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Operative Neurosurgery (Hagerstown, Md.) Feb 2021Spinal cord herniation (SCH) is a rare condition that is typically of idiopathic origin. Although SCH is mostly found in the thoracic region because of a dural defect,...
Spinal cord herniation (SCH) is a rare condition that is typically of idiopathic origin. Although SCH is mostly found in the thoracic region because of a dural defect, there are some reports of cervical SCH following surgery or trauma.1-3 Spinal cord tethering can be a result of SCH or as a standalone issue.4,5 These conditions can lead to progressive neurological deficits, including numbness, gait disturbances, and decreased muscle strength, requiring surgical correction. There are limited reports of surgical procedures for ventral SCHs. Several reports exist using a ventral approach for intradural tumors, but it is not commonly employed because of the inability to obtain adequate dural closure.6 Much of the literature on SCH comes from idiopathic and congenital cases in the thoracic spine.7,8 Posterior and posterolateral approaches for a ventral thoracic SCH have been described, as well as an anterior approach for a ventral cervical SCH.9-12 In this video, we describe a posterior approach for a ventral cervical SCH. A 38-yr-old male presented with progressive cervical myelopathy 9 yr after a C2-C3 schwannoma resection requiring an anterior approach and corpectomy of C3 with partial corpectomies of C2 and C4. A preoperative magnetic resonance imaging showed a ventrally herniated spinal cord at the top of the C3 vertebral body and below the C4 vertebral body. Informed consent was obtained. The posterior surgical approach involved a C1-C5 laminectomy, sectioning the dentate ligament, ventral cord untethering, removal of residual tumor, and placement of a ventral sling. A significant improvement in sensory and motor function was observed postoperatively.
Topics: Cervical Cord; Cervical Vertebrae; Hernia; Humans; Male; Spinal Cord Diseases
PubMed: 33372993
DOI: 10.1093/ons/opaa340 -
Neuroscience May 1982The agranular insular cortex is transitional in location and structure between the ventrally adjacent olfactory allocortex primutivus and dorsally adjacent sensory-motor...
The agranular insular cortex is transitional in location and structure between the ventrally adjacent olfactory allocortex primutivus and dorsally adjacent sensory-motor isocortex. Its ventral anterior division receives major afferent projections from olfactory areas of the limbic system (posterior primary olfactory cortex, posterolateral cortical amygdaloid nucleus and lateral entorhinal cortex) while its dorsal anterior division does so from non-olfactory limbic areas (lateral and basolateral amygdaloid nuclei). The medial segment of the mediodorsal thalamic nucleus projects to both the ventral and dorsal divisions of the agranular insular cortex, to the former from its anterior portion and to the latter from its posterior portion. Other thalamic inputs to the two divisions arise from the gelatinosus, central medial, rhomboid and parafascicular nuclei. The dorsal division, but not the ventral division, receives input from neurons in the lateral hypothalamus and posterior hypothalamus. The medial frontal cortex projects topographically and bilaterally upon both ventral and dorsal anterior insular cortex, to the former from the ventrally located medial orbital and infralimbic areas, to the latter from the dorsally-located anterior cingulate and medial precentral areas, and to both from the intermediately located prelimbic area. Similarly, the ipsilateral posterior agranular insular cortex and perirhinal cortex project in a topographic manner upon the two divisions of the agranular insular cortex. Commissural input to both divisions originates from pyramidal neurons in the respective contralateral homotopical cortical area. In each case, pyramidal neurons in layer V contribute 90% of this projection and 10% arises from layer III pyramidals. In the brainstem, the dorsal raphe nucleus projects to the ventral and dorsal divisions of the agranular insular cortex and the parabrachial nucleus projects to the dorsal division. Based on their cytoarchitecture, pattern of afferent connections and known functional properties, we consider the ventral and dorsal divisions of the agranular insular cortex to be, respectively, periallocortical and proisocortical portions of the limbic cortex.
Topics: Afferent Pathways; Amygdala; Animals; Cerebral Cortex; Corpus Callosum; Cricetinae; Dominance, Cerebral; Frontal Lobe; Gyrus Cinguli; Horseradish Peroxidase; Hypothalamus; Male; Mesocricetus; Motor Cortex; Neurons; Olfactory Bulb; Somatosensory Cortex; Thalamic Nuclei
PubMed: 7110587
DOI: 10.1016/0306-4522(82)91133-2 -
The Journal of Neuroscience : the... Sep 2001Axons from dorsal/ventral tiers of substantia nigra pars compacta (SNc), ventral tegmental area (VTA), and retrorubral field (RRF) were traced after injecting their cell...
