The Experts below are selected from a list of 14352 Experts worldwide ranked by ideXlab platform
Christian Xerri - One of the best experts on this subject based on the ideXlab platform.
-
Early and Moderate Sensory Stimulation Exerts a Protective Effect on Perilesion Representations of Somatosensory Cortex after Focal Ischemic Damage
PLoS ONE, 2014Co-Authors: Christian Xerri, Yoh'i Zennou-azoguiAbstract:Previous studies have shown that intensive training within an early critical time window after focal Cortical ischemia increases the area of damaged tissue and is detrimental to behavioral recovery. We postulated that moderate stimulation initiated soon after the lesion could have protective effects on peri-infarct Cortical somatotopic representations. Therefore, we have assessed the effects of mild cutaneous stimulation delivered in an attention-demanding behavioral context on the functional organization of the perilesion somatosensory cortex using high-density electrophysiological Mapping. We compared the effects of 6-day training initiated on the 3rd day postlesion (early training; ET) to those of same-duration training started on the 8th day (delayed training; DT). Our findings confirm previous work showing that the absence of training aggravates representational loss in the perilesion zone. In addition, ET was found to be sufficient to limit expansion of the ischemic lesion and reduce tissue loss, and substantially maintain the neuronal responsiveness to tactile stimulation, thereby preserving somatotopic Map arrangement in the peri-infarct Cortical territories. By contrast, DT did not prevent tissue loss and only partially reinstated lost representations in a use-dependent manner within the spared peri-infarct Cortical area. This study differentiates the effects of early versus delayed training on perilesion tissue and Cortical Map reorganization, and underscores the neuroprotective influence of mild rehabilitative stimulation on neuronal response properties in the peri-infarct cortex during an early critical period. Citation: Xerri C, Zennou-Azogui Y (2014) Early and Moderate Sensory Stimulation Exerts a Protective Effect on Perilesion Representations of Somatosensory Cortex after Focal Ischemic Damage. PLoS ONE 9(6): e99767.
-
Plasticity of Cortical Maps Multiple Triggers for Adaptive Reorganization following Brain Damage and Spinal Cord Injury
The Neuroscientist : a review journal bringing neurobiology neurology and psychiatry, 2011Co-Authors: Christian XerriAbstract:Sensory and motor representations embedded in topographic Cortical Maps are use-dependent, dynamically maintained, and self-organizing functional mosaics that constitute idiosyncratic entities involved in perceptual and motor learning abilities. Studies of Cortical Map plasticity have substantiated the view that local reorganization of sensory and motor areas has great significance in recovery of function following brain damage or spinal cord injury. In addition, the transfer of function to distributed Cortical areas and subCortical structures represents an adaptive strategy for functional compensation. There is a growing consensus that subject-environment interactions, by continuously refining the canvas of synaptic connectivity and reshaping the anatomical and functional architecture of neural circuits, promote adaptive behavior throughout life. Taking advantage of use-dependent neural plasticity, early initiated rehabilitative procedures improve the potential for recovery.
-
differential tactile and motor recovery and Cortical Map alteration after c4 c5 spinal hemisection
Experimental Neurology, 2010Co-Authors: Marina Martinez, Christian Xerri, Maxime Delcour, Michael Russier, Yohi Zennouazogui, Jacquesolivier Coq, Jean-michel BrezunAbstract:Abstract After incomplete spinal cord injury (SCI), the adult central nervous system is spontaneously capable of substantial reorganizations that can underlie functional recovery. Most studies have focused on intraspinal reorganizations after SCI and not on the correlative Cortical remodeling. Yet, differential studies of neural correlates of the recovery of sensory and motor abilities may be conducted by segregating motor and somatosensory representations in distinct and topologically organized primary Cortical areas. This study was aimed at evaluating the effects of a cervical (C4–C5) spinal cord hemisection on sensorimotor performances and electrophysiological Maps in primary somatosensory (S1) and motor (M1) cortices in adult rats. After SCI, an enduring loss of the affected forepaw tactile sensitivity was paralleled by the abolishment of somatosensory evoked responses in the deprived forepaw area within the S1 cortex. In contrast, severe motor deficits in unilateral forelimb were partially restored over the first postoperative month, despite remnant deficits in distal movement. The overall M1 Map size was drastically reduced in SCI rats relative to intact rats. In the remaining M1 Map, the shoulder and elbow movements were over-represented, consistent with the behavioral recovery of proximal joint movements in almost all rats. By contrast, residual wrist representations were observed in M1 Maps of half of the rats that did not systematically correlate with a behavioral recovery of these joint movements. This study highlights the differential potential of ascending and descending pathways to reorganize after SCI.
