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1.
Int J Neural Syst ; 34(11): 2450059, 2024 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-39252681

RESUMO

Since the spiking neural P system (SN P system) was proposed in 2006, it has become a research hotspot in the field of membrane computing. The SN P system performs computations through the encoding, processing, and transmission of spiking information and can be regarded as a third-generation neural network. As a variant of the SN P system, the global asynchronous numerical spiking neural P system (ANSN P system) is adaptable to a broader range of application scenarios. However, in biological neuroscience, some neurons work synchronously within a community to perform specific functions in the brain. Inspired by this, our work investigates a global asynchronous spiking neural P system (ANSN P system) that incorporates certain local synchronous neuron sets. Within these local synchronous sets, neurons must execute their production functions simultaneously, thereby reducing dependence on thresholds and enhancing control uncertainty in ANSN P systems. By analyzing the ADD, SUB, and FIN modules in the generating mode, as well as the INPUT and ADD modules in the accepting mode, this paper demonstrates the novel system's computational capacity as both a generator and an acceptor. Additionally, this paper compares each module to those in other SN P systems, considering the maximum number of neurons and rules per neuron. The results show that this new ANSN P system is at least as effective as the existing SN P systems.


Assuntos
Potenciais de Ação , Modelos Neurológicos , Redes Neurais de Computação , Neurônios , Neurônios/fisiologia , Potenciais de Ação/fisiologia , Humanos , Simulação por Computador , Animais
2.
Proc Natl Acad Sci U S A ; 121(38): e2404169121, 2024 Sep 17.
Artigo em Inglês | MEDLINE | ID: mdl-39254998

RESUMO

In interval reproduction tasks, animals must remember the event starting the interval and anticipate the time of the planned response to terminate the interval. The interval reproduction task thus allows for studying both memory for the past and anticipation of the future. We analyzed previously published recordings from the rodent medial prefrontal cortex [J. Henke et al., eLife10, e71612 (2021)] during an interval reproduction task and identified two cell groups by modeling their temporal receptive fields using hierarchical Bayesian models. The firing in the "past cells" group peaked at the start of the interval and relaxed exponentially back to baseline. The firing in the "future cells" group increased exponentially and peaked right before the planned action at the end of the interval. Contrary to the previous assumption that timing information in the brain has one or two time scales for a given interval, we found strong evidence for a continuous distribution of the exponential rate constants for both past and future cell populations. The real Laplace transformation of time predicts exponential firing with a continuous distribution of rate constants across the population. Therefore, the firing pattern of the past cells can be identified with the Laplace transform of time since the past event while the firing pattern of the future cells can be identified with the Laplace transform of time until the planned future event.


Assuntos
Neurônios , Córtex Pré-Frontal , Córtex Pré-Frontal/fisiologia , Córtex Pré-Frontal/citologia , Animais , Ratos , Neurônios/fisiologia , Teorema de Bayes , Masculino , Modelos Neurológicos , Memória/fisiologia , Percepção do Tempo/fisiologia , Potenciais de Ação/fisiologia
3.
Nat Commun ; 15(1): 8122, 2024 Sep 16.
Artigo em Inglês | MEDLINE | ID: mdl-39285176

RESUMO

Spiking neural networks and neuromorphic hardware platforms that simulate neuronal dynamics are getting wide attention and are being applied to many relevant problems using Machine Learning. Despite a well-established mathematical foundation for neural dynamics, there exists numerous software and hardware solutions and stacks whose variability makes it difficult to reproduce findings. Here, we establish a common reference frame for computations in digital neuromorphic systems, titled Neuromorphic Intermediate Representation (NIR). NIR defines a set of computational and composable model primitives as hybrid systems combining continuous-time dynamics and discrete events. By abstracting away assumptions around discretization and hardware constraints, NIR faithfully captures the computational model, while bridging differences between the evaluated implementation and the underlying mathematical formalism. NIR supports an unprecedented number of neuromorphic systems, which we demonstrate by reproducing three spiking neural network models of different complexity across 7 neuromorphic simulators and 4 digital hardware platforms. NIR decouples the development of neuromorphic hardware and software, enabling interoperability between platforms and improving accessibility to multiple neuromorphic technologies. We believe that NIR is a key next step in brain-inspired hardware-software co-evolution, enabling research towards the implementation of energy efficient computational principles of nervous systems. NIR is available at neuroir.org.


