A further examination of effects of cortical stimulation on primate spinothalamic tract cells

1983 ◽  
Vol 49 (2) ◽  
pp. 424-441 ◽  
Author(s):  
R. P. Yezierski ◽  
K. D. Gerhart ◽  
B. J. Schrock ◽  
W. D. Willis
Keyword(s):  
Motor Cortex ◽  
Sensorimotor Cortex ◽  
Dynamic Range ◽  
Cortical Stimulation ◽  
Cortical Inhibition ◽  
Sensory Cortex ◽  
High Threshold ◽  
Spinothalamic Tract ◽  
Average Latency ◽  
Stimulation Of

1. Stimulation of the sensorimotor cortex was found to excite and/or inhibit nociceptive spinothalamic tract cells. Thirteen wide dynamic range cells were inhibited by cortical stimulation, 6 were excited and 14 were both excited and inhibited. Four of six high-threshold cells were excited and one was inhibited. 2. Intermediate (200 ms) or long (2 s) duration conditioning trains were effective in reducing responses of spinothalamic cells evoked by noxious mechanical or thermal stimuli and by A- and C-fiber volleys in the sural nerve. Preferential inhibition of low-threshold responses with little or no effect on high-threshold discharges was observed in some cases. 3. Inhibitory actions were obtained primarily from stimulation of the SI sensory cortex and area 5, while excitation or excitation followed by inhibition was the dominant effect from motor cortex (area 4). Spinothalamic cells were also excited by stimulation of the medullary pyramid. 4. In eight animals extensive mapping of the sensorimotor cortex showed that for a given cell, stimulation of the sensory cortex produced inhibition while stimulation of motor cortex resulted in excitation. 5. The average latency of inhibition from sensory cortex was 29.8 +/- 10 ms, while the average latency of excitation from motor cortex was significantly shorter, 13.5 +/- 9 ms. The shortest latencies for excitation from pyramidal stimulation in the cases evaluated ranged from 2 to 9 ms. 6. Spinal cord lesions were made in five animals to determine the descending pathway(s) mediating corticofugal effects. Cortical and pyramidal effects were eliminated or considerably reduced by lesions involving the dorsal part of the lateral funiculus. This observation combined with latency data suggest that the corticospinal tract may be involved in the mediation of cortical excitation, while both pyramidal and extrapyramidal pathways are likely to be involved in cortical inhibition.

Primate nucleus gracilis neurons: responses to innocuous and noxious stimuli

1988 ◽  
Vol 59 (3) ◽  
pp. 886-907 ◽  
Author(s):  
D. G. Ferrington ◽  
J. W. Downie ◽  
W. D. Willis
Keyword(s):  
Conduction Velocity ◽  
Dynamic Range ◽  
Subcutaneous Tissue ◽  
Receptive Fields ◽  
High Threshold ◽  
Spinothalamic Tract ◽  
Sinusoidal Vibration ◽  
Nucleus Gracilis ◽  
Pressure Sensitive ◽  
Stimulation Of