-
Sensorimotor training promotes functional recovery and somatosensory Cortical Map reactivation following cervical spinal cord injury.
The European journal of neuroscience, 2009Co-Authors: Marina Martinez, Jean-michel Brezun, Yohâi Zennou-azogui, Nathalie Baril, Christian XerriAbstract:Sensorimotor activity has been shown to play a key role in functional recovery after partial spinal cord injury (SCI). Most studies in rodents have focused on the rehabilitation of hindlimb locomotor functions after thoracic or lumbar SCI, whereas forelimb motor and somatosensory abilities after cervical SCI remain largely uninvestigated, despite the high incidence of such injuries in humans. Moreover, little is known about the neurophysiological substrates of training-induced recovery in supraspinal structures. This study was aimed at evaluating the effects of a training procedure combining both motor and sensory stimulation on behavioral performance and somatosensory Cortical Map remodeling after cervical (C4-C5) spinal hemisection in rats. This SCI severely impaired both sensory and motor capacities in the ipsilateral limbs. Without training, post-lesion motor capacities gradually improved, whereas forepaw tactile abilities remained impaired. Consistently, no stimulus-evoked responses were recorded within the forepaw representational zone in the primary somatosensory (S1) cortex at 2 months after the SCI. However, our data reveal that with training started from the 7th day post-lesion, a nearly complete recovery (characterized by an early and rapid improvement of motor functions) was associated with a gradual compensation of tactile deficits. Furthermore, the recovery of tactile abilities was correlated with the areal extent of reactivation of S1 cortex forepaw representations. Rehabilitative training promoted post-lesion adaptive plasticity, probably by enhancing endogenous activity within spared spinal and supraspinal circuits and pathways sustaining sensory and motor functions. This study highlights the beneficial effect of sensorimotor training in motor improvement and its critical influence on tactile recovery after SCI.
-
Experience-dependent changes in spatiotemporal properties of cutaneous inputs remodel somatosensory Cortical Maps following skin flap rotation
European Journal of Neuroscience, 2008Co-Authors: Céline Rosselet, Yoh'i Zennou-azogui, Guy Escoffier, Fatma Kirmaci, Christian XerriAbstract:Contiguous skin surfaces that tend to be synchronously stimulated are represented in neighbouring sectors of primary somatosensory Maps. Moreover, neuronal receptive fields (RFs) are reshaped through ongoing competitive/cooperative interactions that segregate/desegregate inputs converging onto Cortical neuronal targets. The present study was designed to evaluate the influence of spatio-temporal constraints on somatotopic Map organization. A vascularized and innervated pedicle flap of the ventrum skin bearing nipples was rotated by 180 degrees . Electrophysiological Maps of ventrum skin were elaborated in the same rats at 24 h after surgery and 2 weeks after parturition. Neurones with split RFs resulting from the surgical separation of formerly adjoining skin surfaces were more numerous in non-nursing than nursing rats. RFs that included newly adjacent skin surfaces on both sides of the scar line emerged in nursing rats, suggesting that the spatial contiguity of formerly separated skin surfaces induced a fusion of their Cortical representations through nursing-induced stimulation. In addition, nursing-dependent inputs were found to reincorporate the rotated skin flap representation in an updated topographical organization of the Cortical Map. A skin territory including recipient and translocated skin areas was costimulated for 7 h, using a brushing device. Neural responses evoked by a piezoelectric-induced skin indentation before and after skin brushing confirmed the emergence of RFs crossing the scar line and contraction of non-brushed components of split RFs. Our findings provide further evidence that the spatiotemporal structure of sensory inputs changing rapidly or evolving in a natural context is critical for experience-dependent reorganization of Cortical Map topography.
Michael P Kilgard - One of the best experts on this subject based on the ideXlab platform.
