Transcallosal removal of cranio-pharyngiomas within the third ventricle

✓ Six cases of craniopharyngioma located wholly, or largely, within the third ventricle are described; these include four adults with tumors completely within the ventricular system and two children with recurrent tumors primarily within the third ventricle. Four of these patients were operated on by a transcallosal approach. Gross total removal was possible in all patients, but two have suffered recurrence and only one is alive and tumor-free. There were no signs or symptoms present preoperatively that allowed the intraventricular nature of the neoplasm to be correctly diagnosed. Air encephalography provided definitive tumor localization in each case. Three patients died of massive gastrointestinal hemorrhage in the immediate postoperative period. The surgical technique of transcallosal approach for removal of these neoplasms is described in detail.

Partial agenesis of the corpus callosum simulating a neoplasm. Case report

✓ A case of partial agenesis of the corpus callosum is reported. The differential diagnosis is discussed and the significance of correlating clinical signs with the angiographic findings in the lateral view is emphasized.

Prolonged learning and split-brain cats

A definite relation is shown between interhemispheric transfer and speed of learning. Split-brain cats were trained in a variety of discriminations, and the success or failure of interhemispheric transfer was evaluated with regard to rate of learning. When interhemispheric transfer succeeds, learning time is normal; when interhemispheric transfer fails, learning time is prolonged, becoming at least twice that of normal. Retention is also poor in those animals that exhibit prolonged learning. A normal learning curve appears to be the product of interaction between both cerebral hemispheres during learning.