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Tian Y, Sun P. Characteristics of the neural coding of causality. Phys Rev E 2021; 103:012406. [PMID: 33601638 DOI: 10.1103/physreve.103.012406] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Accepted: 12/21/2020] [Indexed: 02/02/2023]
Abstract
While causality processing is an essential cognitive capacity of the neural system, a systematic understanding of the neural coding of causality is still elusive. We propose a physically fundamental analysis of this issue and demonstrate that the neural dynamics encodes the original causality between external events near homomorphically. The causality coding is memory robust for the amount of historical information and features high precision but low recall. This coding process creates a sparser representation for the external causality. Finally, we propose a statistic characterization for the neural coding mapping from the original causality to the coded causality in neural dynamics.
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Affiliation(s)
- Yang Tian
- Department of Psychology, Tsinghua University, Beijing 100084, China and Tsinghua Brain and Intelligence Lab, Beijing 100084, China
| | - Pei Sun
- Department of Psychology, Tsinghua University, Beijing 100084, China and Tsinghua Brain and Intelligence Lab, Beijing 100084, China
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2
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Jiang T, Handley E, Brizuela M, Dawkins E, Lewis KEA, Clark RM, Dickson TC, Blizzard CA. Amyotrophic lateral sclerosis mutant TDP-43 may cause synaptic dysfunction through altered dendritic spine function. Dis Model Mech 2019; 12:dmm.038109. [PMID: 31036551 PMCID: PMC6550035 DOI: 10.1242/dmm.038109] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Accepted: 04/12/2019] [Indexed: 12/12/2022] Open
Abstract
Altered cortical excitability and synapse dysfunction are early pathogenic events in amyotrophic lateral sclerosis (ALS) patients and animal models. Recent studies propose an important role for TAR DNA-binding protein 43 (TDP-43), the mislocalization and aggregation of which are key pathological features of ALS. However, the relationship between ALS-linked TDP-43 mutations, excitability and synaptic function is not fully understood. Here, we investigate the role of ALS-linked mutant TDP-43 in synapse formation by examining the morphological, immunocytochemical and excitability profile of transgenic mouse primary cortical pyramidal neurons that over-express human TDP-43A315T. In TDP-43A315T cortical neurons, dendritic spine density was significantly reduced compared to wild-type controls. TDP-43A315T over-expression increased the total levels of the α-amino-3-hydroxy-5-methyl-4-isoxazolepropinionic acid (AMPA) glutamate receptor subunit GluR1, yet the localization of GluR1 to the dendritic spine was reduced. These postsynaptic changes were coupled with a decrease in the amount of the presynaptic marker synaptophysin that colocalized with dendritic spines. Interestingly, action potential generation was reduced in TDP-43A315T pyramidal neurons. This work reveals a crucial effect of the over-expression mutation TDP-43A315T on the formation of synaptic structures and the recruitment of GluR1 to the synaptic membrane. This pathogenic effect may be mediated by cytoplasmic mislocalization of TDP-43A315T. Loss of synaptic GluR1, and reduced excitability within pyramidal neurons, implicates hypoexcitability and attenuated synaptic function in the pathogenic decline of neuronal function in TDP-43-associated ALS. Further studies into the mechanisms underlying AMPA receptor-mediated excitability changes within the ALS cortical circuitry may yield novel therapeutic targets for treatment of this devastating disease. Summary: Loss of synaptic GluR1, and reduced excitability within pyramidal neurons, implicates hypoexcitability and attenuated synaptic function in the pathogenic decline of neuronal function in TDP-43-associated ALS.
