The Experts below are selected from a list of 240 Experts worldwide ranked by ideXlab platform
Guglielmo Foffani - One of the best experts on this subject based on the ideXlab platform.
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Spinal direct current stimulation modulates the activity of Gracile Nucleus and primary somatosensory cortex in anaesthetized rats.
The Journal of Physiology, 2011Co-Authors: J. Aguilar, F Pulecchi, Antonio Oliviero, Robertino Dilena, Guglielmo FoffaniAbstract:Non-Technical Summary Stimulation of the human brain with direct current is a simple but effective neuromodulation technique that is becoming increasingly popular due to its potentiality for non-invasively treating a variety of neurological and neuropsychiatric disorders. Recently, this neuromodulation technique has been extended to the stimulation of the human spinal cord. Here we investigated the mechanisms of action of spinal direct current stimulation (sDCS) in anaesthetized rats. We found that sDCS can selectively modulate the spontaneous activity entering the brain through the spinal cord via the somatosensory system, consequently modulating both the internal state of the brain and its responsiveness to external somatosensory stimuli. These findings have at least two levels of significance: from a physiological perspective, they remark on the importance of the spinal cord in regulating the state of the brain; from a clinical perspective, they offer a mechanistic rationale for the development of sDCS as an effective bottom-up neuromodulation technique. Abstract Afferent somatosensory activity from the spinal cord has a profound impact on the activity of the brain. Here we investigated the effects of spinal stimulation using direct current, delivered at the thoracic level, on the spontaneous activity and on the somatosensory evoked potentials of the Gracile Nucleus, which is the main entry point for hindpaw somatosensory signals reaching the brain from the dorsal columns, and of the primary somatosensory cortex in anaesthetized rats. Anodal spinal direct current stimulation (sDCS) increased the spontaneous activity and decreased the amplitude of evoked responses in the Gracile Nucleus, whereas cathodal sDCS produced the opposite effects. At the level of the primary somatosensory cortex, the changes in spontaneous activity induced by sDCS were consistent with the effects observed in the Gracile Nucleus, but the changes in cortical evoked responses were more variable and state dependent. Therefore, sDCS can modulate in a polarity-specific manner the supraspinal activity of the somatosensory system, offering a versatile bottom-up neuromodulation technique that could potentially be useful in a number of clinical applications.
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Spinal direct current stimulation modulates the activity of Gracile Nucleus and primary somatosensory cortex in anaesthetized rats.
The Journal of physiology, 2011Co-Authors: J. Aguilar, F Pulecchi, Antonio Oliviero, Robertino Dilena, Alberto Priori, Guglielmo FoffaniAbstract:Afferent somatosensory activity from the spinal cord has a profound impact on the activity of the brain. Here we investigated the effects of spinal stimulation using direct current, delivered at the thoracic level, on the spontaneous activity and on the somatosensory evoked potentials of the Gracile Nucleus, which is the main entry point for hindpaw somatosensory signals reaching the brain from the dorsal columns, and of the primary somatosensory cortex in anaesthetized rats. Anodal spinal direct current stimulation (sDCS) increased the spontaneous activity and decreased the amplitude of evoked responses in the Gracile Nucleus, whereas cathodal sDCS produced the opposite effects. At the level of the primary somatosensory cortex, the changes in spontaneous activity induced by sDCS were consistent with the effects observed in the Gracile Nucleus, but the changes in cortical evoked responses were more variable and state dependent. Therefore, sDCS can modulate in a polarity-specific manner the supraspinal activity of the somatosensory system, offering a versatile bottom-up neuromodulation technique that could potentially be useful in a number of clinical applications.
Koichi Noguchi - One of the best experts on this subject based on the ideXlab platform.
