1
|
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.
Collapse
|
2
|
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.
Collapse
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
| |
Collapse
|
3
|
Insufficient developmental excitatory neuronal activity fails to foster establishment of normal levels of inhibitory neuronal activity. Int J Dev Neurosci 2016; 55:66-71. [PMID: 27686511 DOI: 10.1016/j.ijdevneu.2016.09.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Revised: 09/16/2016] [Accepted: 09/17/2016] [Indexed: 11/22/2022] Open
Abstract
The nervous system is composed of excitatory and inhibitory neurons. One major class of inhibitory neurons release the neurotransmitter γ-Aminobutyric acid (GABA). GABAergic inhibitory activity maintains the balance that is disrupted in conditions such as epilepsy. At least some GABAergic neurons are initially excitatory and undergo a developmental conversion to convert to inhibitory neurons. The mechanism(s) behind this conversion are thought to include a critical developmental increase in excitatory activity. To test this hypothesis, we subjected ex vivo developing neuronal networks on multi-electrode arrays to various stimulation and pharmacological regimens. Synaptic activity of networks initially consists of epileptiform-like high-amplitude individual "spikes", which convert to organized bursts of activity over the course of approximately 1 month. Stimulation of networks with a digitized synaptic signal for 5days hastened the decrease of epileptiform activity. By contrast, stimulation for a single day delayed the appearance of bursts and instead increased epileptiform signaling. GABA treatment reduced total signals in unstimulated networks and networks stimulated for 5days, but instead increased signaling in networks stimulated for 1day. This increase was prevented by co-treatment with (2R)-amino-5-phosphonopentanoate and 6-cyano-7-nitroquinoxaline-2,3-dione, confirming that GABA invoked excitatory activity in networks stimulated for 1day. Glutamate increased signals in networks subjected to all stimulation regimens; the GABA receptor antagonist bicuculline prevented this increase only in networks stimulated for 1day. These latter findings are consistent with the induction of so-called "mixed" synapses (which release a combination of excitatory and inhibitory neurotransmitters) in networks stimulated for 1day, and support the hypothesis that a critical level of excitatory activity fosters the developmental transition of GABAergic neurons from excitatory to inhibitory.
Collapse
|
4
|
Doulames VM, Vilcans M, Lee S, Shea TB. Social interaction attenuates the extent of secondary neuronal damage following closed head injury in mice. Front Behav Neurosci 2015; 9:275. [PMID: 26528156 PMCID: PMC4606018 DOI: 10.3389/fnbeh.2015.00275] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Accepted: 09/28/2015] [Indexed: 11/13/2022] Open
Abstract
Recovery following Traumatic Brain Injury (TBI) can vary tremendously among individuals. Lifestyle following injury, including differential social interactions, may modulate the extent of secondary injury following TBI. To examine this possibility under controlled conditions, closed head injury (CHI) was induced in C57Bl6 mice using a standardized weight drop device after which mice were either housed in isolation or with their original cagemates (“socially-housed”) for 4 weeks. CHI transiently impaired novel object recognition (NOR) in both isolated and social mice, confirming physical and functional injury. By contrast, Y maze navigation was impaired in isolated but not social mice at 1–4 weeks post CHI. CHI increased excitotoxic signaling in hippocampal slices from all mice, which was transiently exacerbated by isolation at 2 weeks post CHI. CHI slightly increased reactive oxygen species and did not alter levels of amyloid beta (Abeta), total or phospho-tau, total or phosphorylated neurofilaments. CHI increased serum corticosterone in both groups, which was exacerbated by isolation. These findings support the hypothesis that socialization may attenuate secondary damage following TBI. In addition, a dominance hierarchy was noted among socially-housed mice, in which the most submissive mouse displayed indices of stress in the above analyses that were statistically identical to those observed for isolated mice. This latter finding underscores that the nature and extent of social interaction may need to vary among individuals to provide therapeutic benefit.
Collapse
Affiliation(s)
- Vanessa M Doulames
- Center for Neurobiology and Neurodegeneration Research, UMass Lowell Lowell, MA, USA ; Biomedical and Biotechnology Program, University of Massachusetts Lowell Lowell, MA, USA
| | - Meghan Vilcans
- Center for Neurobiology and Neurodegeneration Research, UMass Lowell Lowell, MA, USA ; Department of Biological Sciences, University of Massachusetts Lowell Lowell, MA, USA
| | - Sangmook Lee
- Center for Neurobiology and Neurodegeneration Research, UMass Lowell Lowell, MA, USA ; Department of Biological Sciences, University of Massachusetts Lowell Lowell, MA, USA
| | - Thomas B Shea
- Center for Neurobiology and Neurodegeneration Research, UMass Lowell Lowell, MA, USA ; Biomedical and Biotechnology Program, University of Massachusetts Lowell Lowell, MA, USA ; Department of Biological Sciences, University of Massachusetts Lowell Lowell, MA, USA
| |
Collapse
|
5
|
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.
Collapse
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.
| |
Collapse
|