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Kim J, Ryu SB, Lee SE, Shin J, Jung HH, Kim SJ, Kim KH, Chang JW. Motor cortex stimulation and neuropathic pain: how does motor cortex stimulation affect pain-signaling pathways? J Neurosurg 2015; 124:866-76. [PMID: 26274988 DOI: 10.3171/2015.1.jns14891] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECTIVE Neuropathic pain is often severe. Motor cortex stimulation (MCS) is used for alleviating neuropathic pain, but the mechanism of action is still unclear. This study aimed to understand the mechanism of action of MCS by investigating pain-signaling pathways, with the expectation that MCS would regulate both descending and ascending pathways. METHODS Neuropathic pain was induced in Sprague-Dawley rats. Surface electrodes for MCS were implanted in the rats. Tactile allodynia was measured by behavioral testing to determine the effect of MCS. For the pathway study, immunohistochemistry was performed to investigate changes in c-fos and serotonin expression; micro-positron emission tomography (mPET) scanning was performed to investigate changes of glucose uptake; and extracellular electrophysiological recordings were performed to demonstrate brain activity. RESULTS MCS was found to modulate c-fos and serotonin expression. In the mPET study, altered brain activity was observed in the striatum, thalamic area, and cerebellum. In the electrophysiological study, neuronal activity was increased by mechanical stimulation and suppressed by MCS. After elimination of artifacts, neuronal activity was demonstrated in the ventral posterolateral nucleus (VPL) during electrical stimulation. This neuronal activity was effectively suppressed by MCS. CONCLUSIONS This study demonstrated that MCS effectively attenuated neuropathic pain. MCS modulated ascending and descending pain pathways. It regulated neuropathic pain by affecting the striatum, periaqueductal gray, cerebellum, and thalamic area, which are thought to regulate the descending pathway. MCS also appeared to suppress activation of the VPL, which is part of the ascending pathway.
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Affiliation(s)
- Jinhyung Kim
- Brain Korea 21 PLUS Project for Medical Science and Brain Research Institute and.,Department of Neurosurgery, Yonsei University College of Medicine, Seoul;,Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Korea
| | - Sang Baek Ryu
- Department of Biomedical Engineering, College of Health Science, Yonsei University, Wonju
| | - Sung Eun Lee
- School of Electrical Engineering and Computer Science.,Nano Bioelectronics and System Research Center, and
| | - Jaewoo Shin
- Brain Korea 21 PLUS Project for Medical Science and Brain Research Institute and.,Department of Neurosurgery, Yonsei University College of Medicine, Seoul
| | - Hyun Ho Jung
- Department of Neurosurgery, Yonsei University College of Medicine, Seoul
| | - Sung June Kim
- School of Electrical Engineering and Computer Science.,Nano Bioelectronics and System Research Center, and.,Inter-University Semiconductor Research Center, Seoul National University, Seoul; and
| | - Kyung Hwan Kim
- Department of Biomedical Engineering, College of Health Science, Yonsei University, Wonju
| | - Jin Woo Chang
- Brain Korea 21 PLUS Project for Medical Science and Brain Research Institute and.,Department of Neurosurgery, Yonsei University College of Medicine, Seoul
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Kim J, Shin J, Oh JH, Jung HH, Kim YB, Cho ZH, Chang JW. Longitudinal FDG microPET imaging of neuropathic pain: does cerebellar activity correlate with neuropathic pain development in a rat model? Acta Neurochir (Wien) 2015; 157:1051-7. [PMID: 25916400 DOI: 10.1007/s00701-015-2415-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Accepted: 03/25/2015] [Indexed: 12/19/2022]
Abstract
BACKGROUND We used [F-18] FDG microPET imaging as part of a longitudinal study to investigate changes in the brain. METHODS Glucose metabolism during the development of neuropathic pain after tibial and sural nerve transection (TST) model rats. MicroPET images were obtained 1 week before operation and then weekly for 8 weeks post-operation. RESULTS The behavioral test was performed immediately after the every FDG administration. After TST modeling, neuropathic pain rats showed increased mechanical sensitivity of the injured hind paw. The withdrawal response to mechanical pain stimulation by von Frey filaments was observed within the first week (3.8 ± 0.73), and it rapidly increased in the third week (7.13 ± 0.82). This response reached a peak in the fourth week after surgery (9.0 ± 0.53), which persisted until the eighth week. In microPET scan imaging, cerebellum, which initially started from the ansiform lobule, was activated gradually to all part from the third week in all image acquisitions through the eighth week. CONCLUSIONS The longitudinal microPET scan study of brains from neuropathic pain rat models showed sequential cerebellar activity that was in accordance with results from behavioral test responses, thus supporting a role for the cerebellum in the development of neuropathic pain.