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de novo expression of nav1 7 in injured putative proprioceptive afferents multiple tetrodotoxin sensitive sodium channels are retained in the rat dorsal root after spinal nerve ligation
Neuroscience, 2015Co-Authors: Tetsuo Fukuoka, Kan Miyoshi, Koichi NoguchiAbstract:Tetrodotoxin-sensitive (TTX-s) spontaneous activity is recorded from the dorsal roots after peripheral nerve injury. Primary sensory neurons in the dorsal root ganglion (DRG) express multiple TTX-s voltage-gated sodium channel α-subunits (Navs). Since Nav1.3 increases, whereas all other Navs decrease, in the DRG neurons after peripheral nerve lesion, Nav1.3 is proposed to be critical for the generation of these spontaneous discharges and the contributions of other Navs have been ignored. Here, we re-evaluate the changes in expression of three other TTX-s Navs, Nav1.1, Nav1.6 and Nav1.7, in the injured 5th lumbar (L5) primary afferent components following L5 spinal nerve ligation (SNL) using in situ hybridization histochemistry and immunohistochemistry. While the overall signal intensities for these Nav mRNAs decreased, many injured DRG neurons still expressed these transcripts at clearly detectable levels. All these Nav proteins accumulated at the proximal stump of the ligated L5 spinal nerve. The immunostaining patterns of Nav1.6 and Nav1.7 associated with the nodes of Ranvier were maintained in the ipsilateral L5 dorsal root. Interestingly, putative proprioceptive neurons characterized by α3 Na+/K+ ATPase-immunostaining specifically lacked Nav1.7 mRNA in naive DRG but displayed de novo expression of this transcript following SNL. Nav1.7-immunoreactive fibers were significantly increased in the ipsilateral Gracile Nucleus where central axonal branches of the injured A-fiber afferents terminated. These data indicate that multiple TTX-s channel subunits could contribute to the generation and propagation of the spontaneous discharges in the injured primary afferents. Specifically, Nav1.7 may cause some functional changes in sensory processing in the Gracile Nucleus after peripheral nerve injury.
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dorsal column thalamic pathway is involved in thalamic hyperexcitability following peripheral nerve injury a lesion study in rats with experimental mononeuropathy
Pain, 2000Co-Authors: K. Miki, Koichi Iwata, Yoshiyuki Tsuboi, Toshifumi Morimoto, Eiji Kondo, Yi Dai, Ke Ren, Koichi NoguchiAbstract:A total of 68 neurons were recorded from the ventro-postero-lateral Nucleus of thalamus (VPL) in rats with a unilateral chronic constriction injury (CCI) of the sciatic nerve (n=20), sham operation (n=24) and naive rats (n=24), and effects of the lesion of dorsal column (DC) pathway [DC lesion or DC+Gracile Nucleus lesions] on VPL Nucleus neuronal activities were studied. In the VPL Nucleus contralateral to the CCI (receiving input from the injured nerve), response latencies of low threshold mechanoreceptive (LTM) and wide dynamic range (WDR) neurons to electrical stimulation of the sciatic nerve were significantly longer than that in the contralateral VPL Nucleus receiving input from the sham-operated side (P 0.05). Background activity of WDR neurons was significantly higher in the VPL Nucleus contralateral to the CCI side when compared to neurons in the VPL Nucleus contralateral to the sham operated side and in naive animals. Responses of LTM and WDR neurons to innocuous mechanical stimulation of the receptive fields were significantly decreased after DC and DC+Gracile Nucleus lesions in all animals. However, the responses of WDR neurons to noxious stimuli were selectively reduced only in rats with CCI by DC and DC+Gracile Nucleus lesions (P<0.05). The decrease in noxious stimulus-evoked responses of WDR neurons in the VPL Nucleus contralateral to the CCI side after DC and DC+Gracile Nucleus lesions was greater than that in the VPL Nucleus contralateral to the sham operated side and naive animals. These results indicated that DC and DC+Gracile Nucleus lesions produced selective and stronger effect on noxious responses of VPL Nucleus WDR neurons receiving input from the site of nerve injury. The findings suggest that the Gracile Nucleus-thalamic pathway conveys, or modulates, nociceptive information to the VPL Nucleus following peripheral nerve injury, resulting in an increase in VPL Nucleus response to noxious stimuli that contributes to the development of mechanical hyperalgesia.