1. Recordings were made from 67 neurons in the nucleus gracilis (NG) of anesthetized macaque monkeys. All of the cells were activated antidromically from the ventral posterior lateral (VPL) nucleus of the contralateral thalamus. Stimuli used to activate the cells orthodromically were graded innocuous and noxious mechanical stimuli, including sinusoidal vibration and thermal pulses. 2. The latencies of antidromic action potentials following stimulation in the VPL nucleus were significantly shorter for cells in the caudal compared with the rostral NG. The mean minimum afferent conduction velocity of the afferent conduction velocity of the afferent fibers exciting the NG cells was 52 m/s, as judged from the latencies of the cells to orthodromic volleys evoked by electrical stimulation of peripheral nerves. The overall conduction velocity of the pathway from peripheral nerve to thalamus was approximately 40 m/s. 3. Cutaneous receptive fields on the distal hindlimb usually occupied an area equivalent to much less than a single digit. However, a few cells had receptive fields up to or exceeding the area of the foot. 4. NG cells were classified by their responses to graded mechanical stimulation of the skin as low threshold (LT) or wide dynamic range (WDR). No high-threshold NG cells were found. A special subcategory of pressure-sensitive LT (SA) neurons was recognized. Many of these cells were maximally responsive to maintained indentation of the skin. The sample of NG cells differed from the population of primate spinothalamic and spinocervicothalamic pathways so far examined, in having a larger proportion of LT neurons and a smaller proportion of WDR cells. A few NG cells responded best to manipulation of subcutaneous tissue. 5. Discriminant analysis permitted the NG cells to be assigned to classes determined by a k-means cluster analysis of the responses of a reference set of 318 primate spinothalamic tract (STT) cells. There were four classes of cells based on normalized responses of individual neurons and another four classes based upon responses compared across the population of cells. The NG cells were allocated to the various categories in different proportions than either primate STT cells or spinocervicothalamic neurons, consistent with the view that the functional roles of these somatosensory pathways differ. 6. Some of the pressure-sensitive NG cells were excited when the skin was stretched, suggesting an input from type II slowly adapting (Ruffini) mechanoreceptors.(ABSTRACT TRUNCATED AT 400 WORDS)

Afferent-efferent linkages in motor cortex for single forelimb muscles

1975 ◽  
Vol 38 (4) ◽  
pp. 990-1014 ◽  
Author(s):  
J. T. Murphy ◽  
Y. C. Wong ◽  
H. C. Kwan
Keyword(s):  
Motor Cortex ◽  
High Velocity ◽  
Cortical Neurons ◽  
Dentate Nucleus ◽  
Dynamic Range ◽  
Sensory Cortex ◽  
High Threshold ◽  
Medial Lemniscus ◽  
Low Velocity ◽  
Low Threshold

1. In locally anesthetized cats, extracellular recordings were made from single neurons in the lateral cruciate gyrus of cerebral cortex. These neurons responded to natural activation of stretch receptors in single, contralateral, forelimb wrist muscles, typically with phasic excitation. Low-velocity stretches, which activate primary endings of muscle spindles, excited one set of neurons at a mean latency of 11 ms; high-velocity stretches, which principally activate Golgi tendon organs and/or secondary spindle endings, excited a second set at 18 ms. The cortical neurons showing threshold responses to low-velocity stretches were found exclusively within restricted columns, 0.5-2.0 mm in diameter, which were spatially separate for each muscle. Neurons exhibiting threshold responses to high-velocity stretches were present in high density within the same columns and were also distributed, although more sparsely, outside the columns. 2. These afferent columns were located in cytoarchitectonic area 4gamma, and were shown by intracortical microstimulation to coincide with the efferent columns for contraction of the same muscle from which in input rose. Discrete afferent columns were also found for single muscles in the peridimple region of sensory cortex (area 3a), spatially separate from the columns in motor cortex. The excitation of the columns in motor cortex by these inputs from muscle was independent of that in sensory cortex. 3. The role of the cerebellum in controlling these feedback systems to motor cortex was investigated by selective cooling of interpositus and dentate nucleus, respectively. Cooling of interpositus markedly reduced transmission in the high-threshold system; cooling of dentate had a similar effect on the low-threshold system. 4. The latency, threshold, and cooling data indicated that the low-threshold system to motor cortex utilizes extracerebellar pathways including medial lemniscus and is facilitated by dentate nucleus. The high-threshold system involves a transcerebellar pathway including interpositus nucleus. Both systems transmit velocity-related information, with each showing different and complementary sensitivity and dynamic range. 5. The results are discussed with reference to the cortical load-compensation mechanism postulated by Phillips (37-38).

