Failure to Replicate Evoked Potential Observations Suggesting Corpus Callosum Dysfunction in Schizophrenia

1983 ◽  
Vol 142 (5) ◽  
pp. 471-476 ◽  
Author(s):  
Charles Shagass ◽  
Richard C. Josiassen ◽  
Richard A. Roemer ◽  
John J. Straumanis ◽  
Stephen M. Slepner
Keyword(s):  
Corpus Callosum ◽  
Evoked Potential ◽  
Test Procedure ◽  
Conduction Time ◽  
Contralateral Hemisphere ◽  
Normal Controls

SummarySomatosensory potentials (SEPs) evoked by vibrotactile finger stimulation have been reported to be the same in both hemispheres in schizophrenics, whereas they are asymmetrical in normals, with the contralateral hemisphere leading the ipsilateral (Jones and Miller, 1981). These findings were taken to indicate that the corpus callosum is nonfunctional in schizophrenics. To attempt replication of these results, vibrotactile SEPs of 6 schizophrenics and 6 normal controls were recorded with both bipolar and monopolar derivations. Assymetrical bipolar SEPs were obtained in both schizophrenics and controls; previous observations of schizophrenic-control differences were not replicated. Acceptable evidence of ipsilateral early SEPs was not obtained; the test procedure seems inappropriate for measuring callosal conduction time.

Properties of area 17/18 border neurons contributing to the visual transcallosal pathway in the cat

1990 ◽  
Vol 5 (1) ◽  
pp. 83-98 ◽  
Author(s):  
M.E. McCourt ◽  
J. Thalluri ◽  
G.H. Henry
Keyword(s):  
Corpus Callosum ◽  
Distribution Curve ◽  
Ocular Dominance ◽  
Stereoscopic Vision ◽  
Synaptic Delay ◽  
Conduction Time ◽  
Area 17 ◽  
C Cells ◽  
Contralateral Hemisphere ◽  
Stimulating Electrodes

AbstractIn a series of physiological experiments, a total of 203 neurons at the Area 17/18 border were recorded with a callosal link either demonstrated by antidromic or transsynaptic activation from stimulating electrodes located in the homotopic contralateral hemisphere (CH), or in the splenial segment of the corpus callosum (CC). Forty-four percent of the transcallosal cells could also be driven from stimulating electrodes in or just above the lateral geniculate nucleus (OR1). The majority (69%) of transcallosal neurons were classifiable as belonging to the complex family (B and C cells) and most of these were found in the supragranular laminae and in lamina 4A. The ocular dominance distribution of transcallosal cells was trimodal, consisting of roughly equal numbers of monocularly dominated and binocularly balanced neurons. Estimates of conduction time and synaptic delay were obtained for neurons driven from CH, CC, and from OR1, and in most instances the response latency was short enough to suggest a monosynaptic input from either the ipsi- or contra-lateral hemisphere. The distribution of transcallosal conduction times showed that S cells, as a class, had significantly faster conduction than cells of the complex family but otherwise there was no obvious signs of multimodality in the distribution curve. An analysis of the synaptic delays in transcallosal activation produced a mean of 0.6 to 0.7 ms but some were too short to be consistent with a transsynaptic drive, suggesting that some cells with an antidromic drive may have been included in the transsynaptic category. Results are interpreted in terms of the contribution made by the corpus callosum to stereoscopic vision.

Interhemispheric Transmission of Visuomotor Information in Humans: fMRI Evidence

2002 ◽  
Vol 88 (2) ◽  
pp. 1051-1058 ◽  
Author(s):  
M. Tettamanti ◽  
E. Paulesu ◽  
P. Scifo ◽  
A. Maravita ◽  
F. Fazio ◽  
...  
Keyword(s):  
Corpus Callosum ◽  
Visual Information ◽  
Human Subjects ◽  
Conduction Time ◽  
Clear Cut ◽  
Cortical Areas ◽  
Poffenberger Paradigm ◽  
Interhemispheric Transmission ◽  
Hemispheric Activation ◽  
Normal Human

Normal human subjects underwent functional magnetic resonance imaging (fMRI) while performing a simple visual manual reaction-time (RT) task with lateralized brief stimuli, the so-called Poffenberger's paradigm. This paradigm was employed to measure interhemispheric transmission (IT) time by subtracting mean RT for the uncrossed hemifield-hand conditions, that is, those conditions not requiring an IT, from the crossed hemifield-hand conditions, that is, those conditions requiring an IT to relay visual information from the hemisphere of entry to the hemisphere subserving the response. The obtained difference is widely believed to reflect callosal conduction time, but so far there is no direct physiological evidence in humans. The aim of our experiment was twofold: first, to test the hypothesis that IT of visuomotor information requires the corpus callosum and to identify the cortical areas specifically activated during IT. Second, we sought to discover whether IT occurs mainly at premotor or perceptual stages of information processing. We found significant activations in a number of frontal, parietal, and temporal cortical areas and in the genu of the corpus callosum. These activations were present only in the crossed conditions and therefore were specifically related to IT. No selective activation was present in the uncrossed conditions. The location of the activated callosal and cortical areas suggests that IT occurs mainly, but not exclusively, at premotor level. These results provide clear cut evidence in favor of the hypothesis that the crossed-uncrossed difference in the Poffenberger paradigm depends on IT rather than on a differential hemispheric activation.

