Improved reversal learning and working memory and enhanced reactivity to novelty in mice with enhanced GABAergic innervation in the dentate gyrus.
The process of learning involves stable changes in synaptic efficacy for which long-term potentiation (LTP) provides a widely adopted mammalian model. Synaptic modification induced by learning or LTP may involve the action of cell adhesion molecules. One such candidate is the ubiquitous neuronal glycoprotein Thy-1. In mice in which the gene encoding Thy-1 has been inactivated, we find a regionally selective impairment of LTP in vivo in the hippocampal formation: LTP is normal in area CA1 but strongly inhibited in the dentate gyrus. Spatial learning by Thy-1-deficient mice, as assessed in the watermaze, is unimpaired. Thus LTP in the cortical input to the dentate gyrus seems not to be required for spatial learning.