Classical conditioning in a simple withdrawal reflex in Aplysia californica.
Open accessAbstract
The ability of Aplysia and other gastropod molluscs to exhibit complex behaviors that can be modified by associative learning has encouraged us to search for an elementary behavior controlled by a simple and well analyzed neural circuit that also can be modified by this type of learning. Toward that end, we have now produced classical conditioning in the defensive siphon and gill withdrawal reflex of Aplysia. We used as a conditioned stimulus (CS) a light tactile stimulus to the siphon, which produces weak siphon and gill withdrawal. As the unconditioned stimulus (US), we used a strong electric shock to the tail, which produces a massive withdrawal reflex. Specific temporal pairing of the CS and US endowed the CS with the ability of triggering enhanced withdrawal of both the siphon and the gill. Random or unpaired presentations of the CS and US, as well as presentations of the CS or US alone, produced either no enhancement or significantly less enhancement than paired presentations of the CS and US. The conditioning is acquired rapidly (within 15 trials) and is retained for several days. The conditioned response is abolished completely by removal of the abdominal ganglion and many of the neurons involved in the conditioning have been identified in this ganglion previously. These include the sensory neurons and several interneurons in the CS pathway and the siphon and gill motor neurons of the conditioned and unconditioned response pathways. Moreover, the sensory neurons of the US pathway have been identified in the pleural ganglia. As a result of its simplicity, it should be possible in this reflex to specify neurons that are causally related to the conditioned response. Since this reflex also exhibits nonassociative learning, it also may be possible to compare associative and nonassociative learning on a mechanistic level.
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Aplysia californica is only capable of modifying the strength of preexisting associations between reflex-eliciting stimuli, and thus its mode of associative learning does not meet UAL condition ii.
“For example, Aplysia californica is only capable of modifying the strength of preexisting associations between reflex-eliciting stimuli, and thus its mode of AL does not meet condition ii (see Carew et al., 1981; Hawkins et al., 1983; Brembs et al., 2002; Hawkins and Byrne, 2015 provide a review).”
From The Transition to Minimal Consciousness through the Evolution of Associative Learning (2016) · cites this paper as Carew et al., 1981
The paper’s discussion (page unavailable in our copy) explicitly says Aplysia has a spectrum of learning capabilities, including a more complex conditioned internal state that can modulate much of its behavior. Although the study demonstrates enhanced withdrawal after pairing two reflex-eliciting stimuli, that does not support the claim that Aplysia is *only* capable of modifying such responses. The paper does not assess UAL condition ii. (LLM, conf=0.86)
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References 35 · Cited by 281
Research works printed but not linked: 5
- Castehucci, V. F., and E. R. Kandel (1974) A quantaI analysis of the synaptic depression underlying habituation of the gih- withdrawal reflex in Aplysia. Proc. Natl. Acad. Sci. U. S. A. 71: 5004-5008.
- Kandel, E. R., and J. H. Schwartz (1982) Molecular biology of an elementary form of learning: Modulation of transmitter release through CAMP-dependent protein kinase. Science, in press.
- SahIey, C. L., A. Gelperin, and J. W. Rudy (1981a) One-trial associative learning in a terrestrial mollusc. Proc. Natl. Acad. Sci. U. S. A. 78: 640-642.
- Walters, E. T., T. J. Carew, and E. R. Kandel(1979) Associative learning in Aplysia californica. Proc. Natl. Acad. Sci. U. S. A. 76: 6675-6679.
- Wells, M. J. (1968) Lower Animals, McGraw-Hi& New York.
- Authors
- Carew, T., Walters, E., & Kandel, E.
- Affiliations
- Columbia University (US)
- Venue
- The Journal of Neuroscience
- Publisher
- Society for Neuroscience
- Published
- 1981-12-01
- Volume
- 1
- Issue
- 12
- Pages
- 1426-1437
- ISSN
- 0270-6474 (ISSN-L)
- 1529-2401
- PMC
- PMC6564124
- OpenAlex
- W1884538784
- Cited by
- 281
- References
- 35
- Citations by year
- 2026: 4 · 2025: 3 · 2024: 9 · 2023: 6 · 2022: 5 · 2021: 6 · 2020: 3 · 2019: 7 · 2018: 8 · 2017: 8 · 2016: 9 · 2015: 6 · 2014: 10 · 2013: 5 · 2012: 6
- FWCI
- 6.19
- Type
- journal article
- Language
- en
- Open access
- hybrid
- doi.org
- Licence
- Locations
- Journal of Neuroscience (publishedVersion, cc-by-nc-sa)
- PubMed Central (publishedVersion)
- PubMed (publishedVersion)
- Funders
- National Institute of Mental Health
- 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
- classical conditioning, Aplysia californica, defensive reflex, associative learning, non-associative learning, abdominal ganglion, interneurons, motor neurons, sensory neurons, conditioned stimulus, unconditioned stimulus, neural circuits
- MeSH terms
- Animals, Aplysia, Conditioning, Psychological, Electric Stimulation, Extinction, Psychological, Gills, Reflex
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