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Guet-McCreight A, Chameh HM, Mazza F, Prevot TD, Valiante TA, Sibille E, Hay E. In-silico testing of new pharmacology for restoring inhibition and human cortical function in depression. Commun Biol 2024; 7:225. [PMID: 38396202 PMCID: PMC10891083 DOI: 10.1038/s42003-024-05907-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Accepted: 02/09/2024] [Indexed: 02/25/2024] Open
Abstract
Reduced inhibition by somatostatin-expressing interneurons is associated with depression. Administration of positive allosteric modulators of α5 subunit-containing GABAA receptor (α5-PAM) that selectively target this lost inhibition exhibit antidepressant and pro-cognitive effects in rodent models of chronic stress. However, the functional effects of α5-PAM on the human brain in vivo are unknown, and currently cannot be assessed experimentally. We modeled the effects of α5-PAM on tonic inhibition as measured in human neurons, and tested in silico α5-PAM effects on detailed models of human cortical microcircuits in health and depression. We found that α5-PAM effectively recovered impaired cortical processing as quantified by stimulus detection metrics, and also recovered the power spectral density profile of the microcircuit EEG signals. We performed an α5-PAM dose-response and identified simulated EEG biomarker candidates. Our results serve to de-risk and facilitate α5-PAM translation and provide biomarkers in non-invasive brain signals for monitoring target engagement and drug efficacy.
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Affiliation(s)
- Alexandre Guet-McCreight
- Krembil Centre for Neuroinformatics, Centre for Addiction and Mental Health, Toronto, ON, Canada.
| | | | - Frank Mazza
- Krembil Centre for Neuroinformatics, Centre for Addiction and Mental Health, Toronto, ON, Canada
- Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Thomas D Prevot
- Department of Psychiatry, University of Toronto, Toronto, ON, Canada
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, ON, Canada
| | - Taufik A Valiante
- Krembil Brain Institute, University Health Network, Toronto, ON, Canada
- Institute of Medical Sciences, University of Toronto, Toronto, ON, Canada
- Department of Electrical and Computer Engineering, University of Toronto, Toronto, ON, Canada
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, ON, Canada
- Department of Surgery, University of Toronto, Toronto, ON, Canada
- Center for Advancing Neurotechnological Innovation to Application, Toronto, ON, Canada
- Max Planck-University of Toronto Center for Neural Science and Technology, Toronto, ON, Canada
| | - Etienne Sibille
- Department of Psychiatry, University of Toronto, Toronto, ON, Canada
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, ON, Canada
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, ON, Canada
| | - Etay Hay
- Krembil Centre for Neuroinformatics, Centre for Addiction and Mental Health, Toronto, ON, Canada.
- Department of Physiology, University of Toronto, Toronto, ON, Canada.
- Department of Psychiatry, University of Toronto, Toronto, ON, Canada.
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Milicevic KD, Barbeau BL, Lovic DD, Patel AA, Ivanova VO, Antic SD. Physiological features of parvalbumin-expressing GABAergic interneurons contributing to high-frequency oscillations in the cerebral cortex. CURRENT RESEARCH IN NEUROBIOLOGY 2023; 6:100121. [PMID: 38616956 PMCID: PMC11015061 DOI: 10.1016/j.crneur.2023.100121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Revised: 11/13/2023] [Accepted: 12/01/2023] [Indexed: 04/16/2024] Open
Abstract
Parvalbumin-expressing (PV+) inhibitory interneurons drive gamma oscillations (30-80 Hz), which underlie higher cognitive functions. In this review, we discuss two groups/aspects of fundamental properties of PV+ interneurons. In the first group (dubbed Before Axon), we list properties representing optimal synaptic integration in PV+ interneurons designed to support fast oscillations. For example: [i] Information can neither enter nor leave the neocortex without the engagement of fast PV+ -mediated inhibition; [ii] Voltage responses in PV+ interneuron dendrites integrate linearly to reduce impact of the fluctuations in the afferent drive; and [iii] Reversed somatodendritic Rm gradient accelerates the time courses of synaptic potentials arriving at the soma. In the second group (dubbed After Axon), we list morphological and biophysical properties responsible for (a) short synaptic delays, and (b) efficient postsynaptic outcomes. For example: [i] Fast-spiking ability that allows PV+ interneurons to outpace other cortical neurons (pyramidal neurons). [ii] Myelinated axon (which is only found in the PV+ subclass of interneurons) to secure fast-spiking at the initial axon segment; and [iii] Inhibitory autapses - autoinhibition, which assures brief biphasic voltage transients and supports postinhibitory rebounds. Recent advent of scientific tools, such as viral strategies to target PV cells and the ability to monitor PV cells via in vivo imaging during behavior, will aid in defining the role of PV cells in the CNS. Given the link between PV+ interneurons and cognition, in the future, it would be useful to carry out physiological recordings in the PV+ cell type selectively and characterize if and how psychiatric and neurological diseases affect initiation and propagation of electrical signals in this cortical sub-circuit. Voltage imaging may allow fast recordings of electrical signals from many PV+ interneurons simultaneously.
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Affiliation(s)
- Katarina D. Milicevic
- University of Connecticut Health, School of Medicine, Institute for Systems Genomics, Farmington, CT, 06030, USA
- University of Belgrade, Faculty of Biology, Center for Laser Microscopy, Belgrade, 11000, Serbia
| | - Brianna L. Barbeau
- University of Connecticut Health, School of Medicine, Institute for Systems Genomics, Farmington, CT, 06030, USA
| | - Darko D. Lovic
- University of Connecticut Health, School of Medicine, Institute for Systems Genomics, Farmington, CT, 06030, USA
- University of Belgrade, Faculty of Biology, Center for Laser Microscopy, Belgrade, 11000, Serbia
| | - Aayushi A. Patel
- University of Connecticut Health, School of Medicine, Institute for Systems Genomics, Farmington, CT, 06030, USA
| | - Violetta O. Ivanova
- University of Connecticut Health, School of Medicine, Institute for Systems Genomics, Farmington, CT, 06030, USA
| | - Srdjan D. Antic
- University of Connecticut Health, School of Medicine, Institute for Systems Genomics, Farmington, CT, 06030, USA
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de Kock CPJ, Feldmeyer D. Shared and divergent principles of synaptic transmission between cortical excitatory neurons in rodent and human brain. Front Synaptic Neurosci 2023; 15:1274383. [PMID: 37731775 PMCID: PMC10508294 DOI: 10.3389/fnsyn.2023.1274383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Accepted: 08/21/2023] [Indexed: 09/22/2023] Open
Abstract
Information transfer between principal neurons in neocortex occurs through (glutamatergic) synaptic transmission. In this focussed review, we provide a detailed overview on the strength of synaptic neurotransmission between pairs of excitatory neurons in human and laboratory animals with a specific focus on data obtained using patch clamp electrophysiology. We reach two major conclusions: (1) the synaptic strength, measured as unitary excitatory postsynaptic potential (or uEPSP), is remarkably consistent across species, cortical regions, layers and/or cell-types (median 0.5 mV, interquartile range 0.4-1.0 mV) with most variability associated with the cell-type specific connection studied (min 0.1-max 1.4 mV), (2) synaptic function cannot be generalized across human and rodent, which we exemplify by discussing the differences in anatomical and functional properties of pyramidal-to-pyramidal connections within human and rodent cortical layers 2 and 3. With only a handful of studies available on synaptic transmission in human, it is obvious that much remains unknown to date. Uncovering the shared and divergent principles of synaptic transmission across species however, will almost certainly be a pivotal step toward understanding human cognitive ability and brain function in health and disease.
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Affiliation(s)
- Christiaan P. J. de Kock
- Center for Neurogenomics and Cognitive Research, Vrije Universiteit Amsterdam, Amsterdam, Netherlands
| | - Dirk Feldmeyer
- Research Center Juelich, Institute of Neuroscience and Medicine, Jülich, Germany
- Department of Psychiatry, Psychotherapy, and Psychosomatics, RWTH Aachen University Hospital, Aachen, Germany
- Jülich-Aachen Research Alliance, Translational Brain Medicine (JARA Brain), Aachen, Germany
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4
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Szegedi V, Bakos E, Furdan S, Kovács BH, Varga D, Erdélyi M, Barzó P, Szücs A, Tamás G, Lamsa K. HCN channels at the cell soma ensure the rapid electrical reactivity of fast-spiking interneurons in human neocortex. PLoS Biol 2023; 21:e3002001. [PMID: 36745683 PMCID: PMC9934405 DOI: 10.1371/journal.pbio.3002001] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Revised: 02/16/2023] [Accepted: 01/17/2023] [Indexed: 02/07/2023] Open
Abstract
Accumulating evidence indicates that there are substantial species differences in the properties of mammalian neurons, yet theories on circuit activity and information processing in the human brain are based heavily on results obtained from rodents and other experimental animals. This knowledge gap may be particularly important for understanding the neocortex, the brain area responsible for the most complex neuronal operations and showing the greatest evolutionary divergence. Here, we examined differences in the electrophysiological properties of human and mouse fast-spiking GABAergic basket cells, among the most abundant inhibitory interneurons in cortex. Analyses of membrane potential responses to current input, pharmacologically isolated somatic leak currents, isolated soma outside-out patch recordings, and immunohistochemical staining revealed that human neocortical basket cells abundantly express hyperpolarization-activated cyclic nucleotide-gated cation (HCN) channel isoforms HCN1 and HCN2 at the cell soma membrane, whereas these channels are sparse at the rodent basket cell soma membrane. Antagonist experiments showed that HCN channels in human neurons contribute to the resting membrane potential and cell excitability at the cell soma, accelerate somatic membrane potential kinetics, and shorten the lag between excitatory postsynaptic potentials and action potential generation. These effects are important because the soma of human fast-spiking neurons without HCN channels exhibit low persistent ion leak and slow membrane potential kinetics, compared with mouse fast-spiking neurons. HCN channels speed up human cell membrane potential kinetics and help attain an input-output rate close to that of rodent cells. Computational modeling demonstrated that HCN channel activity at the human fast-spiking cell soma membrane is sufficient to accelerate the input-output function as observed in cell recordings. Thus, human and mouse fast-spiking neurons exhibit functionally significant differences in ion channel composition at the cell soma membrane to set the speed and fidelity of their input-output function. These HCN channels ensure fast electrical reactivity of fast-spiking cells in human neocortex.
