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Shea TB. An Overview of Studies Demonstrating that ex vivo Neuronal Networks Display Multiple Complex Behaviors: Emergent Properties of Nearest-Neighbor Interactions of Excitatory and Inhibitory Neurons. Open Neurol J 2021. [DOI: 10.2174/1874205x02115010003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The responsiveness of the human nervous system ranges from the basic sensory interpretation and motor regulation to so-called higher-order functions such as emotion and consciousness. Aspects of higher-order functions are displayed by other mammals and birds. In efforts to understand how neuronal interaction can generate such a diverse functionality, murine embryonic cortical neurons were cultured on Petri dishes containing multi-electrode arrays that allowed recording and stimulation of neuronal activity. Despite the lack of major architectural features that govern nervous system development in situ, this overview of multiple studies demonstrated that these 2-dimensional ex vivo neuronal networks nevertheless recapitulate multiple key aspects of nervous system development and activity in situ, including density-dependent, the spontaneous establishment of a functional network that displayed complex signaling patterns, and responsiveness to environmental stimulation including generation of appropriate motor output and long-term potentiation. These findings underscore that the basic interplay of excitatory and inhibitory neuronal activity underlies all aspects of nervous system functionality. This reductionist system may be useful for further examination of neuronal function under developmental, homeostatic, and neurodegenerative conditions.
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Guaraldi M, Lee S, Shea TB. Synaptic Signals from Glutamate-Treated Neurons Induce Aberrant Post-Synaptic Signals in Untreated Neuronal Networks. Open Neurol J 2020. [DOI: 10.2174/1874205x02014010059] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Background and Objective:
Glutamate neurotoxicity is associated with a wide range of disorders and can impair synaptic function. Failure to clear extracellular glutamate fosters additional cycles and spread of regional hyperexcitation.
Methods and Results:
Using cultured murine cortical neurons, herein it is demonstrated that synaptic signals generated by cultures undergoing glutamate-induced hyperactivity can invoke similar effects in other cultures not exposed to elevated glutamate.
Conclusion:
Since sequential synaptic connectivity can encompass extensive cortical regions, this study presents a potential additional contributor to the spread of damage resulting from glutamate excitotoxicity and should be considered in attempts to mitigate neurodegeneration.
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Shea TB, Remington R. Spontaneous Neuronal Signaling is Inherently Musical and Mathematical: Insight into the Universal Human Affinity for Music. Open Neurol J 2018. [DOI: 10.2174/1874205x01812010064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Objective:Audio files of spontaneous signal streams generated byex vivoneuronal networks cultured on multi-electrode arrays generated an oscillating sine wave with an inherent musical quality. This was not anticipated considering that synaptic signals are “all - or – none”, and therefore digital, events.Methods:These findings may provide insight into why music can be perceived as pleasurable and invoke a calm mood despite that music is ultimately perceived and stored as a series of digital signals; it is speculated that music may reinforce and/or enhance this spontaneous digital stream.Results and Conclusion:These findings also support the relationship between music and mathematics.
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Shultz AM, Lee S, Guaraldi M, Shea TB, Yanco HC. Robot-Embodied Neuronal Networks as an Interactive Model of Learning. Open Neurol J 2017; 11:39-47. [PMID: 29151990 PMCID: PMC5678239 DOI: 10.2174/1874205x01711010039] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Revised: 06/19/2017] [Accepted: 08/03/2017] [Indexed: 11/23/2022] Open
Abstract
Background and Objective: The reductionist approach of neuronal cell culture has been useful for analyses of synaptic signaling. Murine cortical neurons in culture spontaneously form an ex vivo network capable of transmitting complex signals, and have been useful for analyses of several fundamental aspects of neuronal development hitherto difficult to clarify in situ. However, these networks lack the ability to receive and respond to sensory input from the environment as do neurons in vivo. Establishment of these networks in culture chambers containing multi-electrode arrays allows recording of synaptic activity as well as stimulation. Method: This article describes the embodiment of ex vivo neuronal networks neurons in a closed-loop cybernetic system, consisting of digitized video signals as sensory input and a robot arm as motor output. Results: In this system, the neuronal network essentially functions as a simple central nervous system. This embodied network displays the ability to track a target in a naturalistic environment. These findings underscore that ex vivo neuronal networks can respond to sensory input and direct motor output. Conclusion: These analyses may contribute to optimization of neuronal-computer interfaces for perceptive and locomotive prosthetic applications. Ex vivo networks display critical alterations in signal patterns following treatment with subcytotoxic concentrations of amyloid-beta. Future studies including comparison of tracking accuracy of embodied networks prepared from mice harboring key mutations with those from normal mice, accompanied with exposure to Abeta and/or other neurotoxins, may provide a useful model system for monitoring subtle impairment of neuronal function as well as normal and abnormal development.
