Acute and chronic experiments were performed on albino rats using high-frequency electrical brain stimulation of the dorsal mesencephalon. It was found that: (i) Certain areas of rat mesencephalon generate intense, tonic electrocorticogram activation as well as tonic depression of photic, cortical evoked potential amplitudes. (ii) Often this tonic activation appears suddenly; that is, there is a threshold for activation. (iii) Invariably, if such a threshold is seen, the rat manifests the first escape response coincident with onset of activation. (iv) In some rats no threshold is seen; duration of electrocorticogram activation is monotonic with current intensity. But at some point of moderate intensity (< 80 μA) an escape reaction is elicited. (v) Neither threshold properties nor monotonic relations characterize behaviorally neutral electrical brain stimulation or its application to perirubral reticular formation. From these and other data a hypothetical neural circuit is postulated as being responsible for tonic reticular activation and the production of escape responses.
ASJC Scopus subject areas
- Developmental Neuroscience