Abstract

BackgroundHistorically, the primary sensory areas of the cerebral cortex have been exclusively associated with the processing of a single sensory modality. Yet the presence of tactile responses in the primary visual (V1) cortex has challenged this view, leading to the notion that primary sensory areas engage in cross-modal processing, and that the associated circuitry is modifiable by such activity. To explore this notion, here we assessed whether the exploration of novel objects in the dark induces the activation of plasticity markers in the V1 cortex of rats.MethodsAdult rats were allowed to freely explore for 20 min a completely dark box with four novel objects of different shapes and textures. Animals were euthanized either 1 (n = 5) or 3 h (n = 5) after exploration. A control group (n = 5) was placed for 20 min in the same environment, but without the objects. Frontal sections of the brains were submitted to immunohistochemistry to measure protein levels of egr-1 and c-fos, and phosphorylated calcium-dependent kinase (pCaKMII) in V1 cortex.ResultsThe amount of neurons labeled with monoclonal antibodies against c-fos, egr-1 or pCaKMII increased significantly in V1 cortex after one hour of exploration in the dark. Three hours after exploration, the number of labeled neurons decreased to basal levels.ConclusionsOur results suggest that non-visual exploration induces the activation of immediate-early genes in V1 cortex, which is suggestive of cross-modal processing in this area. Besides, the increase in the number of neurons labeled with pCaKMII may signal a condition promoting synaptic plasticity.

Highlights

  • At the beginning of the last century, Korbinian Brodmann proposed that the neocortex is divided into several cytOarchitectonically distinct areas, each one devoted to a distinct function (Brodmann, 2006; Guimaraes, Santos & Freire, 2016)

  • We showed that the whisker-based exploration of novel objects in the darkness leads to a marked upregulation of the mRNA levels of calcium-dependent immediate-early genes (IEGs) in primary visual (V1) cortex of calcium-dependent immediate-early genes (IEGs) which are associated with memory consolidation (Ribeiro et al, 2007)

  • We investigated the causes and consequences of cross-modal mRNA IEG induction in V1 cortex, by assessing the levels of phosphorylated CaMKII, a calciumdependent kinase upstream of c-fos and egr-1 transcripts with a well-documented role in plasticity (Kaczmarek & Chaudhuri, 1997)

Read more

Summary

Introduction

At the beginning of the last century, Korbinian Brodmann proposed that the neocortex is divided into several cytOarchitectonically distinct areas, each one devoted to a distinct function (Brodmann, 2006; Guimaraes, Santos & Freire, 2016). The presence of tactile responses in the primary visual (V1) cortex has challenged this view, leading to the notion that primary sensory areas engage in cross-modal processing, and that the associated circuitry is modifiable by such activity. To explore this notion, here we assessed whether the exploration of novel objects in the dark induces the activation of plasticity markers in the V1 cortex of rats. The increase in the number of neurons labeled with pCaKMII may signal a condition promoting synaptic plasticity

Methods
Results
Conclusion

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.