Assuntos
Encéfalo , Modelos Neurológicos , Redes Neurais de Computação , Software , Encéfalo/fisiologia , Humanos , Neurônios/fisiologia , Simulação por Computador , Aprendizado de Máquina , Potenciais de Ação/fisiologia
4.
Nat Commun ; 15(1): 7964, 2024 Sep 11.
Artigo em Inglês | MEDLINE | ID: mdl-39261491

RESUMO

Fixational eye movements alter the number and timing of spikes transmitted from the retina to the brain, but whether these changes enhance or degrade the retinal signal is unclear. To quantify this, we developed a Bayesian method for reconstructing natural images from the recorded spikes of hundreds of retinal ganglion cells (RGCs) in the macaque retina (male), combining a likelihood model for RGC light responses with the natural image prior implicitly embedded in an artificial neural network optimized for denoising. The method matched or surpassed the performance of previous reconstruction algorithms, and provides an interpretable framework for characterizing the retinal signal. Reconstructions were improved with artificial stimulus jitter that emulated fixational eye movements, even when the eye movement trajectory was assumed to be unknown and had to be inferred from retinal spikes. Reconstructions were degraded by small artificial perturbations of spike times, revealing more precise temporal encoding than suggested by previous studies. Finally, reconstructions were substantially degraded when derived from a model that ignored cell-to-cell interactions, indicating the importance of stimulus-evoked correlations. Thus, fixational eye movements enhance the precision of the retinal representation.


Assuntos
Movimentos Oculares , Fixação Ocular , Retina , Células Ganglionares da Retina , Animais , Células Ganglionares da Retina/fisiologia , Retina/fisiologia , Movimentos Oculares/fisiologia , Masculino , Fixação Ocular/fisiologia , Macaca mulatta , Teorema de Bayes , Algoritmos , Potenciais de Ação/fisiologia , Estimulação Luminosa , Modelos Neurológicos
5.
Nat Commun ; 15(1): 7958, 2024 Sep 11.
Artigo em Inglês | MEDLINE | ID: mdl-39261492

RESUMO

Cortical neurons exhibit temporally irregular spiking patterns and heterogeneous firing rates. These features arise in model circuits operating in a 'fluctuation-driven regime', in which fluctuations in membrane potentials emerge from the network dynamics. However, it is still debated whether the cortex operates in such a regime. We evaluated the fluctuation-driven hypothesis by analyzing spiking and sub-threshold membrane potentials of neurons in the frontal cortex of mice performing a decision-making task. We showed that while standard fluctuation-driven models successfully account for spiking statistics, they fall short in capturing the heterogeneity in sub-threshold activity. This limitation is an inevitable outcome of bombarding single-compartment neurons with a large number of pre-synaptic inputs, thereby clamping the voltage of all neurons to more or less the same average voltage. To address this, we effectively incorporated dendritic morphology into the standard models. Inclusion of dendritic morphology in the neuronal models increased neuronal selectivity and reduced error trials, suggesting a functional role for dendrites during decision-making. Our work suggests that, during decision-making, cortical neurons in high-order cortical areas operate in a fluctuation-driven regime.


Assuntos
Potenciais de Ação , Modelos Neurológicos , Neurônios , Animais , Neurônios/fisiologia , Camundongos , Potenciais de Ação/fisiologia , Córtex Cerebral/fisiologia , Córtex Cerebral/citologia , Tomada de Decisões/fisiologia , Potenciais da Membrana/fisiologia , Dendritos/fisiologia , Masculino , Camundongos Endogâmicos C57BL , Lobo Frontal/fisiologia , Lobo Frontal/citologia
6.
Elife ; 132024 Sep 12.
Artigo em Inglês | MEDLINE | ID: mdl-39264364

RESUMO

Alzheimer's disease (AD) leads to progressive memory decline, and alterations in hippocampal function are among the earliest pathological features observed in human and animal studies. GABAergic interneurons (INs) within the hippocampus coordinate network activity, among which type 3 interneuron-specific (I-S3) cells expressing vasoactive intestinal polypeptide and calretinin play a crucial role. These cells provide primarily disinhibition to principal excitatory cells (PCs) in the hippocampal CA1 region, regulating incoming inputs and memory formation. However, it remains unclear whether AD pathology induces changes in the activity of I-S3 cells, impacting the hippocampal network motifs. Here, using young adult 3xTg-AD mice, we found that while the density and morphology of I-S3 cells remain unaffected, there were significant changes in their firing output. Specifically, I-S3 cells displayed elongated action potentials and decreased firing rates, which was associated with a reduced inhibition of CA1 INs and their higher recruitment during spatial decision-making and object exploration tasks. Furthermore, the activation of CA1 PCs was also impacted, signifying early disruptions in CA1 network functionality. These findings suggest that altered firing patterns of I-S3 cells might initiate early-stage dysfunction in hippocampal CA1 circuits, potentially influencing the progression of AD pathology.