-
the interval between vns tone pairings determines the extent of Cortical Map plasticity
Neuroscience, 2018Co-Authors: Michael S. Borland, William A. Vrana, Nicole A. Moreno, Pryanka Sharma, Sven Vanneste, Meghan Pantalia, Mark C Lane, Robert L Rennaker, Michael P KilgardAbstract:Abstract Repeatedly pairing vagus nerve stimulation (VNS) with a tone or movement drives highly specific and long-lasting plasticity in auditory or motor cortex, respectively. Based on this robust enhancement of plasticity, VNS paired with rehabilitative training has emerged as a potential therapy to improve recovery, even when delivered long after the neurological insult. Development of VNS delivery paradigms that reduce therapy duration and maximize efficacy would facilitate clinical translation. The goal of the current study was to determine whether primary auditory cortex (A1) plasticity can be generated more quickly by shortening the interval between VNS-tone pairing events or by delivering fewer VNS-tone pairing events. While shortening the inter-stimulus interval between VNS-tone pairing events resulted in significant A1 plasticity, reducing the number of VNS-tone pairing events failed to alter A1 responses. Additionally, shortening the inter-stimulus interval between VNS-tone pairing events failed to normalize neural and behavioral responses following acoustic trauma. Extending the interval between VNS-tone pairing events yielded comparable A1 frequency Map plasticity to the standard protocol, but did so without increasing neural excitability. These results indicate that the duration of the VNS-event pairing session is an important parameter that can be adjusted to optimize neural plasticity for different clinical needs.
-
Cortical Map Plasticity as a Function of Vagus Nerve Stimulation Intensity.
Brain stimulation, 2015Co-Authors: Michael S. Borland, William A. Vrana, Nicole A. Moreno, E.a. Fogarty, Elizabeth P. Buell, Pryanka Sharma, Michael P KilgardAbstract:Abstract Background Pairing sensory or motor events with vagus nerve stimulation (VNS) can reorganize sensory or motor cortex. Repeatedly pairing a tone with a brief period of VNS increases the proportion of primary auditory cortex (A1) responding to the frequency of the paired tone. However, the relationship between VNS intensity and Cortical Map plasticity is not known. Objective/hypothesis The primary goal of this study was to determine the range of VNS intensities that can be used to direct Cortical Map plasticity. Methods The rats were exposed to a 9 kHz tone paired with VNS at intensities of 0.4, 0.8, 1.2, or 1.6 mA. Results In rats that received moderate (0.4–0.8 mA) intensity VNS, 75% more Cortical neurons were tuned to frequencies near the paired tone frequency. A two-fold effective range is broader than expected based on previous VNS studies. Rats that received high (1.2–1.6 mA) intensity VNS had significantly fewer neurons tuned to the same frequency range compared to the moderate intensity group. Conclusion This result is consistent with previous results documenting that VNS is memory enhancing as a non-monotonic relationship of VNS intensity.
-
Cortical Map Plasticity Improves Learning but Is Not Necessary for Improved Performance
Neuron, 2011Co-Authors: Amanda C. Reed, Jonathan Riley, Ryan S. Carraway, Andres Carrasco, Claudia A. Perez, Vikram Jakkamsetti, Michael P KilgardAbstract:SUMMARY Cortical Map plasticity is believed to be a key substrate of perceptual and skill learning. In the current study, we quantified changes in perceptual ability after pairing tones with stimulation of the cholinergic nucleus basalis to induce auditory cortex Map plasticity outside of a behavioral context. Our results provide evidence that Cortical Map plasticity can enhance perceptual learning. However, auditory cortex Map plasticity fades over weeks even though tone discrimination performance remains stable. This observation is consistent with recent reports that Cortical Map expansions associated with perceptual and motor learning are followed by a period of Map renormalization without a decrement inperformance.Our results indicatethatCortical Map plasticity enhances perceptual learning, but is not necessary to maintain improved discriminative ability.
-
Cortical Map reorganization without cholinergic modulation.
Neuron, 2005Co-Authors: Michael P KilgardAbstract:Acetylcholine has been shown to modulate many forms of Cortical plasticity. New evidence indicates that reorganization of adult primary auditory cortex is still possible after removal of cholinergic inputs. This finding suggests that acetylcholine may act less as a gate and more as a gain control on Cortical plasticity.
