A Review of Evidence Linking Disrupted Neural Plasticity to Schizophrenia

Abstract

The adaptations resulting from neural plasticity lead to changes in cognition and behaviour, which are strengthened through repeated exposure to the novel environment or stimulus. Learning and memory have been hypothesized to occur through modifications of the strength of neural circuits, particularly in the hippocampus and cortex. Cognitive deficits, specifically in executive functioning and negative symptoms, may be a corollary to deficits in neural plasticity. Moreover, the main excitatory and inhibitory neurotransmitters associated with neural plasticity have also been extensively investigated for their role in the cognitive deficits associated with schizophrenia. Transcranial magnetic stimulation (TMS) represents some of the most promising approaches to directly explore the physiological manifestations of neural plasticity in the human brain. Three TMS paradigms (use-dependent plasticity, paired associative stimulation, and repetitive TMS) have been used to evaluate neurophysiological measures of neural plasticity in the healthy brain and in patients with schizophrenia, and to examine the brain's responses to such stimulation. In schizophrenia, deficits in neural plasticity have been consistently shown which parallel the molecular evidence appearing to be entwined with this debilitating disorder. Such pathophysiology may underlie the learning and memory deficits that are key symptoms of this disorder and may even be a key mechanism involved in treatment with antipsychotics. W W W Une revue des données probantes liant la plasticité neuronale déréglée à la schizophrénieLes adaptations issues de la plasticité neuronale entraînent des changements de la cognition et du comportement, lesquels sont renforcés par l'exposition répétée au nouvel environnement ou stimulus. Une hypothèse veut que l'apprentissage et la mémoire surviennent par des modifications de la force des circuits neuronaux, particulièrement dans l'hippocampe et le cortex. Les déficits cognitifs, spécifiquement ceux du fonctionnement exécutif et des symptômes négatifs, peuvent être un corollaire des déficits de la plasticité neuronale. En outre, les principaux neurotransmetteurs excitateurs et inhibiteurs associés à la plasticité neuronale ont également fait l'objet de recherches poussées quant à leur rôle dans les déficits cognitifs associés à la schizophrénie. La stimulation magnétique transcrânienne (SMT) représente certaines des approches les plus prometteuses qui explorent directement les manifestations physiologiques de la plasticité neuronale dans le cerveau humain. Trois paradigmes de la SMT (plasticité activité-dépendante, stimulation couplée associative, et SMT répétitive) ont servi à évaluer les mesures neurophysiologiques de la plasticité neuronale dans le cerveau en santé et chez les patients souffrant de schizophrénie, et à examiner les réponses du cerveau à cette stimulation. Dans la schizophrénie, les déficits de plasticité neuronale ont été constamment démontrés, ce qui correspond aux éléments de preuve moléculaires qui semblent êtr...

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