Assuntos
Doença de Alzheimer , Região CA1 Hipocampal , Modelos Animais de Doenças , Interneurônios , Camundongos Transgênicos , Peptídeo Intestinal Vasoativo , Animais , Doença de Alzheimer/fisiopatologia , Doença de Alzheimer/patologia , Doença de Alzheimer/metabolismo , Interneurônios/fisiologia , Interneurônios/metabolismo , Região CA1 Hipocampal/fisiopatologia , Região CA1 Hipocampal/patologia , Peptídeo Intestinal Vasoativo/metabolismo , Camundongos , Potenciais de Ação/fisiologia , Masculino , Humanos
7.
Brain Behav ; 14(9): e3632, 2024 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-39279260

RESUMO

INTRODUCTION: Reliable, noninvasive early diagnostics of neuromuscular function in Bell's palsy, which causes facial paralysis and reduced quality of life, remain to be established. Here, we aimed to evaluate the utility of the motor unit number index (MUNIX) for the quantitative electrophysiological assessment of early-stage Bell's palsy, its correlation with clinical assessments, changes following treatment, and association with clinical prognosis. METHODS: MUNIX measures were recorded from the bilateral zygomaticus, orbicularis oculi, and orbicularis oris muscles of 10 healthy individuals and 64 patients with Bell's palsy. The patients were assessed by two specialist neurologists using the House-Brackmann and Sunnybrook Facial Grading Systems. Repeat assessments were performed on 20 patients with Bell's palsy who received treatment. Additionally, the 64 patients were reassessed using clinical scales after a 1-month interval. RESULTS: The MUNIX values of the main affected muscles on the affected side were lower than those on the healthy side in patients with Bell's palsy (p < .05). The MUNIX measurements significantly correlated with the clinical facial nerve palsy scale scores (p < .05). Significant improvements were observed in the MUNIX values on repeat testing following treatment (p < .05). The baseline motor unit size index (the compound muscle action potential amplitude divided by MUNIX) was positively associated with improved clinical presentation after 1 month (p < .05). CONCLUSION: MUNIX can be used as an electrophysiological biomarker for the quantitative assessment of facial nerve palsy and treatment response, and as a prognostic biomarker, in patients with early Bell's palsy, and is recommended as a complement to conventional neurophysiological examinations.


Assuntos
Paralisia de Bell , Eletromiografia , Humanos , Paralisia de Bell/fisiopatologia , Paralisia de Bell/diagnóstico , Masculino , Feminino , Adulto , Pessoa de Meia-Idade , Eletromiografia/métodos , Músculos Faciais/fisiopatologia , Adulto Jovem , Idoso , Biomarcadores , Neurônios Motores/fisiologia , Diagnóstico Precoce , Potenciais de Ação/fisiologia
8.
Commun Biol ; 7(1): 1076, 2024 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-39223260

RESUMO

Temporal interference (TI) stimulation is a popular non-invasive neurostimulation technique that utilizes the following salient neural behavior: pure sinusoid (generated in off-target brain regions) appears to cause no stimulation, whereas modulated sinusoid (generated in target brain regions) does. To understand its effects and mechanisms, we examine responses of different cell types, excitatory pyramidal (Pyr) and inhibitory parvalbumin-expressing (PV) neurons, to pure and modulated sinusoids, in intact network as well as in isolation. In intact network, we present data showing that PV neurons are much less likely than Pyr neurons to exhibit TI stimulation. Remarkably, in isolation, our data shows that almost all Pyr neurons stop exhibiting TI stimulation. We conclude that TI stimulation is largely a network phenomenon. Indeed, PV neurons actively inhibit Pyr neurons in the off-target regions due to pure sinusoids (in off-target regions) generating much higher PV firing rates than modulated sinusoids in the target regions. Additionally, we use computational studies to support and extend our experimental observations.