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calcitonin gene related peptide increase in the rat spinal dorsal horn and dorsal column Nucleus following peripheral nerve injury up regulation in a subpopulation of primary afferent sensory neurons
Neuroscience, 1997Co-Authors: K. Miki, Tetsuo Fukuoka, Koichi NoguchiAbstract:Abstract Calcitonin gene-related peptide in sensory primary afferent neurons has an excitatory effect on postsynaptic neurons and potentiates the effect of substance P in the rat spinal dorsal horn. It has been established that calcitonin gene-related peptide expression in dorsal root ganglion neurons is depressed, and the effect of calcitonin gene-related peptide on dorsal horn neurons is attenuated, following peripheral nerve injury. We report here that a subpopulation of injured dorsal root ganglion neurons show increased expression of calcitonin gene-related peptide. Using in situ hybridization and the retrograde tracer, FluoroGold, we detected an increased number of medium- to large-sized rat dorsal root ganglion neurons projecting to the Gracile Nucleus that expressed α -calcitonin gene-related peptide messenger RNA following spinal nerve transection. Immunohistochemistry revealed a significant increase in calcitonin gene-related peptide immunoreactivity in the Gracile Nucleus and in laminae III–IV of the spinal dorsal horn. These results indicate that a subpopulation of dorsal root ganglion neurons express α -calcitonin gene-related peptide messenger RNA in response to peripheral nerve injury, and transport this peptide to the Gracile Nucleus and to laminae III–IV of the spinal dorsal horn. The increase of the excitatory neuropeptide, calcitonin gene-related peptide, in sites of primary afferent termination may affect the excitability of postsynaptic neurons, and have a role in neuronal plasticity following peripheral nerve injury.
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substance p induced by peripheral nerve injury in primary afferent sensory neurons and its effect on dorsal column Nucleus neurons
The Journal of Neuroscience, 1995Co-Authors: Koichi Noguchi, Y. Kawai, Emiko Senba, Tetsuo Fukuoka, K. MikiAbstract:Using in situ hybridization and the retrograde tracer, Fluorogold, we examined the expression of preprotachykinin (PPT) mRNA in the rat dorsal root ganglion neurons projecting to the Gracile Nucleus. Seven days after unilateral sciatic nerve transection, some medium- to large- sized neurons in the rat dorsal root ganglia projecting to the Gracile Nucleus express PPT mRNA, whereas very few Gracile Nucleus-projecting neurons on the contralateral side express PPT mRNA. Immunohistochemistry revealed an increase in substance P (SP) immunoreactivity in the Gracile Nucleus and large myelinated fibers in the dorsal root 2 weeks after unilateral sciatic nerve transection. The results suggest that medium to large DRG cells that project to the Gracile Nucleus express PPT mRNA de novo in response to peripheral nerve injury, and increased SP is transported to the Gracile Nucleus through large myelinated fibers. To determine whether the increased SP might affect the excitability of the Gracile Nucleus neurons postsynaptically, Fos expression after electrical stimulation of the injured sciatic nerve was examined. Multiple injections of the NK-1 receptor antagonist, CP-96,345, suppressed stimulus-induced Fos expression in Gracile Nucleus neurons including thalamic relay neurons. The inactive enantiomer, CP-96,344, had no effect on stimulus-induced Fos expression. These data indicate that the de novo synthesized SP in the lesioned primary afferent neurons may be involved in an augmentation of excitability in the dorsal column-medial lemniscus sensory pathway. This hyperexcitability may play a role in the pathogenesis of abnormal neuropathic sensations following peripheral nerve injury.
J. Aguilar - One of the best experts on this subject based on the ideXlab platform.
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Spinal direct current stimulation modulates the activity of Gracile Nucleus and primary somatosensory cortex in anaesthetized rats.
