News: Entrained rhythmic activities of neuronal ensembles as perceptual memory of time interval
Nature 456, 102-106 (6 November 2008) | doi :10.1038/nature07351; Received 14 April 2008; Accepted 20 August 2008; Published online 15 October 2008
Entrained rhythmic activities of neuronal ensembles as perceptual memory of time interval
Germán Sumbre1,3, Akira Muto2, Herwig Baier2 & Mu-ming Poo1
- Division of Neurobiology, Department of Molecular and Cell Biology, Helen Wills Neuroscience Institute, University of California, Berkeley, California 94720, USA
- Department of Physiology, University of California, San Francisco, California 94158, USA
- Present address: Laboratoire de Neurobiologie, UMR 8544, École Normale Supérieure, 46 rue d'Ulm, 75005 Paris, France.
Correspondence to: Mu-ming Poo1 Correspondence and requests for materials should be addressed to M.-m.P. (Email: mpoo@...).
The ability to process temporal information is fundamental to sensory perception, cognitive processing and motor behaviour of all living organisms, from amoebae to humans. Neural circuit mechanisms based on neuronal and synaptic properties have been shown to process temporal information over the range of tens of microseconds to hundreds of milliseconds. How neural circuits process temporal information in the range of seconds to minutes is much less understood. Studies of working memory in monkeys and rats have shown that neurons in the prefrontal cortex, the parietal cortex and the thalamus exhibit ramping activities that linearly correlate with the lapse of time until the end of a specific time interval of several seconds that the animal is trained to memorize. Many organisms can also memorize the time interval of rhythmic sensory stimuli in the timescale of seconds and can coordinate motor behaviour accordingly, for example, by keeping the rhythm after exposure to the beat of music. Here we report a form of rhythmic activity among specific neuronal ensembles in the zebrafish optic tectum, which retains the memory of the time interval (in the order of seconds) of repetitive sensory stimuli for a duration of up to 20 s. After repetitive visual conditioning stimulation (CS) of zebrafish larvae, we observed rhythmic post-CS activities among specific tectal neuronal ensembles, with a regular interval that closely matched the CS. Visuomotor behaviour of the zebrafish larvae also showed regular post-CS repetitions at the entrained time interval that correlated with rhythmic neuronal ensemble activities in the tectum. Thus, rhythmic activities among specific neuronal ensembles may act as an adjustable 'metronome' for time intervals in the order of seconds, and serve as a mechanism for the short-term perceptual memory of rhythmic sensory experience.
Robert Karl Stonjek