-
Cortical Map reorganization enabled by nucleus basalis activity
Science, 1998Co-Authors: Michael P Kilgard, Michael M MerzenichAbstract:Little is known about the mechanisms that allow the cortex to selectively improve the neural representations of behaviorally important stimuli while ignoring irrelevant stimuli. Diffuse neuromodulatory systems may facilitate Cortical plasticity by acting as teachers to mark important stimuli. This study demonstrates that episodic electrical stimulation of the nucleus basalis, paired with an auditory stimulus, results in a massive progressive reorganization of the primary auditory cortex in the adult rat. Receptive field sizes can be narrowed, broadened, or left unaltered depending on specific parameters of the acoustic stimulus paired with nucleus basalis activation. This differential plasticity parallels the receptive field remodeling that results from different types of behavioral training. This result suggests that input characteristics may be able to drive appropriate alterations of receptive fields independently of explicit knowledge of the task. These findings also suggest that the basal forebrain plays an active instructional role in representational plasticity.
Tansu Celikel - One of the best experts on this subject based on the ideXlab platform.
-
Cellular diversity of the somatosensory Cortical Map plasticity
Neuroscience and biobehavioral reviews, 2017Co-Authors: Koen Kole, Wim J.j.m. Scheenen, Paul H. E. Tiesinga, Tansu CelikelAbstract:Sensory Maps are representations of the sensory epithelia in the brain. Despite the intuitive explanatory power behind sensory Maps as being neuronal precursors to sensory perception, and sensory Cortical plasticity as a neural correlate of perceptual learning, molecular mechanisms that regulate Map plasticity are not well understood. Here we perform a meta-analysis of transcriptional and translational changes during altered whisker use to nominate the major molecular correlates of experience-dependent Map plasticity in the barrel cortex. We argue that brain plasticity is a systems level response, involving all cell classes, from neuron and glia to non-neuronal cells including endothelia. Using molecular pathway analysis, we further propose a gene regulatory network that could couple activity dependent changes in neurons to adaptive changes in neurovasculature, and finally we show that transcriptional regulations observed in major brain disorders target genes that are modulated by altered sensory experience. Thus, understanding the molecular mechanisms of experience-dependent plasticity of sensory Maps might help to unravel the cellular events that shape brain plasticity in health and disease.
-
Modulation of spike timing by sensory deprivation during induction of Cortical Map plasticity
Nature neuroscience, 2004Co-Authors: Tansu Celikel, Vanessa A Szostak, Daniel E. FeldmanAbstract:Deprivation-induced plasticity of sensory Cortical Maps involves long-term potentiation (LTP) and depression (LTD) of Cortical synapses, but how sensory deprivation triggers LTP and LTD in vivo is unknown. Here we tested whether spike timing-dependent forms of LTP and LTD are involved in this process. We measured spike trains from neurons in layer 4 (L4) and layers 2 and 3 (L2/3) of rat somatosensory cortex before and after acute whisker deprivation, a manipulation that induces whisker Map plasticity involving LTD at L4-to-L2/3 (L4-L2/3) synapses. Whisker deprivation caused an immediate reversal of firing order for most L4 and L2/3 neurons and a substantial decorrelation of spike trains, changes known to drive timing-dependent LTD at L4-L2/3 synapses in vitro. In contrast, spike rate changed only modestly. Thus, whisker deprivation is likely to drive Map plasticity by spike timing-dependent mechanisms.
-
Long-term depression induced by sensory deprivation during Cortical Map plasticity in vivo.
Nature neuroscience, 2003Co-Authors: Cara B. Allen, Tansu Celikel, Daniel E. FeldmanAbstract:Cortical Map plasticity is thought to involve long-term depression (LTD) of Cortical synapses, but direct evidence for LTD during plasticity or learning in vivo is lacking. One putative role for LTD is in the reduction of Cortical responsiveness to behaviorally irrelevant or unused sensory stimuli, a common feature of Map plasticity. Here we show that whisker deprivation, a manipulation that drives Map plasticity in rat somatosensory cortex (S1), induces detectable LTD-like depression at intraCortical excitatory synapses between Cortical layer 4 (L4) and L2/3 pyramidal neurons. This synaptic depression occluded further LTD, enhanced LTP, was column specific, and was driven in part by competition between active and inactive whiskers. The synaptic locus of LTD and these properties suggest that LTD underlies the reduction of Cortical responses to deprived whiskers, a major component of S1 Map plasticity.
