Electrophysiology of the isolated central nervous system of the northern octopusEledone cirrhosa

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Abstract
A successful preparation has been devised for maintaining the octopus brain in a viable condition to allow microelectrode studies of individual nerve cells. Impalements of cells within the sub‐oesophageal mass reveal that three populations of neurones are present These have different resting potentials, ranging from approximately 60 mV down to under 30 mV. Spontaneous activity is recorded from many neurones but some are silent and others exhibit only synaptic noise. Electrical stimulation of silent cells may lead to no response (large resting potential cells) or provoke trains of impulses (30–45 mV cells). Typical action potentials have durations of 20 msec. IPSP and EPSP activity may be observed. Burster cells or oscillators are located in one specific region, and a variety of activity may be recorded. These periodic bursts may be modified by hyperpolarisation so that spiking ceases but the underlying oscillatory potential remains. Some units exhibit two spike sizes, often uncorrelated in discharge.