Electrophysiological study of spinothalamic inputs to ventrolateral and adjacent thalamic nuclei of the cat

1991 ◽  
Vol 66 (3) ◽  
pp. 1033-1047 ◽  
Author(s):  
C. T. Yen ◽  
C. N. Honda ◽  
E. G. Jones
Keyword(s):  
Dynamic Range ◽  
Electrophysiological Study ◽  
The Other ◽  
Reticular Nucleus ◽  
High Threshold ◽  
Medial Lemniscus ◽  
Spinothalamic Tract ◽  
Conduction Velocities ◽  
Lateral Nucleus ◽  
Stimulation Of

1. Extracellular and intracellular methods were used to record from fibers and neurons in the ventral lateral (VL) and adjacent nuclei of the cat thalamus. The receptive fields of the recorded units were analyzed and the units tested for inputs from the medial lemniscus (ML) and spinothalamic tract (STT) by electrical stimulation of the dorsal columns (DC) and ventrolateral funiculus (VLF) at the C2-3 spinal level. 2. Thirty-eight STT fibers were isolated in the thalamus. Their conduction velocities ranged from 15 to 75 m/s (mode 36 m/s). Adequate stimuli were found for 23 of these fibers. Seventeen were low-threshold (LT), 3 were wide-dynamic-range (WDR), and 3 were high-threshold (HT) units. 3. Five STT fibers were intra-axonally injected. Three were sufficiently well filled for analysis of their terminal fields. An intermediate-velocity STT fiber (conduction velocity 38 m/s) had a 4.3-microns axon and a single large terminal field in the central lateral nucleus (CL). The other two STT fibers were smaller, with diameters of 2.5 and 2.3 microns, conduction velocities of 15 and 19 m/s, and terminal fields made up of a few small boutons at the borders of the ventral posterior lateral nucleus (VPL). 4. Of 319 neurons isolated, 14 out of 129 (10.8%) in VL, 14 out of 76 (18.4%) in the VPL or ventral posterior medial (VPM) nucleus, 27 out of 64 (42.2%) in the CL nucleus, and 5 out of 50 (10%) in the reticular nucleus (R) responded at latencies less than 50 ms to VLF stimuli. A train of three pulses was more effective in driving VLF-responding neurons in all these nuclei than a single pulse. VLF-responding cells were widely dispersed in VL, concentrated in a focus in CL, and distributed around the borders of VPL. Most of those in VL and a small number in CL could be antidromically activated by stimulation of motor cortex. 5. Latencies of presynaptic responses (STT fibers) to VLF stimulation were short and varied from 0.8 to 3.9 ms (mode 1.6 ms). Despite this, very few fast-responding neurons were found. These were six VPL neurons (2.5 to 4 ms), one VL neuron (3 ms), and four CL neurons (3-4 ms). The initial spike latencies of the majority of thalamic neurons responding to VLF stimulation appeared in two peaks, one between 6 and 8 ms and the other at 10-15 ms.(ABSTRACT TRUNCATED AT 400 WORDS)

Responses of primate T1-T5 spinothalamic neurons to gallbladder distension

1984 ◽  
Vol 247 (6) ◽  
pp. R995-R1002 ◽  
Author(s):  
W. S. Ammons ◽  
R. W. Blair ◽  
R. D. Foreman
Keyword(s):  
Chest Pain ◽  
Dynamic Range ◽  
Discharge Rate ◽  
Gallbladder Disease ◽  
High Rate ◽  
High Threshold ◽  
Spinothalamic Tract ◽  
Left Chest ◽  
Afferent Fibers ◽  
Upper Thoracic

Extracellular unit recordings were obtained from 44 spinothalamic tract (STT) neurons in the T1-T5 segments of 15 alpha-chloralose anesthesized monkeys (Macaca fascicularis). Each cell had a somatic receptive field in the left chest region and was excited by electrical stimulation of cardiopulmonary sympathetic afferent fibers. Gallbladder distension to pressures between 20 and 100 mmHg increased activity in 16 of 44 neurons. Responses usually consisted of bursts of activity associated with increased gallbladder pressure (phasic responses) followed by maintained activity during the distension (tonic responses). Magnitude of phasic responses was linearly related to the distending pressure and was consistently greater than magnitude of tonic responses. The gallbladder-responsive and nonresponsive groups included similar proportions of wide dynamic range, high threshold, and high-threshold inhibitory cells. Nine of 10 gallbladder-responsive cells and 11 of 21 gallbladder-nonresponsive cells increased their discharge rate after injection of 2 micrograms/kg bradykinin into left atrium. Activity of cells with gallbladder input increased from 14 +/- 4 to 33 +/- 4 spikes/s. Cells without gallbladder input increased their discharge rate to a significantly less degree (10 +/- 3-23 +/- 4 spikes/s). These results indicate that upper thoracic STT neurons may increase their activity during gallbladder distension. Convergence of afferent information from the chest and gallbladder may explain chest pain occurring during gallbladder disease. Furthermore the tendency of gallbladder-responsive cells to respond to bradykinin injections with a high rate of discharge could explain how this chest pain of gallbladder origin may closely mimic pain of angina pectoris.