Assuntos
Neurônios , Animais , Camundongos , Neurônios/fisiologia , Potenciais de Ação , Células Piramidais/fisiologia , Córtex Cerebral/fisiologia , Parvalbuminas/metabolismo , Masculino , Modelos Neurológicos
9.
Open Biol ; 14(9): 240138, 2024 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-39226928

RESUMO

In this study, we develop an in silico model of a neuron's behaviour under demyelination caused by a cytokine storm to investigate the effects of viral infections in the brain. We use a comprehensive model to measure how cytokine-induced demyelination affects the propagation of action potential (AP) signals within a neuron. We analysed the effects of neuron-neuron communications by applying information and communication theory at different levels of demyelination. Our simulations demonstrate that virus-induced degeneration can play a role in the signal power and spiking rate, which compromise the propagation and processing of information between neurons. We propose a transfer function to model the weakening effects on the AP. Our results show that demyelination induced by a cytokine storm not only degrades the signal but also impairs its propagation within the axon. Our proposed in silico model can analyse virus-induced neurodegeneration and enhance our understanding of virus-induced demyelination.


Assuntos
Simulação por Computador , Doenças Desmielinizantes , Neurônios , Doenças Desmielinizantes/patologia , Doenças Desmielinizantes/metabolismo , Doenças Desmielinizantes/virologia , Neurônios/metabolismo , Humanos , Modelos Neurológicos , Potenciais de Ação , Síndrome da Liberação de Citocina , Animais , Citocinas/metabolismo , Axônios/metabolismo , Axônios/patologia
10.
Europace ; 26(9)2024 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-39230049

RESUMO

AIMS: Atrial fibrosis and autonomic remodelling are proposed pathophysiological mechanisms in atrial fibrillation (AF). Their impact on conduction velocity (CV) dynamics and wavefront propagation was evaluated. METHODS AND RESULTS: Local activation times (LATs), voltage, and geometry data were obtained from patients undergoing ablation for persistent AF. LATs were obtained at three pacing intervals (PIs) in sinus rhythm (SR). LATs were used to determine CV dynamics and their relationship to local voltage amplitude. The impact of autonomic modulation- pharmacologically and with ganglionated plexi (GP) stimulation, on CV dynamics, wavefront propagation, and pivot points (change in wavefront propagation of ≥90°) was determined in SR. Fifty-four patients were included. Voltage impacted CV dynamics whereby at non-low voltage zones (LVZs) (≥0.5 mV) the CV restitution curves are steeper [0.03 ± 0.03 m/s ΔCV PI 600-400 ms (PI1), 0.54 ± 0.09 m/s ΔCV PI 400-250 ms (PI2)], broader at LVZ (0.2-0.49 mV) (0.17 ± 0.09 m/s ΔCV PI1, 0.25 ± 0.11 m/s ΔCV PI2), and flat at very LVZ (<0.2 mV) (0.03 ± 0.01 m/s ΔCV PI1, 0.04 ± 0.02 m/s ΔCV PI2). Atropine did not change CV dynamics, while isoprenaline and GP stimulation resulted in greater CV slowing with rate. Isoprenaline (2.7 ± 1.1 increase/patient) and GP stimulation (2.8 ± 1.3 increase/patient) promoted CV heterogeneity, i.e. rate-dependent CV (RDCV) slowing sites. Most pivot points co-located to RDCV slowing sites (80.2%). Isoprenaline (1.3 ± 1.1 pivot increase/patient) and GP stimulation (1.5 ± 1.1 increase/patient) also enhanced the number of pivot points identified. CONCLUSION: Atrial CV dynamics is affected by fibrosis burden and influenced by autonomic modulation which enhances CV heterogeneity and distribution of pivot points. This study provides further insight into the impact of autonomic remodelling in AF.


Assuntos
Fibrilação Atrial , Fibrose , Átrios do Coração , Humanos , Feminino , Masculino , Fibrilação Atrial/fisiopatologia , Fibrilação Atrial/cirurgia , Pessoa de Meia-Idade , Átrios do Coração/fisiopatologia , Átrios do Coração/inervação , Idoso , Potenciais de Ação , Ablação por Cateter , Remodelamento Atrial , Frequência Cardíaca , Técnicas Eletrofisiológicas Cardíacas , Sistema Nervoso Autônomo/fisiopatologia , Função do Átrio Esquerdo , Isoproterenol/farmacologia , Atropina/farmacologia , Fatores de Tempo , Sistema de Condução Cardíaco/fisiopatologia , Resultado do Tratamento
11.
PLoS One ; 19(9): e0308809, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-39231135

