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Cerebral Cortex (New York, N.Y. : 1991) Nov 2023A multi-scale approach elucidated the origin of the error-related-negativity (ERN), with its associated theta-rhythm, and the post-error-positivity (Pe) in macaque...
A multi-scale approach elucidated the origin of the error-related-negativity (ERN), with its associated theta-rhythm, and the post-error-positivity (Pe) in macaque supplementary eye field (SEF). Using biophysical modeling, synaptic inputs to a subpopulation of layer-3 (L3) and layer-5 (L5) pyramidal cells (PCs) were optimized to reproduce error-related spiking modulation and inter-spike intervals. The intrinsic dynamics of dendrites in L5 but not L3 error PCs generate theta rhythmicity with random phases. Saccades synchronized the phases of the theta-rhythm, which was magnified on errors. Contributions from error PCs to the laminar current source density (CSD) observed in SEF were negligible and could not explain the observed association between error-related spiking modulation in L3 PCs and scalp-EEG. CSD from recorded laminar field potentials in SEF was comprised of multipolar components, with monopoles indicating strong electro-diffusion, dendritic/axonal electrotonic current leakage outside SEF, or violations of the model assumptions. Our results also demonstrate the involvement of secondary cortical regions, in addition to SEF, particularly for the later Pe component. The dipolar component from the observed CSD paralleled the ERN dynamics, while the quadrupolar component paralleled the Pe. These results provide the most advanced explanation to date of the cellular mechanisms generating the ERN.
Topics: Animals; Electroencephalography; Theta Rhythm; Pyramidal Cells; Frontal Lobe; Axons; Macaca; Evoked Potentials
PubMed: 37804250
DOI: 10.1093/cercor/bhad367 -
Neuroscience Bulletin Nov 2023Epilepsy is a common, chronic neurological disorder that has been associated with impaired neurodevelopment and immunity. The chemokine receptor CXCR5 is involved in...
Epilepsy is a common, chronic neurological disorder that has been associated with impaired neurodevelopment and immunity. The chemokine receptor CXCR5 is involved in seizures via an unknown mechanism. Here, we first determined the expression pattern and distribution of the CXCR5 gene in the mouse brain during different stages of development and the brain tissue of patients with epilepsy. Subsequently, we found that the knockdown of CXCR5 increased the susceptibility of mice to pentylenetetrazol- and kainic acid-induced seizures, whereas CXCR5 overexpression had the opposite effect. CXCR5 knockdown in mouse embryos via viral vector electrotransfer negatively influenced the motility and multipolar-to-bipolar transition of migratory neurons. Using a human-derived induced an in vitro multipotential stem cell neurodevelopmental model, we determined that CXCR5 regulates neuronal migration and polarization by stabilizing the actin cytoskeleton during various stages of neurodevelopment. Electrophysiological experiments demonstrated that the knockdown of CXCR5 induced neuronal hyperexcitability, resulting in an increased number of seizures. Finally, our results suggested that CXCR5 deficiency triggers seizure-related electrical activity through a previously unknown mechanism, namely, the disruption of neuronal polarity.
Topics: Animals; Humans; Mice; Actin Cytoskeleton; Actins; Epilepsy; Neurons; Receptors, CXCR5; Seizures
PubMed: 37460877
DOI: 10.1007/s12264-023-01087-w -
ELife Mar 2024Radial neuronal migration is a key neurodevelopmental event for proper cortical laminar organization. The multipolar-to-bipolar transition, a critical step in...
Radial neuronal migration is a key neurodevelopmental event for proper cortical laminar organization. The multipolar-to-bipolar transition, a critical step in establishing neuronal polarity during radial migration, occurs in the subplate/intermediate zone (SP/IZ), a distinct region of the embryonic cerebral cortex. It has been known that the extracellular matrix (ECM) molecules are enriched in the SP/IZ. However, the molecular constitution and functions of the ECM formed in this region remain poorly understood. Here, we identified neurocan (NCAN) as a major chondroitin sulfate proteoglycan in the mouse SP/IZ. NCAN binds to both radial glial-cell-derived tenascin-C (TNC) and hyaluronan (HA), a large linear polysaccharide, forming a ternary complex of NCAN, TNC, and HA in the SP/IZ. Developing cortical neurons make contact with the ternary complex during migration. The enzymatic or genetic disruption of the ternary complex impairs radial migration by suppressing the multipolar-to-bipolar transition. Furthermore, both TNC and NCAN promoted the morphological maturation of cortical neurons in vitro. The present results provide evidence for the cooperative role of neuron- and radial glial-cell-derived ECM molecules in cortical development.