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Affiliation(s)
- Viktor Szegedi
- Department of Physiology, Anatomy and Neuroscience, University of Szeged, Szeged, Hungary
- Hungarian Centre of Excellence for Molecular Medicine Research Group for Human neuron physiology and therapy, Szeged, Hungary
| | - Emőke Bakos
- Department of Physiology, Anatomy and Neuroscience, University of Szeged, Szeged, Hungary
- Hungarian Centre of Excellence for Molecular Medicine Research Group for Human neuron physiology and therapy, Szeged, Hungary
| | - Szabina Furdan
- Department of Physiology, Anatomy and Neuroscience, University of Szeged, Szeged, Hungary
- Hungarian Centre of Excellence for Molecular Medicine Research Group for Human neuron physiology and therapy, Szeged, Hungary
| | - Bálint H. Kovács
- Department of Optics and Quantum Electronics, University of Szeged, Szeged, Hungary
| | - Dániel Varga
- Department of Optics and Quantum Electronics, University of Szeged, Szeged, Hungary
| | - Miklós Erdélyi
- Department of Optics and Quantum Electronics, University of Szeged, Szeged, Hungary
| | - Pál Barzó
- Department of Neurosurgery, University of Szeged, Szeged, Hungary
| | - Attila Szücs
- Hungarian Centre of Excellence for Molecular Medicine Research Group for Human neuron physiology and therapy, Szeged, Hungary
- Neuronal Cell Biology Research Group, Eötvös Loránd University, Budapest, Budapest, Hungary
| | - Gábor Tamás
- MTA-SZTE Research Group for Cortical Microcircuits, Department of Physiology, Anatomy and Neuroscience, University of Szeged, Szeged, Hungary
| | - Karri Lamsa
- Department of Physiology, Anatomy and Neuroscience, University of Szeged, Szeged, Hungary
- Hungarian Centre of Excellence for Molecular Medicine Research Group for Human neuron physiology and therapy, Szeged, Hungary
- * E-mail: ,
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Intrathecally administered pizotifen alleviates neuropathic and inflammatory pain in mice by enhancing GABAergic inhibition. Neurosci Lett 2022; 775:136545. [DOI: 10.1016/j.neulet.2022.136545] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 02/07/2022] [Accepted: 02/18/2022] [Indexed: 11/16/2022]
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Yao HK, Guet-McCreight A, Mazza F, Moradi Chameh H, Prevot TD, Griffiths JD, Tripathy SJ, Valiante TA, Sibille E, Hay E. Reduced inhibition in depression impairs stimulus processing in human cortical microcircuits. Cell Rep 2022; 38:110232. [PMID: 35021088 DOI: 10.1016/j.celrep.2021.110232] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 10/07/2021] [Accepted: 12/16/2021] [Indexed: 12/01/2022] Open
Abstract
Cortical processing depends on finely tuned excitatory and inhibitory connections in neuronal microcircuits. Reduced inhibition by somatostatin-expressing interneurons is a key component of altered inhibition associated with treatment-resistant major depressive disorder (depression), which is implicated in cognitive deficits and rumination, but the link remains to be better established mechanistically in humans. Here we test the effect of reduced somatostatin interneuron-mediated inhibition on cortical processing in human neuronal microcircuits using a data-driven computational approach. We integrate human cellular, circuit, and gene expression data to generate detailed models of human cortical microcircuits in health and depression. We simulate microcircuit baseline and response activity and find a reduced signal-to-noise ratio and increased false/failed detection of stimuli due to a higher baseline activity in depression. We thus apply models of human cortical microcircuits to demonstrate mechanistically how reduced inhibition impairs cortical processing in depression, providing quantitative links between altered inhibition and cognitive deficits.
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Affiliation(s)
- Heng Kang Yao
- Krembil Centre for Neuroinformatics, Centre for Addiction and Mental Health, Toronto, ON M5T 1R7, Canada; Department of Physiology, University of Toronto, Toronto, ON M5S 1A1, Canada
| | - Alexandre Guet-McCreight
- Krembil Centre for Neuroinformatics, Centre for Addiction and Mental Health, Toronto, ON M5T 1R7, Canada
| | - Frank Mazza
- Krembil Centre for Neuroinformatics, Centre for Addiction and Mental Health, Toronto, ON M5T 1R7, Canada; Department of Physiology, University of Toronto, Toronto, ON M5S 1A1, Canada
| | | | - Thomas D Prevot
- Department of Psychiatry, University of Toronto, Toronto, ON M5S 1A1, Canada; Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, ON M5T 1R7, Canada
| | - John D Griffiths
- Krembil Centre for Neuroinformatics, Centre for Addiction and Mental Health, Toronto, ON M5T 1R7, Canada; Department of Psychiatry, University of Toronto, Toronto, ON M5S 1A1, Canada; Institute of Medical Sciences, University of Toronto, Toronto, ON M5S 1A1, Canada
| | - Shreejoy J Tripathy
- Krembil Centre for Neuroinformatics, Centre for Addiction and Mental Health, Toronto, ON M5T 1R7, Canada; Department of Physiology, University of Toronto, Toronto, ON M5S 1A1, Canada; Department of Psychiatry, University of Toronto, Toronto, ON M5S 1A1, Canada; Institute of Medical Sciences, University of Toronto, Toronto, ON M5S 1A1, Canada
| | - Taufik A Valiante
- Krembil Research Institute, University Health Network, Toronto, ON M5T 0S8, Canada; Institute of Medical Sciences, University of Toronto, Toronto, ON M5S 1A1, Canada; Department of Electrical and Computer Engineering, University of Toronto, Toronto, ON M5S 1A1; Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, ON M5S 1A1, Canada; Department of Surgery, University of Toronto, Toronto, ON M5S 1A1, Canada; Max Planck-University of Toronto Center for Neural Science and Technology, University of Toronto, Toronto, ON M5S 1A1, Canada; Center for Advancing Neurotechnological Innovation to Application, University of Toronto, Toronto, ON M5S 1A1, Canada
| | - Etienne Sibille
- Department of Psychiatry, University of Toronto, Toronto, ON M5S 1A1, Canada; Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, ON M5T 1R7, Canada; Department of Pharmacology & Toxicology, University of Toronto, Toronto, ON M5S 1A1, Canada
| | - Etay Hay
- Krembil Centre for Neuroinformatics, Centre for Addiction and Mental Health, Toronto, ON M5T 1R7, Canada; Department of Physiology, University of Toronto, Toronto, ON M5S 1A1, Canada; Department of Psychiatry, University of Toronto, Toronto, ON M5S 1A1, Canada.
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Maratha S, Sharma V, Walia V. Possible involvement of NO-sGC-cGMP signaling in the antidepressant like effect of pyridoxine in mice. Metab Brain Dis 2022; 37:173-183. [PMID: 34739660 DOI: 10.1007/s11011-021-00858-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Accepted: 10/23/2021] [Indexed: 11/28/2022]
Abstract
The present study was designed to determine the antidepressant like effect of pyridoxine in mice. Pyridoxine (12.5, 25 and 50 mg/kg, i.p.) was administered to the mice and depression related behavioral and neurochemical alterations were determined. It was observed that pyridoxine (50 mg/kg, i.p.) treatment decreased the immobility period in tail suspension test (TST) and forced swim test (FST) significantly as compared to control. Pyridoxine (50 mg/kg, i.p.) treatment increased the level of serotonin (5-HT) and decreased the level of nitrite in the brain of mice significantly as compared to control. Pyridoxine thus confer antidepressant like effect by increasing the level of 5-HT and by decreasing the level of nitrite in the brain of mice. Further the influence of nitric oxide (NO)/ soluble guanylate cyclase (sGC)/ cyclic guanosine monophosphate (cGMP) in antidepressant-like effect of pyridoxine was studied. It was observed that the pretreatment of NO donor (i.e. L-Arginine) and cGMP modulator (i.e. sildenafil) counteracted while the pretreatment of NO/sGC inhibitor (i.e. methylene blue) potentiated the effect of pyridoxine in TST and FST. Pretreatment of NO donor did not influence, pretreatment of NO/sGC inhibitor decreased while the pretreatment of cGMP modulator increased the level of brain nitrite in pyridoxine treated mice. Further the pretreatment of NO donor and cGMP modulator decreased while the pretreatment of NO/sGC inhibitor increased the level of brain serotonin in pyridoxine treated mice. Pyridoxine thus exerted antidepressant like effect and NO-sGC-cGMP signaling modulated the antidepressant like effect of pyridoxine in mice.
