The long-latency component of cerebral evoked potentials in anesthetized cats

1986 ◽  
Vol 65 (3) ◽  
pp. 392-397 ◽  
Author(s):  
Kyu Ho Lee ◽  
Jun Kim ◽  
Jin Mo Chung
Keyword(s):  
Evoked Potentials ◽  
Sural Nerve ◽  
Evoked Potential ◽  
Afferent Input ◽  
Late Component ◽  
Content Type ◽  
C Fibers ◽  
Long Latency ◽  
Fine Print ◽  
Stimulation Of

✓ A late component of the cortical evoked potential elicited by somatosensory afferent input was studied in cats anesthetized with α-chloralose. Cortical evoked potentials were recorded from the somatosensory-motor cortex during stimulation of the sural nerve with graded intensities. The stimulus intensity was adjusted to activate Aαβ fibers only, then both Aαβ and Aδ fibers, and both A and C fibers, as judged by afferent volleys monitored from the sural nerve proximal to the stimulating site. In addition to early components reported previously, a very late component was identified at a latency of 400 to 600 msec following stimulation of the sural nerve with intensities above threshold for Aδ fibers. A further increase in stimulation intensity to include activation of C fibers did not reveal any more components. This late component was depressed by a systemic intravenous injection of morphine (2 mg/kg), and intravenous naloxone (0.1 mg/kg) reversed the effect of morphine. The late component of the evoked potential could also be recorded from subcortical tissue after decortication of the sensorimotor cortex. From these results, it appears that a very late component of the cortical evoked potential can be recorded from cats anesthetized with α-chloralose. The late component is evoked by activation of peripheral Aδ fibers. Furthermore, its morphine sensitivity suggests that this component may be elicited by nociceptive afferent fibers. If further investigations prove this, the late component, which is analogous to human long-latency potentials, could be used in an experimental model for pain research.

Neurophysiological effects of dorsal column stimulation in man and monkey

1974 ◽  
Vol 41 (2) ◽  
pp. 217-223 ◽  
Author(s):  
Sanford J. Larson ◽  
Anthony Sances ◽  
Donald H. Riegel ◽  
Glenn A. Meyer ◽  
Donald E. Dallmann ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Evoked Potentials ◽  
Evoked Potential ◽  
Intractable Pain ◽  
Current Application ◽  
Content Type ◽  
Bipolar Recording ◽  
Stimulating Electrodes ◽  
Recording Electrodes ◽  
Fine Print

✓ In 18 patients with cancer and intractable pain, capacitatively coupled pulses of 0.25 msec duration were delivered transcutaneously at 100 Hz to sets of five in-line electrodes implanted subdurally over the dorsal columns. Averaged somatosensory-evoked potentials were recorded from scalp electrodes before, during, and after application of current. All but one patient experienced relief of pain during stimulation, persisting for as long as several hours afterward. Eleven patients developed hyperactive deep reflexes, pathological reflexes, and decreased perception of joint rotation, pain, and touch below the level of current application. Somatosensory-evoked potential amplitudes were markedly reduced. All neurological findings returned to control values within 1 hour after each of repeated applications of current. Histological examination of spinal cord sections from four cancer patients showed no changes secondary to long-term current application. Similar currents were applied to the spinal cord of 15 monkeys with chronically implanted bipolar recording or stimulating electrodes over the lower, middle, and upper thoracic cord, in nucleus ventralis posterior lateralis (VPL), and over the sensory motor cortex (SMC). With application of current, the responses in VPL and SMC to peripheral stimulation were abolished. Evoked potential responses were abolished between bipolar stimulating electrodes and bipolar recording electrodes separated by the five in-line electrodes used to supply the 100 Hz current. However, when both stimulating and recording electrodes were either above or below the five in-line electrode set, evoked responses were unaffected. The findings indicate that applied currents blocked neuronal transmission by producing local changes in the cord. The prolonged alteration of cerebral evoked potentials and relief of pain, however, could also be related to involvement of supraspinal neurons.

Noninvasive localization of brain-stem lesions in the cat with multimodality evoked potentials

1981 ◽  
Vol 54 (6) ◽  
pp. 740-750 ◽  
Author(s):  
Richard P. Greenberg ◽  
Donald M. Stablein ◽  
Donald P. Becker
Keyword(s):  
Evoked Potentials ◽  
Brain Stem ◽  
Evoked Potential ◽  
Animal Experiments ◽  
Content Type ◽  
Central Nervous System Dysfunction ◽  
Multimodality Evoked Potentials ◽  
Stem Lesions ◽  
The Brain ◽  
Fine Print

