Octopuses are considered one of the most intelligent invertebrates. With over 300 million neurons, octopuses have the most complex invertebrate brain. Their brain is composed of many neurons organized into many lobes. Until now, scientists have studied the functions of individual lobes by intentionally damaging them and observing what abilities the animal loses in this way. In other species, such studies use electrodes attached to the head. Unfortunately, this process has not been possible with octopuses because they lack solid structures to which electrodes can be attached. Furthermore, octopuses can remove foreign objects attached to their bodies. As a result, researchers had only been using electrodes on anesthetized or immobilized octopuses. However, this has now changed.
A team of scientists from Japan, Ukraine, Germany, Italy, and Switzerland made a groundbreaking achievement; they recorded brain waves in an awake octopus while it could still move freely. This marks the first time such an accomplishment has been recorded in history. The brain activity recording was synchronized with video material, allowing scientists to see which neuron activity correlated with animal behavior.
The team led by Dr. Tamar Gutnick used the Neurologger from TSE Systems – a small device for wireless recording of EEG activity in small animals. Three Octopus cyanea were implanted with the devices, and upon awakening, they quickly resumed normal activities within the aquarium. The researchers monitored their brain activity for 12 hours as the animals slept, ate, and moved around while capturing video footage of their behavior.
The study published on current biology shows the existence of different brain activity patterns. Some were similar in duration and intensity to mammalian brain activity, while others – stable and slow oscillations – were observed for the first time. Using this method, scientists can conduct brain studies on other octopus species, providing insight into their memory, learning abilities, socialization methods, and how they coordinate and control their arms. This approach promises to answer many long-standing questions in the field.
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Octopuses, which are among the most intelligent invertebrates,1,2,3,4 have no skeleton and eight flexible arms whose sensory and motor activities are at once autonomous and coordinated by a complex central nervous system.5,6,7,8 The octopus brain contains a very large number of neurons, organized into numerous distinct lobes, the functions of which have been proposed based largely on the results of lesioning exoeriments.