ABSTRACT
PURPOSE: The loss of calculation skills due to brain lesions leads to a major reduction in the quality of life and is often associated with difficulties of returning to work and a normal life. Very little is known about the neural mechanisms underlying performance improvement due to calculation training during rehabilitation. The current study investigates the neural basis of training-induced changes in patients with acalculia following ischemic stroke or traumatic brain lesions. METHODS: Functional hemodynamic responses (fMRI) were recorded in seven patients during calculation and perceptual tasks both before and after acalculia training. RESULTS: Despite the heterogeneity of brain lesions associated with acalculia in our patient sample, a common pattern of training-induced changes emerged. Performance improvements were associated with widespread deactivations in the prefrontal cortex. These deactivations were calculation-specific and only observed in patients exhibiting a considerable improvement after training. CONCLUSION: These findings suggest that the training-induced changes in our patients rely on an increase of frontal processing efficiency.
Subject(s)
Brain Mapping , Brain/pathology , Learning Disabilities/rehabilitation , Mathematics , Problem Solving/physiology , Teaching/methods , Adult , Brain/blood supply , Brain Injuries/complications , Brain Injuries/pathology , Brain Injuries/rehabilitation , Computer-Assisted Instruction/methods , Humans , Image Processing, Computer-Assisted , Learning Disabilities/etiology , Magnetic Resonance Imaging , Male , Middle Aged , Neuropsychological Tests , Oxygen/bloodABSTRACT
OBJECTIVE: Cognitive impairment is a common symptom of multiple sclerosis (MS). The present study aimed to assess fatigue-related diurnal variations of cognitive performance in MS patients. METHOD: Subjective cognitive fatigue and cognitive performance in three reaction time tasks differing in cognitive demands (alertness, Go/NoGo, divided attention) was measured at three different times of day on two consecutive days for MS patients, stroke patients, and healthy control participants. RESULTS: Objective measures of cognitive performance revealed poorer performance for both groups of patients than for controls. A diurnal decline of cognitive performance was only observed for the two groups of patients but not for healthy controls. This decline corresponded to the patients' subjective reports of increasing cognitive fatigue during the day. CONCLUSION: Cognitive fatigue in both MS and stroke patients is not only reflected in subjective ratings but also affects objectively measured performance in cognitive tasks.