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Affiliation(s)
| | - Sangmook Lee
- Laboratory for Neuroscience, Department of Biological Sciences University of Massachusetts Lowell, Lowell, MA 01854, USA
| | - Mary Guaraldi
- Laboratory for Neuroscience, Department of Biological Sciences University of Massachusetts Lowell, Lowell, MA 01854, USA
| | - Thomas B Shea
- Laboratory for Neuroscience, Department of Biological Sciences University of Massachusetts Lowell, Lowell, MA 01854, USA
| | - Holly C Yanco
- Robotics Laboratory, Department of Computer Science, USA
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Lee S, Sohal IS, Therrien MA, Pal AK, Bello D, Shea TB. Additive Impairment of Synaptic Signaling in Cultured Cortical Neurons by Exogenously-Applied Oligomerized Amyloid-β and Airborne Nanoparticles Generated during Photocopying. J Alzheimers Dis 2016; 47:49-54. [PMID: 26402753 DOI: 10.3233/jad-150099] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Photocopying in offices and printing centers releases nanoparticles that can reach the brain following inhalation. We examined whether subcytotoxic levels of airborne photocopy-emitted nanoparticles could potentiate perturbation of synaptic signaling in cultured neurons following exposure to amyloid-β (Aβ). Signaling was only transiently inhibited by Aβ or nanoparticles individually, but remained statistically reduced in cultures receiving both after 24 h. In vitro and in vivo studies with copier emitted nanoparticles have consistently demonstrated inflammation, oxidative stress, and cytotoxicity. Since Aβ can accumulate years before cognitive decline, subcytotoxic levels of nanoparticles are one factor that could potentiate Aβ-induced impairment of synaptic activity during these early stages.
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Affiliation(s)
- Sangmook Lee
- Laboratory for Neuroscience, University of Massachusetts Lowell, Lowell, MA, USA.,Departments of Biological Sciences, University of Massachusetts Lowell, Lowell, MA, USA
| | - Ikjot S Sohal
- Laboratory for Neuroscience, University of Massachusetts Lowell, Lowell, MA, USA.,Biomedical Engineering and Biotechnology Program, University of Massachusetts Lowell, Lowell, MA, USA
| | - Mikaela A Therrien
- Laboratory for Neuroscience, University of Massachusetts Lowell, Lowell, MA, USA.,Departments of Biological Sciences, University of Massachusetts Lowell, Lowell, MA, USA
| | - Anoop K Pal
- Departments of Work Environment, University of Massachusetts Lowell, Lowell, MA, USA.,Biomedical Engineering and Biotechnology Program, University of Massachusetts Lowell, Lowell, MA, USA
| | - Dhimiter Bello
- Nanomanufacturing Center for Excellence, University of Massachusetts Lowell, Lowell, MA, USA.,Departments of Work Environment, University of Massachusetts Lowell, Lowell, MA, USA
| | - Thomas B Shea
- Laboratory for Neuroscience, University of Massachusetts Lowell, Lowell, MA, USA.,Departments of Biological Sciences, University of Massachusetts Lowell, Lowell, MA, USA
