scholarly journals Multiple synaptic connections into a single cortical pyramidal cell or interneuron in the anterior cingulate cortex of adult mice

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Jung-Hyun Alex Lee ◽  
Zhuang Miao ◽  
Qi-Yu Chen ◽  
Xu-Hui Li ◽  
Min Zhuo

AbstractThe ACC is an important brain area for the processing of pain-related information. Studies of synaptic connections within the ACC provide an understanding of basic cellular and molecular mechanisms for brain functions such as pain, emotion and related cognitive functions. Previous study of ACC synaptic transmission mainly focused on presumably thalamic inputs into pyramidal cells. In the present study, we developed a new mapping technique by combining single neuron whole-cell patch-clamp recording with 64 multi-channel field potential recording (MED64) to examine the properties of excitatory inputs into a single neuron in the ACC. We found that a single patched pyramidal neuron or interneuron simultaneously received heterogeneous excitatory synaptic innervations from different subregions (ventral, dorsal, deep, and superficial layers) in the ACC. Conduction velocity is faster as stimulation distance increases in pyramidal neurons. Fast-spiking interneurons (FS-IN) show slower inactivation when compared to pyramidal neurons and regular-spiking interneurons (RS-IN) while pyramidal neurons displayed the most rapid activation. Bath application of non-competitive AMPA receptor antagonist GYKI 53655 followed by CNQX revealed that both FS-INs and RS-INs have AMPA and KA mediated components. Our studies provide a new strategy and technique for studying the network of synaptic connections.

2021 ◽  
Author(s):  
Jung-Hyun Alex Lee ◽  
Zhuang Miao ◽  
Qi-Yu Chen ◽  
Xu-Hui Li ◽  
Min Zhuo

Abstract The ACC is an important brain area for the processing of pain-related information. Studies of synaptic connections within the ACC provide an understanding of basic cellular and molecular mechanisms for brain functions such as pain, emotion and related cognitive functions. Previous study of ACC synaptic transmission mainly focused on presumably thalamic inputs into pyramidal cells. In the present study, we developed a new mapping technique by combining single neuron whole-cell patch-clamp recording with 64 multi-channel field potential recording (MED64) to examine the properties of excitatory inputs into a single neuron in the ACC. We found that a single patched pyramidal neuron or interneuron simultaneously received heterogeneous excitatory synaptic innervations from different subregions (ventral, dorsal, deep, and superficial layers) in the ACC. Conduction velocity is faster as stimulation distance increases in pyramidal neurons. Fast-spiking interneurons (FS-IN) show slower inactivation when compared to pyramidal neurons and regular-spiking interneurons (RS-IN) while pyramidal neurons displayed the most rapid activation. Bath application of non-competitive AMPA receptor antagonist GYKI 53655 followed by CNQX revealed that both FS-INs and RS-INs have AMPA and KA mediated components. Our studies provide a new strategy and technique for studying the network of synaptic connections.


2005 ◽  
Vol 1 ◽  
pp. 1744-8069-1-23 ◽  
Author(s):  
MF Wu ◽  
ZP Pang ◽  
M Zhuo ◽  
ZC Xu

The anterior cingulate cortex (ACC) plays an important role in higher brain functions including learning, memory, and persistent pain. Long-term potentiation of excitatory synaptic transmission has been observed in the ACC after digit amputation, which might contribute to plastic changes associated with the phantom pain. Here we report a long-lasting membrane potential depolarization in ACC neurons of adult rats after digit amputation in vivo. Shortly after digit amputation of the hind paw, the membrane potential of intracellularly recorded ACC neurons quickly depolarized from ∼−70 mV to ∼−15 mV and then slowly repolarized. The duration of this amputation-induced depolarization was about 40 min. Intracellular staining revealed that these neurons were pyramidal neurons in the ACC. The depolarization is activity-dependent, since peripheral application of lidocaine significantly reduced it. Furthermore, the depolarization was significantly reduced by a NMDA receptor antagonist MK-801. Our results provide direct in vivo electrophysiological evidence that ACC pyramidal cells undergo rapid and prolonged depolarization after digit amputation, and the amputation-induced depolarization in ACC neurons might be associated with the synaptic mechanisms for phantom pain.


