ABSTRACT
Acute deafferentation of a limb results in bilateral cortical reorganization, but the behavioral consequences of this phenomenon are unknown. Here we found rapid improvements in tactile spatial acuity and changes in cortical processing for the left hand during cutaneous anesthesia of the right hand. The site-specific improvement in tactile spatial acuity may represent a behavioral compensatory gain.
Subject(s)
Evoked Potentials, Somatosensory/physiology , Sensory Thresholds/physiology , Touch/physiology , Action Potentials/physiology , Adolescent , Adult , Afferent Pathways/physiology , Anesthesia, Local/methods , Female , Foot/innervation , Foot/physiology , Hand/innervation , Hand/physiology , Humans , Male , Middle Aged , Nerve BlockABSTRACT
In order to expand the repertoire of somatosensory functions that can be effectively studied through functional MRI, we have developed a tactile stimulator which can deliver rich and varied combinations of stimulation that simulate natural tactile exploration. The system is computer controlled and compatible with an MRI environment. Complex aspects of somesthesis can thus be studied independent of confounds introduced by motor activity or problems with precision, accuracy or reproducibility of stimulus delivery.
Subject(s)
Computing Methodologies , Magnetic Resonance Imaging , Somatosensory Cortex/blood supply , Somatosensory Cortex/physiology , Touch/physiology , Brain Mapping , Humans , Oxygen/blood , Physical Stimulation/instrumentation , Physical Stimulation/methods , Reaction Time/physiology , User-Computer InterfaceSubject(s)
Causalgia/physiopathology , Hand/physiopathology , Motor Cortex/physiopathology , Nerve Block/methods , Neuronal Plasticity/physiology , Action Potentials/drug effects , Action Potentials/radiation effects , Afferent Pathways/drug effects , Afferent Pathways/physiopathology , Electric Stimulation , Evoked Potentials, Motor/drug effects , Functional Laterality , GABA Modulators/pharmacology , Hand/radiation effects , Humans , Lorazepam/pharmacology , Magnetics , Muscle, Skeletal/drug effects , Muscle, Skeletal/physiopathology , Neural Inhibition/physiology , Neural Inhibition/radiation effects , Neuronal Plasticity/drug effects , Neuronal Plasticity/radiation effects , Orientation , Scalp , Somatosensory Cortex/drug effects , Somatosensory Cortex/physiopathology , Somatosensory Cortex/radiation effects , Time Factors , Transcutaneous Electric Nerve StimulationABSTRACT
Improved diagnosis and treatment of traumatic brain injury (TBI) and posttraumatic stress disorder (PTSD) are needed for our military and veterans, their families, and society at large. Advances in brain imaging offer important biomarkers of structural, functional, and metabolic information concerning the brain. This article reviews the application of various imaging techniques to the clinical problems of TBI and PTSD. For TBI, we focus on findings and advances in neuroimaging that hold promise for better detection, characterization, and monitoring of objective brain changes in symptomatic patients with combat-related, closed-head brain injuries not readily apparent by standard computed tomography or conventional magnetic resonance imaging techniques.
Subject(s)
Brain Injuries/diagnosis , Stress Disorders, Post-Traumatic/diagnosis , Blast Injuries/diagnosis , Blast Injuries/pathology , Brain Injuries/pathology , Diffusion Tensor Imaging , Humans , Magnetic Resonance Imaging , Magnetic Resonance Spectroscopy , Positron-Emission Tomography , Stress Disorders, Post-Traumatic/pathologyABSTRACT
To elucidate the neural basis of the recognition of tactile form and location, we used functional MRI while subjects discriminated gratings delivered to the fingertip of either the right or left hand. Subjects were required to selectively attend to either grating orientation or grating location under identical stimulus conditions. Independent of the hand that was stimulated, grating orientation discrimination selectively activated the left intraparietal sulcus, whereas grating location discrimination selectively activated the right temporoparietal junction. Hence, hemispheric dominance appears to be an organizing principle for cortical processing of tactile form and location.