The nigrostriatal pathway in the rat: A single-axon study of the relationship between dorsal and ventral tier nigral neurons and the striosome/matrix striatal compartments.
Axons from dorsal/ventral tiers of substantia nigra pars compacta (SNc), ventral tegmental area (VTA), and retrorubral field (RRF) were traced after injecting their cell body with biotinylated dextran amine. Fifty-three single axons were reconstructed from serial sagittal sections with a camera lucida, and mu-opiate receptor immunostaining served to differentiate the striosome/matrix striatal compartments. Most dorsal tier SNc axons terminate within the matrix of the dorsal striatum, but their patterns of arborization vary markedly; some axons innervate one specific matriceal area, whereas others arborize in multiple discontinuous loci. Some dorsal tier SNc axons also project to both striosomes and matrix. Other dorsal tier SNc axons, as well as VTA axons, innervate the ventral striatum and send collaterals to striosomes lying ventrally in the dorsal striatum or to the ventral sector of the subcallosal streak (SS). Ventral tier SNc axons arborize principally in striosomes, but some ramify in both compartments or in striosomes and the SS. Ventral tier neurons that form deep clusters in substantia nigra pars reticulata innervate principally the matrix and the SS. The amygdala and ventral pallidum receive secondary collaterals from striatal axons of dorsal/ventral tier neurons or RRF neurons. The subthalamic nucleus receives collaterals from striatal axons of SNc clustered neurons, whereas the globus pallidus gets collaterals from striatal axons of dorsal/ventral tier SNc neurons. These findings reveal that the nigrostriatal pathway is composed of several neuronal subsystems, each endowed with a widely distributed axonal arborization that allows them to exert a multifaceted influence on striatal and/or extrastriatal structures.
Topics: Animals; Axons; Biotin; Corpus Striatum; Dextrans; Female; Immunohistochemistry; Male; Neural Pathways; Neurons; Organelles; Rats; Rats, Sprague-Dawley; Receptors, Opioid, mu; Substantia Nigra
PubMed: 11549735
DOI: 10.1523/JNEUROSCI.21-18-07247.2001 -
Neurosurgical Focus: Video Oct 2023Large ventrally located spinal meningiomas are typically resected via a posterolateral or lateral approach. Optimal outcomes are associated with good preoperative...
Large ventrally located spinal meningiomas are typically resected via a posterolateral or lateral approach. Optimal outcomes are associated with good preoperative functional status (i.e., modified McCormick grade < 4), while recurrence rates may be predicted by degree and quality of resection (i.e., low Simpson grade). This video describes the operative techniques for resection of a large ventral C2 intradural extramedullary meningioma in a 71-year-old male presenting with hemibody sensory loss and abnormal gait. A paramedian approach was performed, allowing for adequate exposure and gross-total resection. The patient was discharged on postoperative day 2 and showed near-complete resolution of sensory deficits.
PubMed: 37854646
DOI: 10.3171/2023.7.FOCVID2351 -
BMC Zoology May 2022Freshwater planarians of the genus Dugesia (Platyhelminthes, Tricladida, Dugesiidae) are distributed in a major part of the Old World and Australia, although until...
BACKGROUND
Freshwater planarians of the genus Dugesia (Platyhelminthes, Tricladida, Dugesiidae) are distributed in a major part of the Old World and Australia, although until recently only very few species were known from China.
RESULTS
Two new species of Dugesia from Southern China are described on the basis of an integrative taxonomic approach. BI and ML phylogenetic trees based on the independent genes and on the concatenated dataset had similar topologies, only differing in some nodes that were weakly supported. Phylogenetic trees based on the concatenated dataset revealed that D. adunca Chen & Sluys, sp. nov. and D. tumida Chen & Sluys, sp. nov. are not closely related and belong to different clades. The two new species occupy separate long branches with high support values and, thus, are well-differentiated from their congeners. Separate species status of D. adunca and D. tumida is supported also by the genetic distances between the species included in our analysis, albeit that COI distances varied greatly among species. Dugesia adunca from Guangxi Province is characterized by the following features: living mature animals rather small; asymmetrical openings of the oviducts into the bursal canal; penis papilla with shape of an aquiline bill, albeit with a blunt tip; asymmetrical penis papilla, with a large antero-dorsal lip and a much smaller ventro-posterior lip; very large seminal vesicle, provided with trabeculae; small diaphragm; mixoploid karyotype with diploid complements of 2n = 2x = 16 and triploid complements of 2n = 3x = 24, with all chromosomes being metacentric. Dugesia tumida from Guangdong Province is characterized by a penis papilla provided with a large, symmetrical penial valve from the middle of which arises the small, distal section of the papilla; a duct intercalated between the seminal vesicle and the small diaphragm; ventrally displaced ejaculatory duct curving upwards before opening to the exterior; penis papilla highly asymmetrical, having a slim and long ventral portion and a short and stubby dorsal part; vasa deferentia separately opening into antero-dorsal portion of seminal vesicle; oviducts openings symmetrically into ventral portion of the bursal canal, near its opening into the atrium; mixoploid karyotype, with diploid chromosome portraits of 2n = 2x = 16, and triploid complements of 2n = 3x = 24, with all chromosomes being metacentric. In the context of the various kinds of mixoploidy and the sexualization of specimens, reproductive modalities within the genus Dugesia are shortly discussed.
