Brain and behavioural evidence for rest-activity cycles in Octopus vulgaris

Octopus vulgaris maintained under a 12/12 h light/dark cycle exhibit a pronounced nocturnal activity pattern. Animals deprived of rest during the light period show a marked ‘rebound’ in activity in the following 24 h. ‘Active’ octopuses attack faster than ‘quiet’ animals and brain activity recorded electrically intensifies during ‘quiet’ behaviour. Thus, in Octopus as in vertebrates, brain areas involved in memory or ‘higher’ processes exhibit ‘off-line’ activity during rest periods.