Search results for "Senso"
showing 10 items of 4750 documents
Subcortical somatosensory evoked potentials after median nerve stimulation in children.
2000
We report our normative data of subcortical somatosensory evoked potentials (SEPs) after median nerve stimulation from a group of 55 children 4–15 years of age and 18 young adults 18–29 years of age. We recorded near-field potentials from the brachial plexus, the cervical cord and the somatosensory cortex. The far-field potentials P13, P14 and N18 from the brainstem were recorded from the scalp electrodes, when a non-cephalic reference at the contralateral Erb's point or an ear reference was used. The N9 (brachial plexus), N13a (dorsal horn), P13 (caudal medulla oblongata), N18 (medulla oblongata) and N20 (somatosensory cortex) were present in all subjects. The N13b (dorsal column near the …
Abnormal Somatosensory Evoked Potentials Indicate Compressive Cervical Myelopathy in Mucopolysaccharidoses
2000
Compressive myelopathy at the cranio-cervical junction is a complication of mucopolysaccharidoses (MPS). To detect cervical myelopathy we recorded median and posterior tibial nerve SEPs in 15 patients aged 2.4 - 33.4 years (median 8.8 years) with MPS I-S (n = 3), MPS IVA (n = 8) and MPS VI (n = 4). In addition to the cortical waveforms we recorded the subcortical median nerve SEPs N13b and P13 generated near the cranio-cervical junction and the lemniscal P30 after posterior tibial nerve stimulation. MRI studies in 13 subjects revealed spinal cord compression at the cranio-cervical junction in 10 patients; 5 patients had an increased signal intensity on the T2-weighted initial MRI indicating…
Determining the Corticospinal Responses to Single Bouts of Skill and Strength Training
2019
Mason, J, Frazer, AK, Jaberzadeh, S, Ahtiainen, JP, Avela, J, Rantalainen, T, Leung, M, and Kidgell, DJ. Determining the corticospinal responses to single bouts of skill and strength training. J Strength Cond Res 33(9): 2299-2307, 2019-Neuroplastic changes in the primary motor cortex accompany performance improvements following motor practice. Recent evidence suggests that the corticospinal responses to strength and skill training are similar, following both a single session and repeated bouts of training, promoting discussion that strength training is a form of motor learning. However, these findings are limited by the lack of a light-load strength training group. Therefore, the aim of the…
Human eyes do not need monochromatic aberrations for dynamic accommodation
2017
Purpose To determine if human accommodation uses the eye's own monochromatic aberrations to track dynamic accommodative stimuli. Methods Wavefront aberrations were measured while subjects monocularly viewed a monochromatic Maltese cross moving sinusoidally around 2D of accommodative demand with 1D amplitude at 0.2 Hz. The amplitude and phase (delay) of the accommodation response were compared to the actual vergence of the stimulus to obtain gain and temporal phase, calculated from wavefront aberrations recorded over time during experimental trials. The tested conditions were as follows: Correction of all the subject's aberrations except defocus (C); Correction of all the subject's aberratio…
Eye closure in darkness animates sensory systems.
2003
Single subject and group analyses (n = 12) showed that the eyes-open and eyes-closed states in complete darkness considerably and consistently differ in the patterns of associated brain activation in fMRI. During nonchanging external stimulation, ocular motor and attentional systems were activated when the eyes were open; the visual, somatosensory, vestibular, and auditory systems were activated when the eyes were closed. These data suggest that there are two different states of mental activity: with the eyes closed, an "interoceptive" state characterized by imagination and multisensory activity and with the eyes open, an "exteroceptive" state characterized by attention and ocular motor act…
Brainstem evoked potentials and magnetic resonance imaging abnormalities in differential diagnosis of intracranial hypotension.
2019
Summary Objective To compare brainstem acoustic evoked potentials (BAEP) and magnetic resonance imaging (MRI) in the differential diagnosis of intracranial hypotension (IH), Chiari malformation (CM) and sensorineural hearing loss (SNHL). Methods BAEP were recorded in 18 IH, 18 CM, 20 SNHL patients and 52 controls. MRI were acquired in all IH and CM patients. Results Abnormal BAEP were observed in 94% of IH patients, in 33% of CM and 70% of SNHL patients. After recovery from IH, BAEP abnormalities disappeared. Internal auditory canal (IAC) MRI abnormalities were described in 88% of IH patients. MRI signs of IH were observed in 33–78% in IH patients, but the most frequent MRI sign was 8th ner…
Specific forms of neural activity associated with tactile space awareness
2002
Left tactile extinction, in which a left tactile stimulus fails to access consciousness only when a right stimulus is presented simultaneously, offers a model for studying tactile awareness from its transitory absence. Pairs of transcranial magnetic stimuli (TMS) on the parietal cortex inhibit contralateral tactile perception when separated by an interval of 1 ms. We have applied this technique on the left parietal cortex of right brain damaged (RBD) patients and normal subjects and have shown a selective lack of paired TMS inhibitory effects on right tactile perception of patients during bimanual stimulation. TMS effects were normal during unimanual right stimulation. These results suggest…
fMRI signal increases and decreases in cortical areas during small-field optokinetic stimulation and central fixation
2001
Small-field optokinetic nystagmus (OKN) was performed in seven healthy volunteers in order to analyze the activation and deactivation patterns of visual motion, ocular motor, and multisensory vestibular cortex areas by means of fMRI during coherent visual motion stimulation. BOLD signal decreases (deactivations) were found in the first and second long insular gyri and retroinsular areas (the human homologue of the parietoinsular vestibular cortex and the visual posterior sylvian area in the monkey) of both hemispheres, extending into the transverse temporal gyrus and inferior-anterior parts of the superior temporal gyrus (BA 22), and the precentral gyri at two separate sites (BA 4 and 6). F…
Evidence for cortical visual substitution of chronic bilateral vestibular failure (an fMRI study).
2007
Bilateral vestibular failure (BVF) is a rare disorder of the labyrinth or the eighth cranial nerve which has various aetiologies. BVF patients suffer from unsteadiness of gait combined with blurred vision due to oscillopsia. Functional MRI (fMRI) in healthy subjects has shown that stimulation of the visual system induces an activation of the visual cortex and ocular motor areas bilaterally as well as simultaneous deactivations of multisensory vestibular cortex areas. Our question was whether the chronic absence of bilateral vestibular input (BVF) causes a plastic cortical reorganization of the above-described visual-vestibular interaction. We used fMRI to measure the differential effects of…
Position but not color deviants result in visual mismatch negativity in an active oddball task.
2009
Changes in the visual environment might be detected automatically. This function is provided by the sensory systems and showed, for instance, by the pop-out phenomenon. Automatic change detection is also observable within visual oddball paradigms, where rare changes are introduced in an irrelevant stimulus feature; the detection of deviant stimuli is accompanied by a negative component (so-called visual mismatch negativity) in the human event-related brain potential. In this study, the deviating stimulus feature was embedded in a task-relevant object presented in the focus of attention. With this, visual mismatch negativity was observable only with position deviants presented in the upper v…