Induction of early growth response gene 2 expression in the forebrain of mice performing an attention-set-shifting...

Early growth response (egr) genes encode transcription factors that are induced by stimuli that cause synaptic plasticity. Here we show that the expression of one member of this family, egr-2, is induced in the orbital frontal cortex (OFC) and medial prefrontal cortex (mPFC) of mice performing an attention-set-shifting task (ASST). The ASST is a series of two-choice perceptual discriminations between different odors and textures. Within the OFC and mPFC, different subregions exhibited egr-2 induction in response to different test-related features. In the medial OFC and the anterior cingulate subregion of the mPFC, egr-2 induction occurred in response to exposure to the novel odor stimulus. In the ventrolateral OFC and the pre- and infralimbic mPFC, additional egr-2 induction occurred during the associative learning phase of the ASST. In the infralimbic mPFC, further egr-2 induction occurred when mice performed set-shifting and reversal learning phases of the ASST. Mice with enhanced set-shifting performance exhibited decreased egr-2 induction in the mPFC indicating that the magnitude of egr-2 induction correlates with the magnitude of attentional demand. This decrease was largest in the infralimbic mPFC suggesting further that egr-2 induction in this region plays a role in the attentional control during set-shifting. In contrast to egr-2, neither egr-1 nor egr-3 expression was altered in ASST-tested mice, and no egr-2 induction occurred in mice that performed a spatial working memory task. These findings suggest a specific role of egr-2-mediated transcriptional activation in cognitive functions associated with attention.