Electrical activity of the cerebral hemispheres after section of the brainstem (bremer's method) in dogs of various ages

Summary

The EEG was studied in puppies of various ages after the brainstem had been divided at various levels by Bremer's method. In puppies 2–3 months old there was a complete correspondence between the EEG and behavior, just as in encéphale isolé and cerveau isolé preparations of adult dogs. In 8–9-day-old puppies the EEG did not correspond to that found in the two preparations of adult dogs. Division of the midbrain through the anterior corpora quadrigemina which correspond to the cerveau isolé preparation of adults was accompanied in young puppies by the immediate disappearance of electrical activity from the cerebral hemispheres. The first indications of an EEG characteristic of the encéphale and cerveau isolé preparations of adult dogs occurred after the 18–20th day.

Young puppies manifest the characteristic electrical cortical activity found in encéphale isolé and cerveau isolé preparations of adult dogs; the explanation proposed is in terms of the ascending reticular activating system of the brainstem and the absence of any function in the nonspecific nuclei up to a certain stage of development.