Cynthia Wolf

Behavioral correlates of vitamin D deficiency.

Rats deprived of vitamin D at weaning were compared to control rats on open field, stabilimeter, radial arm maze and spatial reversal tasks in order to test the hypothesis that vitamin D deficiency alters behavior and learning. The deficient animals engaged in statistically less open field rearing activity and spent more time each day negotiating the radial maze than did the control rats. These findings are consistent with the known influence of vitamin D on the musculoskeletal system. The deprived rats did not differ from the control animals on the learning measures. This would indicate that vitamin D deficiency may not significantly impair cognitive functions in young adult rats.

Large and small medial frontal cortex lesions and spatial performance of the rat

Rats with sham operations, or small or large medial frontal cortex lesions were compared for the acquisition of a position habit and for learning a series of 4 position habit reversals. No differences were found during acquisition of the position habit. On the reversals, the rats with the larger lesions were markedly impaired, while less severe deficits or control-like performance characterized the rats with the smaller ablations. Analyses of the error scores showed that the rats with the larger lesions made more perseverative errors than the other groups and performed more sporadically even after breaking a previous position habit. These results confirm the hypothesis that a strong relationship exists between medial frontal cortex lesion features (depth and length) and performance. The differences found in acquisition vs. reversal learning, and the nature of the errors observed, also suggest that this part of the brain functions as more than simply a spatial analyzer.

Severe early malnutrition and DRL performance in the rat

Rats with a history of severe early malnutrition (6% casein) were compared to well-fed control animals on an ascending series of DRL values ranging from 5 to 60 seconds. The 6% rats who were dietarily-rehabilitated at weaning did not differ from control animals in efficiency, responses per reinforcement or response rate. In contrast, rats chronically exposed to 6% diets performed so poorly during training with continuous reinforcement that they did not advance to even the first DRL (5-sec) condition. These findings show that severely-undernourished rats can perform within normal limits on even high DRL values, provided they are well trained and that they have adequate nutritional rehabilitation.