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Affiliation(s)
- Jinhyung Kim
- Brain Korea 21 Project for Medical Science and Brain Research Institute, Yonsei University College of Medicine, Seoul, Korea
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Kutz DF, Kaulich T, Föhre W, Gerwig M, Timmann D, Kolb FP. Comparison of the classically conditioned withdrawal reflex in cerebellar patients and healthy control subjects during stance: 2. Biomechanical characteristics. Neurobiol Learn Mem 2014; 109:178-92. [PMID: 24445111 DOI: 10.1016/j.nlm.2013.12.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Revised: 12/18/2013] [Accepted: 12/27/2013] [Indexed: 10/25/2022]
Abstract
This study addresses cerebellar involvement in classically conditioned nociceptive lower limb withdrawal reflexes in standing humans. A preceding study compared electromyographic activities in leg muscles of eight patients with cerebellar disease (CBL) and eight age-matched controls (CTRL). The present study extends and completes that investigation by recording biomechanical signals from a strain-gauge-equipped platform during paired auditory conditioning stimuli (CS) and unconditioned stimuli (US) trials and during US-alone trials. The withdrawal reflex performance-lifting the stimulated limb (decreasing the vertical force from that leg, i.e. 'unloading') and transferring body weight to the supporting limb (increasing the vertical force from that leg, i.e. 'loading')-was quantified by the corresponding forces exerted onto the platform. The force changes were not simultaneous but occurred as a sequence of multiple force peaks at different times depending on the specific limb task (loading or unloading). Motor learning, expressed by the occurrence of conditioned responses (CR), is characterized by this sequence beginning already within the CSUS window. Loading and unloading were delayed and prolonged in CBL, resulting in incomplete rebalancing during the analysis period. Trajectory loops of the center of vertical pressure-derived from vertical forces-were also incomplete in CBL within the recording period. However, exposing CBL to a CS resulted in motor improvement reflected by shortening the time of rebalancing and by optimizing the trajectory loop. In summary, associative responses in CBL are not absent although they are less frequent and of smaller amplitude than in CTRL.
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Affiliation(s)
- D F Kutz
- Institute of Physiology, University of Munich, Pettenkoferstr. 12, 80336 München, Germany.
| | - Th Kaulich
- Institute of Physiology, University of Munich, Pettenkoferstr. 12, 80336 München, Germany.
| | - W Föhre
- Institute of Physiology, University of Munich, Pettenkoferstr. 12, 80336 München, Germany.
| | - M Gerwig
- Department of Neurology, University of Duisburg-Essen, Hufelandstr. 55, 45122 Essen, Germany.
| | - D Timmann
- Department of Neurology, University of Duisburg-Essen, Hufelandstr. 55, 45122 Essen, Germany.
| | - F P Kolb
- Institute of Physiology, University of Munich, Pettenkoferstr. 12, 80336 München, Germany.
