Exploration of a novel environment leads to the expression of inducible transcription factors in barrel-related columns

Tactile information acquired through the vibrissae is of high behavioral re levance for rodents. Numerous physiological studies have shown adaptive pla sticity of cortical receptive field properties due to stimulation and/or ma nipulation of the whiskers. However, the cellular mechanisms leading to the se plastic processes remain largely unknown. Although genomic responses are anticipated to take place in this sequel, virtually no data so far exist f or freely behaving animals concerning this issue. Thus, adult rats were pla ced overnight in an enriched environment and most of them were also subject ed to clipping of different sets of whiskers. This type of stimulation led to a specific and statistically significant increase in the expression of t he protein products of the inducible transcription factors c-Fos, JunB, ind ucible cyclic-AMP early repressor and Krox-24 (also frequently named Zif268 or Egr-1), but not c-Jun. The response was found in columns of the barrel cortex corresponding to the stimulated vibrissae; it displayed a layer-spec ific pattern. However, no induction of transcription factors was observed i n the subcortical relay stations of the whisker-to-barrel pathway, i.e, the trigeminal nuclei and the ventrobasal complex. These results strongly suggest that a coordinated transcriptional response is initiated in the barrel cortex as a consequence of processing of novel e nvironmental stimuli. (C) 2000 IBRO. Published by Elsevier Science Ltd. All rights reserved.