CONCLUSION
Molecular, morphological, and karyological markers show that the two populations examined represent members of the genus Dugesia and constitute two new, distinct species.
PubMed: 37170346
DOI: 10.1186/s40850-022-00127-8 -
Journal of Neurophysiology Mar 2017Spinal cord direct current stimulation (sDCS) has the potential for promoting motor function after injury through its modulatory actions on sensory processing, reflex...
Spinal cord direct current stimulation (sDCS) has the potential for promoting motor function after injury through its modulatory actions on sensory processing, reflex functions, the motor cortex (M1) motor map, and motor output. Here we addressed systems-level mechanisms underlying sDCS neuromodulation of spinal circuits activated by M1 and peripheral forelimb electrical stimulation in anesthetized healthy rats. We determined the effects of cathodal and anodal sDCS (c- and a-sDCS) on local field potentials (LFP) and single-unit activity recorded at 32 sites simultaneously within the sixth cervical segment using a silicon multielectrode array. M1 stimulation produced distinctive dorsomedial and ventral LFP responses that showed polarity-dependent sDCS modulation. c-sDCS enhanced and a-sDCS depressed significantly ventral M1 responses; neither modulated dorsal responses significantly. Using evoked changes in β- and γ-oscillations to assay network function, c-sDCS enhanced and a-sDCS reduced oscillation power ventrally. c-sDCS increased and a-sDCS decreased background firing and firing synchrony of recorded pairs of single units. Peripheral stimulation produced a region-dependent response that showed polarity-dependent sDCS modulation. The dorsomedial LFP was unaffected by c-sDCS and weakly suppressed with a-sDCS. Peripheral-evoked unit responses showed limited polarity dependence. Our findings stress that ventral motor network behavior is enhanced by the neuromodulatory actions of c-sDCS. The combined actions of c-sDCS on M1-evoked neural responses and network behavior in the cervical spinal cord help explain the reported enhanced motor effects of this neuromodulation approach and inform the mechanisms of sDCS for promoting motor rehabilitation after spinal cord or brain injury. Spinal cord direct current stimulation (sDCS) modulates spinal functions and shows potential for neural rehabilitation after motor systems injury. Using a multichannel electrode array, we found that cathodal DCS enhanced, and anodal depressed, M1-evoked local field potentials, network oscillations, neuronal activity, and neuronal synchrony, especially in the ventral horn. With this new understanding, it is hoped that sDCS can be developed into a tunable spinal neuromodulatory tool for promoting function after brain or spinal injury.
Topics: Afferent Pathways; Analysis of Variance; Animals; Biophysics; Brain Mapping; Brain Waves; Evoked Potentials, Motor; Motor Cortex; Neurons; Rats; Rats, Sprague-Dawley; Spectrum Analysis; Spinal Cord; Spinal Cord Stimulation
PubMed: 28031400
DOI: 10.1152/jn.00584.2016 -
Research Square Jan 2023Adult neurogenesis is reduced during aging and impaired in disorders of stress, memory, and cognition though its normal function remains unclear. Moreover, a systems...
Adult neurogenesis is reduced during aging and impaired in disorders of stress, memory, and cognition though its normal function remains unclear. Moreover, a systems level understanding of how a small number of young hippocampal neurons could dramatically influence brain function is lacking. We examined whether adult neurogenesis sustains hippocampal connections cumulatively across the life span. Long-term suppression of neurogenesis as occurs during stress and aging resulted in an accelerated decline in hippocampal acetylcholine signaling and a slow and progressing emergence of profound working memory deficits. These deficits were accompanied by compensatory reorganization of cholinergic dentate gyrus inputs with increased cholinergic innervation to the ventral hippocampus and recruitment of ventrally projecting neurons by the dorsal projection. While increased cholinergic innervation was dysfunctional and corresponded to overall decreases in cholinergic levels and signaling, it could be recruited to correct the resulting memory dysfunction even in old animals. Our study demonstrates that hippocampal neurogenesis supports memory by maintaining the septohippocampal cholinergic circuit across the lifespan. It also provides a systems level explanation for the progressive nature of memory deterioration during normal and pathological aging and indicates that the brain connectome is malleable by experience.