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Timmann D, Kaulich T, Föhre W, Kutz DF, Gerwig M, Kolb FP. Comparison of the classically conditioned withdrawal reflex in cerebellar patients and healthy control subjects during stance: I. electrophysiological characteristics. THE CEREBELLUM 2012; 12:108-26. [PMID: 22836373 DOI: 10.1007/s12311-012-0400-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
The aim of this study was to demonstrate the involvement of the human cerebellum in the classically conditioned lower limb withdrawal reflex in standing subjects. Electromyographic activity was recorded from the main muscle groups of both legs of eight patients with cerebellar disease (CBL) and eight control subjects (CTRL). The unconditioned stimulus (US) consisted of electrical stimulation of the tibial nerve at the medial malleolus. The conditioning stimulus (CS) was an auditory signal given via headphones. Experiments started with 70 paired conditioning stimulus-unconditioned stimulus(CSUS) trials followed by 50 US-alone trials. The general reaction consisted of lifting and flexing the stimulated (stepping) leg with accompanying activation of the contralateral (supporting) leg. In CTRL, the ipsilateral (side of stimulation) flexor and contralateral extensor muscles were activated characteristically. In CBL, the magnitudes of ipsilateral flexor and contralateral extensor muscle activation were reduced comparably. In CTRL, the conditioning process increased the incidence of conditioned responses (CR), following a typical learning curve, while CBL showed a clearly lower CR incidence with a marginal increase, albeit, at a shorter latency. Conditioning processes also modified temporal parameters by shortening unconditioned response (UR) onset latencies and UR times to peak and, more importantly in CBL, also the sequence of activation of muscles, which became similar to that of CTRL. The expression of this reflex in standing subjects showed characteristic differences in the groups tested with the underlying associative processes not being restricted exclusively to the CR but also modifying parameters of the innate UR.
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Affiliation(s)
- D Timmann
- Department of Neurology, University of Duisburg-Essen, Hufelandstr. 55, 45122, Essen, Germany
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Sang L, Qin W, Liu Y, Han W, Zhang Y, Jiang T, Yu C. Resting-state functional connectivity of the vermal and hemispheric subregions of the cerebellum with both the cerebral cortical networks and subcortical structures. Neuroimage 2012; 61:1213-25. [PMID: 22525876 DOI: 10.1016/j.neuroimage.2012.04.011] [Citation(s) in RCA: 191] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2012] [Revised: 04/04/2012] [Accepted: 04/06/2012] [Indexed: 11/28/2022] Open
Abstract
The human cerebellum is a heterogeneous structure, and the pattern of resting-state functional connectivity (rsFC) of each subregion has not yet been fully characterized. We aimed to systematically investigate rsFC pattern of each cerebellar subregion in 228 healthy young adults. Voxel-based analysis revealed that several subregions showed similar rsFC patterns, reflecting functional integration; however, different subregions displayed distinct rsFC patterns, representing functional segregation. The same vermal and hemispheric subregions showed either different patterns or different strengths of rsFCs with the cerebrum, and different subregions of lobules VII and VIII displayed different rsFC patterns. Region of interest (ROI)-based analyses also confirmed these findings. Specifically, strong rsFCs were found: between lobules I-VI and vermal VIIb-IX and the visual network; between hemispheric VI, VIIb, VIIIa and the auditory network; between lobules I-VI, VIII and the sensorimotor network; between lobule IX, vermal VIIIb and the default-mode network; between lobule Crus I, hemispheric Crus II and the fronto-parietal network; between hemispheric VIIb, VIII and the task-positive network; between hemispheric VI, VIIb, VIII and the salience network; between most cerebellar subregions and the thalamus; between lobules V, VIIb and the midbrain red nucleus; between hemispheric Crus I, Crus II, vermal VIIIb, IX and the caudate nucleus; between lobules V, VI, VIIb, VIIIa and the pallidum and putamen; and between lobules I-V, hemispheric VIII, IX and the hippocampus and amygdala. These results confirm the existence of both functional integration and segregation among cerebellar subregions and largely improve our understanding of the functional organization of the human cerebellum.
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Affiliation(s)
- Li Sang
- Department of Radiology, Tianjin Medical University General Hospital, Tianjin 300052, China
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Moulton EA, Schmahmann JD, Becerra L, Borsook D. The cerebellum and pain: passive integrator or active participator? BRAIN RESEARCH REVIEWS 2010; 65:14-27. [PMID: 20553761 PMCID: PMC2943015 DOI: 10.1016/j.brainresrev.2010.05.005] [Citation(s) in RCA: 245] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2010] [Revised: 05/19/2010] [Accepted: 05/21/2010] [Indexed: 01/21/2023]
Abstract
The cerebellum is classically considered to be a brain region involved in motor processing, but it has also been implicated in non-motor, and even cognitive, functions. Though previous research suggests that the cerebellum responds to noxious stimuli, its specific role during pain is unclear. Pain is a multidimensional experience that encompasses sensory discriminative, affective motivational, and cognitive evaluative components. Cerebellar involvement during the processing of pain could thus potentially reflect a number of different functional processes. This review will summarize the animal and human research to date that indicates that (1) primary afferents conduct nociceptive (noxious) input to the cerebellum, (2) electrical and pharmacological stimulation of the cerebellum can modulate nociceptive processing, and (3) cerebellar activity occurs during the presence of acute and chronic pain. Possible functional roles for the cerebellum relating to pain will be considered, including perspectives relating to emotion, cognition, and motor control in response to pain.
