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Developmental Dynamics : An Official... Apr 2018Motor behaviors are precisely controlled by the integration of sensory and motor systems in the central nervous system (CNS). Proprioceptive sensory neurons, key... (Review)
Review
Motor behaviors are precisely controlled by the integration of sensory and motor systems in the central nervous system (CNS). Proprioceptive sensory neurons, key components of the sensory system, are located in the dorsal root ganglia and project axons both centrally to the spinal cord and peripherally to muscles and tendons, communicating peripheral information about the body to the CNS. Changes in muscle length detected by muscle spindles, and tension variations in tendons conveyed by Golgi tendon organs, are communicated to the CNS through group Ia /II, and Ib proprioceptive sensory afferents, respectively. Group Ib proprioceptive sensory neurons connect with motor neurons indirectly through spinal interneurons, whereas group Ia/II axons form both direct (monosynaptic) and indirect connections with motor neurons. Although monosynaptic sensory-motor circuits between spindle proprioceptive sensory neurons and motor neurons have been extensively studied since 1950s, the molecular mechanisms underlying their formation and upkeep have only recently begun to be understood. We will discuss our current understanding of the molecular foundation of monosynaptic circuit development and maintenance involving proprioceptive sensory neurons and motor neurons in the mammalian spinal cord. Developmental Dynamics 247:581-587, 2018. © 2017 Wiley Periodicals, Inc.
Topics: Animals; Central Nervous System; Humans; Motor Neurons; Proprioception; Sensory Receptor Cells; Spinal Cord
PubMed: 29226492
DOI: 10.1002/dvdy.24611 -
Neurotherapeutics : the Journal of the... Jul 2020Pain is a percept of critical importance to our daily survival. In most cases, it serves both an adaptive function by helping us respond appropriately in a potentially... (Review)
Review
Pain is a percept of critical importance to our daily survival. In most cases, it serves both an adaptive function by helping us respond appropriately in a potentially hostile environment and also a protective role by alerting us to tissue damage. Normally, it is evoked by the activation of peripheral nociceptive nerve endings and the subsequent relay of information to distinct cortical and sub-cortical regions, but under pathological conditions that result in chronic pain, it can become spontaneous. Given that one in three chronic pain patients do not respond to the treatments currently available, the need for more effective analgesics is evident. Two principal obstacles to the development of novel analgesic therapies are our limited understanding of how neuronal circuits that comprise these pain pathways transmit and modulate sensory information under normal circumstances and how these circuits change under pathological conditions leading to chronic pain states. In this review, we focus on the role of inhibitory interneurons in setting pain thresholds and, in particular, how disinhibition in the spinal dorsal horn can lead to aberrant sensory processing associated with chronic pain states.
Topics: Analgesics; Animals; Central Nervous System; Drug Delivery Systems; Humans; Interneurons; Receptors, GABA; Spinal Cord; Spinal Cord Dorsal Horn
PubMed: 33029722
DOI: 10.1007/s13311-020-00936-0 -
Current Opinion in Neurology Aug 2020Ultra-high field 7 T MRI has multiple applications for the in vivo characterization of the heterogeneous aspects underlying multiple sclerosis including the... (Review)
Review
PURPOSE OF REVIEW
Ultra-high field 7 T MRI has multiple applications for the in vivo characterization of the heterogeneous aspects underlying multiple sclerosis including the identification of cortical lesions, characterization of the different types of white matter plaques, evaluation of structures difficult to assess with conventional MRI (thalamus, cerebellum, spinal cord, meninges).
RECENT FINDINGS
The sensitivity of cortical lesion detection at 7 T is twice than at lower field MRI, especially for subpial lesions, the most common cortical lesion type in multiple sclerosis. Cortical lesion load accrual is independent of that in the white matter and predicts disability progression.Seven Tesla MRI provides details on tissue microstructure that can be used to improve white matter lesion characterization. These include the presence of a central vein, whose identification can be used to improve multiple sclerosis diagnosis, or the appearance of an iron-rich paramagnetic rim on susceptibility-weighted images, which corresponds to iron-rich microglia at the periphery of slow expanding lesions. Improvements in cerebellar and spinal cord tissue delineation and lesion characterization have also been demonstrated.
SUMMARY
Imaging at 7 T allows assessing more comprehensively the complementary pathophysiological aspects of multiple sclerosis, opening up novel perspectives for clinical and therapeutics evaluation.
Topics: Disease Progression; Humans; Magnetic Resonance Imaging; Multiple Sclerosis; Spinal Cord; White Matter
PubMed: 32657883
DOI: 10.1097/WCO.0000000000000839 -
PloS One 2015Vertebral column resection is associated with a risk of spinal cord injury. In the present study, using a goat model, we aimed to investigate the relationship between...
