Actions of dexamphetamine and amphetamine-like amines in chickens with brain transections

1. A method for preparing the encéphale isolé preparation in young fowls is described. Certain important differences were found between electrocortical activity of chicken and mammalian encéphale isolé preparations. Electrocortical effects of excitant sympathomimetic amines and their antagonism were readily quantified because of stable electrocortical activity of the chick encéphale isolé preparation.2. Amphetamine-like excitant amines ((+)- and (-)-amphetamine, alpha-methyltryptamine, tryptamine, beta-phenethylamine, cyclopentamine, beta-tetrahydronaphthylamine and tuaminoheptane) evoked electrocortical desynchronization in chick encéphale isolé preparations, confirming the central origin of these effects. Behavioural changes were also observed.3. The electrocortical response to these amines was antagonized by methysergide, a selective tryptamine antagonist and by a catecholamine, alpha-methylnoradrenaline. Behavioural changes were also antagonized.4. Electrocortical desynchronization to dexamphetamine was prevented by an anterior transection of the brain which separated the telencephalon from the diencephalon. More posterior transections reduced the duration of the electrocortical response to dexamphetamine; intensity of response was either increased or decreased.