The Journal of Neuroscience, September 1, 2002, 22(17):7809-7817
Conceptual, Spatial, and Cue Learning in the Morris Water Maze in
Fast or Slow Kindling Rats: Attention Deficit Comorbidity
Hymie
Anisman and
Dan C.
McIntyre
Institute of Neuroscience, Carleton University, Ottawa, Ontario,
Canada, K1S 5B6
Rat lines selectively bred for differences in amygdala
excitability, manifested by "fast" or "slow" kindling
epileptogenesis, display several comorbid features related to anxiety
and learning. To assess the nature of the learning deficits in fast
kindling rats, performance was evaluated in several variants of a
Morris water-maze test. Regardless of whether the location of the
platform was fixed or varied over days (matching-to-place task), the
fast rats displayed inferior performance, suggesting both working and reference memory impairments. Furthermore, when the position of the
platform was altered after the response was acquired, fast rats were
more persistent in emitting the previously acquired response. The poor
performance of fast rats was also evident in both cued and uncued
tasks, indicating that their disturbed learning was not simply a
reflection of a spatial deficit. Moreover, fast rats could be easily
distracted by irrelevant cues, suggesting that these animals suffered
from an attentional disturbance. Interestingly, when rats received
several training trials with the platform elevated, permitting them to
develop the concept of facile escape, the performance of fast rats
improved greatly. The performance disturbance in fast rats may reflect
difficulties in forming a conceptual framework under conditions
involving some degree of ambiguity, as well as greater distractibility
by irrelevant cues. These various attributes of the fast rats may serve
as a potentially useful animal model of disorders characterized by an
attention deficit.
Key words:
seizure susceptibility; genetic differences; spatial
learning; cued learning; concept formation; attention
Copyright © 2002 Society for Neuroscience 0270-6474/02/22177809-09$05.00/0