Vertebral column resection is associated with a risk of spinal cord injury. In the present study, using a goat model, we aimed to investigate the relationship between changes in spinal cord volume and spinal cord injury due to spinal shortening, and to quantify the spinal cord volume per 1-mm height in order to clarify a safe limit for shortening. Vertebral column resection was performed at T10 in 10 goats. The spinal cord was shortened until the somatosensory-evoked potential was decreased by 50% from the baseline amplitude or delayed by 10% relative to the baseline peak latency. A wake-up test was performed, and the goats were observed for two days postoperatively. Magnetic resonance imaging was used to measure the spinal cord volume, T10 height, disc height, osteotomy segment height, and spinal segment height pre- and postoperatively. Two of the 10 goats were excluded, and hence, only data from eight goats were analyzed. The somatosensory-evoked potential of these eight goats demonstrated meaningful changes. With regard to neurologic function, five and three goats were classified as Tarlov grades 5 and 4 at two days postoperatively. The mean shortening distance was 23.6 ± 1.51 mm, which correlated with the d-value (post-pre) of the spinal cord volume per 1-mm height of the osteotomy segment (r = 0.95, p < 0.001) and with the height of the T10 body (r = 0.79, p = 0.02). The mean d-value (post-pre) of the spinal cord volume per 1-mm height of the osteotomy segment was 142.87 ± 0.59 mm3 (range, 142.19-143.67 mm3). The limit for shortening was approximately 106% of the vertebral height. The mean volumes of the osteotomy and spinal segments did not significantly change after surgery (t = 0.310, p = 0.765 and t = 1.241, p = 0.255, respectively). Thus, our results indicate that the safe limit for shortening can be calculated using the change in spinal cord volume per 1-mm height.
Topics: Animals; Disease Models, Animal; Evoked Potentials, Somatosensory; Goats; Laminectomy; Magnetic Resonance Imaging; Organ Size; Spinal Cord; Spinal Cord Injuries; Thoracic Vertebrae
PubMed: 26001196
DOI: 10.1371/journal.pone.0127624 -
Mechanical Mapping of Spinal Cord Growth and Repair in Living Zebrafish Larvae by Brillouin Imaging.Biophysical Journal Sep 2018The mechanical properties of biological tissues are increasingly recognized as important factors in developmental and pathological processes. Most existing mechanical...
The mechanical properties of biological tissues are increasingly recognized as important factors in developmental and pathological processes. Most existing mechanical measurement techniques either necessitate destruction of the tissue for access or provide insufficient spatial resolution. Here, we show for the first time to our knowledge a systematic application of confocal Brillouin microscopy to quantitatively map the mechanical properties of spinal cord tissues during biologically relevant processes in a contact-free and nondestructive manner. Living zebrafish larvae were mechanically imaged in all anatomical planes during development and after spinal cord injury. These experiments revealed that Brillouin microscopy is capable of detecting the mechanical properties of distinct anatomical structures without interfering with the animal's natural development. The Brillouin shift within the spinal cord remained comparable during development and transiently decreased during the repair processes after spinal cord transection. By taking into account the refractive index distribution, we explicitly determined the apparent longitudinal modulus and viscosity of different larval zebrafish tissues. Importantly, mechanical properties differed between tissues in situ and in excised slices. The presented work constitutes the first step toward an in vivo assessment of spinal cord tissue mechanics during regeneration, provides a methodical basis to identify key determinants of mechanical tissue properties, and allows us to test their relative importance in combination with biochemical and genetic factors during developmental and regenerative processes.
Topics: Animals; Biomechanical Phenomena; Elasticity; Image Processing, Computer-Assisted; Larva; Mechanical Phenomena; Microscopy; Spinal Cord; Viscosity; Zebrafish
PubMed: 30122291
DOI: 10.1016/j.bpj.2018.07.027 -
Magnetic Resonance in Medicine Aug 2022To develop a wireless integrated parallel reception, excitation, and shimming (iPRES-W) coil array for simultaneous imaging and wireless localized B shimming, and to...
PURPOSE
To develop a wireless integrated parallel reception, excitation, and shimming (iPRES-W) coil array for simultaneous imaging and wireless localized B shimming, and to demonstrate its ability to correct for distortions in DTI of the spinal cord in vivo.
METHODS
A 4-channel coil array was modified to allow an RF current at the Larmor frequency and a direct current to flow on each coil element, enabling imaging and localized B shimming, respectively. One coil element was further modified to allow additional RF currents within a wireless communication band to flow on it to wirelessly control the direct currents for shimming, which were supplied from a battery pack within the scanner bore. The RF signals for imaging were transferred via conventional wired connections. Experiments were conducted to evaluate the RF, B shimming, and wireless performance of this coil design.
RESULTS
The coil modifications did not degrade the SNR. Wireless localized B shimming with the iPRES-W coil array substantially reduced the B RMSE (-57.5% on average) and DTI distortions in the spinal cord. The antenna radiation efficiency, antenna gain pattern, and battery power consumption of an iPRES-W coil measured in an anechoic chamber were minimally impacted by the introduction of a saline phantom representing tissue.
CONCLUSION
The iPRES-W coil array can perform imaging and wireless localized B shimming of the spinal cord with no SNR degradation, with minimal change in wireless performance and without any scanner modifications or additional antenna systems within the scanner bore.
