Changes in somatosensory evoked potentials and reflectory reactions of human hand muscles to nociceptive stimulation of index finger before and during ischemia

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.

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Comparison of scalp distribution of short latency somatosensory evoked potentials (SSEPs) to stimulation of different nerves in the lower extremity

Electroencephalography and Clinical Neurophysiology/Evoked Potentials Section ◽

10.1016/0168-5597(88)90046-9 ◽

1988 ◽

Vol 71 (6) ◽

pp. 422-428 ◽

Cited By ~ 32

Author(s):

Luciana Pelosi ◽

Joan B. Cracco ◽

Roger Q. Cracco ◽

Nasser F. Hassan

Keyword(s):

Lower Extremity ◽

Evoked Potentials ◽

Somatosensory Evoked Potentials ◽

Short Latency ◽

Scalp Distribution ◽

Stimulation Of

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BOLD fMRI and somatosensory evoked potentials are well correlated over a broad range of frequency content of somatosensory stimulation of the rat forepaw

Brain Research ◽

10.1016/j.brainres.2007.11.036 ◽

2008 ◽

Vol 1195 ◽

pp. 67-76 ◽

Cited By ~ 22

Author(s):

Artem G. Goloshevsky ◽

Afonso C. Silva ◽

Stephen J. Dodd ◽

Alan P. Koretsky

Keyword(s):

Evoked Potentials ◽

Somatosensory Evoked Potentials ◽

Frequency Content ◽

Somatosensory Stimulation ◽

Bold Fmri ◽

Stimulation Of

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

Journal of Neurophysiology ◽

10.1152/jn.01030.2010 ◽

2011 ◽

Vol 106 (6) ◽

pp. 3082-3090 ◽

Cited By ~ 30

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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Evidence that low-threshold muscle afferents evoke long-latency stretch reflexes in human hand muscles

Journal of Neurophysiology ◽

10.1152/jn.1991.65.5.1089 ◽

1991 ◽

Vol 65 (5) ◽

pp. 1089-1097 ◽

Cited By ~ 19

Author(s):

J. Noth ◽

M. Schwarz ◽

K. Podoll ◽

F. Motamedi

Keyword(s):

Index Finger ◽

Angular Displacement ◽

Metacarpophalangeal Joint ◽

Muscle Afferents ◽

Human Hand ◽

Hand Muscles ◽

Long Latency ◽

M2 Response ◽

Spinal Afferents ◽

Wrist Flexors

1. The aim of the present study was to identify the type of spinal afferents involved in the generation of the long-latency response in intrinsic human hand muscles. Position-controlled extensions were imposed on the index finger or on the wrist of healthy subjects who were exerting a steady voluntary flexion force at the relevant joint. Averaged surface electromyographic (EMG) responses of the first dorsal interosseus muscle (FDI) or of the wrist flexors were evaluated with respect to latency and size. 2. Small transient angular displacements of the index finger (1 degree, as measured at the metacarpophalangeal joint), which are supposed to excite primary rather than secondary afferents, evoked two clearly discernible EMG responses with mean latencies of 32.3 ms (M1 response) and 54.7 ms (M2 response), respectively. The size of the M2 response exceeded the size of the M1 response by 60%. In the wrist flexors, transient stretch (1 degree) gave rise to a large M1 response (latency 22.8 ms) and a small, inconstent M2 response. 3. Small-amplitude vibration of the index finger elicited EMG responses in the FDI that were qualitatively and quantitatively similar to those seen in response to small transient stretches of the index finger. This was also true for fast ramp-and-hold stretches (stretch velocity 400 degrees/s, amplitude 5 degrees), whereas slow ramp-and-hold stretches (125 degrees/s, 5 degrees) elicited predominantly M2 responses. 4. In the FDI, the mechanical threshold of the M1 and M2 response to the transient angular displacement was approximately 0.15 degrees, with a tendency for the M2 response to appear at a lower threshold.(ABSTRACT TRUNCATED AT 250 WORDS)

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