Amber Badgerow
October 19, 2011
PSY 213
John Olmsted
Restoration of the Brain after Damage
Question:
There are amazing stories of people with brain damage regaining use of limbs, speech, etc. What changes occur in the brain after damage that could aid in recovery and must those changes be facilitated?
Prediction:
Neuroplasticity occurs during maturation, learning, and after an injury. The changes in the brain after damage may be new connections, strengthened connections, and/or new growth in order for the area of the brain that is undamaged to partially take over the tasks of the damaged area. In order for changes to occur, effort toward rehabilitation may be needed or an effort could expedite recovery since it means relearning tasks, which may promote neuroplasticity.
Article 1: “Remodeling the Brain Plastic Structural Brain Changes Produced by Different Motor Therapies After Stroke”
Lynne V. Gauthier, MA, Edward Taub, PhD, Christi Perkins, BS, Magdalene Ortmann, Victor W. Mark, MD, and Gitendra Uswatte, PhD wrote this article to find evidence for structural brain changes induced by an effective rehabilitation program. Sixteen stroke patients received constraint-induced (CI) movement therapy (that also encouraged use of the affected arm in daily activities at home) and twenty received a comparison therapy. Structural MRI scans were taken on patients before and after therapy for voxel-based morphometry (VBM). Results showed that not only did CI therapy patients obtain more use of the affected arm than the comparison therapy patients, but that they also displayed significant increases in ipsilateral and contralateral sensory and motor area gray matter. There was also in increase in the gray matter of the hippocampus, which is associated with learning and memory. Comparison therapy patients did not show an increase in gray matter. This indicated that changes in brain morphology may be responsive to a motor task's behavioral relevance. The observed neuroplasticity (growth in gray matter) could have been due to increased generation of neuronal or glial stem cells to aid in repair, reorganization or increased size of dendrites and greater synaptic density, proliferation of astrocytes, and/or angiogenesis.
Article 2: “Dynamic Neuroplasticity after Human Prefrontal Cortex Damage”
This article by Bradley Voytek, Matar Davis, Elena Yago, Francisco Barcelo´, Edward K. Vogel, and Robert T. Knight discussed their study that was conducted to provide evidence that, depending on the situation and cognitive load, the intact prefrontal cortex (PFC) compensates for the PFC with a unilateral lesion. They used electroencephalography (EEG) to measure the compensation. First, six patients performed lateralized visual working memory tasks. Contralesional stimuli produced sustained frontal theta activity that increased with memory load over the intact PFC. Ipsilesional stimuli did not produce electrophysiological changes and such changes were not observed in the control group. After the memory tasks patients performed a lateralized visual attention task, which was to find targets in swiftly progressing stimuli presented to the left or right visual field. When targets were presented to the damaged hemisphere there was late frontal activity that increased over the intact PFC. The fact that the undamaged hemisphere showed activity in less time and with less of a load when the damaged PFC was challenged suggested a powerful compensatory process involving neural changes to aid the damaged hemisphere.
Source Validity:
The first article has a few limitations that were noted: the experiment needs to be repeated, the
VBM method does not allow for the identification of the means of gray matter changes, and there was a small sample group. Article two also has a couple issues that may affect reliability: there was a very small subject group and an imbalance of right and left hemisphere lesions in patients. Despite these issues both articles were written by reputable authors, had experiments that controlled for age, education, and medical conditions, and provided evidence from other research that supported their results.
Reflection on Hypothesis:
This research supports my hypothesis that there are possible strengthened connections and/or new connections and that there is growth in the brain after damage. There is also evidence that the undamaged hemisphere compensates for the damaged one. Although the study in the first article indicates that morphologic neuroplasticity after brain damage only occurs with specific rehabilitation programs, more research must be done on the subject to fully support the hypothesis that neuroplasticity for recovery must be facilitated. There is still the question of whether the observed neuroplasticity is an effect of the functional changes or if it causes the functional changes.
Works Cited:
Gauthier Lynne V. et al. “Remodeling the Brain Plastic Structural Brain Changes Produced
by Different Motor Therapies After Stroke.” Stroke 39.5 (2008):1520-1525. American Heart
Association. GoogleScholar (“Structural Neuroplasticity Stroke”, PDF from
stroke.ahajournals.org). Web. Oct. 19, 2011.
< http://stroke.ahajournals.org/content/39/5/1520.full.pdf+html>
Voytek Bradley et al. “Dynamic Neuroplasticity after Human Prefrontal Cortex Damage.”
Neuron 68 (2010): 401–408. Elsevier Inc. GoogleScholar (“Neuroplasticity Cortex Damage”).
wonderful discussion of neural plasticity.
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