The initial mechanical insult resulting from traumatic spinal cord injury (SCI) causes the disruption of local vasculature and tissue structure followed by a secondary wave of injury involving hemorrhage, ischemia, ed...
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The initial mechanical insult resulting from traumatic spinal cord injury (SCI) causes the disruption of local vasculature and tissue structure followed by a secondary wave of injury involving hemorrhage, ischemia, edema, excitotoxicity, and inflammation, which leads to neuronal death, axonal degeneration, and inhibitory glial scar formation.
Attention deficit hyperactivity disorder (ADHD) is a developmental psychiatric disorder thought to affect approximately 5 to 10% of school-age children, of whom 30 to 65% continue to exhibit symptoms into adulthood. T...
Attention deficit hyperactivity disorder (ADHD) is a developmental psychiatric disorder thought to affect approximately 5 to 10% of school-age children, of whom 30 to 65% continue to exhibit symptoms into adulthood. The prevalence of ADHD in adults is also an estimated 4%, second only to depression. Across studies there appear to be significant network dysfunctions involved in ADHD. Typically the foci of interest in ADHD included the insular cortices, frontal lobes, basal ganglia, and cerebellum. More recently, attention has been directed to the default network of the brain and its functional integrity in ADHD with focus on the precuneus and parietal lobes and interactions with medial prefrontal cortices. Functional magnetic resonance imaging (fMRI) measures neurovascular coupling as measured by the blood oxygenated level dependent signal (BOLD). Electroencephalogram (EEG) measures brain electrical information. Because fMRI is an indirect measure of neuronal activity and EEG is a direct measure, combining the results from these two imaging modalities under the same task conditions may provide a more complete story as to the what (EEG) and where (fMRI) activity exists. This article discusses the benefits of using standardized low resolution electromagnetic tomography (sLORETA) analysis of the EEG as compared to fMRI. The goal of the study, the data from which we use for our justification, was to discover the functional differences in ADHD and non-ADHD brains with different brain imaging modalities. We hoped to elucidate functional connectivity patterns by interpreting the data acquired with the EEG using sLORETA and the data acquired with the fMRI scans. We further hoped to find correlation with the sLORETA and fMRI interpretations so as to confirm that EEG is an adequate stand-alone methodology to evaluate ADHD. Participants included 6 ADHD and 7 non-ADHD subjects. They were initially interviewed by phone and administered the Connors Rating Scale and the Mini Intern
The entorhinal cortex plays an important role in spatial memory and episodic memory functions. These functions may result from cellular mechanisms for integration of the afferent input to entorhinal cortex. This artic...
The entorhinal cortex plays an important role in spatial memory and episodic memory functions. These functions may result from cellular mechanisms for integration of the afferent input to entorhinal cortex. This article reviews physiological data on persistent spiking and membrane potential oscillations in entorhinal cortex then presents models showing how both these cellular mechanisms could contribute to properties observed during unit recording, including grid cell firing, and how they could underlie behavioural functions including path integration. The interaction of oscillations and persistent firing could contribute to encoding and retrieval of trajectories through space and time as a mechanism relevant to episodic memory.
Numerous studies have focused on the mechanisms of Hebbian synaptic plasticity within the hippocampal formation and neocortical structures, but the specific role of this plasticity in regulating behavior remains uncle...
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ISBN:
(纸本)0780390482
Numerous studies have focused on the mechanisms of Hebbian synaptic plasticity within the hippocampal formation and neocortical structures, but the specific role of this plasticity in regulating behavior remains unclear. This paper presents a model demonstrating how Hebbian synaptic modification could mediate the context-dependent retrieval of episodes necessary for memory-guided behavior in specific tasks, and could also contribute to prefrontal mechanisms for regulation of goal-directed behavior. This modeling effectively links neurophysiological data to the functional role of Hebbian synaptic modification and theta rhythm oscillations. The model simulates data on neuronal spike firing and field potentials in the hippocampus, including 1.) the phenomenon of theta phase precession of place cells, 2.) the contextsensitivity of neuronal firing ("splitter cells") during spatial alternation, and 3.) the selective changes in theta phase precession across different trials on the same day.
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