scholarly journals Peculiarities of motor evoked potential in healthy children of different age

2019 ◽  
Vol 19 (4) ◽  
pp. 228-231
Author(s):  
Vladislav B. Voitenkov ◽  
N. V. Skripchenko ◽  
A. V. Klimkin ◽  
A. I. Aksenova
Keyword(s):  
Normative Data ◽  
Evoked Potential ◽  
Motor Evoked Potentials ◽  
Pediatric Population ◽  
Motor Evoked Potential ◽  
Conduction Time ◽  
Healthy Children ◽  
Abductor Hallucis ◽  
Abductor Pollicis Brevis ◽  
Pediatric Disorders

Aim of the work The implementation of the database for reference values of motor evoked potentials (MEP) in healthy children of different ages. Methods 95 healthy children were enrolled. Age ranged from 1 to 204 months. Three subgroups were established: children of 1-12 months (n=31, 18 males, 13 females), 12-144 months (n=27, 14 males, 13 females) and 144-204 (n=37, 20 males, 17 females) months. All children were healthy. Diagnostic transcranial magnetic stimulation (TMS) was performed in all patients. MEP shape, threshold, latency and amplitudes were recorded for hands (m. Abductor pollicis brevis) and legs (m. Abductor Hallucis). Central motor conduction time (CMCT) was calculated. Results. Along with age there was observed the elongation of MEP latency, gain in amplitudes and shape normalization. There were significant differences in the elongation of MEP latency between children aged of 1-12 months and children from two other subgroups (12-144 and 144-204 months). Conclusions. Our normative data can be usedfor comparative studies in the broad spectrum of pediatric disorders. Age restrictions have to be taken in a consideration when performing the TMS in pediatric population.

Vestibular Electrical Evoked Potential (VEEP) Findings in Normal Controls and in Patients with Vestibular Dysfunction (P02.251)

Neurology ◽  
2012 ◽  
Vol 78 (Meeting Abstracts 1) ◽  
pp. P02.251-P02.251
Author(s):  
B. Smith ◽  
M. Cevette ◽  
J. Stepanek ◽  
D. Cocco ◽  
G. Pradhan ◽  
...  
Keyword(s):  
Evoked Potential ◽  
Vestibular Dysfunction ◽  
Normal Controls

Motor threshold, motor evoked potential, central motor conduction time

2021 ◽  
Author(s):  
Sein H. Schmidt ◽  
Stephan A. Brandt
Keyword(s):  
Magnetic Stimulation ◽  
Evoked Potential ◽  
Motor Evoked Potentials ◽  
Motor Evoked Potential ◽  
Conduction Time ◽  
Optical Navigation ◽  
Motor Threshold ◽  
Pathological Conditions ◽  
Latency Variability ◽  
First Time

In this chapter, we survey parameters influencing the assessment of the size and latency of motor evoked potentials (MEP), in normal and pathological conditions, and methods to allow for a meaningful quantification of MEP characteristics. In line with the first edition of this textbook, we extensively discuss three established mechanisms of intrinsic physiological variance and collision techniques that aim to minimize their influence. For the first time, in line with the ever wider use of optical navigation and targeting systems in brain stimulation, we discuss novel methods to capture and minimize the influence of extrinsic biophysical variance. Together, following the rules laid out in this chapter, transcranial magnetic stimulation (TMS) can account for spinal and extrinsic biophysical variance to advance investigations of the central origins of MEP size and latency variability.

Visual-field map in the transcallosal sending zone of area 17 in the cat

1991 ◽  
Vol 7 (3) ◽  
pp. 201-219 ◽  
Author(s):  
B. R. Payne
Keyword(s):  
Visual Field ◽  
Horseradish Peroxidase ◽  
Corpus Callosum ◽  
Constant Width ◽  
Receptive Fields ◽  
Retrograde Transport ◽  
Area 17 ◽  
Horizontal Meridian ◽  
Contralateral Hemisphere ◽  
Opposite Hemisphere

AbstractThe representation of the visual field in the part of area 17 containing neurons that project axons across the corpus callosum to the contralateral hemisphere was defined in the cat. Of 1424 sites sampled along 77 electrode tracks, 768 proved to be in the callosal sending zone, which was identified by retrograde transport of horseradish peroxidase that had been deposited in the opposite hemisphere. The results show that the callosal sending zone has a fairly constant width of between 3 and 4 mm at most levels in area 17. However, the representation of the contralateral field at the different elevations of the visual field is not equal in this zone. The zone represents positions within 4 deg of the midline at the 0-deg horizontal meridian, and positions out to 15-deg azimuths in the upper hemifield and out to positions of 25-deg azimuth in the lower hemifield. The shape of the representation is approximately mirror-symmetric about the horizontal meridian, although there is a greater extent in the lower hemifield, which can be accounted for by the greater range of elevations (>60 deg) represented there compared with the upper hemifield (-40 deg). The representation in the sending zone of one hemisphere matches that present in the area 17/18 transition zone, which receives the bulk of transcallosal projections, in the opposite hemisphere. The observations on the sending zone show that callosal connections of area 17 are concerned with a vertical hour-glass-shaped region of the visual field centered on the midline. The observations suggest that in addition to interactions between neurons concerned with positions immediately adjacent to the midline, there are positions, especially high and low in the visual field, where interactions can occur between neurons that have receptive fields displaced some distance from the midline.

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