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Affiliation(s)
- Eric A Moulton
- P.A.I.N. Group, Brain Imaging Center, Department of Psychiatry, McLean Hospital and Harvard Medical School, Belmont, MA 02478, USA.
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Kaulich T, Föhre W, Kutz DF, Gerwig M, Timmann D, Kolb FP. Differences in unconditioned and conditioned responses of the human withdrawal reflex during stance: muscle responses and biomechanical data. Brain Res 2010; 1326:81-95. [PMID: 20188078 DOI: 10.1016/j.brainres.2010.02.051] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2009] [Revised: 02/16/2010] [Accepted: 02/17/2010] [Indexed: 11/24/2022]
Abstract
The aim of this study was to characterize differences between unconditioned and classically conditioned lower limb withdrawal reflexes in young subjects during standing. Electromyographic activity in the main muscle groups and biomechanical signals from a strain-gauge-equipped platform on which subjects stood were recorded from 17 healthy subjects during unconditioned stimulus (US)-alone trials and during auditory conditioning stimuli (CS) and US trials. In US-alone trials the leg muscle activation sequence was characteristic: ipsilateral, distal muscles were activated prior to proximal muscles; contralaterally the sequence was reversed. In CSUS trials latencies were shorter. Subjects unloaded the stimulated leg and shifted body weight to the supporting leg. In US-alone and in CSUS trials leg forces on each side were inversely related and asymmetric, due to preparation for unloading, whilst conditioned responses (CR), representing the unloading preparation, were symmetric. The trajectory of the center of vertical pressure during US-alone trials moved initially forward (a preparatory balance reaction) and to the stimulation side, followed by a large lateral shift to the side of the supporting limb. During CSUS trials the forwards shift was absent but the CR (early lateral shift) represented a preponed preparatory unloading. Electrophysiological and biomechanical responses of the classically conditioned lower limb withdrawal reflex in standing subjects changed significantly in CSUS trials compared to US-alone trials with higher sensitivity in the biomechanics. These findings will serve as a basis for a subsequent study on a group of patients with cerebellar diseases in whom the success of establishing procedural processes is known to be impaired.
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Affiliation(s)
- Thomas Kaulich
- Institute of Physiology, University of Munich, Munich, Germany
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Kolb TFB, Lachauer S, Schoch B, Gerwig M, Timmann D, Kolb FP. Comparison of the electrically evoked leg withdrawal reflex in cerebellar patients and healthy controls. Exp Brain Res 2006; 177:493-508. [PMID: 17051385 DOI: 10.1007/s00221-006-0706-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2006] [Accepted: 08/30/2006] [Indexed: 11/25/2022]
Abstract
The aim of this study was to analyze the contribution of the cerebellum in the performance of the lower limb withdrawal reflexes. This has been accomplished by comparing the electrically evoked responses in cerebellar patients (CBL) with those in sex- and age-matched healthy control subjects (CTRL). The stimulus was applied to the subjects' medial plantar nerve in four blocks of ten trials each with switching the stimulus from one leg to the other after each block. Responses of the main muscle groups (tibial muscle: TA; gastrocnemius muscle: GA; rectus femoris muscle: RF; biceps femoris muscle: BI) of both legs were recorded during each stimulus. The group of CBL patients consisted of both focally lesioned patients (CBLf) and patients presenting a diffuse degenerative pathology (CBLd). (1) For the withdrawal reflex in CTRL subjects, responses were observed in distal and proximal muscles of the ipsilateral side and corresponding concomitant responses on the side contralateral to the stimulation, whereas in CBL patients responses were restricted primarily to distal muscles, particularly the TA of the ipsilateral, i.e. the stimulated, side. (2) The sequence of activation of the different distal and proximal muscles ipsilateral to the stimulation, derived from latencies and times-to-peak, was for the CTRL group: TA-GA-BI-RF. This sequence was found also in the CBLf patients on their unaffected side. However, on their affected side CBLf patients showed very early GA activation, almost simultaneously with TA and RF activations and before BI activation. RF activation before BI activation was also found in CBLd. In the latter group, GA was activated after RF but before BI with all responses typically delayed. (3) The general pattern of the electrically evoked lower limb reflex consisted of an early, excitatory F1 component and a later, excitatory F2 component of larger amplitude observed in the CTRL subjects and the CBLd patients. In contrast to this pattern CBLf patients exhibited large F1 components followed by small F2 components. (4) The characteristic differences in the withdrawal reflex responses of cerebellar patients depended on the type of the lesion, providing evidence for an important involvement of the cerebellum in the control of the performance of withdrawal reflexes.
