Response of Cerebral Blood Vessels to Electric Stimulation of the Thalamus and Hypothalamic Regions

The analysis of the literature on cerebral circulation recently published by Forbes and Wolff¹demonstrates the variability of results obtained in this field by different investigators. Inability to obtain active vasomotor responses from the intracranial blood vessels led many to assume that these vessels possess no effective neural control (Schiff;²Schultz;³Riegal and Jolly;⁴Gaertner and Wagner;⁵Bayliss and Hill;⁶Hill;⁷Hill and MacLeod;⁸Gerhardt;⁹Roy and Sherrington;¹⁰Florey,¹¹and others). However, histologic evidence pointing toward the existence of autonomic nerve fibers and nerve endings on the pial and cerebral blood vessels (Obersteiner;¹²Gulland;¹³Morrison;¹⁴Kölliker;¹⁵Huber;¹⁶Hunter;¹⁷Stöhr;¹⁸Clarke;¹⁹Hassin,²⁰and Penfield²¹) supported the accumulating experimental evidence favoring the probability of an active nervous control over these vessels, and only the extreme inconstancy of the obtained results delays