Evidence for the existence of a raphe projection to the substantia nigra in rat.

The effect of electrical stimulation of the median raphe nucleus on the activity of spontaneously firing single neurones in the substantia nigra and mesencephalic reticular formation (MRF) has been investigated in urethane anaesthetized rats. Depression of activity was the predominant effect observed although this was sometimes accompanied by periods of excitation. Some neurones were only excited.

Caudate stimulation and substantia nigra activity in the rat.

1. The responses of spontaneously active single neurones in the substantia nigra and overlying mesencephalic reticular formation have been analysed during the electrical stimulation of the ipsilateral caudate nucleus. Experiments were performed in rats anaesthetized with urethane or pentobarbitone.