RESUMO

Aging is a physiological process that is still poorly understood, especially with respect to effects on the brain. There are open questions about aging that are difficult to answer with an experimental approach. Underlying challenges include the difficulty of recording in vivo single cell and network activity simultaneously with submillisecond resolution, and brain compensatory mechanisms triggered by genetic, pharmacologic, or behavioral manipulations. Mathematical modeling can help address some of these questions by allowing us to fix parameters that cannot be controlled experimentally and investigate neural activity under different conditions. We present a biophysical minimal model of CA1 pyramidal cells (PCs) based on general expressions for transmembrane ion transport derived from thermodynamical principles. The model allows directly varying the contribution of ion channels by changing their number. By analyzing the dynamics of the model, we find parameter ranges that reproduce the variability in electrical activity seen in PCs. In addition, increasing the L-type Ca2+ channel expression in the model reproduces age-related changes in electrical activity that are qualitatively and quantitatively similar to those observed in PCs from aged animals. We also make predictions about age-related changes in PC bursting activity that, to our knowledge, have not been reported previously. We conclude that the model's biophysical nature, flexibility, and computational simplicity make it a potentially powerful complement to experimental studies of aging.


Assuntos
Envelhecimento , Região CA1 Hipocampal , Células Piramidais , Células Piramidais/metabolismo , Células Piramidais/fisiologia , Animais , Envelhecimento/fisiologia , Região CA1 Hipocampal/fisiologia , Região CA1 Hipocampal/citologia , Região CA1 Hipocampal/metabolismo , Modelos Neurológicos , Potenciais de Ação/fisiologia , Canais de Cálcio Tipo L/metabolismo , Fenômenos Biofísicos
12.
Elife ; 122024 Sep 11.
Artigo em Inglês | MEDLINE | ID: mdl-39259198

RESUMO

Lesion studies have historically been instrumental for establishing causal connections between brain and behavior. They stand to provide additional insight if integrated with multielectrode techniques common in systems neuroscience. Here, we present and test a platform for creating electrolytic lesions through chronically implanted, intracortical multielectrode probes without compromising the ability to acquire neuroelectrophysiology. A custom-built current source provides stable current and allows for controlled, repeatable lesions in awake-behaving animals. Performance of this novel lesioning technique was validated using histology from ex vivo and in vivo testing, current and voltage traces from the device, and measurements of spiking activity before and after lesioning. This electrolytic lesioning method avoids disruptive procedures, provides millimeter precision over the extent and submillimeter precision over the location of the injury, and permits electrophysiological recording of single-unit activity from the remaining neuronal population after lesioning. This technique can be used in many areas of cortex, in several species, and theoretically with any multielectrode probe. The low-cost, external lesioning device can also easily be adopted into an existing electrophysiology recording setup. This technique is expected to enable future causal investigations of the recorded neuronal population's role in neuronal circuit function, while simultaneously providing new insight into local reorganization after neuron loss.


Over the past three decades, the field of neuroscience has made significant leaps in understanding how the brain works. This is largely thanks to microelectrode arrays, devices which are surgically implanted into the outermost layer of the brain known as the cortex. Once inserted, these devices can precisely monitor the electrical activity of a few hundred neurons while also stimulating neurons to reversibly modulate their activity. However, current microelectrode arrays are missing a key function: they cannot irreversibly inactivate neurons over long-time scales. This ability would allow researchers to understand how networks of neurons adapt and re-organize after injury or during neurodegenerative diseases where brain cells are progressively lost. To address this limitation, Bray, Clarke, et al. developed a device capable of creating consistent amounts of neuron loss, while retaining the crucial ability to record electrical activity following a lesion. Calibration tests in sheep and pigs provided the necessary parameters for this custom circuit, which was then verified as safe in non-human primates. These experiments demonstrated that the device could effectively cause neuron loss without compromising the recording capabilities of the microelectrode array. By seamlessly integrating neuron inactivation with monitoring of neuronal activity, scientists can now investigate the direct effects of such damage and subsequent neural reorganization. This device could help neuroscientists to explore neural repair and rehabilitation after brain cell loss, which may lead to better treatments for neurodegenerative diseases. In addition, this technique could offer insights into the interactions between neural circuits that drive behavior, enhancing our understanding of the complex mechanisms underlying how the brain works.


Assuntos
Neurônios , Animais , Neurônios/fisiologia , Eletrodos Implantados , Eletrólise/métodos , Ratos , Eletrofisiologia/métodos , Eletrofisiologia/instrumentação , Potenciais de Ação/fisiologia
13.
Science ; 385(6713): 1120-1127, 2024 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-39236189

RESUMO

New memories are integrated into prior knowledge of the world. But what if consecutive memories exert opposing demands on the host brain network? We report that acquiring a robust (food-context) memory constrains the mouse hippocampus within a population activity space of highly correlated spike trains that prevents subsequent computation of a flexible (object-location) memory. This densely correlated firing structure developed over repeated mnemonic experience, gradually coupling neurons in the superficial sublayer of the CA1 stratum pyramidale to whole-population activity. Applying hippocampal theta-driven closed-loop optogenetic suppression to mitigate this neuronal recruitment during (food-context) memory formation relaxed the topological constraint on hippocampal coactivity and restored subsequent flexible (object-location) memory. These findings uncover an organizational principle for the peer-to-peer coactivity structure of the hippocampal cell population to meet memory demands.


