Search results for " Brain function"
showing 10 items of 119 documents
Haptic information differentially interferes with visual analysis in reaching-grasping control and in perceptual processes.
1998
We used an interference paradigm in order to study integration between haptic and visual information in motor control and in perceptual analysis. Subjects either reached and grasped a visually presented sphere or matched its size with their left hand while manipulating with their right hand another sphere whose size could be smaller or greater. In four experiments haptic analysis of the manipulated sphere could be either automatically incorporated with or explicitly dissociated from visual analysis. In a fifth experiment reaching-grasping and matching were executed with the right hand, whereas manipulation was executed with the left hand. Manipulation with the right hand influenced finger s…
Impaired control of an action after supplementary motor area lesion: A case study
2000
The kinematics of the action formed by reaching-grasping an object and placing it on a second target was studied in a patient who suffered from an acute vascular left brain lesion, which affected the Supplementary Motor Area proper (SMA-proper) (Matelli M, Luppino G. Thalamic input to mesial and superior area 6 in the macaque monkey. Journal of Comparative Neurology 1996;372:59-87, Matelli M, Luppino G, Fogassi L, Rizzolatti G. Thalamic input to inferior area 6 and area 4 in the macaque monkey. Journal of Comparative Neurology 1989;280:468-488), and in five healthy control subjects. The reach kinematics of the controls was affected by the positions of both the reaching-grasping and the plac…
Interoceptive and multimodal functions of the operculo-insular cortex: tactile, nociceptive and vestibular representations.
2013
The operculo-insular cortex has been termed the 'homeostatic control center' or 'general magnitude estimator' of the human mind. In this study, somatosensory, nociceptive and caloric vestibular stimuli were applied to reveal, whether there are mainly common, or possibly specific regions activated by one modality alone and whether lateralization effects, time pattern differences or influences of the aversive nature of the stimuli could be observed. Activation of the dorsal posterior insula was caused by all stimuli alike thus terming this area multimodal. Early phases of the noxious heat and caloric vestibular stimulation led to responses in the anterior insula. Using conjunction analyses we…
ErbB4 genotype predicts left frontotemporal structural connectivity in human brain.
2008
Diminished left frontotemporal connectivity is among the most frequently reported findings in schizophrenia and there is evidence that altered neuronal myelination may in part account for this deficit. Several investigations have suggested that variations of the genes that encode the Neuregulin 1 (NRG1)-ErbB4 receptor complex are associated with schizophrenia illness. As NRG1--ErbB4 has been implicated in neuronal myelination, we investigated with diffusion tensor imaging (DTI) whether fractional anisotropy (FA)--a putative measure of neuronal myelination--is predicted by a risk haplotype of the ErbB4 gene. The effects of the ErbB4 genotype were investigated in healthy subjects (N=59; mean …
Abnormal motor asymmetry only during bimanual movement in schizophrenic patients compared with healthy subjects.
2003
In schizophrenia, research on motor asymmetry has focused on the direction and the degree of handedness using unimanual motor tests and tasks. However, typically both hands collaborate in the production of most manual movements. This study explored motor asymmetry exhibited during unimanual and bimanual tasks in schizophrenic and healthy subjects using a new experimental motor battery. Specifically, the authors investigated the motor indices of laterality during finger-tapping and hand-turning tasks in four unimanual and four bimanual conditions in 84 schizophrenic and 31 healthy subjects, all right-handed. The schizophrenic patients showed reduced motor asymmetries only during bimanual tap…
Reanimation of the Paralyzed Human Larynx With an Implantable Electrical Stimulation Device
2003
Objectives/Hypothesis Electrical stimulation of the posterior cricoarytenoid muscle, when paced with inspiration, offers a physiological approach to restore ventilation in bilateral laryngeal paralysis without any of the disadvantages associated with conventional treatment. Study Design A prospective study of six patients. Methods The patients were successfully implanted with an Itrel II stimulator (Medtronic, Inc). In postoperative sessions, stimulated vocal fold abduction, patient ventilation, and voice were assessed and compared with preoperative values. Results The optimum stimulus paradigm was a 1- to 2-second train of 1-millisecond pulses delivered at a frequency of 30 to 40 Hz and am…
S-Ketamine-Induced NMDA Receptor Blockade during Natural Speech Production and Its Implications for Formal Thought Disorder in Schizophrenia: A Pharm…
2017
Structural and functional changes in the lateral temporal language areas have been related to formal thought disorder (FTD) in schizophrenia. Continuous, natural speech production activates the right lateral temporal lobe in schizophrenia, as opposed to the left in healthy subjects. Positive and negative FTD can be elicited in healthy subjects by glutamatergic NMDA blockade with ketamine. It is unclear whether the glutamate system is related to the reversed hemispheric lateralization during speaking in patients. In a double-blind, crossover, placebo-controlled study, 15 healthy, male, right-handed volunteers overtly described 7 pictures for 3 min each while BOLD signal changes were acquired…
Anatomical correlates of visual and tactile extinction in humans: a clinical CT scan study.
1994
The anatomical correlates of tactile and visual extinction with double simultaneous stimulation were investigated in a series of 159 patients with right brain damage caused by stroke. Forty six patients showed extinction (22 tactile, 14 visual, 10 tactile and visual). Over 50% of the patients with extinction had deep lesions, which were found in about 25% of the patients with visuospatial neglect not associated with extinction. In the patients with extinction and cortico-subcortical damage the paraventricular occipital white matter and the dorsolateral frontal cortex were most often involved. By contrast, when neglect was also present, the lesions clustered in the inferior parietal lobule. …
Exploring the relationship between semantics and space
2009
The asymmetric distribution of human spatial attention has been repeatedly documented in both patients and healthy controls. Biases in the distribution of attention and/or in the mental representation of space may also affect some aspects of language processing. We investigated whether biases in attention and/or mental representation of space affect semantic representations. In particular, we investigated whether semantic judgments could be modulated by the location in space where the semantic information was presented and the role of the left and right parietal cortices in this task. Healthy subjects were presented with three pictures arranged horizontally (one middle and two outer picture…
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…