Stable Abnormalities in the Lateralisation of early Cortical Somatosensory Evoked Potentials in Schizophrenic Patients

1985 ◽  
Vol 146 (6) ◽  
pp. 585-593 ◽  
Author(s):  
J. E. Cooper ◽  
H. Andrews ◽  
C. Barber
Keyword(s):  
Evoked Potentials ◽  
Somatosensory Evoked Potentials ◽  
Tactile Stimulus ◽  
The Other ◽  
Technical Problems ◽  
Affective Illness ◽  
Schizophrenic Patients ◽  
Evoked Cortical Potentials ◽  
Stimulation Of ◽  
Cortical Potentials

SummaryDuring the investigation of somatosensory evoked cortical potentials arising from a complex vibro-tactile stimulus to the forefingers, an abnormal lack of lateralisation of response was found in 10 out of 21 schizophrenic patients. Eight patients with severe affective illness all had the expected degree of lateralisation of cortical potentials, as did 12 out of 15 normals. Three normals and 3 schizophrenic patients had a loss of lateralisation of the evoked response on stimulation of one hand but a normal lateralisation on stimulation of the other. The considerable technical problems of this and related techniques are discussed, but it is suggested that further exploration of this technique is justified. At this stage, no conclusion can be drawn about the cause of the abnormalities.

Localization of Stereotactic Targets by Microrecording of Thalamic Somatosensory Evoked Potentials

Neurosurgery ◽  
1991 ◽  
Vol 28 (2) ◽  
pp. 223-230 ◽  
Author(s):  
Fumio Shima ◽  
Takato Morioka ◽  
Shozo Tobimatsu ◽  
Omiros Kavaklis ◽  
Motohiro Kato ◽  
...  
Keyword(s):  
Evoked Potentials ◽  
Median Nerve ◽  
Somatosensory Evoked Potentials ◽  
Practical Method ◽  
The Other ◽  
Basal Region ◽  
Thalamic Nuclei ◽  
Median Nerve Stimulation ◽  
Lower Amplitude ◽  
Stimulation Of

Abstract To improve the localization of stereotactic targets, somatosensory evoked potentials (SEPs) were recorded from the thalamus and subthalamic area using a specially designed semimicroelectrode in 61 patients and a conventional “macroclectrode” in 17 patients. By means of the semimicroelectrode, median nerve stimulation evoked two distinct SEPs, consisting of a diphasic wave with a huge positivity restricted to the nucleus ventrocaudalis (Vc) and a triphasic wave of lower amplitude with a major negativity in the ventral part of the nucleus ventrointermedius (Vim) and nucleus ventrooralis posterior (Vop) as well as the subthalamic lemniscal pathway. The Vim-Vc junction could thus be clearly delineated by an abrupt transition of SEPs from one type to the other with a precision of 1 mm. The parvicellular part of the Vc (Vcpc). situated in its basal region, was distinguishable from the Vc proper by a significant reduction of the positivity elicited by stimulation of the median nerve and by a rapid growth of a diphasic SEPs to stimulation of the posterior tibial nerve. In the other thalamic nuclei, stimulation of the median nerve elicited triphasic SEPs of a very small amplitude, suggesting a volume conduction current from the lemniscal pathway. With the macroclectrode, the positivity in the Vc was sensitive to electrode manipulation and the thalamic nuclei could not be distinctly outlined. SEP monitoring using the semimicroelectrode significantly improved the precision of target localization, which allowed minimizing of the volume of the therapeutic lesion without losing surgical effectiveness, while avoiding complications associated with increased penetration of the coagulating electrode. It is suggested that recording serial thalamic SEPs with the semimicroelectrode is a practical method to refine stereotactic targets in the thalamus.

Monocular and Binocular Visual Evoked Potentials before and after Cataract Surgery

1979 ◽  
Vol 49 (3) ◽  
pp. 699-704
Author(s):  
J. L. Andreassi ◽  
S. S. Zalkind ◽  
J. A. Gallichio ◽  
N. E. Young
Keyword(s):  
Evoked Potentials ◽  
Cataract Surgery ◽  
Visual Evoked Potentials ◽  
Mature Cataract ◽  
Before And After ◽  
Evoked Cortical Potentials ◽  
Stimulation Of ◽  
Visual Evoked ◽  
Cortical Potentials

Visual evoked cortical potentials (VEPs) were recorded from an individual with a mature cataract in one eye. Stimulation was both monocular and binocular and VEPs were obtained from three occipital scalp sites. Comparisons of recordings taken prior to cataract removal and after removal showed a dramatic increase in amplitude of potentials derived through stimulation of the affected eye. Slight differences in hemispheric amplitude prior to surgery suggest a greater degree of opacity in one portion of the affected lens.