2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Bastiaan van der Veen ◽  
Sampath K. T. Kapanaiah ◽  
Kasyoka Kilonzo ◽  
Peter Steele-Perkins ◽  
Martin M. Jendryka ◽  
...  

AbstractPathological impulsivity is a debilitating symptom of multiple psychiatric diseases with few effective treatment options. To identify druggable receptors with anti-impulsive action we developed a systematic target discovery approach combining behavioural chemogenetics and gene expression analysis. Spatially restricted inhibition of three subdivisions of the prefrontal cortex of mice revealed that the anterior cingulate cortex (ACC) regulates premature responding, a form of motor impulsivity. Probing three G-protein cascades with designer receptors, we found that the activation of Gi-signalling in layer-5 pyramidal cells (L5-PCs) of the ACC strongly, reproducibly, and selectively decreased challenge-induced impulsivity. Differential gene expression analysis across murine ACC cell-types and 402 GPCRs revealed that - among Gi-coupled receptor-encoding genes - Grm2 is the most selectively expressed in L5-PCs while alternative targets were scarce. Validating our approach, we confirmed that mGluR2 activation reduced premature responding. These results suggest Gi-coupled receptors in ACC L5-PCs as therapeutic targets for impulse control disorders.


2009 ◽  
Vol 101 (2) ◽  
pp. 1016-1032 ◽  
Author(s):  
Marc Fischer ◽  
Julia Reuter ◽  
Florian J. Gerich ◽  
Belinda Hildebrandt ◽  
Sonja Hägele ◽  
...  

Rett syndrome is a neurodevelopmental disorder caused by mutations in the X-chromosomal MECP2 gene encoding for the transcriptional regulator methyl CpG binding protein 2 (MeCP2). Rett patients suffer from episodic respiratory irregularities and reduced arterial oxygen levels. To elucidate whether such intermittent hypoxic episodes induce adaptation/preconditioning of the hypoxia-vulnerable hippocampal network, we analyzed its responses to severe hypoxia in adult Rett mice. The occurrence of hypoxia-induced spreading depression (HSD)—an experimental model for ischemic stroke—was hastened in Mecp2− /y males. The extracellular K+ rise during HSD was attenuated in Mecp2− /y males and the input resistance of CA1 pyramidal neurons decreased less before HSD onset. CA1 pyramidal neurons were smaller and more densely packed, but the cell swelling during HSD was unaffected. The intrinsic optical signal and the propagation of HSD were similar among the different genotypes. Basal synaptic function was intact, but Mecp2− /y males showed reduced paired-pulse facilitation and higher field potential/fiber volley ratios, but no increased seizure susceptibility. Synaptic failure during hypoxia was complete in all genotypes and the final degree of posthypoxic synaptic recovery indistinguishable. Cellular ATP content was normal in Mecp2− /y males, but their hematocrit was increased as was HIF-1α expression throughout the brain. This is the first study showing that in Rett syndrome, the susceptibility of telencephalic neuronal networks to hypoxia is increased; the underlying molecular mechanisms apparently involve disturbed K+ channel function. Such an increase in hypoxia susceptibility may potentially contribute to the vulnerability of male Rett patients who are either not viable or severely disabled.


2020 ◽  
Author(s):  
Zhi Ruan ◽  
Dhruba Pathak ◽  
Srinidhi Venkatesan Kalavai ◽  
Asuka Yoshii-Kitahara ◽  
Satoshi Muraoka ◽  
...  

