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Sun X, Bernstein MJ, Meng M, Rao S, Sørensen AT, Yao L, Zhang X, Anikeeva PO, Lin Y. Functionally Distinct Neuronal Ensembles within the Memory Engram. Cell 2020; 181:410-423.e17. [PMID: 32187527 PMCID: PMC7166195 DOI: 10.1016/j.cell.2020.02.055] [Citation(s) in RCA: 113] [Impact Index Per Article: 28.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 10/31/2019] [Accepted: 02/26/2020] [Indexed: 10/24/2022]
Abstract
Memories are believed to be encoded by sparse ensembles of neurons in the brain. However, it remains unclear whether there is functional heterogeneity within individual memory engrams, i.e., if separate neuronal subpopulations encode distinct aspects of the memory and drive memory expression differently. Here, we show that contextual fear memory engrams in the mouse dentate gyrus contain functionally distinct neuronal ensembles, genetically defined by the Fos- or Npas4-dependent transcriptional pathways. The Fos-dependent ensemble promotes memory generalization and receives enhanced excitatory synaptic inputs from the medial entorhinal cortex, which we find itself also mediates generalization. The Npas4-dependent ensemble promotes memory discrimination and receives enhanced inhibitory drive from local cholecystokinin-expressing interneurons, the activity of which is required for discrimination. Our study provides causal evidence for functional heterogeneity within the memory engram and reveals synaptic and circuit mechanisms used by each ensemble to regulate the memory discrimination-generalization balance.
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Affiliation(s)
- Xiaochen Sun
- McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Molecular and Cellular Neuroscience Graduate Program, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Max J Bernstein
- McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Meizhen Meng
- McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Siyuan Rao
- McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Andreas T Sørensen
- McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Li Yao
- State Key Laboratory of Cognitive Neuroscience & Learning and IDG/McGovern Institute for Brain Research, Beijing Normal University, Beijing 100875, China
| | - Xiaohui Zhang
- State Key Laboratory of Cognitive Neuroscience & Learning and IDG/McGovern Institute for Brain Research, Beijing Normal University, Beijing 100875, China
| | - Polina O Anikeeva
- McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Yingxi Lin
- McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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Roet M, Hescham SA, Jahanshahi A, Rutten BPF, Anikeeva PO, Temel Y. Progress in neuromodulation of the brain: A role for magnetic nanoparticles? Prog Neurobiol 2019; 177:1-14. [PMID: 30878723 DOI: 10.1016/j.pneurobio.2019.03.002] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Revised: 03/05/2019] [Accepted: 03/07/2019] [Indexed: 12/19/2022]
Abstract
The field of neuromodulation is developing rapidly. Current techniques, however, are still limited as they i) either depend on permanent implants, ii) require invasive procedures, iii) are not cell-type specific, iv) involve slow pharmacokinetics or v) have a restricted penetration depth making it difficult to stimulate regions deep within the brain. Refinements into the different fields of neuromodulation are thus needed. In this review, we will provide background information on the different techniques of neuromodulation discussing their latest refinements and future potentials including the implementation of nanoparticles (NPs). In particular we will highlight the usage of magnetic nanoparticles (MNPs) as transducers in advanced neuromodulation. When exposed to an alternating magnetic field (AMF), certain MNPs can generate heat through hysteresis. This MNP heating has been promising in the field of cancer therapy and has recently been introduced as a method for remote and wireless neuromodulation. This indicates that MNPs may aid in the exploration of brain functions via neuromodulation and may eventually be applied for treatment of neuropsychiatric disorders. We will address the materials chemistry of MNPs, their biomedical applications, their delivery into the brain, their mechanisms of stimulation with emphasis on MNP heating and their remote control in living tissue. The final section compares and discusses the parameters used for MNP heating in brain cancer treatment and neuromodulation. Concluding, using MNPs for nanomaterial-mediated neuromodulation seem promising in a variety of techniques and could be applied for different neuropsychiatric disorders when more extensively investigated.
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Affiliation(s)
- Milaine Roet
- School for Mental Health and Neuroscience, Department of Neurosurgery, Maastricht University, Maastricht, 6200, MD, The Netherlands; European Graduate School of Neuroscience (EURON), The Netherlands
| | - Sarah-Anna Hescham
- School for Mental Health and Neuroscience, Department of Neurosurgery, Maastricht University, Maastricht, 6200, MD, The Netherlands; European Graduate School of Neuroscience (EURON), The Netherlands
| | - Ali Jahanshahi
- School for Mental Health and Neuroscience, Department of Neurosurgery, Maastricht University, Maastricht, 6200, MD, The Netherlands; European Graduate School of Neuroscience (EURON), The Netherlands
| | - Bart P F Rutten
- School for Mental Health and Neuroscience, Department of Psychiatry and Neuropsychology, Maastricht University, Maastricht, 6200, MD, The Netherlands; European Graduate School of Neuroscience (EURON), The Netherlands
| | - Polina O Anikeeva
- Department of Materials Science and Engineering, Department of Brain and Cognitive Sciences, Research Laboratory of Electronics, McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, 02139, MA, United States of America
| | - Yasin Temel
- School for Mental Health and Neuroscience, Department of Neurosurgery, Maastricht University, Maastricht, 6200, MD, The Netherlands; European Graduate School of Neuroscience (EURON), The Netherlands; Department of Neurosurgery, Maastricht University Medical Center, Maastricht, 6202, AZ, The Netherlands.