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Lee S, Zemianek JM, Shultz A, Vo A, Maron BY, Therrien M, Courtright C, Guaraldi M, Yanco HA, Shea TB. Synaptic signal streams generated by ex vivo neuronal networks contain non-random, complex patterns. Int J Dev Neurosci 2014; 38:184-94. [PMID: 25172170 DOI: 10.1016/j.ijdevneu.2014.08.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Revised: 08/19/2014] [Accepted: 08/19/2014] [Indexed: 11/27/2022] Open
Abstract
Cultured embryonic neurons develop functional networks that transmit synaptic signals over multiple sequentially connected neurons as revealed by multi-electrode arrays (MEAs) embedded within the culture dish. Signal streams of ex vivo networks contain spikes and bursts of varying amplitude and duration. Despite the random interactions inherent in dissociated cultures, neurons are capable of establishing functional ex vivo networks that transmit signals among synaptically connected neurons, undergo developmental maturation, and respond to exogenous stimulation by alterations in signal patterns. These characteristics indicate that a considerable degree of organization is an inherent property of neurons. We demonstrate herein that (1) certain signal types occur more frequently than others, (2) the predominant signal types change during and following maturation, (3) signal predominance is dependent upon inhibitory activity, and (4) certain signals preferentially follow others in a non-reciprocal manner. These findings indicate that the elaboration of complex signal streams comprised of a non-random distribution of signal patterns is an emergent property of ex vivo neuronal networks.
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Affiliation(s)
- Sangmook Lee
- Center for Neurobiology and Neurodegeneration Research, UMass Lowell, Lowell, MA 01854, United States; Department of Biological Sciences, UMass Lowell, Lowell, MA 01854, United States
| | - Jill M Zemianek
- Center for Neurobiology and Neurodegeneration Research, UMass Lowell, Lowell, MA 01854, United States; Department of Biological Sciences, UMass Lowell, Lowell, MA 01854, United States
| | - Abraham Shultz
- Center for Neurobiology and Neurodegeneration Research, UMass Lowell, Lowell, MA 01854, United States; Department of Computer Science, UMass Lowell, Lowell, MA 01854, United States
| | - Anh Vo
- Center for Neurobiology and Neurodegeneration Research, UMass Lowell, Lowell, MA 01854, United States
| | - Ben Y Maron
- Center for Neurobiology and Neurodegeneration Research, UMass Lowell, Lowell, MA 01854, United States
| | - Mikaela Therrien
- Department of Biological Sciences, UMass Lowell, Lowell, MA 01854, United States
| | - Christina Courtright
- Department of Biological Sciences, UMass Lowell, Lowell, MA 01854, United States
| | - Mary Guaraldi
- Center for Neurobiology and Neurodegeneration Research, UMass Lowell, Lowell, MA 01854, United States; Department of Biological Sciences, UMass Lowell, Lowell, MA 01854, United States
| | - Holly A Yanco
- Center for Neurobiology and Neurodegeneration Research, UMass Lowell, Lowell, MA 01854, United States; Department of Computer Science, UMass Lowell, Lowell, MA 01854, United States
| | - Thomas B Shea
- Center for Neurobiology and Neurodegeneration Research, UMass Lowell, Lowell, MA 01854, United States; Department of Biological Sciences, UMass Lowell, Lowell, MA 01854, United States.