The Journal of Physiology, 2011Co-Authors: J. Aguilar, F Pulecchi, Antonio Oliviero, Robertino Dilena, Guglielmo FoffaniAbstract:Non-Technical Summary Stimulation of the human brain with direct current is a simple but effective neuromodulation technique that is becoming increasingly popular due to its potentiality for non-invasively treating a variety of neurological and neuropsychiatric disorders. Recently, this neuromodulation technique has been extended to the stimulation of the human spinal cord. Here we investigated the mechanisms of action of spinal direct current stimulation (sDCS) in anaesthetized rats. We found that sDCS can selectively modulate the spontaneous activity entering the brain through the spinal cord via the somatosensory system, consequently modulating both the internal state of the brain and its responsiveness to external somatosensory stimuli. These findings have at least two levels of significance: from a physiological perspective, they remark on the importance of the spinal cord in regulating the state of the brain; from a clinical perspective, they offer a mechanistic rationale for the development of sDCS as an effective bottom-up neuromodulation technique. Abstract Afferent somatosensory activity from the spinal cord has a profound impact on the activity of the brain. Here we investigated the effects of spinal stimulation using direct current, delivered at the thoracic level, on the spontaneous activity and on the somatosensory evoked potentials of the Gracile Nucleus, which is the main entry point for hindpaw somatosensory signals reaching the brain from the dorsal columns, and of the primary somatosensory cortex in anaesthetized rats. Anodal spinal direct current stimulation (sDCS) increased the spontaneous activity and decreased the amplitude of evoked responses in the Gracile Nucleus, whereas cathodal sDCS produced the opposite effects. At the level of the primary somatosensory cortex, the changes in spontaneous activity induced by sDCS were consistent with the effects observed in the Gracile Nucleus, but the changes in cortical evoked responses were more variable and state dependent. Therefore, sDCS can modulate in a polarity-specific manner the supraspinal activity of the somatosensory system, offering a versatile bottom-up neuromodulation technique that could potentially be useful in a number of clinical applications.
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Spinal direct current stimulation modulates the activity of Gracile Nucleus and primary somatosensory cortex in anaesthetized rats.
The Journal of physiology, 2011Co-Authors: J. Aguilar, F Pulecchi, Antonio Oliviero, Robertino Dilena, Alberto Priori, Guglielmo FoffaniAbstract:Afferent somatosensory activity from the spinal cord has a profound impact on the activity of the brain. Here we investigated the effects of spinal stimulation using direct current, delivered at the thoracic level, on the spontaneous activity and on the somatosensory evoked potentials of the Gracile Nucleus, which is the main entry point for hindpaw somatosensory signals reaching the brain from the dorsal columns, and of the primary somatosensory cortex in anaesthetized rats. Anodal spinal direct current stimulation (sDCS) increased the spontaneous activity and decreased the amplitude of evoked responses in the Gracile Nucleus, whereas cathodal sDCS produced the opposite effects. At the level of the primary somatosensory cortex, the changes in spontaneous activity induced by sDCS were consistent with the effects observed in the Gracile Nucleus, but the changes in cortical evoked responses were more variable and state dependent. Therefore, sDCS can modulate in a polarity-specific manner the supraspinal activity of the somatosensory system, offering a versatile bottom-up neuromodulation technique that could potentially be useful in a number of clinical applications.
K. Miki - One of the best experts on this subject based on the ideXlab platform.
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dorsal column thalamic pathway is involved in thalamic hyperexcitability following peripheral nerve injury a lesion study in rats with experimental mononeuropathy
Pain, 2000Co-Authors: K. Miki, Koichi Iwata, Yoshiyuki Tsuboi, Toshifumi Morimoto, Eiji Kondo, Yi Dai, Ke Ren, Koichi NoguchiAbstract:A total of 68 neurons were recorded from the ventro-postero-lateral Nucleus of thalamus (VPL) in rats with a unilateral chronic constriction injury (CCI) of the sciatic nerve (n=20), sham operation (n=24) and naive rats (n=24), and effects of the lesion of dorsal column (DC) pathway [DC lesion or DC+Gracile Nucleus lesions] on VPL Nucleus neuronal activities were studied. In the VPL Nucleus contralateral to the CCI (receiving input from the injured nerve), response latencies of low threshold mechanoreceptive (LTM) and wide dynamic range (WDR) neurons to electrical stimulation of the sciatic nerve were significantly longer than that in the contralateral VPL Nucleus receiving input from the sham-operated side (P 0.05). Background activity of WDR neurons was significantly higher in the VPL Nucleus contralateral to the CCI side when compared to neurons in the VPL Nucleus contralateral to the sham operated side and in naive animals. Responses of LTM and WDR neurons to innocuous mechanical stimulation of the receptive fields were significantly decreased after DC and DC+Gracile Nucleus lesions in all animals. However, the responses of WDR neurons to noxious stimuli were selectively reduced only in rats with CCI by DC and DC+Gracile Nucleus lesions (P<0.05). The decrease in noxious stimulus-evoked responses of WDR neurons in the VPL Nucleus contralateral to the CCI side after DC and DC+Gracile Nucleus lesions was greater than that in the VPL Nucleus contralateral to the sham operated side and naive animals. These results indicated that DC and DC+Gracile Nucleus lesions produced selective and stronger effect on noxious responses of VPL Nucleus WDR neurons receiving input from the site of nerve injury. The findings suggest that the Gracile Nucleus-thalamic pathway conveys, or modulates, nociceptive information to the VPL Nucleus following peripheral nerve injury, resulting in an increase in VPL Nucleus response to noxious stimuli that contributes to the development of mechanical hyperalgesia.
