Ongoing compound field potentials from octopus brain are labile and vertebrate-like.

Area of Science:

• Neuroscience
• Comparative Physiology
• Invertebrate Neurology

Background:

• Understanding the brain activity of cephalopods, like the octopus, is crucial for comparative neurology.
• Previous studies on invertebrate brain electrical activity have been limited.

Purpose of the Study:

• To record and characterize the ongoing electrical brain activity of an unanesthetized octopus.
• To compare the octopus brain's power spectrum with vertebrate and other invertebrate brains.

Main Methods:

• Semimicroelectrodes were used to record electrical activity from the optic, vertical, and basal lobes of semirestrained, unanesthetized octopuses.
• Flexible lead-in wires allowed for movement without artifacts.
• Urethane was used to reversibly suppress neuronal activity for control.

Main Results:

• Ongoing octopus brain activity is dominated by slow waves (1-70 Hz), with a maximum power below 25 Hz, unlike the 'hashy' high-frequency activity seen in some invertebrates.
• The average power spectrum of octopus brain activity more closely resembles that of vertebrate brains than other invertebrates.
• Electrical activity is episodic, with active periods interspersed with long intervals of near silence, and optic lobe activity shows faster patterns and more high-frequency 'hash' than the vertical lobe.
• Evoked potentials in response to light flashes were observed in the optic lobe as large, slow waves.

Conclusions:

• The octopus brain exhibits unique electrical activity patterns, characterized by slow waves and episodic bursts, sharing similarities with vertebrate brain activity.
• The distinct electrical signatures in different brain lobes (optic vs. vertical) suggest functional specialization.
• This study provides valuable insights into the neurophysiology of octopuses, contributing to the understanding of invertebrate brain function.