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Napoli A, Xie J, Obeid I. Understanding the temporal evolution of neuronal connectivity in cultured networks using statistical analysis. BMC Neurosci 2014; 15:17. [PMID: 24443925 PMCID: PMC3902005 DOI: 10.1186/1471-2202-15-17] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2013] [Accepted: 01/13/2014] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND Micro-Electrode Array (MEA) technology allows researchers to perform long-term non-invasive neuronal recordings in-vitro while actively interacting with the cultured neurons. Despite numerous studies carried out using MEAs, many functional, chemical and structural mechanisms of how dissociated cortical neurons develop and respond to external stimuli are not yet well understood because of the lack of quantitative studies that assess how their development can be affected by chronic external stimulation. METHODS To investigate network changes, we analyzed a large MEA data set composed of neuron spikes recorded from cultures of dissociated rat cortical neurons plated on MEA dishes with 59 recording electrodes each. Neural network activity was recorded during the first five weeks of each culture's in-vitro development. Stimulation sessions were delivered to each of the 59 electrodes. The False Discovery Rate technique was used to quantify the temporal evolution of dissociated cortical neurons. Our analysis focused on network responses that occurred within selected time window durations, namely 50 ms, 100 ms and 150 ms after stimulus onset. RESULTS Our results show an evolution in dissociated cortical neuronal network activity over time, that reflects the network synaptic evolution. Furthermore, we tested the sensitivity of our technique to different observation time windows and found that varying the time windows, allows us to capture different dynamics of the observed responses. In addition, when selecting a 150 ms observation time window, our findings indicate that cultures dissociated from the same brain tissue display trends in their temporal evolution that are more similar than those obtained from different brains. CONCLUSION Our results emphasize that the FDR technique can be implemented without the need to make any particular assumptions about the data a priori. The proposed technique was able to capture the well-known dissociated cortical neuron networks' temporal evolution, that has been previously observed in in-vivo and in intact brain tissue studies. Furthermore, our findings suggest that the time window that is used to capture the stimulus-evoked network responses is a critical parameter to analyze the electrical behavioral and temporal evolution of dissociated cortical neurons.
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Affiliation(s)
- Alessandro Napoli
- Department of Electrical and Computer Engineering, Temple University, Philadelphia, PA, USA.
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Zemianek JM, Lee S, Shea TB. Acceleration of myofiber formation in culture by a digitized synaptic signal. Tissue Eng Part A 2013; 19:2693-702. [PMID: 23859139 DOI: 10.1089/ten.tea.2012.0619] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Developing myofibers require chemical and electrical stimulation to induce functional muscle tissue. Tissue engineering protocols utilize either or both of these to initiate differentiation ex vivo. Current methodologies typically deliver multi-volt electrical signals, which may be hazardous to developing tissues. In attempts to mimic in vivo muscle development, we stimulated cultured muscle precursor cells with a low-voltage (1 mV) digitized synaptic signal derived from cultured cortical neurons. This synaptic signal induced larger and more adherent myofibers, along with markers of myoblast differentiation, compared to those induced following stimulation with a conventional (28 V) square signal. These findings suggest that stimulation with a digitized synaptic signal may be useful in tissue engineering and physical therapy.
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Affiliation(s)
- Jill M Zemianek
- Department of Biological Sciences, Center for Cellular Neurobiology and Neurodegeneration Research, University of Massachusetts at Lowell , Lowell, Massachusetts
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Zemianek JM, Lee S, Guaraldi M, Shea TB. Critical role for inhibitory neurons in modulation of synaptic signaling in ex vivo neuronal networks. Int J Dev Neurosci 2013; 31:308-10. [PMID: 23563174 DOI: 10.1016/j.ijdevneu.2013.03.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2013] [Accepted: 03/24/2013] [Indexed: 02/03/2023] Open
Abstract
A number of laboratories have modeled aspects of synaptic plasticity using neuronal networks established on micro-electrode arrays. Such studies demonstrate that external stimulation can increase or hasten maturation of network signaling as evidenced an increase in complex bursts. Herein, we demonstrate that repetitive stimulation with a recorded synaptic signal was capable of increasing overall signaling, including the percentage of bursts, over a 5-day period, but that this increase was completely prevented by the presence of the GABAergic antagonist bicuculline. These findings demonstrate a critical role for inhibitory neurons in signal maturation following stimulation, which supports the purported role for inhibitory neuronal activity in long-term potentiation and learning in situ.
