Learning in single cell organisms

• Published in: Biochemical and biophysical research communications Vol. 564; pp. 92 - 102
• Main Author: Dussutour, Audrey
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 30.07.2021
• Subjects: Adaptive behavior; Ciliate; Ciliophora; habituation; Learning; Single cell organism; Slime mold; Learning; Slime mold; Single cell organism; Ciliate; Adaptive behavior
• ISSN: 0006-291X; 1090-2104; 1090-2104
• DOI: 10.1016/j.bbrc.2021.02.018

The survival of all species requires appropriate behavioral responses to environmental challenges. Learning is one of the key processes to acquire information about the environment and adapt to changing and uncertain conditions. Learning has long been acknowledged in animals from invertebrates to vertebrates but remains a subject of debate in non-animal systems such a plants and single cell organisms. In this review I will attempt to answer the following question: are single cell organisms capable of learning? I will first briefly discuss the concept of learning and argue that the ability to acquire and store information through learning is pervasive and may be found in single cell organisms. Second, by focusing on habituation, the simplest form of learning, I will review a series of experiments showing that single cell organisms such as slime molds and ciliates display habituation and follow most of the criteria adopted by neuroscientists to define habituation. Then I will discuss disputed evidence suggesting that single cell organisms might also undergo more sophisticated forms of learning such as associative learning. Finally, I will stress out that the challenge for the future is less about whether or not to single cell organisms fulfill the definition of learning established from extensive studies in animal systems and more about acknowledging and understanding the range of behavioral plasticity exhibited by such fascinating organisms. •Single cell organisms are capable of learning.•Slime molds and ciliates display habituation, the simplest form of learning.•Evidence of associative learning in slime molds and ciliates are controversial.•More studies are needed to demonstrate that learning is pervasive in single cell organisms.