Dynamics of information processing and spontaneous activity during sleep
Bibliographic record
Abstract
Brain oscillations are critical for inter-regional communication and the orchestration of higher order cognitive processes such as attention and memory consolidation.Oscillations underlying these phenomena are typically mediated via underlying neural population activity, but the exact mechanisms that determine how the oscillations are generated remain open questions in the field.In this work, I examined two classes of oscillations that are crucial for memory consolidation: the cortical slow wave and hippocampal sharp wave-ripples, in pursuit of elucidating the contributions of single neurons to these processes.Critically, these oscillations occur during sleep, which also enables us to understand the intrinsic mechanisms underlying their spontaneous initiation, devoid of sensory inputs.I used the spatial navigation system as a model to study memory consolidation, as spatially tuned activity is a relatively simple readout compared to other brain systems.Specifically, I examined the organization of sequences in the cortical head-direction system and uncovered a dorsoventral activation pattern.Using the head-direction cell activity as a readout, I was able to elucidate the content of these sequences and showed that population activity rapidly converges towards a stable orientation, and this direction is chosen at random during each oscillatory period.Finally, using a combination of computational modeling, and ex vivo patch clamp experiments I, in collaboration with colleagues from the University of Edinburgh, uncovered a hitherto ignored key player in the dynamics of the slow oscillation in the cortex -hyperpolarization-activated currents.I showed that these currents might play brain-wide roles in the organization of cortical sequences.This finding has important implications for the organization of activity along the dorsoventral axis, a common feature observed throughout the navigation system, and the organization of sequences in the cortex, more generally.I then turned to a downstream structure, the hippocampus, to examine the other key oscillation in memory consolidation -sharp wave-ripples.In collaboration with colleagues from the department of Pharmacology and Therapeutics at McGill University, I worked on a mouse model of Christianson Syndrome, a recently discovered neurodevelopmental and neurodegenerative disorder, and led the first investigation, to our knowledge, into understanding the mechanisms underlying the cognitive deficits in this disorder, focusing on oscillatory activity in the
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".