Effect of Serum from Schizophrenics on Evoked Cortical Potentials in the Rat

1965 ◽  
Vol 111 (473) ◽  
pp. 339-344 ◽  
Author(s):  
D. Stenhouse ◽  
R. Antebi ◽  
E. M. A. Dear ◽  
R. N. Herrington ◽  
C. McCance
Keyword(s):  
Cerebral Cortex ◽  
Rat Cerebral Cortex ◽  
Sensory Area ◽  
Normal Individuals ◽  
Schizophrenic Patients ◽  
Evoked Cortical Potentials ◽  
Stimulation Of ◽  
Cortical Potentials

German (1961, 1963) reported that serum from schizophrenic patients, in contrast to that from normal individuals and non-schizophrenic patients, when applied topically to the rat cerebral cortex, increased the amplitude of potentials evoked in the somato-sensory area by stimulation of the contralateral forepaw. Furthermore, similar changes were found when urine extracts were tested in the same manner (German and Kemali, 1963; Kemali, 1964).

Upper airway afferents are sufficient to evoke the early components of respiratory-related cortical potentials in humans

2004 ◽  
Vol 97 (5) ◽  
pp. 1874-1879 ◽  
Author(s):  
Christine Donzel-Raynaud ◽  
Christian Straus ◽  
Michela Bezzi ◽  
Stefania Redolfi ◽  
Mathieu Raux ◽  
...  
Keyword(s):  
Evoked Potentials ◽  
Cognitive Processing ◽  
Respiratory System ◽  
Somatosensory Evoked Potentials ◽  
Upper Airway ◽  
Cortical Activity ◽  
Stimulus Detection ◽  
Evoked Cortical Potentials ◽  
Cortical Potentials

Repeated inspiratory occlusions in humans elicit respiratory-related cortical potentials, the respiratory counterpart of somatosensory-evoked potentials. These potentials comprise early components (stimulus detection) and late components (cognitive processing). They are considered as the summation of several afferent activities from various part of the respiratory system. This study assesses the role of the upper airway as a determinant of the early and late components of the potentials, taking advantage of the presence of a tracheotomy in patients totally or partially deafferented. Eight patients who could breathe either through the mouth or through a tracheotomy orifice (whole upper airway bypassed) were studied (4 quadriplegic patients with phrenic pacing, 4 patients with various sources of inspiratory pump dysfunction). Respiratory-related evoked potentials were recorded in CZ-C3 and CZ-C4. They were consistently present after mouth occlusions, with a first positive P1 and a first negative N1 components of normal latencies (P1: 40.4 ± 6.1 ms in CZ-C3 and 47.6 ± 7.6 ms in CZ-C4; N1: 84.4 ± 27.1 ms in CZ-C3 and 90.2 ± 17.4 ms in CZ-C4) and amplitudes. Tracheal occlusions did not evoke any cortical activity. Therefore, in patients with inspiratory pump dysfunction, the activation of upper airway afferents is sufficient to produce the early components of the respiratory-related evoked cortical potentials. Per contra, in this setting, pulmonary afferents do not suffice to evoke these components.

Human proprioceptive adaptations during states of height-induced fear and anxiety

2011 ◽  
Vol 106 (6) ◽  
pp. 3082-3090 ◽  
Author(s):  
Justin R. Davis ◽  
Brian C. Horslen ◽  
Kei Nishikawa ◽  
Katie Fukushima ◽  
Romeo Chua ◽  
...  
Keyword(s):  
Evoked Potentials ◽  
Somatosensory Cortex ◽  
Somatosensory Evoked Potentials ◽  
Emotional Experience ◽  
Afferent Feedback ◽  
Triceps Surae ◽  
Feedback Gain ◽  
Postural Threat ◽  
Fear And Anxiety ◽  
Stimulation Of

Clinical and experimental research has demonstrated that the emotional experience of fear and anxiety impairs postural stability in humans. The current study investigated whether changes in fear and anxiety can also modulate spinal stretch reflexes and the gain of afferent inputs to the primary somatosensory cortex. To do so, two separate experiments were performed on two separate groups of participants while they stood under conditions of low and high postural threat. In experiment 1, the proprioceptive system was probed using phasic mechanical stimulation of the Achilles tendon while simultaneously recording the ensuing tendon reflexes in the soleus muscle and cortical-evoked potentials over the somatosensory cortex during low and high threat conditions. In experiment 2, phasic electrical stimulation of the tibial nerve was used to examine the effect of postural threat on somatosensory evoked potentials. Results from experiment 1 demonstrated that soleus tendon reflex excitability was facilitated during states of height-induced fear and anxiety while the magnitude of the tendon-tap-evoked cortical potential was not significantly different between threat conditions. Results from experiment 2 demonstrated that the amplitudes of somatosensory-evoked potentials were also unchanged between threat conditions. The results support the hypothesis that muscle spindle sensitivity in the triceps surae muscles may be facilitated when humans stand under conditions of elevated postural threat, although the presumed increase in spindle sensitivity does not result in higher afferent feedback gain at the level of the somatosensory cortex.

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