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Affiliation(s)
- Sushma Maratha
- SGT College of Pharmacy, SGT University, Gurugram, India
| | - Vijay Sharma
- SGT College of Pharmacy, SGT University, Gurugram, India
| | - Vaibhav Walia
- SGT College of Pharmacy, SGT University, Gurugram, India.
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Yan Z, Rein B. Mechanisms of synaptic transmission dysregulation in the prefrontal cortex: pathophysiological implications. Mol Psychiatry 2022; 27:445-465. [PMID: 33875802 PMCID: PMC8523584 DOI: 10.1038/s41380-021-01092-3] [Citation(s) in RCA: 106] [Impact Index Per Article: 53.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2020] [Revised: 03/13/2021] [Accepted: 03/29/2021] [Indexed: 02/02/2023]
Abstract
The prefrontal cortex (PFC) serves as the chief executive officer of the brain, controlling the highest level cognitive and emotional processes. Its local circuits among glutamatergic principal neurons and GABAergic interneurons, as well as its long-range connections with other brain regions, have been functionally linked to specific behaviors, ranging from working memory to reward seeking. The efficacy of synaptic signaling in the PFC network is profundedly influenced by monoaminergic inputs via the activation of dopamine, adrenergic, or serotonin receptors. Stress hormones and neuropeptides also exert complex effects on the synaptic structure and function of PFC neurons. Dysregulation of PFC synaptic transmission is strongly linked to social deficits, affective disturbance, and memory loss in brain disorders, including autism, schizophrenia, depression, and Alzheimer's disease. Critical neural circuits, biological pathways, and molecular players that go awry in these mental illnesses have been revealed by integrated electrophysiological, optogenetic, biochemical, and transcriptomic studies of PFC. Novel epigenetic mechanism-based strategies are proposed as potential avenues of therapeutic intervention for PFC-involved diseases. This review provides an overview of PFC network organization and synaptic modulation, as well as the mechanisms linking PFC dysfunction to the pathophysiology of neurodevelopmental, neuropsychiatric, and neurodegenerative diseases. Insights from the preclinical studies offer the potential for discovering new medical treatments for human patients with these brain disorders.
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Affiliation(s)
- Zhen Yan
- Department of Physiology and Biophysics, State University of New York at Buffalo, Jacobs School of Medicine and Biomedical Sciences, Buffalo, NY, USA.
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Louth EL, Jørgensen RL, Korshoej AR, Sørensen JCH, Capogna M. Dopaminergic Neuromodulation of Spike Timing Dependent Plasticity in Mature Adult Rodent and Human Cortical Neurons. Front Cell Neurosci 2021; 15:668980. [PMID: 33967700 PMCID: PMC8102156 DOI: 10.3389/fncel.2021.668980] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Accepted: 03/29/2021] [Indexed: 11/29/2022] Open
Abstract
Synapses in the cerebral cortex constantly change and this dynamic property regulated by the action of neuromodulators such as dopamine (DA), is essential for reward learning and memory. DA modulates spike-timing-dependent plasticity (STDP), a cellular model of learning and memory, in juvenile rodent cortical neurons. However, it is unknown whether this neuromodulation also occurs at excitatory synapses of cortical neurons in mature adult mice or in humans. Cortical layer V pyramidal neurons were recorded with whole cell patch clamp electrophysiology and an extracellular stimulating electrode was used to induce STDP. DA was either bath-applied or optogenetically released in slices from mice. Classical STDP induction protocols triggered non-hebbian excitatory synaptic depression in the mouse or no plasticity at human cortical synapses. DA reverted long term synaptic depression to baseline in mouse via dopamine 2 type receptors or elicited long term synaptic potentiation in human cortical synapses. Furthermore, when DA was applied during an STDP protocol it depressed presynaptic inhibition in the mouse but not in the human cortex. Thus, DA modulates excitatory synaptic plasticity differently in human vs. mouse cortex. The data strengthens the importance of DA in gating cognition in humans, and may inform on therapeutic interventions to recover brain function from diseases.
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Affiliation(s)
- Emma Louise Louth
- Department of Biomedicine, Aarhus University, Aarhus, Denmark.,DANDRITE, The Danish Research Institute of Translational Neuroscience, Aarhus University, Aarhus, Denmark
| | | | | | | | - Marco Capogna
- Department of Biomedicine, Aarhus University, Aarhus, Denmark.,DANDRITE, The Danish Research Institute of Translational Neuroscience, Aarhus University, Aarhus, Denmark.,Center for Proteins in Memory-PROMEMO, Danish National Research Foundation, Aarhus University, Aarhus, Denmark
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Arias HR, Targowska-Duda KM, García-Colunga J, Ortells MO. Is the Antidepressant Activity of Selective Serotonin Reuptake Inhibitors Mediated by Nicotinic Acetylcholine Receptors? Molecules 2021; 26:molecules26082149. [PMID: 33917953 PMCID: PMC8068400 DOI: 10.3390/molecules26082149] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Revised: 03/31/2021] [Accepted: 04/05/2021] [Indexed: 12/05/2022] Open
Abstract
It is generally assumed that selective serotonin reuptake inhibitors (SSRIs) induce antidepressant activity by inhibiting serotonin (5-HT) reuptake transporters, thus elevating synaptic 5-HT levels and, finally, ameliorates depression symptoms. New evidence indicates that SSRIs may also modulate other neurotransmitter systems by inhibiting neuronal nicotinic acetylcholine receptors (nAChRs), which are recognized as important in mood regulation. There is a clear and strong association between major depression and smoking, where depressed patients smoke twice as much as the normal population. However, SSRIs are not efficient for smoking cessation therapy. In patients with major depressive disorder, there is a lower availability of functional nAChRs, although their amount is not altered, which is possibly caused by higher endogenous ACh levels, which consequently induce nAChR desensitization. Other neurotransmitter systems have also emerged as possible targets for SSRIs. Studies on dorsal raphe nucleus serotoninergic neurons support the concept that SSRI-induced nAChR inhibition decreases the glutamatergic hyperstimulation observed in stress conditions, which compensates the excessive 5-HT overflow in these neurons and, consequently, ameliorates depression symptoms. At the molecular level, SSRIs inhibit different nAChR subtypes by noncompetitive mechanisms, including ion channel blockade and induction of receptor desensitization, whereas α9α10 nAChRs, which are peripherally expressed and not directly involved in depression, are inhibited by competitive mechanisms. According to the functional and structural results, SSRIs bind within the nAChR ion channel at high-affinity sites that are spread out between serine and valine rings. In conclusion, SSRI-induced inhibition of a variety of nAChRs expressed in different neurotransmitter systems widens the complexity by which these antidepressants may act clinically.
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Affiliation(s)
- Hugo R. Arias
- Department of Pharmacology and Physiology, Oklahoma State University College of Osteopathic Medicine, Tahlequah, OK 74464, USA
- Correspondence: ; Tel.: +1-918-525-6324; Fax: +1-918-280-2515
| | | | - Jesús García-Colunga
- Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Campus Juriquilla, Universidad Nacional Autónoma de México, Querétaro 76230, Mexico;
| | - Marcelo O. Ortells
- Facultad de Medicina, Universidad de Morón, CONICET, Morón 1708, Argentina;
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Fagiolini A, Florea I, Loft H, Christensen MC. Effectiveness of Vortioxetine on Emotional Blunting in Patients with Major Depressive Disorder with inadequate response to SSRI/SNRI treatment. J Affect Disord 2021; 283:472-479. [PMID: 33516560 DOI: 10.1016/j.jad.2020.11.106] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 10/23/2020] [Accepted: 11/14/2020] [Indexed: 12/21/2022]
Abstract
INTRODUCTION Inadequate treatment response and emotional blunting are common challenges with selective serotonin reuptake inhibitors/serotonin-noradrenaline reuptake inhibitors (SSRIs/SNRIs) for major depressive disorder (MDD). We investigated the effectiveness of vortioxetine on emotional blunting in patients with partial response to treatment with SSRIs/SNRIs. METHODS Patients with MDD who experienced a partial response to SSRI/SNRI monotherapy at adequate dose for ≥6 weeks were switched to 8 weeks of vortioxetine treatment 10-20 mg/day (Study NCT03835715). Key inclusion criteria were Montgomery-Åsberg Depression Rating Scale (MADRS) total score >21 and <29, current major depressive episode <12 months, Oxford Depression Questionnaire (ODQ) total score ≥50, and confirmation of emotional blunting by standardized screening question. Emotional blunting was assessed by ODQ and depressive symptoms by MADRS. Other outcomes assessed included motivation and energy (Motivation and Energy Inventory [MEI]), cognitive performance (Digit Symbol Substitution Test [DSST]), and overall functioning (Sheehan Disability Scale [SDS]). RESULTS At week 8, patients (N=143) had improved by -29.8 points (p<0.0001) in ODQ total score; 50% reported no emotional blunting in response to standardized screening question. Significant improvements were observed on the DSST, MEI, and SDS at all time points assessed, and 47% of patients were in remission (MADRS total score ≤10) at week 8. The most common treatment-emergent adverse events included nausea, headache, dizziness, vomiting, and diarrhea. LIMITATIONS No prospective phase before medication switch. CONCLUSION Vortioxetine 10-20 mg effectively improved emotional blunting, overall functioning, motivation and energy, cognitive performance, and depressive symptoms in patients with MDD with partial response to SSRI/SNRI therapy and emotional blunting.