Michael S. Borland - One of the best experts on this subject based on the ideXlab platform.
-
Cortical Map plasticity as a function of vagus nerve stimulation rate.
Brain stimulation, 2018Co-Authors: Elizabeth P. Buell, Michael S. Borland, K W Loerwald, C T Engineer, J M Buell, C A Kelly, I I Khan, S A Hays, M P KilgardAbstract:Repeatedly pairing a brief train of vagus nerve stimulation (VNS) with an external event can reorganize the sensory or motor cortex. A 30 Hz train of sixteen VNS pulses paired with a tone significantly increases the number of neurons in primary auditory cortex (A1) that respond to tones near the paired tone frequency. The effective range of VNS pulse rates for driving Cortical Map plasticity has not been defined. This project investigated the effects of VNS rate on Cortical plasticity. We expected that VNS pulse rate would affect the degree of plasticity caused by VNS-tone pairing. Rats received sixteen pulses of VNS delivered at a low (7.5 Hz), moderate (30 Hz), or high (120 Hz) rate paired with 9 kHz tones 300 times per day over a 20 day period. More A1 neurons responded to the paired tone frequency in rats from the moderate rate VNS group compared to naïve controls. The response strength was also increased in these rats. In contrast, rats that received high or low rate VNS failed to exhibit a significant increase in the number of neurons tuned to sounds near 9 kHz. Our results demonstrate that the degree of Cortical plasticity caused by VNS-tone pairing is an inverted-U function of VNS pulse rate. The apparent high temporal precision of VNS-tone pairing helps identify optimal VNS parameters to achieve the beneficial effects from restoration of sensory or motor function. Copyright © 2018 Elsevier Inc. All rights reserved.
-
the interval between vns tone pairings determines the extent of Cortical Map plasticity
Neuroscience, 2018Co-Authors: Michael S. Borland, William A. Vrana, Nicole A. Moreno, Pryanka Sharma, Sven Vanneste, Meghan Pantalia, Mark C Lane, Robert L Rennaker, Michael P KilgardAbstract:Abstract Repeatedly pairing vagus nerve stimulation (VNS) with a tone or movement drives highly specific and long-lasting plasticity in auditory or motor cortex, respectively. Based on this robust enhancement of plasticity, VNS paired with rehabilitative training has emerged as a potential therapy to improve recovery, even when delivered long after the neurological insult. Development of VNS delivery paradigms that reduce therapy duration and maximize efficacy would facilitate clinical translation. The goal of the current study was to determine whether primary auditory cortex (A1) plasticity can be generated more quickly by shortening the interval between VNS-tone pairing events or by delivering fewer VNS-tone pairing events. While shortening the inter-stimulus interval between VNS-tone pairing events resulted in significant A1 plasticity, reducing the number of VNS-tone pairing events failed to alter A1 responses. Additionally, shortening the inter-stimulus interval between VNS-tone pairing events failed to normalize neural and behavioral responses following acoustic trauma. Extending the interval between VNS-tone pairing events yielded comparable A1 frequency Map plasticity to the standard protocol, but did so without increasing neural excitability. These results indicate that the duration of the VNS-event pairing session is an important parameter that can be adjusted to optimize neural plasticity for different clinical needs.
-
Cortical Map Plasticity as a Function of Vagus Nerve Stimulation Intensity.
