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Letellier M, Levet F, Thoumine O, Goda Y. Differential role of pre- and postsynaptic neurons in the activity-dependent control of synaptic strengths across dendrites. PLoS Biol 2019; 17:e2006223. [PMID: 31166943 PMCID: PMC6576792 DOI: 10.1371/journal.pbio.2006223] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Revised: 06/17/2019] [Accepted: 05/17/2019] [Indexed: 01/07/2023] Open
Abstract
Neurons receive a large number of active synaptic inputs from their many presynaptic partners across their dendritic tree. However, little is known about how the strengths of individual synapses are controlled in balance with other synapses to effectively encode information while maintaining network homeostasis. This is in part due to the difficulty in assessing the activity of individual synapses with identified afferent and efferent connections for a synapse population in the brain. Here, to gain insights into the basic cellular rules that drive the activity-dependent spatial distribution of pre- and postsynaptic strengths across incoming axons and dendrites, we combine patch-clamp recordings with live-cell imaging of hippocampal pyramidal neurons in dissociated cultures and organotypic slices. Under basal conditions, both pre- and postsynaptic strengths cluster on single dendritic branches according to the identity of the presynaptic neurons, thus highlighting the ability of single dendritic branches to exhibit input specificity. Stimulating a single presynaptic neuron induces input-specific and dendritic branchwise spatial clustering of presynaptic strengths, which accompanies a widespread multiplicative scaling of postsynaptic strengths in dissociated cultures and heterosynaptic plasticity at distant synapses in organotypic slices. Our study provides evidence for a potential homeostatic mechanism by which the rapid changes in global or distant postsynaptic strengths compensate for input-specific presynaptic plasticity.
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Affiliation(s)
- Mathieu Letellier
- RIKEN Brain Science Institute, Wako, Saitama, Japan
- Interdisciplinary Institute for Neuroscience, University of Bordeaux, Bordeaux, France
- Interdisciplinary Institute for Neuroscience, Centre National de la Recherche Scientifique (CNRS) UMR 5297, Bordeaux, France
- * E-mail: (ML); (YG)
| | - Florian Levet
- Interdisciplinary Institute for Neuroscience, University of Bordeaux, Bordeaux, France
- Interdisciplinary Institute for Neuroscience, Centre National de la Recherche Scientifique (CNRS) UMR 5297, Bordeaux, France
- Bordeaux Imaging Center, University of Bordeaux, Bordeaux, France
- Bordeaux Imaging Center, CNRS UMS 3420, Bordeaux, France
- Bordeaux Imaging Center, INSERM US04, Bordeaux, France
| | - Olivier Thoumine
- Interdisciplinary Institute for Neuroscience, University of Bordeaux, Bordeaux, France
- Interdisciplinary Institute for Neuroscience, Centre National de la Recherche Scientifique (CNRS) UMR 5297, Bordeaux, France
| | - Yukiko Goda
- RIKEN Center for Brain Science, Wako, Saitama, Japan
- * E-mail: (ML); (YG)
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Kubota Y, Kondo S, Nomura M, Hatada S, Yamaguchi N, Mohamed AA, Karube F, Lübke J, Kawaguchi Y. Functional effects of distinct innervation styles of pyramidal cells by fast spiking cortical interneurons. eLife 2015; 4. [PMID: 26142457 PMCID: PMC4518632 DOI: 10.7554/elife.07919] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2015] [Accepted: 07/04/2015] [Indexed: 01/16/2023] Open
Abstract
Inhibitory interneurons target precise membrane regions on pyramidal cells, but differences in their functional effects on somata, dendrites and spines remain unclear. We analyzed inhibitory synaptic events induced by cortical, fast-spiking (FS) basket cells which innervate dendritic shafts and spines as well as pyramidal cell somata. Serial electron micrograph (EMg) reconstructions showed that somatic synapses were larger than dendritic contacts. Simulations with precise anatomical and physiological data reveal functional differences between different innervation styles. FS cell soma-targeting synapses initiate a strong, global inhibition, those on shafts inhibit more restricted dendritic zones, while synapses on spines may mediate a strictly local veto. Thus, FS cell synapses of different sizes and sites provide functionally diverse forms of pyramidal cell inhibition.