✓ Multimodality evoked potential (MEP) data from over 300 comatose head-injured patients suggest that central nervous system dysfunction of the brain stem and/or hemispheres can be localized with this noninvasive neuroelectric technique. Based on this work, decerebrate motor posturing and prolonged coma are not associated with brain-stem dysfunction but rather with dysfunction of the hemispheres, while absent pupillary and oculocephalic responses are correlated with brain-stem dysfunction alone. However, the accuracy with which MEP data localized human brain-stem or hemispheric dysfunction could not be confirmed by pathological correlation because of low mortality and the small number of autopsies obtained in the patients who died. Therefore, this study was undertaken in an animal model of brain-stem lesion. Complete brain-stem transections were made at the cervicomedullary junction, the medulla just caudal to the eighth nerve, and at the intercollicular region. All cortical visual evoked potential (VEP) peaks were reduced in amplitude and delayed by each of the brain-stem transections, but none of the peaks was abolished. In spite of brain-stem transection, VEP's can be used to gain information about hemispheric function. Somatosensory (SEP) and auditory cortically generated evoked potentials (AEP) were abolished by these brain-stem transections, but early-latency brain-stem SEP and AEP data could accurately localize specific areas of brain-stem dysfunction caused by the lesions. Observations made on human MEP data seem to be confirmed by these animal experiments. Correlations between human and cat MEP data are discussed.

Evoked potentials from direct cerebellar stimulation for monitoring of the rodent spinal cord

1992 ◽  
Vol 76 (2) ◽  
pp. 280-291 ◽  
Author(s):  
R. John Hurlbert ◽  
Charles H. Tator ◽  
Michael G. Fehlings ◽  
Greg Niznik ◽  
R. Dean Linden
Keyword(s):  
Spinal Cord ◽  
Evoked Potentials ◽  
Posterior Fossa ◽  
Evoked Potential ◽  
Thoracic Spinal Cord ◽  
Content Type ◽  
Thoracic Spinal ◽  
Ventral Funiculus ◽  
Fine Print ◽  
Cerebellar Stimulation

✓ Although the assessment of spinal cord function by electrophysiological techniques has become important in both clinical and research environments, current monitoring methods do not completely evaluate all tracts in the spinal cord. Somatosensory and motor evoked potentials primarily reflect dorsal column and pyramidal tract integrity, respectively, but do not directly assess the status of the ventral funiculus. The present study was undertaken to evaluate the use of evoked potentials, elicited by direct cerebellar stimulation, in monitoring the ventral component of the rodent spinal cord. Twenty-nine rats underwent epidural anodal stimulation directly over the cerebellar cortex, with recording of evoked responses from the lower thoracic spinal cord, both sciatic nerves, and/or both gastrocnemius muscles. Stimulation parameters were varied to establish normative characteristics. The pathways conducting these “posterior fossa evoked potentials” were determined after creation of various lesions of the cervical spinal cord. The evoked potential recorded from the thoracic spinal cord consisted of five positive (P1 to P5) and five negative (N1 to N5) peaks. The average conduction velocity (± standard deviation) of the earliest wave (P1) was 53 ± 4 m/sec, with a latency of 1.24 ± 0.10 msec. The other components followed within 4 msec from stimulus onset. Unilateral cerebellar stimulation resulted in bilateral sciatic nerve and gastrocnemius muscle responses; there were no significant differences (p > 0.05) in the thresholds, amplitudes, or latencies of these responses elicited by right- versus left-sided stimulation. Recordings performed following creation of selective lesions of the cervical cord indicated that the thoracic response was carried primarily in the ventral funiculus while the sciatic and gastrocnemius responses were mediated through the dorsal half of the spinal cord. It is concluded that the posterior fossa evoked potential has research value as a method of monitoring pathways within the ventral spinal cord of the rat, and should be useful in the study of spinal cord injury.

Origin of surface potentials evoked by electrical stimulation of oculomotor nerves: are they related to electrooculographic or electromyographic events?

2002 ◽  
Vol 97 (4) ◽  
pp. 941-944 ◽  
Author(s):  
Tatsuya Sasaki ◽  
Kyouichi Suzuki ◽  
Masato Matsumoto ◽  
Taku Sato ◽  
Namio Kodama ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
Evoked Potentials ◽  
Eye Movement ◽  
Extraocular Muscles ◽  
Oculomotor Nerve ◽  
Content Type ◽  
Surface Electrodes ◽  
Oculomotor Nerves ◽  
Fine Print ◽  
Stimulation Of