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Affiliation(s)
- Andrea Fagiolini
- Division of Psychiatry, Department of Molecular and Developmental Medicine, University of Siena School of Medicine, Italy
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Park TIH, Schweder P, Lee K, Dieriks BV, Jung Y, Smyth L, Rustenhoven J, Mee E, Heppner P, Turner C, Curtis MA, Faull RLM, Montgomery JM, Dragunow M. Isolation and culture of functional adult human neurons from neurosurgical brain specimens. Brain Commun 2020; 2:fcaa171. [PMID: 33215086 PMCID: PMC7660143 DOI: 10.1093/braincomms/fcaa171] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 08/20/2020] [Accepted: 08/28/2020] [Indexed: 12/14/2022] Open
Abstract
The ability to characterize and study primary neurons isolated directly from the adult human brain would greatly advance neuroscience research. However, significant challenges such as accessibility of human brain tissue and the lack of a robust neuronal cell culture protocol have hampered its progress. Here, we describe a simple and reproducible method for the isolation and culture of functional adult human neurons from neurosurgical brain specimens. In vitro, adult human neurons form a dense network and express a plethora of mature neuronal and synaptic markers. Most importantly, for the first time, we demonstrate the re-establishment of mature neurophysiological properties in vitro, such as repetitive fast-spiking action potentials, and spontaneous and evoked synaptic activity. Together, our dissociated and slice culture systems enable studies of adult human neurophysiology and gene expression under normal and pathological conditions and provide a high-throughput platform for drug testing on brain cells directly isolated from the adult human brain.
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Affiliation(s)
- Thomas I-H Park
- Department of Pharmacology, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand
| | - Patrick Schweder
- Centre for Brain Research, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand
| | - Kevin Lee
- Centre for Brain Research, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand
| | - Birger V Dieriks
- Centre for Brain Research, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand
| | - Yewon Jung
- Department of Pharmacology, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand
| | - Leon Smyth
- Department of Pharmacology, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand
| | - Justin Rustenhoven
- Department of Pharmacology, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand
| | - Edward Mee
- Department of Neurosurgery, Auckland City Hospital, Auckland, New Zealand
| | - Peter Heppner
- Department of Neurosurgery, Auckland City Hospital, Auckland, New Zealand
| | - Clinton Turner
- Department of Anatomical Pathology, LabPlus, Auckland City Hospital, Auckland, New Zealand
| | - Maurice A Curtis
- Centre for Brain Research, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand
| | - Richard L M Faull
- Centre for Brain Research, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand
| | - Johanna M Montgomery
- Centre for Brain Research, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand
| | - Michael Dragunow
- Department of Pharmacology, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand
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13
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Lee K, Park TIH, Heppner P, Schweder P, Mee EW, Dragunow M, Montgomery JM. Human in vitro systems for examining synaptic function and plasticity in the brain. J Neurophysiol 2020; 123:945-965. [PMID: 31995449 DOI: 10.1152/jn.00411.2019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The human brain shows remarkable complexity in its cellular makeup and function, which are distinct from nonhuman species, signifying the need for human-based research platforms for the study of human cellular neurophysiology and neuropathology. However, the use of adult human brain tissue for research purposes is hampered by technical, methodological, and accessibility challenges. One of the major problems is the limited number of in vitro systems that, in contrast, are readily available from rodent brain tissue. With recent advances in the optimization of protocols for adult human brain preparations, there is a significant opportunity for neuroscientists to validate their findings in human-based systems. This review addresses the methodological aspects, advantages, and disadvantages of human neuron in vitro systems, focusing on the unique properties of human neurons and synapses in neocortical microcircuits. These in vitro models provide the incomparable advantage of being a direct representation of the neurons that have formed part of the human brain until the point of recording, which cannot be replicated by animal models nor human stem-cell systems. Important distinct cellular mechanisms are observed in human neurons that may underlie the higher order cognitive abilities of the human brain. The use of human brain tissue in neuroscience research also raises important ethical, diversity, and control tissue limitations that need to be considered. Undoubtedly however, these human neuron systems provide critical information to increase the potential of translation of treatments from the laboratory to the clinic in a way animal models are failing to provide.
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Affiliation(s)
- Kevin Lee
- Department of Physiology, University of Auckland, Auckland, New Zealand.,Centre for Brain Research, University of Auckland, New Zealand
| | - Thomas I-H Park
- Centre for Brain Research, University of Auckland, New Zealand.,Department of Pharmacology, University of Auckland, Auckland, New Zealand
| | - Peter Heppner
- Centre for Brain Research, University of Auckland, New Zealand.,Department of Neurosurgery, Auckland City Hospital, Auckland, New Zealand
| | - Patrick Schweder
- Centre for Brain Research, University of Auckland, New Zealand.,Department of Neurosurgery, Auckland City Hospital, Auckland, New Zealand
| | - Edward W Mee
- Centre for Brain Research, University of Auckland, New Zealand.,Department of Neurosurgery, Auckland City Hospital, Auckland, New Zealand
| | - Michael Dragunow
- Centre for Brain Research, University of Auckland, New Zealand.,Department of Pharmacology, University of Auckland, Auckland, New Zealand
| | - Johanna M Montgomery
- Department of Physiology, University of Auckland, Auckland, New Zealand.,Centre for Brain Research, University of Auckland, New Zealand
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14
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Szegedi V, Paizs M, Baka J, Barzó P, Molnár G, Tamas G, Lamsa K. Robust perisomatic GABAergic self-innervation inhibits basket cells in the human and mouse supragranular neocortex. eLife 2020; 9:51691. [PMID: 31916939 PMCID: PMC6984819 DOI: 10.7554/elife.51691] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Accepted: 01/08/2020] [Indexed: 01/08/2023] Open
Abstract
Inhibitory autapses are self-innervating synaptic connections in GABAergic interneurons in the brain. Autapses in neocortical layers have not been systematically investigated, and their function in different mammalian species and specific interneuron types is poorly known. We investigated GABAergic parvalbumin-expressing basket cells (pvBCs) in layer 2/3 (L2/3) in human neocortical tissue resected in deep-brain surgery, and in mice as control. Most pvBCs showed robust GABAAR-mediated self-innervation in both species, but autapses were rare in nonfast-spiking GABAergic interneurons. Light- and electron microscopy analyses revealed pvBC axons innervating their own soma and proximal dendrites. GABAergic self-inhibition conductance was similar in human and mouse pvBCs and comparable to that of synapses from pvBCs to other L2/3 neurons. Autaptic conductance prolonged somatic inhibition in pvBCs after a spike and inhibited repetitive firing. Perisomatic autaptic inhibition is common in both human and mouse pvBCs of supragranular neocortex, where they efficiently control discharge of the pvBCs.
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Affiliation(s)
- Viktor Szegedi
- MTA-NAP Research Group for Inhibitory Interneurons and Plasticity, Department of Physiology, Anatomy and Neuroscience, University of Szeged, Szeged, Hungary
| | - Melinda Paizs
- MTA-NAP Research Group for Inhibitory Interneurons and Plasticity, Department of Physiology, Anatomy and Neuroscience, University of Szeged, Szeged, Hungary
| | - Judith Baka
- MTA-SZTE Research Group for Cortical Microcircuits, Department of Physiology, Anatomy and Neuroscience, University of Szeged, Szeged, Hungary
| | - Pál Barzó
- Department of Neurosurgery, University of Szeged, Szeged, Hungary
| | - Gábor Molnár
- MTA-SZTE Research Group for Cortical Microcircuits, Department of Physiology, Anatomy and Neuroscience, University of Szeged, Szeged, Hungary
| | - Gabor Tamas
- MTA-SZTE Research Group for Cortical Microcircuits, Department of Physiology, Anatomy and Neuroscience, University of Szeged, Szeged, Hungary
| | - Karri Lamsa
- MTA-NAP Research Group for Inhibitory Interneurons and Plasticity, Department of Physiology, Anatomy and Neuroscience, University of Szeged, Szeged, Hungary
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15
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Regenhardt RW, Takase H, Lo EH, Lin DJ. Translating concepts of neural repair after stroke: Structural and functional targets for recovery. Restor Neurol Neurosci 2020; 38:67-92. [PMID: 31929129 PMCID: PMC7442117 DOI: 10.3233/rnn-190978] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Stroke is among the most common causes of adult disability worldwide, and its disease burden is shifting towards that of a long-term condition. Therefore, the development of approaches to enhance recovery and augment neural repair after stroke will be critical. Recovery after stroke involves complex interrelated systems of neural repair. There are changes in both structure (at the molecular, cellular, and tissue levels) and function (in terms of excitability, cortical maps, and networks) that occur spontaneously within the brain. Several approaches to augment neural repair through enhancing these changes are under study. These include identifying novel drug targets, implementing rehabilitation strategies, and developing new neurotechnologies. Each of these approaches has its own array of different proposed mechanisms. Current investigation has emphasized both cellular and circuit-based targets in both gray and white matter, including axon sprouting, dendritic branching, neurogenesis, axon preservation, remyelination, blood brain barrier integrity, blockade of extracellular inhibitory signals, alteration of excitability, and promotion of new brain cortical maps and networks. Herein, we review for clinicians recovery after stroke, basic elements of spontaneous neural repair, and ongoing work to augment neural repair. Future study requires alignment of basic, translational, and clinical research. The field continues to grow while becoming more clearly defined. As thrombolysis changed stroke care in the 1990 s and thrombectomy in the 2010 s, the augmentation of neural repair and recovery after stroke may revolutionize care for these patients in the coming decade.
