The Role of Interhemispheric Interactions in Cortical Plasticity

Jan Antoni Jablonka; Robert Binkowski; Marcin Kazmierczak; Maria Sadowska; Władysław Sredniawa; Aleksandra Szlachcic; Paulina Urban

doi:10.3389/fnins.2021.631328

The Role of Interhemispheric Interactions in Cortical Plasticity

Front Neurosci. 2021 Jul 9:15:631328. doi: 10.3389/fnins.2021.631328. eCollection 2021.

Authors

Jan Antoni Jablonka¹, Robert Binkowski¹, Marcin Kazmierczak², Maria Sadowska¹, Władysław Sredniawa^{1

3

4}, Aleksandra Szlachcic¹, Paulina Urban^{1

4}

Affiliations

¹ Faculty of Biology, University of Warsaw, Warsaw, Poland.
² Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, New York, NY, United States.
³ Nencki Institute of Experimental Biology of Polish Academy of Sciences, Warsaw, Poland.
⁴ College of Inter-Faculty Individual Studies in Mathematics and Natural Sciences, University of Warsaw, Warsaw, Poland.

Abstract

Despite the fact that there is a growing awareness to the callosal connections between hemispheres the two hemispheres of the brain are commonly treated as independent structures when peripheral or cortical manipulations are applied to one of them. The contralateral hemisphere is often used as a within-animal control of plastic changes induced onto the other side of the brain. This ensures uniform conditions for producing experimental and control data, but it may overlook possible interhemispheric interactions. In this paper we provide, for the first time, direct proof that cortical, experience-dependent plasticity is not a unilateral, independent process. We mapped metabolic brain activity in rats with 2-[¹⁴C] deoxyglucose (2DG) following experience-dependent plasticity induction after a month of unilateral (left), partial whiskers deprivation (only row B was left). This resulted in ∼45% widening of the cortical sensory representation of the spared whiskers in the right, contralateral barrel field (BF). We show that the width of 2DG visualized representation is less than 20% when only contralateral stimulation of the spared row of whiskers is applied in immobilized animals. This means that cortical map remodeling, which is induced by experience-dependent plasticity mechanisms, depends partially on the contralateral hemisphere. The response, which is observed by 2DG brain mapping in the partially deprived BF after standard synchronous bilateral whiskers stimulation, is therefore the outcome of at least two separately activated plasticity mechanisms. A focus on the integrated nature of cortical plasticity, which is the outcome of the emergent interactions between deprived and non-deprived areas in both hemispheres may have important implications for learning and rehabilitation. There is also a clear implication that there is nothing like "control hemisphere" since any plastic changes in one hemisphere have to have influence on functioning of the opposite one.

Keywords: 2-deoxy-D-glucose; 2DG; barrel field; cortical plasticity; interhemispheric.