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Affiliation(s)
- Yoshiyuki Kubota
- Division of Cerebral Circuitry, National Institute for Physiological Sciences, Okazaki, Japan
| | - Satoru Kondo
- Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, Tokyo, Japan
| | - Masaki Nomura
- Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, Tokyo, Japan
| | - Sayuri Hatada
- Division of Cerebral Circuitry, National Institute for Physiological Sciences, Okazaki, Japan
| | - Noboru Yamaguchi
- Division of Cerebral Circuitry, National Institute for Physiological Sciences, Okazaki, Japan
| | - Alsayed A Mohamed
- Division of Cerebral Circuitry, National Institute for Physiological Sciences, Okazaki, Japan
| | - Fuyuki Karube
- Division of Cerebral Circuitry, National Institute for Physiological Sciences, Okazaki, Japan
| | - Joachim Lübke
- Institute of Neuroscience and Medicine, Research Centre Jülich, Jülich, Germany
| | - Yasuo Kawaguchi
- Division of Cerebral Circuitry, National Institute for Physiological Sciences, Okazaki, Japan
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Hongo Y, Ogawa K, Takahara Y, Takasu K, Royer S, Hasegawa M, Sakaguchi G, Ikegaya Y. Topological organization of CA3-to-CA1 excitation. Eur J Neurosci 2015; 42:2135-43. [PMID: 26036915 DOI: 10.1111/ejn.12969] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2015] [Revised: 05/07/2015] [Accepted: 05/28/2015] [Indexed: 11/30/2022]
Abstract
The CA1-projecting axons of CA3 pyramidal cells, called Schaffer collaterals, constitute one of the major information flow routes in the hippocampal formation. Recent anatomical studies have revealed the non-random structural connectivity between CA3 and CA1, but little is known regarding the functional connectivity (i.e. how CA3 network activity is functionally transmitted downstream to the CA1 network). Using functional multi-neuron calcium imaging of rat hippocampal slices, we monitored the spatiotemporal patterns of spontaneous CA3 and CA1 burst activity under pharmacological GABAergic blockade. We found that spatially clustered CA3 activity patterns were transformed into layered CA1 activity sequences. Specifically, synchronized bursts initiated from multiple hot spots in CA3 ensembles, and CA1 neurons located deeper in the pyramidal cell layer were recruited during earlier phases of the burst events. The order of these sequential activations was maintained across the bursts, but the sequence velocity varied depending on the inter-burst intervals. Thus, CA3 axons innervate CA1 neurons in a highly topographical fashion.
