Retention and Distribution of Dopamine-Dependent Reward Memory in Regenerating Planaria.

Overview

Authors: Kenneth Samuel¹, Abigail K. Hakes², Easter S. Suviseshamuthu³, Maria E. Fichera²

Department of Molecular and Integrative Physiology, University of Illinois Urbana-Champaign, Urbana, IL 61801, USA
Department of Biology, Eastern University, St. Davids, PA 19087, USA; (A.K.H.); (M.E.F.)
Center for Mobility and Rehabilitation Engineering Research, Kessler Foundation, West Orange, NJ 07052, USA

Institutions: University of Illinois Urbana-Champaign (United States); Eastern University (United States); Kessler Foundation (United States)

Journal: Biomolecules, volume 16, issue 5, article 649

Dates: received 14 February 2026; accepted 22 April 2026; published online 27 April 2026

Type: Research article · Language: English

License: CC BY

Identifiers: DOI 10.3390/biom16050649 · PMID 42194000 · PMCID PMC13204754 · OpenAlex W7159784022

Open access: gold, a free copy (OpenAlex)

Status: data only

Categories: other (organism), other condition (population)

Keywords: addiction-like behavior, conditioned place preference, D1 dopamine antagonist, memory retention, planaria

MeSH: Dopamine*, Memory*, Planarians*, Regeneration*, Reward*, Animals, Dopamine Antagonists, Receptors, Dopamine D1, Sucrose (* major topic)

Topic: Planarian Biology and Electrostimulation (Molecular Biology, Biochemistry, Genetics and Molecular Biology), according to OpenAlex

Funding: Kessler Foundation

Citations: not cited yet (Europe PMC); 47 references in the paper

Abstract

Memory is generally thought to be stored within centralized neural circuits. However, whether learned behaviors can persist in the absence of a brain remains unresolved. Planaria (Girardia spp.) possess a primitive cephalic ganglion and a remarkable capacity for regeneration, providing a unique system to examine non-cephalic memory retention. The primary aim of this study was to determine whether sucrose-induced conditioned place preference (CPP) is retained in posterior, brainless planarian fragments. Planaria were trained using a Pavlovian conditioning paradigm in which an initially unpreferred surface was paired with a 10% sucrose solution, resulting in a robust shift in surface preference. Following amputation, anterior fragments containing the cephalic ganglion as well as posterior fragments lacking the brain preserved the conditioned preference, demonstrating that reward-associated memory is stored even outside the cephalic nervous system. As a secondary objective, we examined the role of dopaminergic reinforcement using a D1 dopamine receptor antagonist during training. While antagonist-treated planaria failed to develop a CPP, posterior fragments from these amputated planaria likewise showed no conditioned preference, indicating that dopamine-dependent signaling is essential for sucrose-associated memory formation across the body. These results provide support for the hypothesis that reward-associated memory in planaria is distributed beyond the brain and can be modulated by dopaminergic pathways, highlighting the utility of this model for exploring fundamental mechanisms of reward, memory, and potential pharmacological interventions.

Reproduced under the paper's license (CC BY), from the paper cited above.

Code

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Data

Datasets cited

figshare:31337869, at figshare; found in “Data Availability Statement”

Data Availability Statement

The data collected during this project has been uploaded to the following link: https://doi.org/10.6084/m9.figshare.31337869.

Reproduced under the paper's license (CC BY), from the paper cited above.

Versions

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Version 1, 30 September 2026: the first record

Recorded: type, language, journal, volume, issue, pages, dates, 4 authors, 5 keywords, 9 MeSH terms, 1 funder, 43 references.

Cite

This paper

Samuel, K., Hakes, A. K., Suviseshamuthu, E. S., & Fichera, M. E. (2026). Retention and Distribution of Dopamine-Dependent Reward Memory in Regenerating Planaria. Biomolecules, 16(5), 649. https://doi.org/10.3390/biom16050649

BibTeX

@article{samuel2026retention, author = {Samuel, Kenneth and Hakes, Abigail K. and Suviseshamuthu, Easter S. and Fichera, Maria E.}, title = {{Retention and Distribution of Dopamine-Dependent Reward Memory in Regenerating Planaria}}, journal = {Biomolecules}, year = {2026}, month = apr, volume = {16}, number = {5}, pages = {649}, publisher = {Multidisciplinary Digital Publishing Institute (MDPI)}, issn = {2218-273X}, doi = {10.3390/biom16050649}, url = {https://doi.org/10.3390/biom16050649}, pmid = {42194000}, pmcid = {PMC13204754} }

RIS

TY - JOUR AU - Samuel, Kenneth AU - Hakes, Abigail K. AU - Suviseshamuthu, Easter S. AU - Fichera, Maria E. TI - Retention and Distribution of Dopamine-Dependent Reward Memory in Regenerating Planaria T2 - Biomolecules J2 - Biomolecules PY - 2026 DA - 2026/04/27 VL - 16 IS - 5 SP - 649 SN - 2218-273X PB - Multidisciplinary Digital Publishing Institute (MDPI) DO - 10.3390/biom16050649 UR - https://doi.org/10.3390/biom16050649 LA - en ER -

CSL-JSON

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