Characterization of the planarian surface electroencephalogram

• Published in: BMC neuroscience Vol. 24; no. 1; pp. 29 - 11
• Main Authors: Freiberg, Jannes, Lang, Lukas, Kaernbach, Christian, Keil, Julian
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 03.05.2023; BioMed Central; BMC
• Subjects: 1/f law; Analysis; Animal cognition; Animals; Aperiodic component; Between-subjects design; Cognition in animals; Cognitive ability; Data analysis; EEG; Electrodes; Electroencephalography; Electrophysiology; Experiments; Humans; Identification and classification; Laboratories; Microelectrodes; Mosquitoes; Nervous system; Neural oscillation; Observations; Planarian; Planarians - anatomy & histology; Planarians - physiology; Platyhelminthes; Testing; Turbellaria; Germany; 1/f law; Aperiodic component; Planarian; Neural oscillation; Animal cognition
• ISSN: 1471-2202; 1471-2202
• DOI: 10.1186/s12868-023-00799-z

Despite large morphological differences between the nervous systems of lower animals and humans, striking functional similarities have been reported. However, little is known about how these functional similarities translate to cognitive similarities. As a first step towards studying the cognitive abilities of simple nervous systems, we here characterize the ongoing electrophysiological activity of the planarian Schmidtea mediterranea. One previous report using invasive microelectrodes describes that the ongoing neural activity is characterized by a 1/f power spectrum with the exponent 'x' of the power spectrum close to 1. To extend these findings, we aimed to establish a recording protocol to measure ongoing neural activity safely and securely from alive and healthy planarians under different lighting conditions using non-invasive surface electrodes. As a replication and extension of the previous results, we show that the ongoing neural activity is characterized by a 1/f power spectrum, that the exponent 'x' in living planarians is close to 1, and that changes in lighting induce changes in neural activity likely due to the planarian photophobia. We confirm the existence of continuous EEG activity in planarians and show that it is possible to noninvasively record this activity with surface wire electrodes. This opens up broad possibilities for continuous recordings across longer intervals, and repeated recordings from the same animals to study cognitive processes.