization) in the anterior MTL. Further, in the posterior MTL, HFA was predictive of successful memory formation and positively linked to memory performance, highlighting the importance of posterior MTL HFA to memory formation. In contrast, theta frequency in the anterior MTL was linked to memory performance, and theta-HFA phase-amplitude coupling before scene category responses was predictive of successful memory formation, highlighting the importance of anterior MTL theta oscillations to memory formation. Our findings establish distinct neurophysiological features along the posterior-to-anterior axis of the developing MTL that differentially support the representation of perceptual and conceptual information during memory formation.

neuroscience↗

bioRxiv2025

Eyes-closed resting state EEG reveals clearer and more stable group differences between autistic and neurotypical individuals than eyes-open resting state EEG

BackgroundResting-state electroencephalography (rs-EEG) has been widely used to explore neural dynamics in Autism Spectrum Condition (ASC). However, inconsistencies in findings across studies remain a challenge, partly due to variations in brain state, such as eye conditions (eyes-open vs. eyes-closed). This study aims to examine rs-EEG differences between ASC and neurotypical (NT) participants, focusing on the influence of eye condition. MethodsA total of 300 participants (126 ASC) were included. Rs-EEG data were analysed across eyes-open, eyes-closed, and difference between eye conditions, with 726 variables assessed per participant. Linear regression and effect size (2partial) were used to identify group differences, complemented by cluster-based permutation testing and bootstrapped split-half validation for reliability. ResultsGroup differences were most pronounced in the eyes-closed condition, particularly for relative power and multiscale entropy (MSE). Compared to neurotypical participants, ASC participants exhibited reduced frontal coarse-scale MSE, increased delta power, and decreased alpha power, suggesting altered local-global neural dynamics. Cross-validation revealed greater reliability of effects in the eyes-closed condition compared to eyes-open or difference between eye conditions. ConclusionsEye condition plays a critical role in detecting rs-EEG differences between ASC and NT groups, with the eyes-closed condition yielding more consistent and pronounced effects. These findings highlight the importance of controlling brain state in rs-EEG studies and suggest that integrating eye condition effects with other biomarkers may improve identification of neural differences associated with ASC.

neuroscience↗

bioRxiv2025

Declarative Memory Through the Lens of Single-Trial Peaks in High-Frequency Power

Declarative memory depends on the coordination of local processing, indexed by high-frequency broadband (HFB) activity, with global network organization, indexed by theta oscillations. However, theta and HFB exhibit asynchronous timing, raising the question of how results of local processing are communicated throughout the network. Using intracranial EEG in patients performing a recognition memory task, we examined this coordination across the medial temporal lobe (MTL) and prefrontal cortex (PFC). HFB peak activity was earlier in the MTL than PFC. Anchoring analyses of theta phase clustering and connectivity to HFB peaks revealed strong phase clustering locked to HFB peaks in the PFC, as well as connectivity between the PFC and MTL that predicted individual memory performance. Graph analysis revealed specific connections amidst sparse network connectivity during memory success. This study demonstrates that transient brain states linked to internal physiological events support memory and refines our understanding of local and network-level process interactions. HighlightsO_LIMemory-linked theta activity is time-locked to internal brain events C_LIO_LINetwork connectivity changes dynamically during memory processing C_LIO_LISparse network connectivity supports successful memory C_LIO_LISpecific sequences of transient states may be critical for declarative memory C_LI

neuroscience↗

bioRxiv2024

The development of aperiodic neural activity in the human brain

The neurophysiological mechanisms supporting brain maturation are fundamental to attention and memory capacity across the lifespan. Human brain regions develop at different rates, with many regions developing into the third and fourth decades of life. Here, in this preregistered study (https://osf.io/gsru7), we analyzed intracranial EEG (iEEG) recordings from widespread brain regions in a large developmental cohort. Using task-based (i.e., attention to-be-remembered visual stimuli) and task-free (resting-state) data from 101 children and adults (5.93 - 54.00 years, 63 males; n electrodes = 5691), we mapped aperiodic (1/[f]-like) activity, a proxy of neural noise, with steeper slopes indexing less noise and flatter slopes indexing more noise. We reveal that aperiodic slopes flatten with age into young adulthood in both association and sensorimotor cortices, challenging models of early sensorimotor development based on brain structure. In prefrontal cortex (PFC), attentional state modulated age effects, revealing steeper task-based than task-free slopes in adults and the opposite in children, consistent with the development of cognitive control. Age-related differences in task-based slopes also explained age-related gains in memory performance, linking the development of PFC cognitive control to the development of memory. Last, with additional structural imaging measures, we reveal that age-related differences in gray matter volume are similarly associated with aperiodic slopes in association and sensorimotor cortices. Our findings establish developmental trajectories of aperiodic activity in localized brain regions and illuminate the development of PFC control during adolescence in the development of attention and memory.

neuroscience↗

bioRxiv2023

Comparing rapid rule-learning strategies in humans and monkeys

Inter-species comparisons are key to deriving an understanding of the behavioral and neural correlates of human cognition from animal models. We perform a detailed comparison of macaque monkey and human strategies on an analogue of the Wisconsin Card Sort Test, a widely studied and applied multi-attribute measure of cognitive function, wherein performance requires the inference of a changing rule given ambiguous feedback. We found that well-trained monkeys rapidly infer rules but are three times slower than humans. Model fits to their choices revealed hidden states akin to feature-based attention in both species, and decision processes that resembled a Win-stay lose-shift strategy with key differences. Monkeys and humans test multiple rule hypotheses over a series of rule-search trials and perform inference-like computations to exclude candidates. An attention-set based learning stage categorization revealed that perseveration, random exploration and poor sensitivity to negative feedback explain the under-performance in monkeys.

animal behavior and cognition↗