Assuntos
Região CA1 Hipocampal , Memória , Optogenética , Ritmo Teta , Animais , Masculino , Potenciais de Ação , Região CA1 Hipocampal/fisiologia , Região CA1 Hipocampal/citologia , Memória/fisiologia , Neurônios/fisiologia , Células Piramidais/fisiologia
14.
Zhonghua Yan Ke Za Zhi ; 60(9): 766-772, 2024 Sep 11.
Artigo em Chinês | MEDLINE | ID: mdl-39267555

RESUMO

Objective: To investigate the action potential firing patterns of neurons in the visual sensory layers of the superior colliculus in early postnatal mice and the electrophysiological characteristics of neurons with different firing patterns. Methods: This experimental study utilized whole-cell patch-clamp recordings performed on neurons in the visual sensory layers of the superior colliculus using brain slices from 57 healthy male C57BL/6J mice aged 14 to 20 days (weighing 5.0 to 8.9 g) using brain slices. In current-clamp mode, action potential characteristics were analyzed based on the first action potential generated by depolarizing current, and the firing patterns of neurons were recorded using step depolarizing currents. Neuronal firing patterns were analyzed using hierarchical clustering, and the active electrical properties of neurons with different firing patterns were compared. Results: A total of 135 neurons from the visual sensory layers of the superior colliculus were successfully recorded. Cluster analysis of the neuronal firing patterns identified three types of firing patterns: tonic firing (97, 72%), phasic firing (26, 19%), and single firing (12, 9%). The number of action potentials for each firing pattern was 13.30±7.38, 3.73±3.61, and 0.83±0.39, respectively, with significant differences (P<0.001). There was no significant difference in the membrane potential response to step currents among the three firing pattern types (P>0.05). The action potential amplitudes were (60.45±12.22), (53.67±13.20), and (44.04± 12.92) mV, and the afterhyperpolarization amplitudes were (13.45±13.79), (12.02±13.11), and (20.75±2.85) mV, respectively. The maximum rising slopes were (171.29±77.46), (130.14±61.83), and (78.89±37.08) V/s, and the maximum falling slopes were (-76.33±33.61), (-68.17±31.65), and (-47.97±13.92) V/s, respectively, with all differences being statistically significant (all P<0.05). There were no significant differences in the resting membrane potential, action potential threshold, half-width, and afterhyperpolarization duration among the three firing pattern types (all P>0.05). Conclusions: In the early postnatal mice, neurons in the visual sensory layers of the superior colliculus exhibit three distinct firing patterns: tonic, phasic, and single firing. These firing pattern types show significant differences in action potential amplitude, afterhyperpolarization amplitude, maximum rising slopes, and maximum falling slopes.


Assuntos
Potenciais de Ação , Camundongos Endogâmicos C57BL , Neurônios , Técnicas de Patch-Clamp , Colículos Superiores , Animais , Camundongos , Masculino , Colículos Superiores/fisiologia , Potenciais de Ação/fisiologia , Neurônios/fisiologia , Fenômenos Eletrofisiológicos
15.
Cereb Cortex ; 34(9)2024 Sep 03.
Artigo em Inglês | MEDLINE | ID: mdl-39270676

RESUMO

Cortical processing of auditory information can be affected by interspecies differences as well as brain states. Here we compare multifeature spectro-temporal receptive fields (STRFs) and associated input/output functions or nonlinearities (NLs) of neurons in primary auditory cortex (AC) of four mammalian species. Single-unit recordings were performed in awake animals (female squirrel monkeys, female, and male mice) and anesthetized animals (female squirrel monkeys, rats, and cats). Neuronal responses were modeled as consisting of two STRFs and their associated NLs. The NLs for the STRF with the highest information content show a broad distribution between linear and quadratic forms. In awake animals, we find a higher percentage of quadratic-like NLs as opposed to more linear NLs in anesthetized animals. Moderate sex differences of the shape of NLs were observed between male and female unanesthetized mice. This indicates that the core AC possesses a rich variety of potential computations, particularly in awake animals, suggesting that multiple computational algorithms are at play to enable the auditory system's robust recognition of auditory events.