Responses of spinothalamic tract cells to mechanical and thermal stimulation of skin in rats with experimental peripheral neuropathy

1992 ◽  
Vol 67 (6) ◽  
pp. 1562-1573 ◽  
Author(s):  
J. Palecek ◽  
V. Paleckova ◽  
P. M. Dougherty ◽  
S. M. Carlton ◽  
W. D. Willis
Keyword(s):  
Dynamic Range ◽  
Background Activity ◽  
Thermal Stimulation ◽  
Spontaneous Pain ◽  
Mechanical Stimuli ◽  
Spinothalamic Tract ◽  
High Background ◽  
Threshold Temperatures ◽  
Thermal Stimuli ◽  
Stimulation Of

1. Responses of spinothalamic tract (STT) neurons to mechanical and thermal stimulation of skin were recorded under urethane and pentobarbital anesthesia in 12 control rats and in 20 rats with experimental neuropathy. Activity of the STT cells in neuropathic rats was recorded 7, 14, and 28 days after inducing the neuropathy by placing four loose ligatures on the sciatic nerve. 2. All neuropathic animals showed guarding of the injured hindpaw and a shorter withdrawal latency from a radiant heat source of the neuropathic hindpaw than that of the sham-operated paw. 3. STT neurons in neuropathic animals showed the most profound changes 7 and 14 days after the nerve ligation. When compared with STT cells in unoperated animals, approximately half of the neurons had high background activity, responses to innocuous stimuli represented a larger percentage of the total evoked activity in wide dynamic range neurons, and the occurrence and magnitude of afterdischarges to mechanical and thermal stimuli were increased. 4. The mean threshold temperatures of heat-evoked responses of the STT cells in neuropathic animals were not different than those of cells from control animals. However, in neuropathic rats, cells reacting to small heat stimuli usually already had afterdischarges. 5. The increase in the background activity of STT cells is consistent with behavioral observations of spontaneous pain in this model of experimental neuropathy. Furthermore, the afterdischarges of STT cells may parallel the prolonged paw withdrawal in response to noxious stimuli that is seen in these animals and that is evidence for hyperalgesia. However, there was no indication of a lowered threshold for thermal stimuli as might be expected if the animals have thermal allodynia. Mechanical allodynia may have resulted from a relative increase in responsiveness to innocuous mechanical stimuli. However, responses to noxious mechanical stimuli were reduced compared with control, at least at 28 days after the ligation. Peripheral and central mechanisms responsible for the changes in responses of STT cells in neuropathic animals are suggested.

Grouping of somatosensory neurons in the spinal cord and the gracile nucleus of the rat by cluster analysis

1994 ◽  
Vol 72 (6) ◽  
pp. 2590-2597 ◽  
Author(s):  
J. W. Leem ◽  
B. H. Lee ◽  
W. D. Willis ◽  
J. M. Chung
Keyword(s):  
Cluster Analysis ◽  
Dorsal Horn ◽  
Dynamic Range ◽  
High Threshold ◽  
Spinothalamic Tract ◽  
Wide Dynamic Range ◽  
Gracile Nucleus ◽  
Noxious Stimuli ◽  
Thermal Stimuli ◽  
Wide Dynamic Range Neurons

