Sensory cortex lesion triggers compensatory neuronal plasticity

Manfred Depner,Konstantin Tziridis,Andreas Hess,Holger Schulze

doi:10.1186/1471-2202-15-57

Manfred Depner, Konstantin Tziridis + Show 2 more

Open Access

https://doi.org/10.1186/1471-2202-15-57

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Journal: BMC neuroscience	Publication Date: May 1, 2014
Citations: 60	License type: cc-by

Affiliation: University of Erlangen-Nuremberg

Abstract

BackgroundLesions to the human brain often cause dramatic impairments in the life of patients because of the very limited capacity of the mammalian nervous system to regenerate. On the other hand, neuronal tissue has a high capacity to reorganize itself so that loss of function due to brain damage may be compensated through neuroplastic reorganization of undamaged tissue in brain regions adjacent or contralateral to the lesion site. In this study we investigated the effect of serial lesions of the auditory cortices (AC) in both hemispheres of Mongolian gerbils on discrimination performance for fast amplitude modulated tones (AM). Healthy animals were trained to discriminate two fast AM, an ability that has previously been shown to critically depend on cortical processing. Their ability to maintain significant discrimination performance was retested after unilateral AC lesion, and again after lesion of the contralateral AC, with 15 days of continuing training in between the two lesions.ResultsAfter bilateral cortical ablation of both AC and 45 days of training the animals show no change in pure tone detection threshold as measured with modulation of the acoustic startle reflex which has been shown to rely on subcortical structures. In contrast to simultaneous bilateral ablation of AC that results in complete loss of AM discrimination ability in this paradigm we found compensatory plasticity that seems to be triggered by unilateral cortical ablation with subsequent training and that is able to almost fully compensate for the lost cortical functions.ConclusionsOur results demonstrate that AM discrimination ability that normally depends on AC may be transferred to other brain regions when the brain has time to activate compensatory plasticity between the lesions of the two AC hemispheres. For this process to take place obviously one intact AC hemisphere is needed. This finding may open perspectives for new therapeutic strategies that may alleviate the impairments after multiple ischemic strokes.

Highlights

Lesions to the human brain often cause dramatic impairments in the life of patients because of the very limited capacity of the mammalian nervous system to regenerate
The same argument applies even more for restrictions of possible compensatory plasticity in subcortical structures for lost cortical functions, especially for functions that seem to rely crucially on intact cortex. In this context we could demonstrate in a previous study [25] that Mongolian gerbils with bilateral lesion of the auditory cortex (AC) were unable to discriminate between fast amplitude modulations (AM)
Audiometric controls Animals were tested for a possible general impact of AC lesion on pure tone behavioral audiometry by comparing hearing thresholds prior to the first and after the last training session

Summary

Introduction

Lesions to the human brain often cause dramatic impairments in the life of patients because of the very limited capacity of the mammalian nervous system to regenerate. Regardless of the limitations of compensatory neuronal plasticity after brain lesions it has been demonstrated that specific training may foster such compensatory plasticity (e.g., [12]), resulting in improved rehabilitation outcomes in patients with brain damage (e.g., [8]) How effective such compensatory reorganization may be in restoring lost functions depends, first, on the type of function that is lost or impaired and, second, how specialized the cortical region is with respect to this function. The same argument applies even more for restrictions of possible compensatory plasticity in subcortical structures for lost cortical functions, especially for functions that seem to rely crucially on intact cortex In this context we could demonstrate in a previous study [25] that Mongolian gerbils with bilateral lesion of the AC were unable to discriminate between fast amplitude modulations (AM). Each performance gain after a lesion comes with a cost, in this case a loss of frequency modulation discrimination performance [20,21]

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