Object. Evoked potentials elicited by electrical stimulation of the oculomotor nerve and recorded from surface electrodes placed on the skin around the eyeball reportedly originate in the eye and are represented on electrooculograms. Because evoked potentials recorded from surface electrodes are extremely similar to those of extraocular muscles, which are represented on electromyograms, the authors investigated the true origin of these potentials. Methods. Evoked potentials elicited by electrical stimulation of the canine oculomotor nerve were recorded from surface electrodes placed on the skin around the eyeball. A thread sutured to the center of the cornea was pulled and the potentials that were evoked during the resultant eye movement were recorded. These potentials were confirmed to originate in the eye and to be represented on electrooculograms because their waveforms were unaffected by the administration of muscle relaxant. To eliminate the influence of this source, the retina, a main origin of standing potentials of the eyeball, was removed. This resulted in the disappearance of electrooculography (EOG) waves elicited by eye movement. Surface potentials elicited by oculomotor nerve stimulation were the same before and after removal of the retina. Again the oculomotor nerve was electrically stimulated and electromyography (EMG) response of the extraocular muscles was recorded at the same time that potentials were recorded from the surface electrodes. In their peak latencies, amplitudes, and waveforms, the evoked potentials obtained from surface electrodes were almost identical to EMG responses of extraocular muscles. Conclusions. Evoked potentials elicited by electrical stimulation of the oculomotor nerves and obtained from surface electrodes originated from EMG responses of extraocular muscles. These evoked potentials do not derive from the eye.

Evoked potentials in the clinical neurosciences

1982 ◽  
Vol 56 (1) ◽  
pp. 1-18 ◽  
Author(s):  
Richard P. Greenberg ◽  
Thomas B. Ducker
Keyword(s):  
Nervous System ◽  
Evoked Potentials ◽  
Clinical Data ◽  
Evoked Potential ◽  
Critical Value ◽  
Clinical Applications ◽  
Content Type ◽  
Invasive Techniques ◽  
Fine Print

✓ The use of evoked potentials for the evaluation of disorders of the nervous system has become a most valuable aid to the neurosurgeon and neurologist, often providing information of critical value without recourse to invasive techniques. In order to employ these techniques, it is helpful to understand the principles of evoked potential electrogenesis and the methodology used for analysis of evoked potential clinical data. This article is aimed at providing the clinical neurosurgeon with this type of information and with a review of current clinical applications in this rapidly developing field.

Olfactory evoked potentials: experimental and clinical studies

1996 ◽  
Vol 85 (6) ◽  
pp. 1122-1126 ◽  
Author(s):  
Masanori Sato ◽  
Namio Kodama ◽  
Tatsuya Sasaki ◽  
Mamoru Ohta
Keyword(s):  
Electrical Stimulation ◽  
Evoked Potentials ◽  
Olfactory System ◽  
Olfactory Nerve ◽  
Olfactory Mucosa ◽  
Content Type ◽  
Negative Peak ◽  
Olfactory Tract ◽  
Fine Print ◽  
Stimulation Of

✓ Olfactory evoked potentials (OEPs), obtained by electrical stimulation of the olfactory mucosa, were recorded in dogs and humans to develop an objective method for evaluating olfactory functions. In dogs, OEPs were recorded from the olfactory tract and the scalp. The latency of the first negative peak was approximately 40 msec. A response was not obtained after stimulation of the nasal mucosa and disappeared after sectioning of the olfactory nerve. With increasing frequencies of repetitive stimulation, the amplitude was reduced, suggesting that the response was synaptically mediated. These results demonstrate that evoked potentials from the olfactory tract and the scalp following electrical stimulation of the olfactory mucosa originate specifically from the olfactory system. In humans, a stimulating electrode with a soft catheter was fixed on the olfactory mucosa. The OEPs from the olfactory tract, recorded with a negative peak of approximately 27 msec, had similar characteristics to OEPs found in dogs. The OEPs from the olfactory tract in humans also originate specifically from the olfactory system. The authors postulate that OEPs obtained by electrical stimulation of the olfactory mucosa may prove useful for intraoperative monitoring of olfactory functions.

Geophysical Variables and Behavior: XL. Electromagnetic Stimulation of ‘Extrasensory’ Evoked Potentials

1987 ◽  
Vol 64 (3) ◽  
pp. 1015-1018
Author(s):  
Robert G. Kunzendorf
Keyword(s):  
Evoked Potentials ◽  
Signal Detection ◽  
Evoked Potential ◽  
Cortical Response ◽  
Auditory Evoked Potential ◽  
Electromagnetic Stimulation ◽  
Long Latency ◽  
Psychophysiological Testing ◽  
And Behavior ◽  
Stimulation Of

In psychophysiological testing with 10 subjects, an electromagnetic stimulus evoked a long-latency cortical response similar to the long-latency component (P300) of an auditory evoked potential. On a signal-detection test, the electromagnet elicited no conscious sensations.

