ABSTRACT
In the search for habituatable neurons, two types of habituation have been found. One type was a partial habituation, when the response was divided into two spike groups. One discharge was stable and did not habituate. The other one, mainly a late component, habituated by repeated stimulation and recovered during dishabituation. If a novel stimulus was presented, the standard stimulus to which the organism had earlier habituated then produced a complete response, including the habituatable part as well as the stable part. The second type of habituation-total habituation
of the spike response-could be found in neurons in the hippocampus. Two kinds of neurons were found: novelty neurons that responded with activation of spike discharge to a novel stimulus and response elimination during repeated stimulus presentations, and sameness neurons. The term sameness was used because the firing of spikes in this type of neuron was present if the stimulus was familiar. Presentation of a novel stimulus always results in a depression or elimination of spikes in such neurons.
