A new method to study learning and memory using spontaneous locomotor activity in an open-field arena

Jaise Silva Ferreira; Joaquim Barbosa Leite Junior; João Marcos de Mello Bastos; Richard Ian Samuels; Robert J Carey; Marinete Pinheiro Carrera

doi:10.1016/j.jneumeth.2021.109429

A new method to study learning and memory using spontaneous locomotor activity in an open-field arena

J Neurosci Methods. 2022 Jan 15:366:109429. doi: 10.1016/j.jneumeth.2021.109429. Epub 2021 Nov 28.

Authors

Jaise Silva Ferreira¹, Joaquim Barbosa Leite Junior¹, João Marcos de Mello Bastos¹, Richard Ian Samuels², Robert J Carey³, Marinete Pinheiro Carrera⁴

Affiliations

¹ Behavioral Pharmacology Group, Laboratory of Animal Morphology and Pathology, State University of North Fluminense Darcy Ribeiro, Avenida Alberto Lamego, 2000, Campos dos Goytacazes 28013-602, RJ, Brazil.
² Department of Entomology and Plant Pathology, State University of North Fluminense Darcy Ribeiro, Campos dos Goytacazes, RJ, Brazil.
³ Department of Psychiatry SUNY Upstate Medical University, 800 Irving Avenue, Syracuse, NY 13210, USA.
⁴ Behavioral Pharmacology Group, Laboratory of Animal Morphology and Pathology, State University of North Fluminense Darcy Ribeiro, Avenida Alberto Lamego, 2000, Campos dos Goytacazes 28013-602, RJ, Brazil. Electronic address: marinete@uenf.br.

PMID: 34852253
DOI: 10.1016/j.jneumeth.2021.109429

Abstract

Background: Reduced locomotion with repeated exposure to a novel environment is often used as a measure of the basic adaptive learning process of habituation. While this is a well-established and reliable measure of habituation, it is not useful for the investigation of neurobiological changes before and after habituation because of the uncontrolled differential activity levels in a novel versus habituated environment. In this study we report a behavioral method that uses spontaneous locomotion to measure habituation, in which the total spontaneous locomotion in an initially novel environment does not change with repeated testing but, the ratio of central to peripheral activity does change and is indicative of habituation. The test sessions are brief (5 min) and the locomotion is measured in 2 separate zones. The peripheral zone comprises 8/9 of the test arena and the central zone 1/9 of the arena.

Results/comparison with existing methods: In contrast to methods that use between-session reductions in locomotion to assess habituation, this method employs brief test sessions in which overall activity between sessions does not change, but the distribution of locomotion in the periphery versus the central zone of the arena does change. The brevity of the test session also enables us to utilize post-trial drug treatment protocols to impact memory consolidation.

Conclusions: The progressive change in the central/peripheral activity ratio with repeated testing can be determined independently of total activity and provides a habituation acquisition function that permits the measurement of neurobiological changes without the complication of effects related to changes in locomotor activity per se. The present report also presents evidence that this method can be used with post-trial drug treatment protocols to study the learning and memory effects of the post-trial treatments without the use of explicit rewards and punishments.

Keywords: Central zone; Exploratory behavior; Latent habituation measurement; Morphine; Novel environment; Post-trial conditioning.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Habituation, Psychophysiologic*
Learning
Locomotion*