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Affiliation(s)
- Robert W Regenhardt
- Department of Neurology, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114
| | - Hajime Takase
- Department of Neurology, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114
- Department of Radiology, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114
| | - Eng H Lo
- Department of Neurology, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114
- Department of Radiology, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114
| | - David J Lin
- Department of Neurology, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114
- Center for Neurotechnology and Neurorecovery, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114
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16
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Roles Played by the Na +/Ca 2+ Exchanger and Hypothermia in the Prevention of Ischemia-Induced Carrier-Mediated Efflux of Catecholamines into the Extracellular Space: Implications for Stroke Therapy. Neurochem Res 2019; 45:16-33. [PMID: 31346893 PMCID: PMC6942591 DOI: 10.1007/s11064-019-02842-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Revised: 05/30/2019] [Accepted: 07/04/2019] [Indexed: 12/11/2022]
Abstract
The release of [3H]dopamine ([3H]DA) and [3H]noradrenaline ([3H]NA) in acutely perfused rat striatal and cortical slice preparations was measured at 37 °C and 17 °C under ischemic conditions. The ischemia was simulated by the removal of oxygen and glucose from the Krebs solution. At 37 °C, resting release rates in response to ischemia were increased; in contrast, at 17 °C, resting release rates were significantly reduced, or resting release was completely prevented. The removal of extracellular Ca2+ further increased the release rates of [3H]DA and [3H]NA induced by ischemic conditions. This finding indicated that the Na+/Ca2+ exchanger (NCX), working in reverse in the absence of extracellular Ca2+, fails to trigger the influx of Ca2+ in exchange for Na+ and fails to counteract ischemia by further increasing the intracellular Na+ concentration ([Na+]i). KB-R7943, an inhibitor of NCX, significantly reduced the cytoplasmic resting release rate of catecholamines under ischemic conditions and under conditions where Ca2+ was removed. Hypothermia inhibited the excessive release of [3H]DA in response to ischemia, even in the absence of Ca2+. These findings further indicate that the NCX plays an important role in maintaining a high [Na+]i, a condition that may lead to the reversal of monoamine transporter functions; this effect consequently leads to the excessive cytoplasmic tonic release of monoamines and the reversal of the NCX. Using HPLC combined with scintillation spectrometry, hypothermia, which enhances the stimulation-evoked release of DA, was found to inhibit the efflux of toxic DA metabolites, such as 3,4-dihydroxyphenylacetaldehyde (DOPAL). In slices prepared from human cortical brain tissue removed during elective neurosurgery, the uptake and release values for [3H]NA did not differ from those measured at 37 °C in slices that were previously maintained under hypoxic conditions at 8 °C for 20 h. This result indicates that hypothermia preserves the functions of the transport and release mechanisms, even under hypoxic conditions. Oxidative stress (H2O2), a mediator of ischemic brain injury enhanced the striatal resting release of [3H]DA and its toxic metabolites (DOPAL, quinone). The study supports our earlier findings that during ischemia transmitters are released from the cytoplasm. In addition, the major findings of this study that hypothermia of brain slice preparations prevents the extracellular calcium concentration ([Ca2+]o)-independent non-vesicular transmitter release induced by ischemic insults, inhibiting Na+/Cl−-dependent membrane transport of monoamines and their toxic metabolites into the extracellular space, where they can exert toxic effects.
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17
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Vahid-Ansari F, Albert PR. Chronic Fluoxetine Induces Activity Changes in Recovery From Poststroke Anxiety, Depression, and Cognitive Impairment. Neurotherapeutics 2018; 15:200-215. [PMID: 29204954 PMCID: PMC5794702 DOI: 10.1007/s13311-017-0590-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Poststroke depression (PSD) is a common outcome of stroke that limits recovery and is only partially responsive to chronic antidepressant treatment. In order to elucidate changes in the cortical-limbic circuitry associated with PSD and its treatment, we examined a novel mouse model of persistent PSD. Focal endothelin-1-induced ischemia of the left medial prefrontal cortex (mPFC) in male C57BL6 mice resulted in a chronic anxiety and depression phenotype. Here, we show severe cognitive impairment in spatial learning and memory in the stroke mice. The behavioral and cognitive phenotypes were reversed by chronic (4-week) treatment with fluoxetine, alone or with voluntary exercise (free-running wheel), but not by exercise alone. To assess chronic cellular activation, FosB+ cells were co-labeled for markers of glutamate/pyramidal (VGluT1-3/CaMKIIα), γ-aminobutyric acid (GAD67), and serotonin (TPH). At 6 weeks poststroke versus sham (or 4 days poststroke), left mPFC stroke induced widespread FosB activation, more on the right (contralesional) than on the left side. Stroke activated glutamate cells of the mPFC, nucleus accumbens, amygdala, hippocampus, and raphe serotonin neurons. Chronic fluoxetine balanced bilateral neuronal activity, reducing total FosB and FosB/CamKII+ cells (mPFC, nucleus accumbens), and unlike exercise, increasing FosB/GAD67+ cells (septum, amygdala) or both (hippocampus, raphe). In summary, chronic antidepressant but not exercise mediates recovery in this unilateral ischemic PSD model that is associated with region-specific reversal of stroke-induced pyramidal cell hyperactivity and increase in γ-aminobutyric acidergic activity. Targeted brain stimulation to restore brain activity could provide a rational approach for treating clinical PSD.
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Affiliation(s)
- Faranak Vahid-Ansari
- Ottawa Hospital Research Institute (Neuroscience), UOttawa Brain and Mind Research Institute, Ottawa, ON, K1H 8M5, Canada
| | - Paul R Albert
- Ottawa Hospital Research Institute (Neuroscience), UOttawa Brain and Mind Research Institute, Ottawa, ON, K1H 8M5, Canada.
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18
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Kramvis I, Mansvelder HD, Meredith RM. Neuronal life after death: electrophysiologic recordings from neurons in adult human brain tissue obtained through surgical resection or postmortem. HANDBOOK OF CLINICAL NEUROLOGY 2018; 150:319-333. [PMID: 29496151 DOI: 10.1016/b978-0-444-63639-3.00022-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Recordings from fresh human brain slices derived from surgically resected brain tissue are being used to unravel mechanisms underlying human neurophysiology and for the evaluation of potential therapeutic targets and compounds. Data resulting from these studies provide unique insights into physiologic properties of human neuronal microcircuits. However, substantial limitations still remain with this approach. First, the tissue is always resected from patients, never from healthy controls. Second, the patient population undergoing brain surgery with tissue resection is limited to epilepsy and tumor patients - never from patients with other neurologic disorders. Third, the vast majority of tissue resected is limited largely to temporal cortex and hippocampus, occasionally amygdala. Therefore, the possibility to study brain tissue: (1) from healthy controls; (2) from patients with different neuropathologies; (3) from different brain areas; and (4) from a wide spectrum of ages only exists through autopsy-derived brain tissue. Here we describe methods and results from physiologic recordings of adult human neurons and microcircuits in both surgically derived brain tissue as well as in tissue derived from autopsies. We define postmortem time windows during which physiologic recordings could match data obtained from surgical tissue.