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Affiliation(s)
- Tongcui Jiang
- Menzies Institute for Medical Research, University of Tasmania, Medical Sciences Precinct, 17 Liverpool Street, Hobart, TAS 7000, Australia
| | - Emily Handley
- Menzies Institute for Medical Research, University of Tasmania, Medical Sciences Precinct, 17 Liverpool Street, Hobart, TAS 7000, Australia
| | - Mariana Brizuela
- Menzies Institute for Medical Research, University of Tasmania, Medical Sciences Precinct, 17 Liverpool Street, Hobart, TAS 7000, Australia
| | - Edgar Dawkins
- Menzies Institute for Medical Research, University of Tasmania, Medical Sciences Precinct, 17 Liverpool Street, Hobart, TAS 7000, Australia
| | - Katherine E A Lewis
- Menzies Institute for Medical Research, University of Tasmania, Medical Sciences Precinct, 17 Liverpool Street, Hobart, TAS 7000, Australia
| | - Rosemary M Clark
- Menzies Institute for Medical Research, University of Tasmania, Medical Sciences Precinct, 17 Liverpool Street, Hobart, TAS 7000, Australia
| | - Tracey C Dickson
- Menzies Institute for Medical Research, University of Tasmania, Medical Sciences Precinct, 17 Liverpool Street, Hobart, TAS 7000, Australia
| | - Catherine A Blizzard
- Menzies Institute for Medical Research, University of Tasmania, Medical Sciences Precinct, 17 Liverpool Street, Hobart, TAS 7000, Australia
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Yang Z, Tan Q, Cheng D, Zhang L, Zhang J, Gu EW, Fang W, Lu X, Liu X. The Changes of Intrinsic Excitability of Pyramidal Neurons in Anterior Cingulate Cortex in Neuropathic Pain. Front Cell Neurosci 2018; 12:436. [PMID: 30519160 PMCID: PMC6258991 DOI: 10.3389/fncel.2018.00436] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Accepted: 11/05/2018] [Indexed: 12/13/2022] Open
Abstract
To find satisfactory treatment strategies for neuropathic pain syndromes, the cellular mechanisms should be illuminated. Central sensitization is a generator of pain hypersensitivity, and is mainly reflected in neuronal hyperexcitability in pain pathway. Neuronal excitability depends on two components, the synaptic inputs and the intrinsic excitability. Previous studies have focused on the synaptic plasticity in different forms of pain. But little is known about the changes of neuronal intrinsic excitability in neuropathic pain. To address this question, whole-cell patch clamp recordings were performed to study the synaptic transmission and neuronal intrinsic excitability 1 week after spared nerve injury (SNI) or sham operation in male C57BL/6J mice. We found increased spontaneous excitatory postsynaptic currents (sEPSC) frequency in layer II/III pyramidal neurons of anterior cingulate cortex (ACC) from mice with neuropathic pain. Elevated intrinsic excitability of these neurons after nerve injury was also picked up, which was reflected in gain of input-output curve, inter-spike interval (ISI), spike threshold and Refractory period (RP). Besides firing rate related to neuronal intrinsic excitability, spike timing also plays an important role in neural information processing. The precision of spike timing measured by standard deviation of spike timing (SDST) was decreased in neuropathic pain state. The electrophysiological studies revealed the elevated intrinsic excitation in layer II/III pyramidal neurons of ACC in mice with neuropathic pain, which might contribute to central excitation.
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Affiliation(s)
- Zhilai Yang
- Department of Anesthesiology, First Affiliated Hospital, Anhui Medical University, Hefei, China
| | - Qilian Tan
- Department of Anesthesiology, First Affiliated Hospital, Anhui Medical University, Hefei, China
| | - Dan Cheng
- Department of Anesthesiology, First Affiliated Hospital, Anhui Medical University, Hefei, China
| | - Lei Zhang
- Department of Anesthesiology, First Affiliated Hospital, Anhui Medical University, Hefei, China
| | - Jiqian Zhang
- Department of Anesthesiology, First Affiliated Hospital, Anhui Medical University, Hefei, China
| | - Er-Wei Gu
- Department of Anesthesiology, First Affiliated Hospital, Anhui Medical University, Hefei, China
| | - Weiping Fang
- Department of Anesthesiology, First Affiliated Hospital, Anhui Medical University, Hefei, China
| | - Xianfu Lu
- Department of Anesthesiology, First Affiliated Hospital, Anhui Medical University, Hefei, China
| | - Xuesheng Liu
- Department of Anesthesiology, First Affiliated Hospital, Anhui Medical University, Hefei, China
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Grigonis R, Alaburda A. Spike threshold dynamics in spinal motoneurons during scratching and swimming. J Physiol 2017; 595:5843-5855. [PMID: 28653361 PMCID: PMC5577544 DOI: 10.1113/jp274434] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2017] [Accepted: 06/13/2017] [Indexed: 01/06/2023] Open
Abstract