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Affiliation(s)
- T F B Kolb
- Institute of Physiology, University of Munich, Pettenkoferstr. 12, 80336 München, Germany
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Sandrini G, Serrao M, Rossi P, Romaniello A, Cruccu G, Willer JC. The lower limb flexion reflex in humans. Prog Neurobiol 2005; 77:353-95. [PMID: 16386347 DOI: 10.1016/j.pneurobio.2005.11.003] [Citation(s) in RCA: 372] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2005] [Revised: 11/08/2005] [Accepted: 11/09/2005] [Indexed: 10/25/2022]
Abstract
The flexion or flexor reflex (FR) recorded in the lower limbs in humans (LLFR) is a widely investigated neurophysiological tool. It is a polysynaptic and multisegmental spinal response that produces a withdrawal of the stimulated limb and resembles (having several features in common) the hind-paw FR in animals. The FR, in both animals and humans, is mediated by a complex circuitry modulated at spinal and supraspinal level. At rest, the LLFR (usually obtained by stimulating the sural/tibial nerve and by recording from the biceps femoris/tibial anterior muscle) appears as a double burst composed of an early, inconstantly present component, called the RII reflex, and a late, larger and stable component, called the RIII reflex. Numerous studies have shown that the afferents mediating the RII reflex are conveyed by large-diameter, low-threshold, non-nociceptive A-beta fibers, and those mediating the RIII reflex by small-diameter, high-threshold nociceptive A-delta fibers. However, several afferents, including nociceptive and non-nociceptive fibers from skin and muscles, have been found to contribute to LLFR activation. Since the threshold of the RIII reflex has been shown to correspond to the pain threshold and the size of the reflex to be related to the level of pain perception, it has been suggested that the RIII reflex might constitute a useful tool to investigate pain processing at spinal and supraspinal level, pharmacological modulation and pathological pain conditions. As stated in EFNS guidelines, the RIII reflex is the most widely used of all the nociceptive reflexes, and appears to be the most reliable in the assessment of treatment efficacy. However, the RIII reflex use in the clinical evaluation of neuropathic pain is still limited. In addition to its nocifensive function, the LLFR seems to be linked to posture and locomotion. This may be explained by the fact that its neuronal circuitry, made up of a complex pool of interneurons, is interposed in motor control and, during movements, receives both peripheral afferents (flexion reflex afferents, FRAs) and descending commands, forming a multisensorial feedback mechanism and projecting the output to motoneurons. LLFR excitability, mediated by this complex circuitry, is finely modulated in a state- and phase-dependent manner, rather as we observe in the FR in animal models. Several studies have demonstrated that LLFR excitability may be influenced by numerous physiological conditions (menstrual cycle, stress, attention, sleep and so on) and pathological states (spinal lesions, spasticity, Wallenberg's syndrome, fibromyalgia, headaches and so on). Finally, the LLFR is modulated by several drugs and neurotransmitters. In summary, study of the LLFR in humans has proved to be an interesting functional window onto the spinal and supraspinal mechanisms of pain processing and onto the spinal neural control mechanisms operating during posture and locomotion.