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calcitonin gene related peptide increase in the rat spinal dorsal horn and dorsal column Nucleus following peripheral nerve injury up regulation in a subpopulation of primary afferent sensory neurons
Neuroscience, 1997Co-Authors: K. Miki, Tetsuo Fukuoka, Koichi NoguchiAbstract:Abstract Calcitonin gene-related peptide in sensory primary afferent neurons has an excitatory effect on postsynaptic neurons and potentiates the effect of substance P in the rat spinal dorsal horn. It has been established that calcitonin gene-related peptide expression in dorsal root ganglion neurons is depressed, and the effect of calcitonin gene-related peptide on dorsal horn neurons is attenuated, following peripheral nerve injury. We report here that a subpopulation of injured dorsal root ganglion neurons show increased expression of calcitonin gene-related peptide. Using in situ hybridization and the retrograde tracer, FluoroGold, we detected an increased number of medium- to large-sized rat dorsal root ganglion neurons projecting to the Gracile Nucleus that expressed α -calcitonin gene-related peptide messenger RNA following spinal nerve transection. Immunohistochemistry revealed a significant increase in calcitonin gene-related peptide immunoreactivity in the Gracile Nucleus and in laminae III–IV of the spinal dorsal horn. These results indicate that a subpopulation of dorsal root ganglion neurons express α -calcitonin gene-related peptide messenger RNA in response to peripheral nerve injury, and transport this peptide to the Gracile Nucleus and to laminae III–IV of the spinal dorsal horn. The increase of the excitatory neuropeptide, calcitonin gene-related peptide, in sites of primary afferent termination may affect the excitability of postsynaptic neurons, and have a role in neuronal plasticity following peripheral nerve injury.
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substance p induced by peripheral nerve injury in primary afferent sensory neurons and its effect on dorsal column Nucleus neurons
The Journal of Neuroscience, 1995Co-Authors: Koichi Noguchi, Y. Kawai, Emiko Senba, Tetsuo Fukuoka, K. MikiAbstract:Using in situ hybridization and the retrograde tracer, Fluorogold, we examined the expression of preprotachykinin (PPT) mRNA in the rat dorsal root ganglion neurons projecting to the Gracile Nucleus. Seven days after unilateral sciatic nerve transection, some medium- to large- sized neurons in the rat dorsal root ganglia projecting to the Gracile Nucleus express PPT mRNA, whereas very few Gracile Nucleus-projecting neurons on the contralateral side express PPT mRNA. Immunohistochemistry revealed an increase in substance P (SP) immunoreactivity in the Gracile Nucleus and large myelinated fibers in the dorsal root 2 weeks after unilateral sciatic nerve transection. The results suggest that medium to large DRG cells that project to the Gracile Nucleus express PPT mRNA de novo in response to peripheral nerve injury, and increased SP is transported to the Gracile Nucleus through large myelinated fibers. To determine whether the increased SP might affect the excitability of the Gracile Nucleus neurons postsynaptically, Fos expression after electrical stimulation of the injured sciatic nerve was examined. Multiple injections of the NK-1 receptor antagonist, CP-96,345, suppressed stimulus-induced Fos expression in Gracile Nucleus neurons including thalamic relay neurons. The inactive enantiomer, CP-96,344, had no effect on stimulus-induced Fos expression. These data indicate that the de novo synthesized SP in the lesioned primary afferent neurons may be involved in an augmentation of excitability in the dorsal column-medial lemniscus sensory pathway. This hyperexcitability may play a role in the pathogenesis of abnormal neuropathic sensations following peripheral nerve injury.