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Affiliation(s)
- Ioannis Kramvis
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, VU University Amsterdam, Amsterdam, The Netherlands
| | - Huibert D Mansvelder
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, VU University Amsterdam, Amsterdam, The Netherlands.
| | - Rhiannon M Meredith
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, VU University Amsterdam, Amsterdam, The Netherlands
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19
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High-Precision Fast-Spiking Basket Cell Discharges during Complex Events in the Human Neocortex. eNeuro 2017; 4:eN-NWR-0260-17. [PMID: 29034319 PMCID: PMC5639419 DOI: 10.1523/eneuro.0260-17.2017] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Revised: 09/07/2017] [Accepted: 09/11/2017] [Indexed: 11/21/2022] Open
Abstract
In the human neocortex, solitary action potentials in some layer 2–3 pyramidal cells (PCs) trigger brief episodes of network activity known as complex events through strong excitatory synapses that specifically innervate GABAergic interneurons. Yet, how these “master PCs” configure the local network activity is not well understood. We report that single spikes in the PCs, studied here in synaptically connected cell pairs in frontal or temporal neocortical areas of both males and females, elicit firing of fast-spiking basket cells (FSBCs) with a short delay (on average 2.7 ms). The FSBC discharge is triggered by 13 mV (on average) monosynaptic EPSPs, and the action potential is time locked to the master PC spike with high temporal precision, showing little jitter in delay. In the complex events, the FSBC discharge occurs in the beginning of the activity episode, forming the first wave of the complex event activity. Firing of FSBCs generates GABAergic IPSCs with fast kinetics in layer 2–3 PCs, and similar IPSCs regularly occur time locked to master PC spikes in the beginning of the complex events with high probability and short (median 4.1 ms) delay with little jitter. In comparison, discharge of nonfast spiking interneurons (non-FSINs) investigated here appears inconsistently in the complex events and shows low probability. Thus, firing of layer 2–3 FSBCs with high temporal fidelity characterizes early phase of the complex events in the human neocortex.
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20
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Abstract
Stroke is the leading cause of complex adult disability in the world. Recovery from stroke is often incomplete, which leaves many people dependent on others for their care. The improvement of long-term outcomes should, therefore, be a clinical and research priority. As a result of advances in our understanding of the biological mechanisms involved in recovery and repair after stroke, therapeutic opportunities to promote recovery through manipulation of poststroke plasticity have never been greater. This work has almost exclusively been carried out in preclinical animal models of stroke with little translation into human studies. The challenge ahead is to develop a mechanistic understanding of recovery from stroke in humans. Advances in neuroimaging techniques now enable us to reconcile behavioural accounts of recovery with molecular and cellular changes. Consequently, clinical trials can be designed in a stratified manner that takes into account when an intervention should be delivered and who is most likely to benefit. This approach is expected to lead to a substantial change in how restorative therapeutic strategies are delivered in patients after stroke.
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21
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Lourenço J, Bacci A. Human-Specific Cortical Synaptic Connections and Their Plasticity: Is That What Makes Us Human? PLoS Biol 2017; 15:e2001378. [PMID: 28103228 PMCID: PMC5245906 DOI: 10.1371/journal.pbio.2001378] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
One outstanding difference between Homo sapiens and other mammals is the ability to perform highly complex cognitive tasks and behaviors, such as language, abstract thinking, and cultural diversity. How is this accomplished? According to one prominent theory, cognitive complexity is proportional to the repetition of specific computational modules over a large surface expansion of the cerebral cortex (neocortex). However, the human neocortex was shown to also possess unique features at the cellular and synaptic levels, raising the possibility that expanding the computational module is not the only mechanism underlying complex thinking. In a study published in PLOS Biology, Szegedi and colleagues analyzed a specific cortical circuit from live postoperative human tissue, showing that human-specific, very powerful excitatory connections between principal pyramidal neurons and inhibitory neurons are highly plastic. This suggests that exclusive plasticity of specific microcircuits might be considered among the mechanisms endowing the human neocortex with the ability to perform highly complex cognitive tasks.
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Affiliation(s)
- Joana Lourenço
- Sorbonne Universités, UPMC Univ. Paris 06, CNRS UMR 7225, Inserm U1127, Institut du Cerveau et de la Moelle épinière, Paris, France
| | - Alberto Bacci
- Sorbonne Universités, UPMC Univ. Paris 06, CNRS UMR 7225, Inserm U1127, Institut du Cerveau et de la Moelle épinière, Paris, France
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22
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Szegedi V, Paizs M, Csakvari E, Molnar G, Barzo P, Tamas G, Lamsa K. Plasticity in Single Axon Glutamatergic Connection to GABAergic Interneurons Regulates Complex Events in the Human Neocortex. PLoS Biol 2016; 14:e2000237. [PMID: 27828957 PMCID: PMC5102409 DOI: 10.1371/journal.pbio.2000237] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Accepted: 10/12/2016] [Indexed: 11/18/2022] Open
Abstract
In the human neocortex, single excitatory pyramidal cells can elicit very large glutamatergic EPSPs (VLEs) in inhibitory GABAergic interneurons capable of triggering their firing with short (3–5 ms) delay. Similar strong excitatory connections between two individual neurons have not been found in nonhuman cortices, suggesting that these synapses are specific to human interneurons. The VLEs are crucial for generating neocortical complex events, observed as single pyramidal cell spike-evoked discharge of cell assemblies in the frontal and temporal cortices. However, long-term plasticity of the VLE connections and how the plasticity modulates neocortical complex events has not been studied. Using triple and dual whole-cell recordings from synaptically connected human neocortical layers 2–3 neurons, we show that VLEs in fast-spiking GABAergic interneurons exhibit robust activity-induced long-term depression (LTD). The LTD by single pyramidal cell 40 Hz spike bursts is specific to connections with VLEs, requires group I metabotropic glutamate receptors, and has a presynaptic mechanism. The LTD of VLE connections alters suprathreshold activation of interneurons in the complex events suppressing the discharge of fast-spiking GABAergic cells. The VLEs triggering the complex events may contribute to cognitive processes in the human neocortex, and their long-term plasticity can alter the discharging cortical cell assemblies by learning. Many microscale features in the human neocortex—a part of the brain involved in higher functions such as sensory perception, generation of motor commands, spatial reasoning, and language—are closely similar to those reported in experimental animals commonly used in neuroscience, like mice. However, the human neocortical neurons also exhibit specializations only reported in our species. One such feature is the capacity of excitatory principal cells to elicit firing in local inhibitory interneurons with a single action potential via very strong excitatory synapses. It has been suggested that this feature has specifically evolved to enhance coordinated firing of neuronal ensembles in higher brain functions. However, it is unknown how these circuits are modified by learning. Therefore, we investigated how these very strong excitatory synapses are changed, and if their impact on the firing of local inhibitory neurons is altered by repetitive action potentials mimicking learning-related activity. By recording in human neocortical slices, we report that the strong excitatory synapses on interneurons exhibit robust activity-dependent long-term plasticity. The plasticity also regulates the discharge of local interneurons driven by these synapses. Although these specialized synapses have only been reported in the human neocortex, their plasticity mechanism is evolutionarily conserved. We suggest that the strong synapses with robust plasticity have evolved to enhance complex brain functions and learning.
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Affiliation(s)
- Viktor Szegedi
- MTA-NAP Research Group for Inhibitory Interneurons and Plasticity, Department of Physiology, Anatomy and Neuroscience, University of Szeged, Szeged, Hungary
| | - Melinda Paizs
- MTA-NAP Research Group for Inhibitory Interneurons and Plasticity, Department of Physiology, Anatomy and Neuroscience, University of Szeged, Szeged, Hungary
| | - Eszter Csakvari
- MTA-NAP Research Group for Inhibitory Interneurons and Plasticity, Department of Physiology, Anatomy and Neuroscience, University of Szeged, Szeged, Hungary
| | - Gabor Molnar
- MTA-SZTE Research Group for Cortical Microcircuits, Department of Physiology, Anatomy and Neuroscience, University of Szeged, Szeged, Hungary
| | - Pal Barzo
- Department of Neurosurgery, University of Szeged, Szeged, Hungary
| | - Gabor Tamas
- MTA-SZTE Research Group for Cortical Microcircuits, Department of Physiology, Anatomy and Neuroscience, University of Szeged, Szeged, Hungary
| | - Karri Lamsa
- MTA-NAP Research Group for Inhibitory Interneurons and Plasticity, Department of Physiology, Anatomy and Neuroscience, University of Szeged, Szeged, Hungary
- Department of Pharmacology, Oxford University, Oxford, United Kingdom
- * E-mail:
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23
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Molnár G, Rózsa M, Baka J, Holderith N, Barzó P, Nusser Z, Tamás G. Human pyramidal to interneuron synapses are mediated by multi-vesicular release and multiple docked vesicles. eLife 2016; 5. [PMID: 27536876 PMCID: PMC4999310 DOI: 10.7554/elife.18167] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Accepted: 08/15/2016] [Indexed: 01/08/2023] Open
Abstract
Classic theories link cognitive abilities to synaptic properties and human-specific biophysical features of synapses might contribute to the unparalleled performance of the human cerebral cortex. Paired recordings and multiple probability fluctuation analysis revealed similar quantal sizes, but 4-times more functional release sites in human pyramidal cell to fast-spiking interneuron connections compared to rats. These connections were mediated on average by three synaptic contacts in both species. Each presynaptic active zone (AZ) contains 6.2 release sites in human, but only 1.6 in rats. Electron microscopy (EM) and EM tomography showed that an AZ harbors 4 docked vesicles in human, but only a single one in rats. Consequently, a Katz's functional release site occupies ~0.012 μm(2) in the human presynaptic AZ and ~0.025 μm(2) in the rat. Our results reveal a robust difference in the biophysical properties of a well-defined synaptic connection of the cortical microcircuit of human and rodents.