Localization of the face area of human sensorimotor cortex by intracranial recording of somatosensory evoked potentials

1993 ◽  
Vol 79 (6) ◽  
pp. 874-884 ◽  
Author(s):  
Gregory McCarthy ◽  
Truett Allison ◽  
Dennis D. Spencer
Keyword(s):  
Evoked Potentials ◽  
Median Nerve ◽  
Somatosensory Cortex ◽  
Somatosensory Evoked Potentials ◽  
Content Type ◽  
Face Area ◽  
The Face ◽  
Hand Area ◽  
Fine Print ◽  
Stimulation Of

✓ The authors describe a method of localizing the sensory and motor peri-rolandic cortex representing the face and intraoral structures. Somatosensory evoked potentials (SEP's) to stimulation of the chin, lips, tongue, and palate were recorded in 37 patients studied intraoperatively under general anesthesia or following chronic implantation of cortical surface electrodes. Localization by trigeminal SEP recording was validated by SEP localization of the hand area with median nerve stimulation, and by cortical stimulation of the hand and face areas. The following conclusions were drawn regarding the implementation of face area localization: 1) in general agreement with the results of cortical stimulation in humans and single-unit recordings in monkeys, there is a medial-to-lateral representation in somatosensory cortex of the hand, chin, upper lip, lower lip, tongue, and palate; 2) the chin and lip representations overlap, are adjacent to the hand area, and provide little additional localizing information if the hand area has been identified; 3) stimulation of the tongue and palate evokes reliable, large-amplitude SEP's useful for localization; 4) palatal SEP's allow localization near the sylvian sulcus; 5) for any type of trigeminal stimulation, the largest SEP's are recorded from the somatosensory cortex and provide the most consistent criterion for its identification; and 6) polarity inversion of potentials across the sulcus (a reliable localizing criterion for median nerve SEP's) is a less reliable criterion for trigeminal SEP's.

Experimental study of medullary trigeminal evoked potentials: development of a new method of intraoperative monitoring of the medulla oblongata

2000 ◽  
Vol 93 (1) ◽  
pp. 68-76 ◽  
Author(s):  
Tomoyoshi Oikawa ◽  
Masato Matsumoto ◽  
Tatsuya Sasaki ◽  
Namio Kodama
Keyword(s):  
Electrical Stimulation ◽  
Evoked Potentials ◽  
Medulla Oblongata ◽  
Intraoperative Monitoring ◽  
New Method ◽  
Infraorbital Nerve ◽  
Content Type ◽  
Lateral Portion ◽  
Fine Print ◽  
Stimulation Of

Object. The goal of this study was to develop a new method of intraoperative monitoring of functions located in the lateral portion of the medulla oblongata. Based on the fact that the spinal trigeminal nucleus and tract are located in the lateral portion of the medulla oblongata, the authors intended to investigate the efficacy of trigeminal evoked potentials (TEPs) in intraoperative monitoring for assessing functions of the medulla oblongata.Methods. Trigeminal evoked potentials induced by electrical stimulation of the infraorbital nerve were recorded from the dorsolateral portion of the medulla oblongata (M-TEP) and the cerebral sensory cortex (C-TEP) in dogs. When the lateral one-sixth portion of the medulla was cut, the amplitude of the M-TEP decreased markedly, but the amplitude of the C-TEP and the somatosensory evoked potential (SSEP) did not decrease. When the lateral one-third portion of the medulla was cut, the amplitude of the SSEP decreased, but that of the C-TEP showed no change. When the medulla was retracted, the amplitude of the M-TEP was more sensitive than that of SSEP. Pathological examinations revealed that retraction force less than 10 g and a reduction in the amplitude of the M-TEP less than 50% were safe.Conclusions. These results suggest that M-TEPs obtained from the dorsolateral portion of the medulla oblongata by electrical stimulation of the trigeminal nerve are clinically applicable as a new means of intraoperative monitoring of the functions of the medulla oblongata.

Electrospinogram and spinal and cortical evoked potentials in experimental spinal cord trauma

1975 ◽  
Vol 43 (6) ◽  
pp. 737-741 ◽  
Author(s):  
Glenn Morrison ◽  
Ronald J. Lorig ◽  
Jerald S. Brodkey ◽  
Frank E. Nulsen
Keyword(s):  
Spinal Cord ◽  
Evoked Potentials ◽  
Spinal Cord Compression ◽  
Evoked Potential ◽  
Cord Compression ◽  
Spinal Cord Trauma ◽  
Content Type ◽  
Cortical Evoked Potentials ◽  
Acute Changes ◽  
Fine Print

✓ Studies in 28 traumatized cats showed the following acute changes after spinal cord compression in the cord segment below the trauma: 1) increase in size of the spinal cord evoked potential; 2) increase in size of the electrospinogram; and 3) increase in frequency of the electrospinogram.

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