Role of the Anterior and Mediodorsal Thalamic Nuclei in Cognitive Processes
Bibliographic record
Abstract
Our lab encountered a patient with developmental amnesia due to stroke damage to two subcortical regions: the anterior thalamus (AT) and mediodorsal thalamus (MD). To see cognitive deficits after damage to these subcortical regions was somewhat surprising as most research into amnesia historically focused on the hippocampus or prefrontal cortex. The present dissertation thus sought to explore the involvement of these subcortical regions in cognition. In chapter 1 I used functional magnetic resonance imaging to examine activations of the AT and MD of healthy adults during different phases of an associative memory task. I found that the AT showed a greater deactivation during successful memory encoding but that activations of the MD did not show any relation with task accuracy. In chapter 2 I took a different approach in order to address theories that suggest that the MD is important for other forms of cognition such as executive function. I examined recall, recognition, working memory, executive function, and language performance in a group of 22 patients with stroke damage to the thalamus. All cognitive processes were impaired in the thalamic stroke group but there was not a detectable link between which parts of the thalamus were damaged and specific deficits in cognition. Next, I sought to relate these cognitive functions to brain activity patterns in the cortex of these same thalamic stroke patients. Existing theories suggest that the thalamus, particularly the MD, modulates the way cortical regions communicate with each other. In chapter 3 I explored this theory in humans. I examined how patterns of communication between cortical regions as measured by “resting state” functional connectivity were different in thalamic stroke patients and controls. This analysis did not reveal any indication that MD damage disrupts cortico-cortical modulation. It is possible that the MD plays a more prominent role only during specific tasks or at smaller scales. Overall, the results suggest that the AT is involved in associative forms of memory but the role of the MD is less clear. However, a critical first step was made towards understanding the limitations of MD involvement in modulation of cortico-cortical communication.
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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 | 0.001 |
| Scholarly communication | 0.001 | 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".