Assuntos
Córtex Auditivo , Animais , Córtex Auditivo/fisiologia , Feminino , Masculino , Gatos , Camundongos , Ratos , Estimulação Acústica/métodos , Neurônios/fisiologia , Saimiri , Percepção Auditiva/fisiologia , Especificidade da Espécie , Modelos Neurológicos , Potenciais de Ação/fisiologia , Camundongos Endogâmicos C57BL
16.
Cells ; 13(17)2024 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-39273026

RESUMO

The atrioventricular node (AVN) is a key component of the cardiac conduction system and takes over pacemaking of the ventricles if the sinoatrial node fails. IP3 (inositol 1,4,5 trisphosphate) can modulate excitability of myocytes from other regions of the heart, but it is not known whether IP3 receptor (IP3-R) activation modulates AVN cell pacemaking. Consequently, this study investigated effects of IP3 on spontaneous action potentials (APs) from AVN cells isolated from rabbit hearts. Immunohistochemistry and confocal imaging demonstrated the presence of IP3-R2 in isolated AVN cells, with partial overlap with RyR2 ryanodine receptors seen in co-labelling experiments. In whole-cell recordings at physiological temperature, application of 10 µM membrane-permeant Bt3-(1,4,5)IP3-AM accelerated spontaneous AP rate and increased diastolic depolarization rate, without direct effects on ICa,L, IKr, If or INCX. By contrast, application via the patch pipette of 5 µM of the IP3-R inhibitor xestospongin C led to a slowing in spontaneous AP rate and prevented 10 µM Bt3-(1,4,5)IP3-AM application from increasing the AP rate. UV excitation of AVN cells loaded with caged-IP3 led to an acceleration in AP rate, the magnitude of which increased with the extent of UV excitation. 2-APB slowed spontaneous AP rate, consistent with a role for constitutive IP3-R activity; however, it was also found to inhibit ICa,L and IKr, confounding its use for studying IP3-R. Under AP voltage clamp, UV excitation of AVN cells loaded with caged IP3 activated an inward current during diastolic depolarization. Collectively, these results demonstrate that IP3 can modulate AVN cell pacemaking rate.


Assuntos
Potenciais de Ação , Nó Atrioventricular , Receptores de Inositol 1,4,5-Trifosfato , Inositol 1,4,5-Trifosfato , Miócitos Cardíacos , Animais , Coelhos , Potenciais de Ação/efeitos dos fármacos , Nó Atrioventricular/efeitos dos fármacos , Nó Atrioventricular/metabolismo , Receptores de Inositol 1,4,5-Trifosfato/metabolismo , Inositol 1,4,5-Trifosfato/metabolismo , Miócitos Cardíacos/metabolismo , Miócitos Cardíacos/efeitos dos fármacos , Canal de Liberação de Cálcio do Receptor de Rianodina/metabolismo , Oxazóis/farmacologia , Masculino
17.
PLoS Comput Biol ; 20(9): e1012415, 2024 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-39226309

RESUMO

Revealing the relationship between neural network structure and function is one central theme of neuroscience. In the context of working memory (WM), anatomical data suggested that the topological structure of microcircuits within WM gradient network may differ, and the impact of such structural heterogeneity on WM activity remains unknown. Here, we proposed a spiking neural network model that can replicate the fundamental characteristics of WM: delay-period neural activity involves association cortex but not sensory cortex. First, experimentally observed receptor expression gradient along the WM gradient network is reproduced by our network model. Second, by analyzing the correlation between different local structures and duration of WM activity, we demonstrated that small-worldness, excitation-inhibition balance, and cycle structures play crucial roles in sustaining WM-related activity. To elucidate the relationship between the structure and functionality of neural networks, structural circuit gradients in brain should also be subject to further measurement. Finally, combining anatomical data, we simulated the duration of WM activity across different brain regions, its maintenance relies on the interaction between local and distributed networks. Overall, network structural gradient and interaction between local and distributed networks are of great significance for WM.