Topics: Animals; Mice; Neurons; Extracellular Matrix; Cerebral Cortex; Cell Movement; Chondroitin Sulfate Proteoglycans
PubMed: 38512724
DOI: 10.7554/eLife.92342 -
Clinical Neurophysiology : Official... Aug 2023Reconstruct compound median nerve action currents using magnetoneurography to clarify the physiological characteristics of axonal and volume currents and their...
OBJECTIVE
Reconstruct compound median nerve action currents using magnetoneurography to clarify the physiological characteristics of axonal and volume currents and their relationship to potentials.
METHODS
The median nerves of both upper arms of five healthy individuals were investigated. The propagating magnetic field of the action potential was recorded using magnetoneurography, reconstructed into a current, and analyzed. The currents were compared with the potentials recorded from multipolar surface electrodes.
RESULTS
Reconstructed currents could be clearly visualized. Axonal currents flowed forward or backward in the axon, arcing away from the depolarization zone, turning about the subcutaneous volume conductor, and returning to the depolarization zone. The zero-crossing latency of the axonal current was approximately the same as the peak of its volume current and the negative peak of the surface electrode potential. Volume current waveforms were proportional to the derivative of axonal ones.
CONCLUSIONS
Magnetoneurography allows the visualization and quantitative evaluation of action currents. The currents in axons and in volume conductors could be clearly discriminated with good quality. Their properties were consistent with previous neurophysiological findings.
SIGNIFICANCE
Magnetoneurography could be a novel tool for elucidating nerve physiology and pathophysiology.
Topics: Humans; Action Potentials; Median Nerve; Axons; Evoked Potentials; Magnetic Fields; Electric Stimulation
PubMed: 37307628
DOI: 10.1016/j.clinph.2023.05.006 -
Advanced Science (Weinheim,... Jun 2024The physiological interactions between the peripheral and central auditory systems are crucial for auditory information transmission and perception, while reliable...
The physiological interactions between the peripheral and central auditory systems are crucial for auditory information transmission and perception, while reliable models for auditory neural circuits are currently lacking. To address this issue, mouse and human neural pathways are generated by utilizing a carbon nanotube nanofiber system. The super-aligned pattern of the scaffold renders the axons of the bipolar and multipolar neurons extending in a parallel direction. In addition, the electrical conductivity of the scaffold maintains the electrophysiological activity of the primary mouse auditory neurons. The mouse and human primary neurons from peripheral and central auditory units in the system are then co-cultured and showed that the two kinds of neurons form synaptic connections. Moreover, neural progenitor cells of the cochlea and auditory cortex are derived from human embryos to generate region-specific organoids and these organoids are assembled in the nanofiber-combined 3D system. Using optogenetic stimulation, calcium imaging, and electrophysiological recording, it is revealed that functional synaptic connections are formed between peripheral neurons and central neurons, as evidenced by calcium spiking and postsynaptic currents. The auditory circuit model will enable the study of the auditory neural pathway and advance the search for treatment strategies for disorders of neuronal connectivity in sensorineural hearing loss.
PubMed: 38889308
DOI: 10.1002/advs.202309617 -
The Korean Journal of Physiology &... Mar 2024The slow and regular pacemaking activity of midbrain dopamine (DA) neurons requires proper spatial organization of the excitable elements between the soma and dendritic...
