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The DOI matches its Crossref record; 60 of the 60 references it cites were found in a registry or an index; 2 of the 37 sources its claims cite were checked for support.

Optical activation of lateral amygdala pyramidal cells instructs associative fear learning

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Abstract

Humans and animals can learn that specific sensory cues in the environment predict aversive events through a form of associative learning termed fear conditioning. This learning occurs when the sensory cues are paired with an aversive event occuring in close temporal proximity. Activation of lateral amygdala (LA) pyramidal neurons by aversive stimuli is thought to drive the formation of these associative fear memories; yet, there have been no direct tests of this hypothesis. Here we demonstrate that viral-targeted, tissue-specific expression of the light-activated channelrhodopsin (ChR2) in LA pyramidal cells permitted optical control of LA neuronal activity. Using this approach we then paired an auditory sensory cue with optical stimulation of LA pyramidal neurons instead of an aversive stimulus. Subsequently presentation of the tone alone produced behavioral fear responses. These results demonstrate in vivo optogenetic control of LA neurons and provide compelling support for the idea that fear learning is instructed by aversive stimulus-induced activation of LA pyramidal cells.

Overview

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TL;DR

Viral expression of channelrhodopsin in lateral amygdala (LA) pyramidal cells allowed optical stimulation to substitute for an aversive shock unconditioned stimulus (US), and pairing this stimulation with an auditory cue produced associative fear learning and 24-h memory. The results support the idea that aversive stimulus-induced activation of LA pyramidal cells can instruct fear learning.

Key findings

  • ChR2/YFP expression was largely restricted to CaMKII-expressing pyramidal neurons (92 ± 1%) and very low in GABA-expressing cells (1.8 ± 0.0%).
  • In vivo, 20-Hz laser stimulation with 10-ms pulses produced robust, reliable action potential firing in LA cells (total n = 15 cells from four animals) and activated large numbers of LA neurons, with 253 ± 46 CFOS+ cells/section on the stimulated side versus 29 ± 4 on the nonstimulated side (n = 3 animals); total CaMKII+ cells were 402 ± 37 per LA section.
  • In behaving rats, pairing an auditory CS with laser stimulation of LA pyramidal cells as the US produced greater CS-evoked freezing than GFP/paired or ChR2/unpaired controls, with a significant trial block × treatment interaction (F6,63 = 4.7795, P = 0.00045).
  • At 24-h long-term memory testing in a separate context, ChR2/paired animals froze significantly more than GFP/paired and ChR2/unpaired animals (one-way ANOVA F2,21 = 5.41, P = 0.013; post hoc P = 0.017 for both comparisons).

Methods

  • Male Sprague-Dawley rats (275–300 g) received unilateral LA injections of AAV-CaMKII-ChR2/EYFP or AAV-CaMKII-GFP, with guide cannulae for fiber-optic laser stimulation; experiments included immunocytochemistry, in vivo electrophysiology, CFOS mapping, and behavioral fear conditioning.
  • For conditioning, paired groups received 16 CS–US pairings: a 20-s auditory CS (5-kHz tone pips, 1 Hz, 250 ms on/750 ms off) coterminating with a 2-s laser US (20 Hz, 10-ms pulses); an unpaired group received 16 CS and 16 laser US presentations randomly and explicitly unpaired.
  • Freezing was scored by a blind rater during training and during two CS presentations 24 h later in a novel context; data were analyzed with repeated-measures ANOVA, one-way ANOVA, and Newman–Keuls post hoc tests.

Limitations

  • The paper states that freezing scores during long-term memory testing were relatively low compared with those typically obtained with an electric shock US, and it discusses possible explanations, including the need for plasticity in other fear-circuit regions, more specific cell targeting, or coactivation of neuromodulatory systems for maximal memory formation.
  • The paper notes that laser stimulation itself produced a small but statistically significant amount of unconditioned freezing (paired t5 = 4.89, P = 0.005).
  • Evident from the text: behavioral groups were small (n = 8 per group), CFOS and electrophysiology samples were limited (n = 3 animals; n = 15 cells), only male rats were used, and 3 ChR2/paired and 2 ChR2/unpaired animals were excluded because ChR2 expression or cannula placement criteria were not met.

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Integrity signals

Registry

Crossref · 10.1073/pnas.1002418107

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Metadata

Authors
Johansen, J. P., Hamanaka, H., Monfils, M. H., Behnia, R., Deisseroth, K., Blair, H. T., & LeDoux, J. E.
Affiliations
  • New York University (US)
  • Howard Hughes Medical Institute (US)
  • University of California, Los Angeles (US)
  • Nathan Kline Institute for Psychiatric Research (US)
Venue
Proceedings of the National Academy of Sciences
Published
2010-06-25
Volume
107
Issue
28
Pages
12692-12697
ISSN
  • 0027-8424 (ISSN-L)
  • 1091-6490
OpenAlex
W2090654839
Cited by
308
References
57
Citations by year
2026: 3 · 2025: 8 · 2024: 21 · 2023: 11 · 2022: 8 · 2021: 21 · 2020: 22 · 2019: 21 · 2018: 14 · 2017: 20 · 2016: 21 · 2015: 35 · 2014: 28 · 2013: 32 · 2012: 23
FWCI
14.51
Type
journal article
Language
en
Open access
Locations
  • Proceedings of the National Academy of Sciences (publishedVersion)
  • PubMed Central (publishedVersion)
  • PubMed (publishedVersion)
Funders
  • Howard Hughes Medical Institute
  • Deutsches Krebsforschungszentrum
  • York University
  • National Institute of Mental Health (R01MH046516, F32MH082505)
Topics
  • Life Sciences › Neuroscience › Cognitive Neuroscience › Memory and Neural Mechanisms
  • Life Sciences › Neuroscience › Cellular and Molecular Neuroscience › Neuroscience and Neuropharmacology Research
  • Life Sciences › Neuroscience › Cellular and Molecular Neuroscience › Neurobiology and Insect Physiology Research
Keywords
lateral amygdala, pyramidal neurons, fear conditioning, optogenetics, channelrhodopsin, auditory fear conditioning, aversive stimuli, fear memory, neuronal activity control
MeSH terms
Amygdala, Animals, Conditioning, Psychological, Conditioning, Classical, Cues, Fear, Male, Neurons, Phobic Disorders, Photic Stimulation, Rats, Sprague-Dawley, Pyramidal Cells, Rats

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