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Affiliation(s)
- Giorgio Sandrini
- University Center for Adaptive Disorders and Headache, IRCCS C. Mondino Institute of Neurology Foundation, University of Pavia, Via Mondino 2, 27100 Pavia, Italy.
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Dimitrova A, Kolb FP, Elles HG, Maschke M, Gerwig M, Gizewski E, Timmann D. Cerebellar activation during leg withdrawal reflex conditioning: an fMRI study. Clin Neurophysiol 2004; 115:849-57. [PMID: 15003765 DOI: 10.1016/j.clinph.2003.11.030] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/26/2003] [Indexed: 11/15/2022]
Abstract
OBJECTIVE The aim of the present study was to examine cerebellar areas related to conditioning of the nociceptive leg withdrawal reflex using event-related functional magnetic resonance imaging (fMRI). Because of the aversive nature of the unconditioned stimulus effects of accompanying fear conditioning were expected. METHODS In 20 healthy adult subjects leg withdrawal reflex conditioning was performed using a standard delay protocol during MR-scanning. Electromyographic recordings from the anterior tibial and biceps femoris muscles were used to quantify conditioned responses. Fear-related changes of heart rate were assessed. RESULTS In the group of all subjects a significant increase of cerebellar activation was found in the anterior and posterior vermis. In the group of subjects (n=9) who showed conditioned leg withdrawal responses cerebellar activation was more pronounced in parts of the anterior vermis, which correspond to the known leg representation. In the group of subjects (n=11) who did not develop conditioned responses cerebellar activation was more pronounced in the posterolateral hemispheres. Changes of heart rate, however, did not significantly differ between groups. CONCLUSIONS Results suggest that areas within the anterior vermis are involved in conditioning of the leg withdrawal response. The present results, however, do not allow to differentiate between motor performance, learning or timing-related processes. Areas in the posterior vermis and cerebellar hemispheres may be related to concomitant fear conditioning. SIGNIFICANCE Results of the present event-related fMRI study suggest involvement of the human cerebellum in conditioning of the nociceptive leg withdrawal response.
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Affiliation(s)
- Albena Dimitrova
- Department of Neurology, University of Duisburg-Essen, Hufelandstrasse 55, 45122 Essen, Germany
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Dimitrova A, Kolb FP, Elles HG, Maschke M, Forsting M, Diener HC, Timmann D. Cerebellar responses evoked by nociceptive leg withdrawal reflex as revealed by event-related FMRI. J Neurophysiol 2003; 90:1877-86. [PMID: 12702705 DOI: 10.1152/jn.00053.2003] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The aim of the present study was to examine nociceptive leg withdrawal reflex-related areas in the human cerebellum using event-related functional brain imaging (fMRI). Knowledge about cerebellar areas involved in unconditioned limb withdrawal reflex control has some relevance in understanding data of limb withdrawal reflex conditioning studies. Sixteen healthy adult subjects participated. Nociceptive leg withdrawal reflexes were evoked by electrical stimulation of the left tibial nerve behind the medial malleolus. An event-related fMRI paradigm was applied with a total of 30 stimuli being delivered pseudorandomly during 500 consecutive MR scans. Surface electromyographic (EMG) recordings were performed from the left anterior tibial muscle. Only trials with significant reflex EMG activity were used as active events in fMRI statistical analysis. The specified contrasts compared the active event condition with rest. Leg withdrawal reflex-related areas were located within the vermis, paravermis, and lateral posterior cerebellar hemispheres bilaterally. Vermal and paravermal areas in lobules III/IV in the anterior lobe and in lobule VIII in the posterior lobe agree with the cerebellar representation of climbing and mossy fiber hindlimb afferents and voluntary leg movements. They are likely related to efferent modulation of the leg withdrawal reflex and/or sensory processing of afferent inputs from the reflex and/or the noxious stimulus. Additional activation within vermal lobule VI and hemispheral lobules VI/Crus I may be related to other pain-related processes (e.g., facial grimacing, fear, and startlelike reactions).
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Affiliation(s)
- A Dimitrova
- Department of Neurology, University of Essen, 45122 Essen, Germany
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