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Affiliation(s)
- Yoshie Hongo
- Pain & Neuroscience, Discovery Research Laboratory for Core Therapeutic Areas, Shionogi Co. Ltd, Toyonaka, Osaka, Japan
| | - Koichi Ogawa
- Pain & Neuroscience, Discovery Research Laboratory for Core Therapeutic Areas, Shionogi Co. Ltd, Toyonaka, Osaka, Japan
| | - Yuji Takahara
- Pain & Neuroscience, Discovery Research Laboratory for Core Therapeutic Areas, Shionogi Co. Ltd, Toyonaka, Osaka, Japan
| | - Keiko Takasu
- Pain & Neuroscience, Discovery Research Laboratory for Core Therapeutic Areas, Shionogi Co. Ltd, Toyonaka, Osaka, Japan
| | - Sebastien Royer
- Center for Functional Connectomics, Korea Institute of Science and Technology, Seoul, South Korea
| | - Minoru Hasegawa
- Pain & Neuroscience, Discovery Research Laboratory for Core Therapeutic Areas, Shionogi Co. Ltd, Toyonaka, Osaka, Japan
| | - Gaku Sakaguchi
- Pain & Neuroscience, Discovery Research Laboratory for Core Therapeutic Areas, Shionogi Co. Ltd, Toyonaka, Osaka, Japan
| | - Yuji Ikegaya
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.,Center for Information and Neural Networks, National Institute of Information and Communications Technology, Suita City, Osaka, Japan
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Neishabouri A, Faisal AA. Axonal noise as a source of synaptic variability. PLoS Comput Biol 2014; 10:e1003615. [PMID: 24809823 PMCID: PMC4014398 DOI: 10.1371/journal.pcbi.1003615] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Accepted: 03/26/2014] [Indexed: 11/19/2022] Open
Abstract
Post-synaptic potential (PSP) variability is typically attributed to mechanisms inside synapses, yet recent advances in experimental methods and biophysical understanding have led us to reconsider the role of axons as highly reliable transmission channels. We show that in many thin axons of our brain, the action potential (AP) waveform and thus the Ca++ signal controlling vesicle release at synapses will be significantly affected by the inherent variability of ion channel gating. We investigate how and to what extent fluctuations in the AP waveform explain observed PSP variability. Using both biophysical theory and stochastic simulations of central and peripheral nervous system axons from vertebrates and invertebrates, we show that channel noise in thin axons (<1 µm diameter) causes random fluctuations in AP waveforms. AP height and width, both experimentally characterised parameters of post-synaptic response amplitude, vary e.g. by up to 20 mV and 0.5 ms while a single AP propagates in C-fibre axons. We show how AP height and width variabilities increase with a ¾ power-law as diameter decreases and translate these fluctuations into post-synaptic response variability using biophysical data and models of synaptic transmission. We find for example that for mammalian unmyelinated axons with 0.2 µm diameter (matching cerebellar parallel fibres) axonal noise alone can explain half of the PSP variability in cerebellar synapses. We conclude that axonal variability may have considerable impact on synaptic response variability. Thus, in many experimental frameworks investigating synaptic transmission through paired-cell recordings or extracellular stimulation of presynaptic neurons, causes of variability may have been confounded. We thereby show how bottom-up aggregation of molecular noise sources contributes to our understanding of variability observed at higher levels of biological organisation.
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Affiliation(s)
- Ali Neishabouri
- Department of Bioengineering, Imperial College London, London, United Kingdom
- * E-mail:
| | - A. Aldo Faisal
- Department of Bioengineering, Imperial College London, London, United Kingdom
- Department of Computing, Imperial College London, London, United Kingdom
- MRC Clinical Sciences Centre, London, United Kingdom
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Extracellular calcium controls the expression of two different forms of ripple-like hippocampal oscillations. J Neurosci 2014; 34:2989-3004. [PMID: 24553939 DOI: 10.1523/jneurosci.2826-13.2014] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Hippocampal high-frequency oscillations (HFOs) are prominent in physiological and pathological conditions. During physiological ripples (100-200 Hz), few pyramidal cells fire together coordinated by rhythmic inhibitory potentials. In the epileptic hippocampus, fast ripples (>200 Hz) reflect population spikes (PSs) from clusters of bursting cells, but HFOs in the ripple and the fast ripple range are vastly intermixed. What is the meaning of this frequency range? What determines the expression of different HFOs? Here, we used different concentrations of Ca(2+) in a physiological range (1-3 mM) to record local field potentials and single cells in hippocampal slices from normal rats. Surprisingly, we found that this sole manipulation results in the emergence of two forms of HFOs reminiscent of ripples and fast ripples recorded in vivo from normal and epileptic rats, respectively. We scrutinized the cellular correlates and mechanisms underlying the emergence of these two forms of HFOs by combining multisite, single-cell and paired-cell recordings in slices prepared from a rat reporter line that facilitates identification of GABAergic cells. We found a major effect of extracellular Ca(2+) in modulating intrinsic excitability and disynaptic inhibition, two critical factors shaping network dynamics. Moreover, locally modulating the extracellular Ca(2+) concentration in an in vivo environment had a similar effect on disynaptic inhibition, pyramidal cell excitability, and ripple dynamics. Therefore, the HFO frequency band reflects a range of firing dynamics of hippocampal networks.