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Affiliation(s)
- Gábor Molnár
- MTA-SZTE Research Group for Cortical Microcircuits, Department of Physiology, Anatomy and Neuroscience, University of Szeged, Szeged, Hungary
| | - Márton Rózsa
- MTA-SZTE Research Group for Cortical Microcircuits, Department of Physiology, Anatomy and Neuroscience, University of Szeged, Szeged, Hungary
| | - Judith Baka
- MTA-SZTE Research Group for Cortical Microcircuits, Department of Physiology, Anatomy and Neuroscience, University of Szeged, Szeged, Hungary
| | - Noémi Holderith
- Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| | - Pál Barzó
- Department of Neurosurgery, University of Szeged, Szeged, Hungary
| | - Zoltan Nusser
- Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| | - Gábor Tamás
- MTA-SZTE Research Group for Cortical Microcircuits, Department of Physiology, Anatomy and Neuroscience, University of Szeged, Szeged, Hungary
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5-HT2 receptors mediate functional modulation of GABAa receptors and inhibitory synaptic transmissions in human iPS-derived neurons. Sci Rep 2016; 6:20033. [PMID: 26837719 PMCID: PMC4738270 DOI: 10.1038/srep20033] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Accepted: 12/22/2015] [Indexed: 12/22/2022] Open
Abstract
Neural progenitors differentiated from induced pluripotent stem cells (iPS) hold potentials for treating neurological diseases. Serotonin has potent effects on neuronal functions through multiple receptors, underlying a variety of neural disorders. Glutamate and GABA receptors have been proven functional in neurons differentiated from iPS, however, little is known about 5-HT receptor-mediated modulation in such neuronal networks. In the present study, human iPS were differentiated into cells possessing featured physiological properties of cortical neurons. Whole-cell patch-clamp recording was used to examine the involvement of 5-HT2 receptors in functional modulation of GABAergic synaptic transmission. We found that serotonin and DOI (a selective agonist of 5-HT2A/C receptor) reversibly reduced GABA-activated currents, and this 5-HT2A/C receptor mediated inhibition required G protein, PLC, PKC, and Ca2+ signaling. Serotonin increased the frequency of miniature inhibitory postsynaptic currents (mIPSCs), which could be mimicked by α-methylserotonin, a 5-HT2 receptor agonist. In contrast, DOI reduced both frequency and amplitude of mIPSCs. These findings suggested that in iPS-derived human neurons serotonin postsynaptically reduced GABAa receptor function through 5-HT2A/C receptors, but presynaptically other 5-HT2 receptors counteracted the action of 5-HT2A/C receptors. Functional expression of serotonin receptors in human iPS-derived neurons provides a pre-requisite for their normal behaviors after grafting.
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25
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Generation of functional human serotonergic neurons from fibroblasts. Mol Psychiatry 2016; 21:49-61. [PMID: 26503761 DOI: 10.1038/mp.2015.161] [Citation(s) in RCA: 91] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2015] [Revised: 09/09/2015] [Accepted: 09/14/2015] [Indexed: 12/13/2022]
Abstract
The brain's serotonergic system centrally regulates several physiological processes and its dysfunction has been implicated in the pathophysiology of several neuropsychiatric disorders. While in the past our understanding of serotonergic neurotransmission has come mainly from mouse models, the development of pluripotent stem cell and induced fibroblast-to-neuron (iN) transdifferentiation technologies has revolutionized our ability to generate human neurons in vitro. Utilizing these techniques and a novel lentiviral reporter for serotonergic neurons, we identified and overexpressed key transcription factors to successfully generate human serotonergic neurons. We found that overexpressing the transcription factors NKX2.2, FEV, GATA2 and LMX1B in combination with ASCL1 and NGN2 directly and efficiently generated serotonergic neurons from human fibroblasts. Induced serotonergic neurons (iSNs) showed increased expression of specific serotonergic genes that are known to be expressed in raphe nuclei. iSNs displayed spontaneous action potentials, released serotonin in vitro and functionally responded to selective serotonin reuptake inhibitors (SSRIs). Here, we demonstrate the efficient generation of functional human serotonergic neurons from human fibroblasts as a novel tool for studying human serotonergic neurotransmission in health and disease.
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26
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Human brain slices for epilepsy research: Pitfalls, solutions and future challenges. J Neurosci Methods 2015; 260:221-32. [PMID: 26434706 DOI: 10.1016/j.jneumeth.2015.09.021] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Revised: 09/21/2015] [Accepted: 09/23/2015] [Indexed: 12/17/2022]
Abstract
Increasingly, neuroscientists are taking the opportunity to use live human tissue obtained from elective neurosurgical procedures for electrophysiological studies in vitro. Access to this valuable resource permits unique studies into the network dynamics that contribute to the generation of pathological electrical activity in the human epileptic brain. Whilst this approach has provided insights into the mechanistic features of electrophysiological patterns associated with human epilepsy, it is not without technical and methodological challenges. This review outlines the main difficulties associated with working with epileptic human brain slices from the point of collection, through the stages of preparation, storage and recording. Moreover, it outlines the limitations, in terms of the nature of epileptic activity that can be observed in such tissue, in particular, the rarity of spontaneous ictal discharges, we discuss manipulations that can be utilised to induce such activity. In addition to discussing conventional electrophysiological techniques that are routinely employed in epileptic human brain slices, we review how imaging and multielectrode array recordings could provide novel insights into the network dynamics of human epileptogenesis. Acute studies in human brain slices are ultimately limited by the lifetime of the tissue so overcoming this issue provides increased opportunity for information gain. We review the literature with respect to organotypic culture techniques that may hold the key to prolonging the viability of this material. A combination of long-term culture techniques, viral transduction approaches and electrophysiology in human brain slices promotes the possibility of large scale monitoring and manipulation of neuronal activity in epileptic microcircuits.
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27
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Luo B, Hu L, Liu C, Guo Y, Wang H. Activation of 5-HT2A/C receptor reduces glycine receptor-mediated currents in cultured auditory cortical neurons. Amino Acids 2015; 48:349-56. [PMID: 26371055 DOI: 10.1007/s00726-015-2086-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Accepted: 08/25/2015] [Indexed: 01/28/2023]
Abstract
Glycine receptors (GlyRs) permeable to chloride only mediate tonic inhibition in the cerebral cortex where glycinergic projection is completely absent. The functional modulation of GlyRs was largely studied in subcortical brain regions with glycinergic transmissions, but the function of cortical GlyRs was rarely addressed. Serotonin could broadly modulate many ion channels through activating 5-HT2 receptor, but whether cortical GlyRs are subjected to serotonergic modulation remains unexplored. The present study adopted patch clamp recordings to examine functional regulation of strychnine-sensitive GlyRs currents in cultured cortical neurons by DOI (2,5-Dimethoxy-4-iodoamphetamine), a 5-HT2A/C receptor agonist. DOI caused a concentration-dependent reduction of GlyR currents with unchanged reversal potential. This reduction was blocked by the selective receptor antagonists (ritanserin and risperidone) and G protein inhibitor (GDP-β-s) demonstrated that the reducing effect of DOI on GlyR current required the activation of 5-HT2A/C receptors. Strychnine-sensitive tonic currents revealed the inhibitory tone mediated by nonsynaptic GlyRs, and DOI similarly reduced the tonic inhibition. The impaired microtube-dependent trafficking or clustering of GlyRs was thought to be involved in that nocodazole as a microtube depolymerizing drug largely blocked the inhibition mediated by 5-HT2A/C receptors. Our results suggested that activation of 5-HT2A/C receptors might suppress cortical tonic inhibition mediated by GlyRs, and the findings would provide important insight into serotonergic modulation of tonic inhibition mediated by GlyRs, and possibly facilitate to develop the therapeutic treatment of neurological diseases such as tinnitus through regulating cortical GlyRs.
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Affiliation(s)
- Bin Luo
- Department of Otolaryngology, Anhui Provincial Hospital Affiliated to Anhui Medical University, Hefei, 230001, China
| | - Lingli Hu
- Key Laboratory of Regenerative Biology, Guangzhou Institute of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, 510530, Guangdong, China.,Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, Guangzhou, 510530, Guangdong, China
| | - Chunhua Liu
- Key Laboratory of Regenerative Biology, Guangzhou Institute of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, 510530, Guangdong, China.,Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, Guangzhou, 510530, Guangdong, China
| | - Yiping Guo
- Key Laboratory of Regenerative Biology, Guangzhou Institute of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, 510530, Guangdong, China.,Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, Guangzhou, 510530, Guangdong, China
| | - Haitao Wang
- Key Laboratory of Regenerative Biology, Guangzhou Institute of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, 510530, Guangdong, China. .,Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, Guangzhou, 510530, Guangdong, China.
