Learning and memory in Octopus vulgaris: search of the underlying biological machinery

Abstract

The cephalopod mollusc Octopus vulgaris is known for the richness of behavioral repertoire, neural and behavioral plasticity, and complex cognition rivaling higher Vertebrates. Animals are known to learn over a variety of tasks, equipped with different sensory-motor systems, i.e. visual and tactile, and able to recall the outcomes of their experience for long term (e.g., ‘one month’ Sutherland, 1957; ‘some months’ Sanders, 1970). In the present study, a fear conditioning training protocol was adopted to evaluate O. vulgaris behavioral responses to an artificial stimulus to be avoided. Behavioral outcomes have been tested for the effect of a protein synthesis inhibitor on memory acquisition and retention, and for changes in the pattern of expression of genes potentially involved in memory formation. Applying the 3Rs principle, I used samples from a previous study, thus limiting the number or live animals humanely killed for the aims of this PhD project. My experiments and analysis allowed to: i. Identify that cycloheximide-induced protein synthesis inhibition did not alter the octopus ability to acquire an avoidance learning task. However, octopuses ability to retain and recall the memory was impaired; ii. Data available to me did not allow to rule out a state-dependent effect of cycloheximide injection that somehow affects memory recall and octopuses ability to learn; iii. Identify 24 target genes, nine memory-related genes and 15 epigenetic modifiers, from O. vulgaris transcriptome, and studied their gene expression profile in relation with learning and memory consolidation.