Paper review: Neural Reorganization Following Sensory Loss: The Opportunity of Change

Merabet, L. B. & Pascual-Leone A. Neural Reorganization Following Sensory Loss: The Opportunity of Change, Nature Reviews Neuroscience, vol 11, pp 44-52, 2009

It is apparent from a long growing mass of evidences that the part of a brain responsible for processing information from a particular sensory channel gets recruited for other activities after loss of that particular channel. This phenomenon is referred to as “neuroplastic” behavior of brain. When it contributes to the improvement of other sensory channels, it is called “crossmodal neuroplasticity”. This paper refers to a considerable amount of reported evidences on crossmodal neuroplasticity following sensory deprivation and came to some conclusions based on those observations.

It particularly discussed about the following aspects of neuroplasticity. Firstly, it refers to a significant amount of reported experiments and their results on the effect of loss of vision and auditory capabilities. Analyzing these experiments, a conclusion was made that the loss of a sensory channel translates into an improved or at least an equal performance in behavioral and sensory tasks. Experimental proofs have been referred in this paper where it is reported that blind individuals showed equal or superior performance in tactile-discrimination thresholds, auditory-pitch discrimination, spatial sound localization, speech discrimination, verbal recall etc. In addition, it has been discussed that electroencephalographic and neuro-imaging technologies provide strong evidence on an altered association of brain areas for proficient utilization of other sensory channels. Similar works have also been showed for deafness and loss of multiple sensory channels.

Other than collecting evidences of crossmodal neuroplasticity, this paper also discussed on reported experiments which can explain the potential causes and mechanisms under this phenomenon. A potentially viable cause of recruitment of cortical areas followed by a sensory loss is thought to be the direct connection of the neurons to the intact sensory area. This paper also discussed on the endeavors made for determining the critical age for crossmodal plasticity. The recent experiments showed that neuroplasticity can occur in a much later age than that were presumed earlier.

Lastly, the paper discussed that in spite of the compensatory behavioral gain, the neuroplasticity cannot be viewed as universally adaptive. It may also have unintended consequences. Following the rehabilitative training, the neuroplastic changes can undermine the ability of the cortex to return back to its primary function.

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