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Le Duigou C, Simonnet J, Teleñczuk MT, Fricker D, Miles R. Recurrent synapses and circuits in the CA3 region of the hippocampus: an associative network. Front Cell Neurosci 2014; 7:262. [PMID: 24409118 PMCID: PMC3884140 DOI: 10.3389/fncel.2013.00262] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2013] [Accepted: 12/02/2013] [Indexed: 11/29/2022] Open
Abstract
In the CA3 region of the hippocampus, pyramidal cells excite other pyramidal cells and interneurons. The axons of CA3 pyramidal cells spread throughout most of the region to form an associative network. These connections were first drawn by Cajal and Lorente de No. Their physiological properties were explored to understand epileptiform discharges generated in the region. Synapses between pairs of pyramidal cells involve one or few release sites and are weaker than connections made by mossy fibers on CA3 pyramidal cells. Synapses with interneurons are rather effective, as needed to control unchecked excitation. We examine contributions of recurrent synapses to epileptiform synchrony, to the genesis of sharp waves in the CA3 region and to population oscillations at theta and gamma frequencies. Recurrent connections in CA3, as other associative cortices, have a lower connectivity spread over a larger area than in primary sensory cortices. This sparse, but wide-ranging connectivity serves the functions of an associative network, including acquisition of neuronal representations as activity in groups of CA3 cells and completion involving the recall from partial cues of these ensemble firing patterns.
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Affiliation(s)
- Caroline Le Duigou
- Centre de Recherche de l'Institut du Cerveau et de la Moelle, INSERM U975, CHU Pitié-Salpêtrière, Université Pierre et Marie Curie Paris, France
| | - Jean Simonnet
- Centre de Recherche de l'Institut du Cerveau et de la Moelle, INSERM U975, CHU Pitié-Salpêtrière, Université Pierre et Marie Curie Paris, France
| | - Maria T Teleñczuk
- Centre de Recherche de l'Institut du Cerveau et de la Moelle, INSERM U975, CHU Pitié-Salpêtrière, Université Pierre et Marie Curie Paris, France
| | - Desdemona Fricker
- Centre de Recherche de l'Institut du Cerveau et de la Moelle, INSERM U975, CHU Pitié-Salpêtrière, Université Pierre et Marie Curie Paris, France
| | - Richard Miles
- Centre de Recherche de l'Institut du Cerveau et de la Moelle, INSERM U975, CHU Pitié-Salpêtrière, Université Pierre et Marie Curie Paris, France
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Sasaki T. The axon as a unique computational unit in neurons. Neurosci Res 2013; 75:83-8. [PMID: 23298528 DOI: 10.1016/j.neures.2012.12.004] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2012] [Revised: 12/11/2012] [Accepted: 12/17/2012] [Indexed: 11/25/2022]
Abstract
In the mammalian cortex, axons are highly ramified and link an enormous number of neurons over large distances. The conventional view assumes that action potentials (APs) are initiated at the axon initial segment in an all-or-none fashion and are then self-propagated orthodromically along axon collaterals without distortion of the AP waveform. By contrast, recent experimental results suggest that the axonal AP waveform can be modified depending on the activation states of the ion channels and receptors on axonal cell membranes. This AP modulation can regulate neurotransmission to postsynaptic neurons. In addition, the latest studies have provided evidence that cortical axons can integrate somatic burst firings and promote activity-dependent ectopic AP generation, which may underlie the oscillogenesis of fast rhythmic network activity. These seminal observations indicate that axons can perform diverse functional operations that extend beyond the prevailing model of axon physiology.
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Affiliation(s)
- Takuya Sasaki
- Division of Cerebral Structure, National Institute for Physiological Sciences, Okazaki 444-8787, Japan.
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