PubMed: 36778445
DOI: 10.21203/rs.3.rs-1851645/v1 -
Schizophrenia Research Jan 2013To (a) compare the size of the dorsal and ventral striatum (caudate and putamen) in a large sample of antipsychotic-naïve individuals with schizotypal personality...
OBJECTIVE
To (a) compare the size of the dorsal and ventral striatum (caudate and putamen) in a large sample of antipsychotic-naïve individuals with schizotypal personality disorder (SPD) and healthy control participants; (b) examine symptom correlates of striatal size in SPD.
METHODS
The left and right caudate and putamen were hand-traced on structural MRI at five dorsal to ventral slice levels in 76 SPD and 148 healthy control participants. A Group×Region (caudate, putamen)×Slice (1-5: ventral, 2, 3, 4, dorsal)×Hemisphere (left, right) mixed-model MANOVA was conducted on size relative to whole brain.
RESULTS
Primary results showed that compared with the controls, the SPD group showed (a) larger bilateral putamen size overall and this enlargement was more pronounced at the most ventral and dorsal levels; in contrast, there were no between-group differences in caudate volume; (b) larger bilateral size of the striatum ventrally, averaged across the caudate and putamen. Among the SPD group, larger striatal size ventrally, particularly in the left hemisphere was associated with less severe paranoid symptoms.
CONCLUSIONS
Striatal size is abnormal in SPD and resembles that of patients with schizophrenia who respond well to antipsychotic treatment. The results suggest that striatal size may be an important endophenotype to consider when developing new pharmacological treatments and when studying factors mitigating psychosis.
Topics: Adolescent; Adult; Aged; Corpus Striatum; Female; Functional Laterality; Humans; Image Processing, Computer-Assisted; Magnetic Resonance Imaging; Male; Middle Aged; Multivariate Analysis; Putamen; Schizotypal Personality Disorder; Severity of Illness Index; Young Adult
PubMed: 23187070
DOI: 10.1016/j.schres.2012.11.003 -
Neurosurgical Focus: Video Oct 2023The surgical management of ventral upper cervical meningiomas poses significant challenges due to their deep location and limited accessibility. These tumors have the...
The surgical management of ventral upper cervical meningiomas poses significant challenges due to their deep location and limited accessibility. These tumors have the potential to compress or involve nearby neurovascular structures, leading to various neurological complications including inferior cranial nerve palsy, motor deficits, and sensory disturbances such as hypoesthesia, paresthesia, and impaired coordination. To address this issue, surgical intervention through an anterolateral or far lateral approach has been recognized as the optimal treatment strategy. In this video, the authors present a detailed demonstration of the operative technique using an anterolateral upper cervical approach to safely resect a ventrally located C1-2 meningioma.
PubMed: 37854652
DOI: 10.3171/2023.6.FOCVID2377 -
Frontiers in Neuroanatomy 2019Signals issued by dorsal roof and ventral floor plates, respectively, underlie the major patterning process of dorsalization and ventralization during vertebrate neural...
Signals issued by dorsal roof and ventral floor plates, respectively, underlie the major patterning process of dorsalization and ventralization during vertebrate neural tube development. The ventrally produced morphogen Sonic hedgehog (SHH) is crucial for vertebrate hindbrain and spinal motor neuron development. One diagnostic gene for motor neurons is the LIM/homeodomain gene , which has additional ventral expression domains extending into mid- and forebrain. In order to corroborate motor neuron development and, in particular, to improve on the identification of poorly documented zebrafish forebrain populations, we studied adult brains of transgenic -GFP zebrafish (3 and 6 months). This molecular neuroanatomical analysis was supported by immunostaining these brains for tyrosine hydroxylase (TH) or choline acetyltransferase (ChAT), respectively, revealing zebrafish catecholaminergic and cholinergic neurons. The present analysis of ChAT and -GFP label confirms ongoing adult expression of in zebrafish (basal plate) midbrain, hindbrain, and spinal motor neurons. In contrast, non-motor cholinergic systems lack expression. Additional presumed basal plate positive systems are described in detail, aided by TH staining which is particularly informative in the diencephalon. Finally, alar plate zebrafish forebrain systems with expression are described (i.e., thalamus, preoptic region, and subpallium). We conclude that adult zebrafish continue to express in the same brain systems as in the larva. Further, pending functional confirmation we hypothesize that the larval expression of () might causally underlie much of adult expression because it explains findings beyond ventrally located systems, for example regarding expression in the zona limitans intrathalamica and correlated -GFP expression in the thalamus.
PubMed: 30863287
DOI: 10.3389/fnana.2019.00019