The search of neural correlates of conscious states in cephalopod molluscs

The inclusion of cephalopod molluscs in the Directive 2010/63/EU, regulating the use of live animals in scientific research, increased attention about their sentience and welfare in various areas of biological sciences and also public awareness. Furthermore, the sophisticated behavioral repertoire and the remarkable cognitive abilities they exhibit support the investigation of the neural basis of conscious states in these organisms very distant from the vertebrate clade. Here we present our preliminary contribution to the identification of the neural correlates of conscious and unconscious status in cephalopod species (Sepia officinalis, Octopus vulgaris). With the aim of identifying spontaneous and/or evoked potentials to be considered analogous to EEG signals, three electrophysiological recording methods were applied: i. a minimally invasive procedure to record efferent and afferent neural activity from/to the peripheral nervous system (pallial nerves) directly connected to higher brain centers; ii. an invasive intra-brain recording using tungsten and silver electrodes to collect electrical activity from the Supraesophageal mass (SEM) of the brain; iii. a non-invasive external recording using silver plate electrodes directly on the external surface of the head of the animal, in location corresponding to SEM and optic lobes. Pallial nerve recordings did not indirectly measure brain activity, but intra-brain recording proved reliable. To minimize invasiveness on the animals and to avoid any bias linked to the surgery, electrodes were placed on the skin near brain centers, showing EEG-like potentials in cephalopods. Preliminary comparisons between the two cephalopod species and previous studies will be presented.