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28
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Treatment of cognitive dysfunction in major depressive disorder—a review of the preclinical evidence for efficacy of selective serotonin reuptake inhibitors, serotonin–norepinephrine reuptake inhibitors and the multimodal-acting antidepressant vortioxetine. Eur J Pharmacol 2015; 753:19-31. [DOI: 10.1016/j.ejphar.2014.07.044] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2014] [Revised: 06/06/2014] [Accepted: 07/24/2014] [Indexed: 02/02/2023]
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29
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Guo F, Zhang Q, Zhang B, Fu Z, Wu B, Huang C, Li Y. Burst-firing patterns in the prefrontal cortex underlying the neuronal mechanisms of depression probed by antidepressants. Eur J Neurosci 2014; 40:3538-47. [DOI: 10.1111/ejn.12725] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Revised: 08/15/2014] [Accepted: 08/15/2014] [Indexed: 01/26/2023]
Affiliation(s)
- Fei Guo
- Key Laboratory of Receptor Research; Shanghai Institute of Materia Medical; Chinese Academy of Sciences; Shanghai 201203 China
| | - Qi Zhang
- Key Laboratory of Receptor Research; Shanghai Institute of Materia Medical; Chinese Academy of Sciences; Shanghai 201203 China
| | - Bing Zhang
- Key Laboratory of Receptor Research; Shanghai Institute of Materia Medical; Chinese Academy of Sciences; Shanghai 201203 China
| | - Zhiwen Fu
- Key Laboratory of Receptor Research; Shanghai Institute of Materia Medical; Chinese Academy of Sciences; Shanghai 201203 China
| | - Bin Wu
- Key Laboratory of Receptor Research; Shanghai Institute of Materia Medical; Chinese Academy of Sciences; Shanghai 201203 China
| | - Chenggang Huang
- Key Laboratory of Receptor Research; Shanghai Institute of Materia Medical; Chinese Academy of Sciences; Shanghai 201203 China
| | - Yang Li
- Key Laboratory of Receptor Research; Shanghai Institute of Materia Medical; Chinese Academy of Sciences; Shanghai 201203 China
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30
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Puzerey PA, Decker MJ, Galán RF. Elevated serotonergic signaling amplifies synaptic noise and facilitates the emergence of epileptiform network oscillations. J Neurophysiol 2014; 112:2357-73. [PMID: 25122717 DOI: 10.1152/jn.00031.2014] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Serotonin fibers densely innervate the cortical sheath to regulate neuronal excitability, but its role in shaping network dynamics remains undetermined. We show that serotonin provides an excitatory tone to cortical neurons in the form of spontaneous synaptic noise through 5-HT3 receptors, which is persistent and can be augmented using fluoxetine, a selective serotonin re-uptake inhibitor. Augmented serotonin signaling also increases cortical network activity by enhancing synaptic excitation through activation of 5-HT2 receptors. This in turn facilitates the emergence of epileptiform network oscillations (10-16 Hz) known as fast runs. A computational model of cortical dynamics demonstrates that these two combined mechanisms, increased background synaptic noise and enhanced synaptic excitation, are sufficient to replicate the emergence fast runs and their statistics. Consistent with these findings, we show that blocking 5-HT2 receptors in vivo significantly raises the threshold for convulsant-induced seizures.
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Affiliation(s)
- Pavel A Puzerey
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, Ohio; and
| | - Michael J Decker
- School of Nursing, Case Western Reserve University, Cleveland, Ohio
| | - Roberto F Galán
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, Ohio; and
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31
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Soudry D, Meir R. The neuronal response at extended timescales: a linearized spiking input-output relation. Front Comput Neurosci 2014; 8:29. [PMID: 24765073 PMCID: PMC3980113 DOI: 10.3389/fncom.2014.00029] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Accepted: 02/24/2014] [Indexed: 11/16/2022] Open
Abstract
Many biological systems are modulated by unknown slow processes. This can severely hinder analysis – especially in excitable neurons, which are highly non-linear and stochastic systems. We show the analysis simplifies considerably if the input matches the sparse “spiky” nature of the output. In this case, a linearized spiking Input–Output (I/O) relation can be derived semi-analytically, relating input spike trains to output spikes based on known biophysical properties. Using this I/O relation we obtain closed-form expressions for all second order statistics (input – internal state – output correlations and spectra), construct optimal linear estimators for the neuronal response and internal state and perform parameter identification. These results are guaranteed to hold, for a general stochastic biophysical neuron model, with only a few assumptions (mainly, timescale separation). We numerically test the resulting expressions for various models, and show that they hold well, even in cases where our assumptions fail to hold. In a companion paper we demonstrate how this approach enables us to fit a biophysical neuron model so it reproduces experimentally observed temporal firing statistics on days-long experiments.
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Affiliation(s)
- Daniel Soudry
- Laboratory for Network Biology Research, Department of Electrical Engineering Technion, Haifa, Israel
| | - Ron Meir
- Laboratory for Network Biology Research, Department of Electrical Engineering Technion, Haifa, Israel
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32
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Functional status of the serotonin 5-HT2C receptor (5-HT2CR) drives interlocked phenotypes that precipitate relapse-like behaviors in cocaine dependence. Neuropsychopharmacology 2014; 39:370-82. [PMID: 23939424 PMCID: PMC3970795 DOI: 10.1038/npp.2013.199] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Revised: 08/02/2013] [Accepted: 08/03/2013] [Indexed: 11/08/2022]
Abstract
Relapse vulnerability in cocaine dependence is rooted in genetic and environmental determinants, and propelled by both impulsivity and the responsivity to cocaine-linked cues ('cue reactivity'). The serotonin (5-hydroxytryptamine, 5-HT) 5-HT2C receptor (5-HT2CR) within the medial prefrontal cortex (mPFC) is uniquely poised to serve as a strategic nexus to mechanistically control these behaviors. The 5-HT2CR functional capacity is regulated by a number of factors including availability of active membrane receptor pools, the composition of the 5-HT2CR macromolecular protein complex, and editing of the 5-HT2CR pre-mRNA. The one-choice serial reaction time (1-CSRT) task was used to identify impulsive action phenotypes in an outbred rat population before cocaine self-administration and assessment of cue reactivity in the form of lever presses reinforced by the cocaine-associated discrete cue complex during forced abstinence. The 1-CSRT task reliably and reproducibly identified high impulsive (HI) and low impulsive (LI) action phenotypes; HI action predicted high cue reactivity. Lower cortical 5-HT2CR membrane protein levels concomitant with higher levels of 5-HT2CR:postsynaptic density 95 complex distinguished HI rats from LI rats. The frequency of edited 5-HT2CR mRNA variants was elevated with the prediction that the protein population in HI rats favors those isoforms linked to reduced signaling capacity. Genetic loss of the mPFC 5-HT2CR induced aggregate impulsive action/cue reactivity, suggesting that depressed cortical 5-HT2CR tone confers vulnerability to these interlocked behaviors. Thus, impulsive action and cue reactivity appear to neuromechanistically overlap in rodents, with the 5-HT2CR functional status acting as a neural rheostat to regulate, in part, the intersection between these vulnerability behaviors.
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33
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Iyer R, Menon V, Buice M, Koch C, Mihalas S. The influence of synaptic weight distribution on neuronal population dynamics. PLoS Comput Biol 2013; 9:e1003248. [PMID: 24204219 PMCID: PMC3808453 DOI: 10.1371/journal.pcbi.1003248] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Accepted: 07/24/2013] [Indexed: 11/19/2022] Open
Abstract
The manner in which different distributions of synaptic weights onto cortical neurons shape their spiking activity remains open. To characterize a homogeneous neuronal population, we use the master equation for generalized leaky integrate-and-fire neurons with shot-noise synapses. We develop fast semi-analytic numerical methods to solve this equation for either current or conductance synapses, with and without synaptic depression. We show that its solutions match simulations of equivalent neuronal networks better than those of the Fokker-Planck equation and we compute bounds on the network response to non-instantaneous synapses. We apply these methods to study different synaptic weight distributions in feed-forward networks. We characterize the synaptic amplitude distributions using a set of measures, called tail weight numbers, designed to quantify the preponderance of very strong synapses. Even if synaptic amplitude distributions are equated for both the total current and average synaptic weight, distributions with sparse but strong synapses produce higher responses for small inputs, leading to a larger operating range. Furthermore, despite their small number, such synapses enable the network to respond faster and with more stability in the face of external fluctuations.
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Affiliation(s)
- Ramakrishnan Iyer
- Allen Institute for Brain Science, Seattle, Washington, United States of America
| | - Vilas Menon
- Allen Institute for Brain Science, Seattle, Washington, United States of America
| | - Michael Buice
- Allen Institute for Brain Science, Seattle, Washington, United States of America
| | - Christof Koch
- Allen Institute for Brain Science, Seattle, Washington, United States of America
| | - Stefan Mihalas
- Allen Institute for Brain Science, Seattle, Washington, United States of America
- * E-mail:
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34
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Bachatene L, Bharmauria V, Cattan S, Molotchnikoff S. Fluoxetine and serotonin facilitate attractive-adaptation-induced orientation plasticity in adult cat visual cortex. Eur J Neurosci 2013; 38:2065-77. [DOI: 10.1111/ejn.12206] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2013] [Revised: 02/26/2013] [Accepted: 02/28/2013] [Indexed: 12/01/2022]
Affiliation(s)
- Lyes Bachatene
- Department of Biological Sciences; University of Montreal; Montreal; QC; Canada
| | - Vishal Bharmauria
- Department of Biological Sciences; University of Montreal; Montreal; QC; Canada
| | - Sarah Cattan
- Department of Biological Sciences; University of Montreal; Montreal; QC; Canada
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