Dissociation of self-stimulation and epileptiform activity

Abstract

1. 1. Ventrolateral tegmental stimulation caused self-stimulation behavior at very high rates but no epileptiform discharges even with much higher current levels. 2. 2. Posterior lateral hypothalamic stimulation caused self-stimulation and (at higher current levels) random spikes which were unrelated to self-stimulation: that is, (a) they did not stop self-stimulation and (b) they appeared even in cases where self-stimulation did not. 3. 3. Anterior lateral hypothalamic stimulation and septal region stimulation caused self-stimulation and (at higher intensity levels) organized epileptiform after-discharges which usually caused self-stimulation behavior to cease for a period during, and a few seconds after the abnormal electrical discharges. 4. 4. Epithalamic and posterior lateral thalamic stimulation sometimes caused self-stimulation; stimulation of these areas also often caused one or the other of the epileptiform patterns described above. 5. 5. For all probes clearly yielding both effects, thresholds for self-stimulation were lower than those for epileptiform discharges during the period of initial tests. However, at a later date (about two months after surgery) epileptiform thresholds were below self-stimulation thresholds in some cases with probes in the anterior lateral hypothalamus or septal area. 6. 6. The random spikes provoked by stimulation in the posterior lateral hypothalamus spread preferentially to tegmental and thalamic probes and much less, if at all, to septal or anterior lateral hypothalamic probes. The organized discharges provoked by stimulation of anterior lateral hypothalamus, septal area, and epithalamus spread preferentially to other members of this triadic group.