AbstractExtracellular vesicles (EVs) propagate tau pathology for Alzheimer’s disease (AD). How EV transmission influences AD are, nonetheless, poorly understood. To these ends, the physicochemical and molecular structure-function relationships of human brain-derived EVs, from AD and prodromal AD (pAD), were compared to non-demented controls (CTRL). AD EVs were shown to be significantly enriched in epitope-specific tau oligomers versus pAD or CTRL EVs assayed by dot-blot and atomic force microscopy tests. AD EVs were efficiently internalized by murine cortical neurons and transferred tau with higher aggregation potency than pAD and CTRL EVs. Strikingly, inoculation of tau-containing AD EVs into the outer molecular layer of the dentate gyrus induced tau propagation throughout the hippocampus. This was seen in 22 months-old C57BL/6 mice at 4.5 months post-injection by semiquantitative brain-wide immunohistochemistry tests with multiple anti-phospho-tau (p-tau) antibodies. Inoculation of the equal amount of tau from CTRL EVs or as oligomer or fibril-enriched fraction from the same AD donor showed little propagation. AD EVs induced tau accumulation in the hippocampus as oligomers or sarkosyl-insoluble proteins. Unexpectedly, p-tau cells were mostly GAD67+ GABAergic neurons and to a lesser extent, GluR2/3+ excitatory mossy cells, showing preferential EV-mediated GABAergic neuronal tau propagation. Whole-cell patch clamp recording of Cornu Ammonis (CA1) pyramidal cells showed significant reduction in the amplitude of spontaneous inhibitory post-synaptic currents. This was accompanied by reductions in c-fos+ GAD67+GABAergic neurons and GAD67+ GABAergic neuronal puncta surrounding pyramidal neurons in the CA1 region confirming reduced interneuronal projections. Our study posits a novel tau-associated pathological mechanism for brain-derived EVs.


2021 ◽  
Vol 118 (10) ◽  
pp. e2015685118
Author(s):  
Xi Liu ◽  
Zhi Qiao ◽  
Yuming Chai ◽  
Zhi Zhu ◽  
Kaijie Wu ◽  
...  

Various neuromodulation approaches have been employed to alter neuronal spiking activity and thus regulate brain functions and alleviate neurological disorders. Infrared neural stimulation (INS) could be a potential approach for neuromodulation because it requires no tissue contact and possesses a high spatial resolution. However, the risk of overheating and an unclear mechanism hamper its application. Here we show that midinfrared stimulation (MIRS) with a specific wavelength exerts nonthermal, long-distance, and reversible modulatory effects on ion channel activity, neuronal signaling, and sensorimotor behavior. Patch-clamp recording from mouse neocortical pyramidal cells revealed that MIRS readily provides gain control over spiking activities, inhibiting spiking responses to weak inputs but enhancing those to strong inputs. MIRS also shortens action potential (AP) waveforms by accelerating its repolarization, through an increase in voltage-gated K+ (but not Na+) currents. Molecular dynamics simulations further revealed that MIRS-induced resonance vibration of –C=O bonds at the K+ channel ion selectivity filter contributes to the K+ current increase. Importantly, these effects are readily reversible and independent of temperature increase. At the behavioral level in larval zebrafish, MIRS modulates startle responses by sharply increasing the slope of the sensorimotor input–output curve. Therefore, MIRS represents a promising neuromodulation approach suitable for clinical application.


2019 ◽  
Author(s):  
Maria Teleńczuk ◽  
Bartosz Teleńczuk ◽  
Alain Destexhe

AbstractSynaptic currents represent a major contribution to the local field potential (LFP) in brain tissue, but the respective contribution of excitatory and inhibitory synapses is not known. Here, we provide estimates of this contribution by using computational models of hippocampal pyramidal neurons, constrained by in vitro recordings. We focus on the unitary LFP (uLFP) generated by single neurons in the CA3 region of the hippocampus. We first reproduce experimental results for hippocampal basket cells, and in particular how inhibitory uLFP are distributed within hippocampal layers. Next, we calculate the uLFP generated by pyramidal neurons, using morphologically-reconstructed CA3 pyramidal cells. The model shows that the excitatory uLFP is of small amplitude, smaller than inhibitory uLFPs. Indeed, when the two are simulated together, inhibitory uLFPs mask excitatory uLFPs, which might create the illusion that the inhibitory field is generated by pyramidal cells. These results provide an explanation for the observation that excitatory and inhibitory uLFPs are of the same polarity, in vivo and in vitro. These results also show that somatic inhibitory currents are large contributors of the LFP, which is important information to interpret this signal. Finally, the results of our model might form the basis of a simple method to compute the LFP, which could be applied to point neurons for each cell type, thus providing a simple biologically-grounded method to calculate LFPs from neural networks.