1. A set of 11 cutaneous stimuli defined previously to differentiate among different types of cutaneous sensory receptors in the rat hindpaw was also effective in differentially activating second-order sensory neurons in the dorsal horn and the gracile nucleus of rats. 2. All sampled units were responsive to more than 1 of the 11 stimuli. However, none responded to innocuous warming or cooling stimuli. Therefore further analysis was restricted to responses to nine of the selected stimuli. 3. Cluster analysis of the responses to nine selected innocuous and noxious mechanical stimuli and noxious thermal stimuli yielded seven classes that seemed functionally distinct from each other: a class of high-threshold neurons, three classes of convergent (wide dynamic range) neurons, a class of a mixture of poorly responsive neurons and neurons receiving Pacinian inputs, and two classes of low-threshold neurons. 4. High-threshold neurons responded predominantly to noxious mechanical and thermal stimuli and presumably received an input from both mechanically and thermally sensitive nociceptors. These cells were located in the dorsal horn, and some were spinothalamic tract cells. Wide dynamic range neurons were excited by innocuous and noxious stimuli, but better by noxious stimuli. These classes of cells were either in the dorsal horn (some were spinothalamic tract cells) or in the nucleus gracilis.(ABSTRACT TRUNCATED AT 250 WORDS)

The modulation of sensory transmission through the medullary dorsal horn during cortically driven mastication

1986 ◽  
Vol 64 (7) ◽  
pp. 999-1005 ◽  
Author(s):  
Joong Soo Kim ◽  
M. Catherine Bushnell ◽  
Gary H. Duncan ◽  
James P. Lund
Keyword(s):  
Dorsal Horn ◽  
Unit Activity ◽  
Sensorimotor Cortex ◽  
Dynamic Range ◽  
Cortical Stimulation ◽  
Motor Nucleus ◽  
Trigeminal Motor Nucleus ◽  
Sensory Transmission ◽  
Medullary Dorsal Horn ◽  
Low Threshold

During mastication, reflexes are modulated and sensory transmission is altered in interneurons and ascending pathways of the rostral trigeminal sensory complex. The current experiment examines the modulation of sensory transmission through the most caudal part of the trigeminal sensory system, the medullary dorsal horn, during fictive mastication produced by cortical stimulation. Extracellular single unit activity was recorded from the medullary dorsal horn, and multiple unit activity was recorded from the trigeminal motor nucleus in anesthetized, paralyzed rabbits. The masticatory area of sensorimotor cortex was stimulated to produce rhythmic activity in the trigeminal motor nucleus (fictive mastication). Activity in the dorsal horn was compared in the presence and absence of cortical stimulation. Fifty-two percent of neurons classified as low threshold and 83% of neurons receiving noxious inputs were influenced by cortical stimulation. The cortical effects were mainly inhibitory, but 21% of wide dynamic range and 6% of low threshold cells were excited by cortical stimulation. The modulation produced by cortical stimulation, whether inhibitory or excitatory, was not phasically related to the masticatory cycle. It is likely that, when masticatory movements are commanded by the sensorimotor cortex, the program includes tonic changes in sensory transmission through the medullary dorsal horn.

Somatosensory response properties of contralaterally projecting spinothalamic and nonspinothalamic neurons in the second cervical segment of the cat

1991 ◽  
Vol 66 (1) ◽  
pp. 83-102 ◽  
Author(s):  
M. V. Smith ◽  
A. V. Apkarian ◽  
C. J. Hodge
Keyword(s):  
Dynamic Range ◽  
Cervical Spinal Cord ◽  
Average Distance ◽  
Whole Body ◽  
High Threshold ◽  
Average Depth ◽  
Spinothalamic Tract ◽  
Antidromic Activation ◽  
Response Properties ◽  
Electrolytic Lesions