Robertino Dilena - One of the best experts on this subject based on the ideXlab platform.
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Spinal direct current stimulation modulates the activity of Gracile Nucleus and primary somatosensory cortex in anaesthetized rats.
The Journal of Physiology, 2011Co-Authors: J. Aguilar, F Pulecchi, Antonio Oliviero, Robertino Dilena, Guglielmo FoffaniAbstract:Non-Technical Summary Stimulation of the human brain with direct current is a simple but effective neuromodulation technique that is becoming increasingly popular due to its potentiality for non-invasively treating a variety of neurological and neuropsychiatric disorders. Recently, this neuromodulation technique has been extended to the stimulation of the human spinal cord. Here we investigated the mechanisms of action of spinal direct current stimulation (sDCS) in anaesthetized rats. We found that sDCS can selectively modulate the spontaneous activity entering the brain through the spinal cord via the somatosensory system, consequently modulating both the internal state of the brain and its responsiveness to external somatosensory stimuli. These findings have at least two levels of significance: from a physiological perspective, they remark on the importance of the spinal cord in regulating the state of the brain; from a clinical perspective, they offer a mechanistic rationale for the development of sDCS as an effective bottom-up neuromodulation technique. Abstract Afferent somatosensory activity from the spinal cord has a profound impact on the activity of the brain. Here we investigated the effects of spinal stimulation using direct current, delivered at the thoracic level, on the spontaneous activity and on the somatosensory evoked potentials of the Gracile Nucleus, which is the main entry point for hindpaw somatosensory signals reaching the brain from the dorsal columns, and of the primary somatosensory cortex in anaesthetized rats. Anodal spinal direct current stimulation (sDCS) increased the spontaneous activity and decreased the amplitude of evoked responses in the Gracile Nucleus, whereas cathodal sDCS produced the opposite effects. At the level of the primary somatosensory cortex, the changes in spontaneous activity induced by sDCS were consistent with the effects observed in the Gracile Nucleus, but the changes in cortical evoked responses were more variable and state dependent. Therefore, sDCS can modulate in a polarity-specific manner the supraspinal activity of the somatosensory system, offering a versatile bottom-up neuromodulation technique that could potentially be useful in a number of clinical applications.
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Spinal direct current stimulation modulates the activity of Gracile Nucleus and primary somatosensory cortex in anaesthetized rats.
The Journal of physiology, 2011Co-Authors: J. Aguilar, F Pulecchi, Antonio Oliviero, Robertino Dilena, Alberto Priori, Guglielmo FoffaniAbstract:Afferent somatosensory activity from the spinal cord has a profound impact on the activity of the brain. Here we investigated the effects of spinal stimulation using direct current, delivered at the thoracic level, on the spontaneous activity and on the somatosensory evoked potentials of the Gracile Nucleus, which is the main entry point for hindpaw somatosensory signals reaching the brain from the dorsal columns, and of the primary somatosensory cortex in anaesthetized rats. Anodal spinal direct current stimulation (sDCS) increased the spontaneous activity and decreased the amplitude of evoked responses in the Gracile Nucleus, whereas cathodal sDCS produced the opposite effects. At the level of the primary somatosensory cortex, the changes in spontaneous activity induced by sDCS were consistent with the effects observed in the Gracile Nucleus, but the changes in cortical evoked responses were more variable and state dependent. Therefore, sDCS can modulate in a polarity-specific manner the supraspinal activity of the somatosensory system, offering a versatile bottom-up neuromodulation technique that could potentially be useful in a number of clinical applications.