1993 ◽  
Vol 70 (6) ◽  
pp. 2251-2259 ◽  
Author(s):  
R. Khazipov ◽  
P. Bregestovski ◽  
Y. Ben-Ari

1. The effects of anoxia on inhibitory synaptic transmission were studied in hippocampal slices of 3- to 4-wk-old rats. CA1 pyramidal cells were examined by whole-cell patch-clamp recording. Synaptic currents were evoked by “distant” (> 0.5 mm) or “close” (< 0.5 mm) electrical stimulation in the stratum radiatum. 2. The excitatory postsynaptic currents (EPSCs) and inhibitory postsynaptic currents (IPSCs) evoked by distant stimulation were completely suppressed by brief anoxia (95% N2-5% CO2 for 4-6 min) and recovered upon reoxygenation. IPSCs were more sensitive to anoxia than EPSCs. EPSCs and IPSCs evoked by distant stimulation were blocked by 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX; 20 microM) and D-2-amino-5-phosphonopentanoate (APV; 50 microM). This indicates that IPSCs were mediated via a polysynaptic pathway that involves glutamate receptors. 3. Synaptic currents evoked by close stimulation were only partly inhibited by anoxia. The bicuculline-sensitive gamma-aminobutyric acid-A (GABAA) receptor-mediated synaptic currents were particularly resistant to anoxia, suggesting that the GABAergic input to pyramidal neurons is not inhibited by anoxia. 4. At close stimulation in the stratum radiatum, monosynaptic IPSCs could be evoked in the presence of CNQX (20 microM) and APV (50 microM). The monosynaptic IPSCs had early bicuculline (15 microM) and late CGP 35348 (100 microM)-sensitive components confirming an involvement of GABAA and GABAB receptors (IPSCA and IPSCB components), respectively. 5. The monosynaptic IPSCA component evoked by close stimulation was not changed significantly during and after brief anoxia. Responses to pressure application of isoguvacine (GABAA agonist) were also not affected by anoxia.(ABSTRACT TRUNCATED AT 250 WORDS)


2005 ◽  
Vol 94 (3) ◽  
pp. 1805-1813 ◽  
Author(s):  
Long-Jun Wu ◽  
Ming-Gao Zhao ◽  
Hiroki Toyoda ◽  
Shanelle W. Ko ◽  
Min Zhuo

Kainate (KA) receptors are expressed widely in the CNS. However, little is known about their functional characterization, molecular identity, and role in synaptic transmission in the forebrain of adult mice. Patch-clamp recordings in genetically modified mice show that postsynaptic KA receptors contribute to fast synaptic transmission in pyramidal neurons in the anterior cingulate cortex (ACC), a forebrain region critical for higher-order cognitive brain functions such as memory and mental disorders. Single-shock stimulation could induce small KA receptor-mediated excitatory postsynaptic currents (KA EPSCs) in the presence of picrotoxin, d-2-amino-5-phosphono-pentanoic acid, and a selective AMPA receptor antagonist, GYKI 53655. KA EPSCs had a significantly slower rise time course and decay time constant compared with AMPA receptor-mediated EPSCs. High-frequency repetitive stimulation significantly facilitated the KA EPSCs. Genetic deletion of the GluR6 or GluR5 subunit significantly reduced, and GluR5 and 6 double knockout completely abolished, KA EPSCs and KA-activated currents in ACC pyramidal neurons. Our results show that KA receptors contribute to synaptic transmission in adult ACC pyramidal neurons and provide a synaptic basis for the physiology and pathology of KA receptors in ACC-related functions.


Author(s):  
Irwin B. Levitan ◽  
Leonard K. Kaczmarek

The Fourth Edition of The Neuron provides a comprehensive first course in the cell and molecular biology of nerve cells. It begins with properties of the many newly discovered ion channels that have emerged through mapping of the genome and which shape the way a single neuron generates varied patterns of electrical activity. It also covers the molecular mechanisms that convert electrical activity into the secretion of neurotransmitter hormones at synaptic junctions between neurons. It discusses the biochemical pathways that are linked to the action of neurotransmitters and that can alter the cellular properties of neurons or sensory cells that transduce information from the outside world into the electrical code used by neurons, and the rapidly expanding knowledge of the molecular factors that induce an undifferentiated cell to become a neuron, and then guide it to form appropriate synaptic connections with its partners. Also addressed is the role of ongoing experience and activity in shaping these connections, and the mechanisms thought to underlie the phenomena of learning and memory.


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