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Affiliation(s)
- Jill M Zemianek
- Center for Cellular Neurobiology & Neurodegeneration Research, University of Massachusetts Lowell, Lowell, MA 01854, USA
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Zemianek JM, Shultz AM, Lee S, Guaraldi M, Yanco HA, Shea TB. Transient epileptiform signaling during neuronal network development: regulation by external stimulation and bimodal GABAergic activity. Int J Dev Neurosci 2012; 31:131-7. [PMID: 23220177 DOI: 10.1016/j.ijdevneu.2012.11.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2012] [Revised: 11/09/2012] [Accepted: 11/10/2012] [Indexed: 01/25/2023] Open
Abstract
A predominance of excitatory activity, with protracted appearance of inhibitory activity, accompanies cortical neuronal development. It is unclear whether or not inhibitory neuronal activity is solicited exclusively by excitatory neurons or whether the transient excitatory activity displayed by developing GABAergic neurons contributes to an excitatory threshold that fosters their conversion to inhibitory activity. We addressed this possibility by culturing murine embryonic neurons on multi-electrode arrays. A wave of individual 0.2-0.4 mV signals ("spikes") appeared between approx. 20-30 days in culture, then declined. A transient wave of high amplitude (>0.5 mV) epileptiform activity coincided with the developmental decline in spikes. Bursts (clusters of ≥3 low-amplitude spikes within 0.7s prior to returning to baseline) persisted following this decline. Addition of the GABAergic antagonist bicuculline initially had no effect on signaling, consistent with delayed development of GABAergic synapses. This was followed by a period in which bicuculline inhibited overall signaling, confirming that GABAergic neurons initially display excitatory activity in ex vivo networks. Following the transient developmental wave of epileptiform signaling, bicuculline induced a resurgence of epileptiform signaling, indicating that GABAergic neurons at this point displayed inhibitory activity. The appearance of transition after the developmental and decline of epileptiform activity, rather than immediately after the developmental decline in lower-amplitude spikes, suggests that the initial excitatory activity of GABAergic neurons contributes to their transition into inhibitory neurons, and that inhibitory GABAergic activity is essential for network development. Prior studies indicate that a minority (25%) of neurons in these cultures were GABAergic, suggesting that inhibitory neurons regulate multiple excitatory neurons. A similar robust increase in signaling following cessation of inhibitory activity in an artificial neural network containing 20% inhibitory neurons supported this conclusion. Even a minor perturbation in GABAergic function may therefore foster initiation and/or amplification of seizure activity, as well as perturbations in long-term potentiation.
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Affiliation(s)
- Jill M Zemianek
- Center for Cellular Neurobiology & Neurodegeneration Research, Department of Biological Sciences, University of Massachusetts Lowell, 01854, USA
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Zemianek JM, Lee S, Guaraldi M, Shea TB. Accelerated establishment of mature signaling patterns following stimulation of developing neuronal networks: "learning" versus "plasticity". Int J Dev Neurosci 2012; 30:602-6. [PMID: 22906544 DOI: 10.1016/j.ijdevneu.2012.08.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2012] [Revised: 08/03/2012] [Accepted: 08/04/2012] [Indexed: 01/19/2023] Open
Abstract
Neuronal networks established on micro-electrode arrays provide useful models for synaptic plasticity. Whether or not this represents a facet of learning is debated since ex vivo networks are deprived of organismal interaction with the environment. We compared developmental signaling of such networks with and without stimulation with a prerecorded synaptic signal from another mature culture as a model of sensory input. Unstimulated networks displayed a developmental increase in individual signals that eventually declined, yielding a pattern containing organized bursts of signaling. Minimal stimulation, to model the onset of sensory input hastened the onset of developmental signaling. However, the overall developmental pattern of stimulated networks, including the total number and type of signals as well as the length of this developmental period, was identical to that of unstimulated networks. One interpretation of these findings is that ongoing plasticity may be essential to establish an appropriate platform for learning once sensory input ensues.
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Affiliation(s)
- Jill M Zemianek
- Center for Cellular Neurobiology & Neurodegeneration Research, Department of Biological Sciences, University of Massachusetts Lowell, Lowell, MA 01854, USA
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