The slow and regular pacemaking activity of midbrain dopamine (DA) neurons requires proper spatial organization of the excitable elements between the soma and dendritic compartments, but the somatodendritic organization is not clear. Here, we show that the dynamic interaction between the soma and multiple proximal dendritic compartments (PDCs) generates the slow pacemaking activity in DA neurons. In multipolar DA neurons, spontaneous action potentials (sAPs) consistently originate from the axon-bearing dendrite. However, when the axon initial segment was disabled, sAPs emerge randomly from various primary PDCs, indicating that multiple PDCs drive pacemaking. Ca measurements and local stimulation/perturbation experiments suggest that the soma serves as a stably-oscillating inertial compartment, while multiple PDCs exhibit stochastic fluctuations and high excitability. Despite the stochastic and excitable nature of PDCs, their activities are balanced by the large centrally-connected inertial soma, resulting in the slow synchronized pacemaking rhythm. Furthermore, our electrophysiological experiments indicate that the soma and PDCs, with distinct characteristics, play different roles in glutamate- induced burst-pause firing patterns. Excitable PDCs mediate excitatory burst responses to glutamate, while the large inertial soma determines inhibitory pause responses to glutamate. Therefore, we could conclude that this somatodendritic organization serves as a common foundation for both pacemaker activity and evoked firing patterns in midbrain DA neurons.
PubMed: 38414399
DOI: 10.4196/kjpp.2024.28.2.165 -
Anatomia, Histologia, Embryologia Jan 2024In this investigation the morphological and morphometrical features of the optic tectum in post-hatch broiler chicken were studied macroscopically and microscopically....
In this investigation the morphological and morphometrical features of the optic tectum in post-hatch broiler chicken were studied macroscopically and microscopically. The present study was conducted on 70 day old broiler chicks which were reared up to 42 days. The whole experimental period of study was divided into seven groups (from group I to VII) at weekly interval (days 0, 7, 14, 21, 28, 35 and 42). The optic lobes were paired and spherical to oval eminences located on the ventro-lateral part of the midbrain in broiler chicken. There was significant increase in length and width of the optic lobes with the advancement of age. Histological analysis of optic tectum shows six basic layers from the external surface to internal one towards the optic ventricle. Different layers of optic tectum were identified as stratum opticum, stratum griseum superficial, stratum griseum central, stratum album central, stratum griseum periventriculare and stratum fibrosum periventriculare with several types of neurons. Among all six layers of the optic tectum the stratum griseum superficial layer showed very high degree of secondry differentiation and evolved into nine sub- layers in all age groups of broiler chickens. Three main cell types had been identified that is, small to medium sized stellate shaped neuron, pyramidal neuron and fusiform neuron, beside these multipolar neuron were also evident. The thickness of all layers of optic tectum significantly increases with the advancement of age of the birds. The optic ventricle was lined with a layer of cuboidal ependymal cells.
Topics: Animals; Superior Colliculi; Chickens; Neurons; Neuroglia; Eye
PubMed: 37984463
DOI: 10.1111/ahe.13002 -
Developmental Dynamics : An Official... Aug 2023The optic tectum is the main visual processor of nonmammalian vertebrates and relays visual information from the eye to the telencephalon via the tectofugal pathway. In...
BACKGROUND
The optic tectum is the main visual processor of nonmammalian vertebrates and relays visual information from the eye to the telencephalon via the tectofugal pathway. In the development of the avian optic tectum, while the multipolar neurons are arranged by tangential migration, the behavior of individual cells in tangential migration, neural differentiation, and cell fate remain unclear. Here, we pursued the transition of tangentially migrating cells and their involvement in visual circuit formation during chick development.
RESULTS
After tangential movement along the axons, the migrating cells relocated to the upper layers and turned back upon differentiation toward the multipolar neurons. The multipolar neurons are destined to differentiate into the stratum griseum central (SGC) neurons with the large dendritic field, which form the tectorotundal projection. Trans-synaptic virus labeling demonstrated that the tangentially migrating cells eventually participate in the tectofugal visual pathway.
CONCLUSIONS
These results indicate that tangential migration is a crucial process in the formation of the tectofugal visual pathway during the development of the optic tectum.
Topics: Animals; Superior Colliculi; Visual Pathways; Chickens; Neurons; Axons
PubMed: 36734001
DOI: 10.1002/dvdy.572