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Panzer MJ, Aidala KE, Anikeeva PO, Halpert JE, Bawendi MG, Bulović V. Nanoscale morphology revealed at the interface between colloidal quantum dots and organic semiconductor films. Nano Lett 2010; 10:2421-2426. [PMID: 20545311 DOI: 10.1021/nl100375b] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The degree of interpenetration at the interface between colloidal quantum dots (QDs) and organic semiconductor molecules commonly employed in hybrid light-emitting devices (QD-LEDs) has been examined using tapping-mode atomic force microscopy. Both phase separation-driven and Contact Printing-enabled QD/semiconductor heterojunction fabrication methodologies lead to significant QD embedment in the underlying organic film with the greatest degree of QD penetration observed for QD monolayers that have been contact printed. The relative performance of QD-LEDs fabricated via three different methods using the same materials set has also been investigated.
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Affiliation(s)
- Matthew J Panzer
- Department of Chemical and Biological Engineering, Tufts University, Medford, Massachusetts 02155, USA.
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Anikeeva PO, Halpert JE, Bawendi MG, Bulović V. Quantum dot light-emitting devices with electroluminescence tunable over the entire visible spectrum. Nano Lett 2009; 9:2532-2536. [PMID: 19514711 DOI: 10.1021/nl9002969] [Citation(s) in RCA: 227] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Improvements in quantum dot light-emitting device (QD-LED) performance are achieved by the choice of organic charge transporting layers, by use of different colloidal QDs for the different parts of the visible spectrum, and by utilizing a recently demonstrated robust QD deposition method. Spectrally narrow electroluminescence of our QD-LEDs is tuned over the entire visible wavelength range from lambda = 460 nm (blue) to lambda = 650 nm (deep red). By printing close-packed monolayers of different QD types inside an identical QD-LED structure, we demonstrate that different color QD-LEDs with QDs of different chemistry can be fabricated on the same substrate. We discuss mechanisms responsible for efficiency increase for green (4-fold) and orange (30%) QD-LEDs as compared to previous reports and outline challenges associated with achieving high-efficiency blue QD-LEDs.
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Affiliation(s)
- Polina O Anikeeva
- Laboratory of Organic Optics and Electronics, Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge Massachusetts 02139, USA
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Kim L, Anikeeva PO, Coe-Sullivan SA, Steckel JS, Bawendi MG, Bulović V. Contact printing of quantum dot light-emitting devices. Nano Lett 2008; 8:4513-7. [PMID: 19053797 DOI: 10.1021/nl8025218] [Citation(s) in RCA: 131] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
We demonstrate a solvent-free contact printing process for deposition of patterned and unpatterned colloidal quantum dot (QD) thin films as the electroluminescent layers within hybrid organic-QD light-emitting devices (QD-LEDs). Our method benefits from the simplicity, low cost, and high throughput of solution-processing methods, while eliminating exposure of device structures to solvents. Because the charge transport layers in hybrid organic/inorganic QD-LEDs consist of solvent-sensitive organic thin films, the ability to avoid solvent exposure during device growth, as presented in this study, provides a new flexibility in choosing organic materials for improved device performance. In addition, our method allows us to fabricate both monochrome and red-green-blue patterned electroluminescent structures with 25 microm critical dimension, corresponding to 1000 ppi (pixels-per-inch) print resolution.
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Affiliation(s)
- LeeAnn Kim
- Laboratory of Organic Optics and Electronics, Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge Massachusetts 02139, USA
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Anikeeva PO, Halpert JE, Bawendi MG, Bulović V. Electroluminescence from a mixed red-green-blue colloidal quantum dot monolayer. Nano Lett 2007; 7:2196-200. [PMID: 17616230 DOI: 10.1021/nl0703424] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
We demonstrate light emitting devices (LEDs) with a broad spectral emission generated by electroluminescence from a mixed-monolayer of red, green, and blue emitting colloidal quantum dots (QDs) in a hybrid organic/inorganic structure. The colloidal QDs are reproducibly synthesized and yield high luminescence efficiency materials suitable for LED applications. Independent processing of the organic charge transport layers and the QD luminescent layer allows for precise tuning of the emission spectrum without changing the device structure, simply by changing the ratio of different color QDs in the active layer. Spectral tuning is demonstrated through fabrication of white QD-LEDs that exhibit external quantum efficiencies of 0.36% (Commission Internationale de l'Eclairage) coordinates of (0.35, 0.41) at video brightness, and color rendering index of 86 as compared to a 5500 K blackbody reference.
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Affiliation(s)
- Polina O Anikeeva
- Laboratory of Organic Optics and Electronics, Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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Ivanov SA, Nanda J, Piryatinski A, Achermann M, Balet LP, Bezel IV, Anikeeva PO, Tretiak S, Klimov VI. Light Amplification Using Inverted Core/Shell Nanocrystals: Towards Lasing in the Single-Exciton Regime. J Phys Chem B 2004. [DOI: 10.1021/jp0483371] [Citation(s) in RCA: 150] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
| | - Jagjit Nanda
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545
| | | | - Marc Achermann
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545
| | | | - Ilia V. Bezel
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545
| | | | - Sergei Tretiak
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545
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