Assuntos
Memória de Curto Prazo , Modelos Neurológicos , Rede Nervosa , Memória de Curto Prazo/fisiologia , Rede Nervosa/fisiologia , Humanos , Biologia Computacional , Animais , Encéfalo/fisiologia , Simulação por Computador , Neurônios/fisiologia , Potenciais de Ação/fisiologia
18.
PLoS Comput Biol ; 20(9): e1012401, 2024 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-39226329

RESUMO

Neural activity in the cortex exhibits a wide range of firing variability and rich correlation structures. Studies on neural coding indicate that correlated neural variability can influence the quality of neural codes, either beneficially or adversely. However, the mechanisms by which correlated neural variability is transformed and processed across neural populations to achieve meaningful computation remain largely unclear. Here we propose a theory of covariance computation with spiking neurons which offers a unifying perspective on neural representation and computation with correlated noise. We employ a recently proposed computational framework known as the moment neural network to resolve the nonlinear coupling of correlated neural variability with a task-driven approach to constructing neural network models for performing covariance-based perceptual tasks. In particular, we demonstrate how perceptual information initially encoded entirely within the covariance of upstream neurons' spiking activity can be passed, in a near-lossless manner, to the mean firing rate of downstream neurons, which in turn can be used to inform inference. The proposed theory of covariance computation addresses an important question of how the brain extracts perceptual information from noisy sensory stimuli to generate a stable perceptual whole and indicates a more direct role that correlated variability plays in cortical information processing.


Assuntos
Potenciais de Ação , Biologia Computacional , Modelos Neurológicos , Neurônios , Neurônios/fisiologia , Humanos , Potenciais de Ação/fisiologia , Redes Neurais de Computação , Rede Nervosa/fisiologia , Aprendizagem/fisiologia , Animais , Simulação por Computador , Encéfalo/fisiologia
19.
Physiol Rep ; 12(17): e70037, 2024 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-39245818

RESUMO

Prior studies have documented the role of the striatum and its dopaminergic input in time processing, but the contribution of local striatal cholinergic innervation has not been specifically investigated. To address this issue, we recorded the activity of tonically active neurons (TANs), thought to be cholinergic interneurons in the striatum, in two male macaques performing self-initiated movements after specified intervals in the seconds range have elapsed. The behavioral data showed that movement timing was adjusted according to the temporal requirements. About one-third of all recorded TANs displayed brief depressions in firing in response to the cue that indicates the interval duration, and the strength of these modulations was, in some instances, related to the timing of movement. The rewarding outcome of actions also impacted TAN activity, as reflected by stronger responses to the cue paralleled by weaker responses to reward when monkeys performed correctly timed movements over consecutive trials. It therefore appears that TAN responses may act as a start signal for keeping track of time and reward prediction could be incorporated in this signaling function. We conclude that the role of the striatal cholinergic TAN system in time processing is embedded in predicting rewarding outcomes during timing behavior.


Assuntos
Corpo Estriado , Macaca mulatta , Recompensa , Animais , Masculino , Projetos Piloto , Corpo Estriado/fisiologia , Neurônios Colinérgicos/fisiologia , Neurônios/fisiologia , Sinais (Psicologia) , Potenciais de Ação/fisiologia , Percepção do Tempo/fisiologia
20.
Artigo em Inglês | MEDLINE | ID: mdl-39213274

RESUMO

EMG filling curve characterizes the EMG filling process and EMG probability density function (PDF) shape change for the entire force range of a muscle. We aim to understand the relation between the physiological and recording variables, and the resulting EMG filling curves. We thereby present an analytical and simulation study to explain how the filling curve patterns relate to specific changes in the motor unit potential (MUP) waveforms and motor unit (MU) firing rates, the two main factors affecting the EMG PDF, but also to recording conditions in terms of noise level. We compare the analytical results with simulated cases verifying a perfect agreement with the analytical model. Finally, we present a set of real EMG filling curves with distinct patterns to explain the information about MUP amplitudes, MU firing rates, and noise level that these patterns provide in the light of the analytical study. Our findings reflect that the filling factor increases when firing rate increases or when newly recruited motor unit have potentials of smaller or equal amplitude than the former ones. On the other hand, the filling factor decreases when newly recruited potentials are larger in amplitude than the previous potentials. Filling curves are shown to be consistent under changes of the MUP waveform, and stretched under MUP amplitude scaling. Our findings also show how additive noise affects the filling curve and can even impede to obtain reliable information from the EMG PDF statistics.


Assuntos
Potenciais de Ação , Algoritmos , Simulação por Computador , Eletromiografia , Neurônios Motores , Músculo Esquelético , Razão Sinal-Ruído , Eletromiografia/métodos , Humanos , Neurônios Motores/fisiologia , Músculo Esquelético/fisiologia , Potenciais de Ação/fisiologia , Contração Muscular/fisiologia , Reprodutibilidade dos Testes , Recrutamento Neurofisiológico/fisiologia , Modelos Estatísticos
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