KEY POINTS Action potential threshold can vary depending on firing history and synaptic inputs. We used an ex vivo carapace-spinal cord preparation from adult turtles to study spike threshold dynamics in motoneurons during two distinct types of functional motor behaviour - fictive scratching and fictive swimming. The threshold potential depolarizes by about 10 mV within each burst of spikes generated during scratch and swim network activity and recovers between bursts to a slightly depolarized level. Slow synaptic integration resulting in a wave of membrane potential depolarization is the factor influencing the threshold potential within firing bursts during motor behaviours. Depolarization of the threshold potential decreases the excitability of motoneurons and may provide a mechanism for stabilization of the response of a motoneuron to intense synaptic inputs to maintain the motor commands within an optimal range for muscle activation. ABSTRACT During functional spinal neural network activity motoneurons receive intense synaptic input, and this could modulate the threshold for action potential generation, providing the ability to dynamically adjust the excitability and recruitment order for functional needs. In the present study we investigated the dynamics of action potential threshold during motor network activity. Intracellular recordings from spinal motoneurons in an ex vivo carapace-spinal cord preparation from adult turtles were performed during two distinct types of motor behaviour - fictive scratching and fictive swimming. We found that the threshold of the first spike in episodes of scratching and swimming was the lowest. The threshold potential depolarizes by about 10 mV within each burst of spikes generated during scratch and swim network activity and recovers between bursts to a slightly depolarized level. Depolarization of the threshold potential results in decreased excitability of motoneurons. Synaptic inputs do not modulate the threshold of the first action potential during episodes of scratching or of swimming. There is no correlation between changes in spike threshold and interspike intervals within bursts. Slow synaptic integration that results in a wave of membrane potential depolarization rather than fast synaptic events preceding each spike is the factor influencing the threshold potential within firing bursts during motor behaviours.
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Affiliation(s)
- Ramunas Grigonis
- Department of Neurobiology and BiophysicsInstitute of Biosciences, Vilnius UniversitySauletekio ave. 7LT‐10257VilniusLithuania
| | - Aidas Alaburda
- Department of Neurobiology and BiophysicsInstitute of Biosciences, Vilnius UniversitySauletekio ave. 7LT‐10257VilniusLithuania
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Wang L, Wang H, Yu L, Chen Y. Spike-Threshold Variability Originated from Separatrix-Crossing in Neuronal Dynamics. Sci Rep 2016; 6:31719. [PMID: 27546614 PMCID: PMC4992847 DOI: 10.1038/srep31719] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Accepted: 07/26/2016] [Indexed: 11/09/2022] Open
Abstract
The threshold voltage for action potential generation is a key regulator of neuronal signal processing, yet the mechanism of its dynamic variation is still not well described. In this paper, we propose that threshold phenomena can be classified as parameter thresholds and state thresholds. Voltage thresholds which belong to the state threshold are determined by the 'general separatrix' in state space. We demonstrate that the separatrix generally exists in the state space of neuron models. The general form of separatrix was assumed as the function of both states and stimuli and the previously assumed threshold evolving equation versus time is naturally deduced from the separatrix. In terms of neuronal dynamics, the threshold voltage variation, which is affected by different stimuli, is determined by crossing the separatrix at different points in state space. We suggest that the separatrix-crossing mechanism in state space is the intrinsic dynamic mechanism for threshold voltages and post-stimulus threshold phenomena. These proposals are also systematically verified in example models, three of which have analytic separatrices and one is the classic Hodgkin-Huxley model. The separatrix-crossing framework provides an overview of the neuronal threshold and will facilitate understanding of the nature of threshold variability.
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Affiliation(s)
- Longfei Wang
- Institute of Theoretical Physics, Lanzhou University, Lanzhou, Gansu 730000, China
| | - Hengtong Wang
- College of Physics and Information Technology, Shaanxi Normal University, Xi'an 710062, China
| | - Lianchun Yu
- Institute of Theoretical Physics, Lanzhou University, Lanzhou, Gansu 730000, China
| | - Yong Chen
- Center of Soft Matter Physics and its Application, Beihang University, Beijing 100191, China.,School of Physics and Nuclear Energy Engineering, Beihang University, Beijing 100191, China
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