Topics: Brain; Cervical Cord; Magnetic Resonance Imaging; Phantoms, Imaging; Spinal Cord
PubMed: 35468243
DOI: 10.1002/mrm.29257 -
Neuroscience Research Feb 2012Men and women exhibit differences in sexual behavior. This indicates that neural circuits within the central nervous system (CNS) that control sexual behavior differ... (Review)
Review
Men and women exhibit differences in sexual behavior. This indicates that neural circuits within the central nervous system (CNS) that control sexual behavior differ between the sexes, although differences in behavior are also influenced by sociocultural and hormonal factors. Sexual differentiation of the body and brain occurs during the embryonic and neonatal periods in humans and persists into adulthood with relatively low plasticity. Male sexual behavior is complex and depends on intrinsic and extrinsic factors, including olfactory, somatosensory and visceral cues. Many advances in our understanding of sexually dimorphic neural circuits have been achieved in animal models, but major issues are yet to be resolved. This review summarizes the sexually dimorphic nuclei controlling male sexual function in the rodent CNS and focuses on the interactions of the brain-spinal cord neural networks controlling male sexual behavior. Possible factors that relate findings from animal studies to human behavior are also discussed.
Topics: Animals; Brain; Female; Fertility; Humans; Male; Neural Pathways; Sex Characteristics; Sexual Behavior; Spinal Cord
PubMed: 22101370
DOI: 10.1016/j.neures.2011.11.002 -
Journal of Neurophysiology Dec 2017Mapping the expression of transcription factors in the mouse spinal cord has identified ten progenitor domains, four of which are cardinal classes of molecularly... (Review)
Review
Mapping the expression of transcription factors in the mouse spinal cord has identified ten progenitor domains, four of which are cardinal classes of molecularly defined, ventrally located interneurons that are integrated in the locomotor circuitry. This review focuses on the properties of these interneuronal populations and their contribution to hindlimb locomotor central pattern generation. Interneuronal populations are categorized based on their excitatory or inhibitory functions and their axonal projections as predictors of their role in locomotor rhythm generation and coordination. The synaptic connectivity and functions of these interneurons in the locomotor central pattern generators (CPGs) have been assessed by correlating their activity patterns with motor output responses to rhythmogenic neurochemicals and sensory and descending fibers stimulations as well as analyzing kinematic gait patterns in adult mice. The observed complex organization of interneurons in the locomotor CPG circuitry, some with seemingly similar physiological functions, reflects the intricate repertoire associated with mammalian motor control and is consistent with high transcriptional heterogeneity arising from cardinal interneuronal classes. This review discusses insights derived from recent studies to describe innovative approaches and limitations in experimental model systems and to identify missing links in current investigational enterprise.
Topics: Animals; Central Pattern Generators; Interneurons; Locomotion; Mice; Spinal Cord; Synaptic Potentials
PubMed: 28855288
DOI: 10.1152/jn.00322.2017 -
Current Opinion in Neurology Aug 2015This review will highlight the latest findings from neuroimaging studies that track structural and functional changes within the central nervous system at both the brain... (Review)
Review
PURPOSE OF REVIEW
This review will highlight the latest findings from neuroimaging studies that track structural and functional changes within the central nervous system at both the brain and spinal cord levels following acute human spinal cord injury (SCI). The putative, underlying biological mechanisms of structural change (e.g. degradation of neural tissue) rostral to the lesion site will be discussed in relation to animal models of SCI and their potential value in clinical studies of human SCI.
RECENT FINDINGS
Recent prospective studies in human acute SCI have begun to reveal the time-course, spatial distribution and extent of structural changes following an acute SCI and their relation to functional outcome. Adaptive changes in sensory and motor pathways above the level of the lesion have prognostic value and complement clinical readouts.
SUMMARY
The introduction of sensitive neuroimaging biomarkers will be an essential step forward in the implementation of interventional trials in which proof-of-concept is currently limited to clinical readouts, but more responsive measures are required to improve the sensitivity of clinical trials.
Topics: Animals; Brain; Humans; Recovery of Function; Spinal Cord; Spinal Cord Injuries
PubMed: 26110798
DOI: 10.1097/WCO.0000000000000224 -
Perception Jul 2022Autonomous sensory meridian response (ASMR) is a perceptual and emotional phenomenon in which specific sensory stimuli elicit a feeling of calm as well as tingling...
Autonomous sensory meridian response (ASMR) is a perceptual and emotional phenomenon in which specific sensory stimuli elicit a feeling of calm as well as tingling sensations on the scalp, neck, and shoulders. In the current study, we use fMRI to examine whether the motoric and sensory regions of the spinal cord segments associated with these body parts show increased activity during ASMR experiences. Nine individuals with ASMR completed six spinal functional magnetic resonance imaging runs while passively viewing videos. Three of the videos were shown (through pre-testing) to elicit ASMR tingles and three videos did not (i.e., control videos). The results demonstrated that ASMR-related stimuli elicited activity in dorsal (sensory) regions of spinal cord segments C1, C5, and C6; activity was observed in ventral (motoric) regions of segments C2-C8. Similar activity was not detected in response to control videos.
Topics: Emotions; Humans; Magnetic Resonance Imaging; Meridians; Spinal Cord
PubMed: 35578557
DOI: 10.1177/03010066221098964