1. The upper cervical spinal cord contains over one-third of the cells of the spinothalamic tract (STT). This study investigated response properties of contralaterally projecting STT neurons in C2 of the cat by the use of single-unit, microelectrode recordings. Standard antidromic stimulation and collision techniques were used to identify STT units projecting to the contralateral thalamus. Once an STT unit was found, its receptive field (RF) and responses to cutaneous stimuli such as touch, pressure, deep muscle squeeze, tap, noxious pinch, and heat were characterized. C2 units that were not activated from the contralateral thalamus (non-STT units) were also characterized. The locations of thalamic stimulation electrodes and spinal recording sites were reconstructed from electrolytic lesions. 2. A total of 48 STT and 68 non-STT units were well characterized. RF sizes were classified as small, intermediate, large, or whole body. Each unit was also classified as having one of two possible response types: simple units were those with homogeneous responses within the RF and were classified as low threshold (LT), high threshold (HT), wide dynamic range (WDR), deep, or tap. Complex units were those that responded differently in different regions of the RF. 3. The average depth of non-STT units subdivided by RF size was 2.1 +/- 0.6 (SD) mm for cells with small RFs, 2.4 +/- 0.8 mm for cells with intermediate RFs, 2.8 +/- 0.3 mm for cells with large RFs, and 2.7 +/- 0.5 mm for cells with whole-body RFs. The average depth of non-STT units based on response type was 2.0 +/- 0.5 mm for LT, 2.3 +/- 0.7 mm for HT, 2.1 +/- 0.7 mm for WDR, 2.6 +/- 0.9 mm for deep, 2.6 +/- 0.5 mm for tap, and 2.4 +/- 0.2 mm for complex. 4. A somatotopic organization along the rostrocaudal length of C2 and upper C3 was observed for non-STT units with small- and intermediate-size RFs. The average distance of the recording sites from the rostralmost dorsal rootlet of C2 was 3.8 +/- 2.1 mm for units with RFs on the face, 7.1 +/- 4.3 mm for units with RFs on the neck, and 11.9 +/- 5.1 mm for units with RFs on the forelimb. 5. The average threshold for antidromic activation of STT units was 175 +/- 120 microA. Most C2 STT units were activated from the ventroposterior region of the thalamus.(ABSTRACT TRUNCATED AT 400 WORDS)

Comparison of Responses of Primate Spinothalamic Tract Neurons to Pruritic and Algogenic Stimuli

2004 ◽  
Vol 91 (1) ◽  
pp. 213-222 ◽  
Author(s):  
Donald A. Simone ◽  
Xijing Zhang ◽  
Jun Li ◽  
Jun-Ming Zhang ◽  
Christopher N. Honda ◽  
...  
Keyword(s):  
Dynamic Range ◽  
Intradermal Injection ◽  
High Threshold ◽  
Mechanical Stimuli ◽  
Spinothalamic Tract ◽  
Wide Dynamic Range ◽  
Antidromic Activation ◽  
Lateral Nucleus ◽  
Maximal Time

We investigated the role of mechanosensitive spinothalamic tract (STT) neurons in mediating 1) the itch evoked by intradermal injection of histamine, 2) the enhanced sense of itch evoked by innocuous stroking (alloknesis), and 3) the enhanced pain evoked by punctate stimulation (hyperalgesia) of the skin surrounding the injection site. Responses to intradermal injections of histamine and capsaicin were compared in STT neurons recorded in either the superficial or the deep dorsal horn of the anesthetized monkey. Each neuron was identified by antidromic activation from the ventral posterior lateral nucleus of thalamus and classified by its initial responses to mechanical stimuli as wide dynamic range (WDR) or high-threshold (HT). Approximately half of the WDRs and one of the HTs responded weakly to histamine, some with a duration > 5 min, the maximal time allotted. WDRs but not HTs exhibited a significant increase in response to punctate stimulation after histamine consistent with their possible role in mediating histamine-induced hyperalgesia. Neither type of neuron exhibited significant changes in response to stroking, consistent with their unlikely role in mediating alloknesis. Furthermore, nearly all STT neurons exhibited vigorous and persistent responses to capsaicin, after which they became sensitized to stroking and to punctate stimulation. We conclude that the STT neurons in our sample are more likely to contribute to pain, allodynia, and hyperalgesia than to itch and alloknesis.

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