Unilateral Frontal Lobe Contusion and Forelimb Function: Chronic Quantitative and Qualitative Impairments in Reflexive and Skilled Forelimb Movements in Rats
Bibliographic record
Abstract
Traumatic brain injury induced by mechanical impacts of the head can be modeled in rats in order to investigate acute and chronic therapy. Because frontal lobe contusion affects the neural representation of the forelimb in both the neocortex and basal ganglia, the purpose of the present experiments was to examine the chronic changes in reflexive and skilled forelimb induced by the injury. Contusions produced a cavity in the sensorimotor cortex, accompanied by shrinkage of the pyramidal tract, loss of cells in the dorsolateral striatum, and enlargement of the lateral ventricle. There were substantial individual differences in lesion size despite use of two different contusion forces, but all rats receiving contusions displayed chronic forelimb deficits. Reflexive tests of forelimb use (limb posture, placing, and support) indicated that impairments were most pronounced in the forelimb contralateral to the lesion. Tests of limb preference indicated that the contusion rats displayed a forelimb asymmetry: they were more likely to lean on their ipsilateral-to-lesion forelimb for support when rearing in a test cylinder, and this impairment was amplified in a home cage test. They also displayed a preference for the forelimb ipsilateral to the lesion when reaching for food, although both forelimbs were equally impaired on measures of success when reaching for food from a tray and reaching for a single food pellet on a shelf. A qualitative analysis from frame-by-frame video records indicated that when reaching for single pellets, impairments in forelimb use primarily affected the contralateral-to-lesion limb, especially limb aiming, supination, and food pellet release. Impairments in the ipsilateral-to-lesion forelimb were generally, but not exclusively, secondary to postural abnormalities. The wide range of chronic impairments in forelimb use following contusion injuries are discussed in relation to the anatomical and behavioral origins of the impairments and the potential use of forelimb tests in the assessment of therapy for traumatic brain injury to the frontal cortex.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 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 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".