Amelioration of sensory attention and sensorimotor deficits by chromaffin cell grafts to the cerebral cortex of nucleus basalis magnocellularis lesioned rats

A novel test for evaluating horses' spontaneous visual attention is predictive of attention in operant learning tasks

Attention is described as the ability to process selectively one aspect of the environment over others. In this study, we characterized horses' spontaneous attention by designing a novel visual attention test (VAT) that is easy to apply in the animal's home environment. The test was repeated over three consecutive days and repeated again 6 months later in order to assess inter-individual variations and intra-individual stability. Different patterns of attention have been revealed: 'overall' attention when the horse merely gazed at the stimulus and 'fixed' attention characterized by fixity and orientation of at least the visual and auditory organs towards the stimulus. The individual attention characteristics remained consistent over time (after 6 months, Spearman correlation test, P < 0.05). The validity of this novel test as a predictor of individual attentional skills was assessed by comparing the results, for the same horses, with those obtained in both a 'classical' experimental attention test the 'five-choice serial reaction time task' (5-CSRTT) and a work situation (lunge working context). Our results revealed that (i) individual variations remained consistent across tests and (ii) the VAT attention measures were not only predictive of attentional skills but also of learning abilities. Differences appeared however between the first day of testing and the following test days: attention structure on the second day was predictive of learning abilities, attention performances in the 5-CSRRT and at work. The VAT appears as a promising easy-to-use tool to assess animals' attention characteristics and the impact of different factors of variation on attention.

Transplants to the cerebral cortex of nucleus basalis magnocellularis-lesioned rats: effects on deficits in latent inhibition

Bilateral quisqualic acid-induced lesions of the nucleus basalis magnocellularis (nbm) in rats disrupted the expression of latent inhibition, a phenomenon thought to be dependent upon selective attention processes. Since grafts of adrenal chromaffin cells to the cerebral cortex of nbm-lesioned rats have been shown to ameliorate other lesion-induced cognitive deficits, we tested here whether expression of latent inhibition could be reinstated by graft placement. Interestingly, grafts of either chromaffin cells or cells from kidney or liver that have been used previously as control grafts, were able to restore latent inhibition in lesioned animals. These results suggest that it may be a host response to graft placement rather than a factor supplied by the grafted tissue itself that is responsible for the amelioration of lesion-induced deficits of latent inhibition.