Brain stimulation, 2015Co-Authors: Michael S. Borland, William A. Vrana, Nicole A. Moreno, E.a. Fogarty, Elizabeth P. Buell, Pryanka Sharma, Michael P KilgardAbstract:Abstract Background Pairing sensory or motor events with vagus nerve stimulation (VNS) can reorganize sensory or motor cortex. Repeatedly pairing a tone with a brief period of VNS increases the proportion of primary auditory cortex (A1) responding to the frequency of the paired tone. However, the relationship between VNS intensity and Cortical Map plasticity is not known. Objective/hypothesis The primary goal of this study was to determine the range of VNS intensities that can be used to direct Cortical Map plasticity. Methods The rats were exposed to a 9 kHz tone paired with VNS at intensities of 0.4, 0.8, 1.2, or 1.6 mA. Results In rats that received moderate (0.4–0.8 mA) intensity VNS, 75% more Cortical neurons were tuned to frequencies near the paired tone frequency. A two-fold effective range is broader than expected based on previous VNS studies. Rats that received high (1.2–1.6 mA) intensity VNS had significantly fewer neurons tuned to the same frequency range compared to the moderate intensity group. Conclusion This result is consistent with previous results documenting that VNS is memory enhancing as a non-monotonic relationship of VNS intensity.
Marina Martinez - One of the best experts on this subject based on the ideXlab platform.
-
differential tactile and motor recovery and Cortical Map alteration after c4 c5 spinal hemisection
Experimental Neurology, 2010Co-Authors: Marina Martinez, Christian Xerri, Maxime Delcour, Michael Russier, Yohi Zennouazogui, Jacquesolivier Coq, Jean-michel BrezunAbstract:Abstract After incomplete spinal cord injury (SCI), the adult central nervous system is spontaneously capable of substantial reorganizations that can underlie functional recovery. Most studies have focused on intraspinal reorganizations after SCI and not on the correlative Cortical remodeling. Yet, differential studies of neural correlates of the recovery of sensory and motor abilities may be conducted by segregating motor and somatosensory representations in distinct and topologically organized primary Cortical areas. This study was aimed at evaluating the effects of a cervical (C4–C5) spinal cord hemisection on sensorimotor performances and electrophysiological Maps in primary somatosensory (S1) and motor (M1) cortices in adult rats. After SCI, an enduring loss of the affected forepaw tactile sensitivity was paralleled by the abolishment of somatosensory evoked responses in the deprived forepaw area within the S1 cortex. In contrast, severe motor deficits in unilateral forelimb were partially restored over the first postoperative month, despite remnant deficits in distal movement. The overall M1 Map size was drastically reduced in SCI rats relative to intact rats. In the remaining M1 Map, the shoulder and elbow movements were over-represented, consistent with the behavioral recovery of proximal joint movements in almost all rats. By contrast, residual wrist representations were observed in M1 Maps of half of the rats that did not systematically correlate with a behavioral recovery of these joint movements. This study highlights the differential potential of ascending and descending pathways to reorganize after SCI.
-
Sensorimotor training promotes functional recovery and somatosensory Cortical Map reactivation following cervical spinal cord injury.
The European journal of neuroscience, 2009Co-Authors: Marina Martinez, Jean-michel Brezun, Yohâi Zennou-azogui, Nathalie Baril, Christian XerriAbstract:Sensorimotor activity has been shown to play a key role in functional recovery after partial spinal cord injury (SCI). Most studies in rodents have focused on the rehabilitation of hindlimb locomotor functions after thoracic or lumbar SCI, whereas forelimb motor and somatosensory abilities after cervical SCI remain largely uninvestigated, despite the high incidence of such injuries in humans. Moreover, little is known about the neurophysiological substrates of training-induced recovery in supraspinal structures. This study was aimed at evaluating the effects of a training procedure combining both motor and sensory stimulation on behavioral performance and somatosensory Cortical Map remodeling after cervical (C4-C5) spinal hemisection in rats. This SCI severely impaired both sensory and motor capacities in the ipsilateral limbs. Without training, post-lesion motor capacities gradually improved, whereas forepaw tactile abilities remained impaired. Consistently, no stimulus-evoked responses were recorded within the forepaw representational zone in the primary somatosensory (S1) cortex at 2 months after the SCI. However, our data reveal that with training started from the 7th day post-lesion, a nearly complete recovery (characterized by an early and rapid improvement of motor functions) was associated with a gradual compensation of tactile deficits. Furthermore, the recovery of tactile abilities was correlated with the areal extent of reactivation of S1 cortex forepaw representations. Rehabilitative training promoted post-lesion adaptive plasticity, probably by enhancing endogenous activity within spared spinal and supraspinal circuits and pathways sustaining sensory and motor functions. This study highlights the beneficial effect of sensorimotor training in motor improvement and its critical influence on tactile recovery after SCI.
