Clinical Neuroscience in Practice: An Experiential Learning Course for Undergraduates Offered by Neurosurgeons and Neuroscientists

Many pre-health students pursue extracurricular shadowing opportunities to gain clinical experience. The Virginia Tech School of Neuroscience introduced a formal course that provides a clinical experience superior to that received by many medical students. This course is composed of weekly 75-minute seminars that cover diseases affecting the nervous system, their diagnosis and treatment, complemented by weekly half-day intensive clinical experiences with unprecedented access to a team of neurosurgeons (in hospital operating rooms, Intensive Care Units, emergency room, angiographic suites, and wards). In the operating rooms, students routinely "scrub-in" for complex surgeries. On hospital rounds, students experience direct patient care and receive in-depth exposure to modern nervous system imaging. Students participate in two 24-hour "on-call" experiences with team providers. After call, students participate in cognitive and psychological studies to assess physiological and psychological effects of call-related sleep deprivation. Students prepare weekly essays on challenging socioeconomic and ethical questions, exploring subjects such as the cost of medicine and inequalities in access to health care. Towards the end of the course, students meet with the admission dean of the Virginia Tech Carilion medical school; they prepare a personal statement for medical school/graduate school applications, and attend a half-day block of mock medical school/graduate school interviews delivered by experienced clinicians. In lieu of a final exam, each student presents to the entire neurosurgery department, an in-depth clinical analysis of a case in which they participated. We provide details on implementation, challenges and outcomes based on experiences from three semesters with a total enrollment of approximately 60 students.

Food intake of domestic fowl injected with adrenergic agonists and antagonists into the hepatic portal vein

Cockerels of an egg-laying strain were used to study the mode of action of epinephrine on food intake in chickens. Intraperitoneal injection of 2500 micrograms epinephrine significantly depressed intake from 1-6 hr after injection. This effect was not modified by vagotomy at the level of the proventriculus (equivalent of subdiaphragmatic vagotomy in the mammal). Injection of 25, 50 or 100 micrograms epinephrine into the hepatic portal vein depressed intake in a dose-related manner. One hundred micrograms epinephrine had similar effects when injected into the jugular vein as into the portal vein, although the latter injection had longer-lasting effects. As the liver is the major site of inactivation of epinephrine this suggests that it acts mainly at that organ. In order to find which type of receptor is stimulated by epinephrine in its action on feeding an alpha-adrenergic agonist, phenylephrine, was injected into the portal vein at doses ranging from 63-3000 micrograms; there was no effect on intake at any dose. A beta-adrenergic agonist, salbutamol (500-2000 micrograms), depressed intake in a dose-related manner following portal vein injection. This effect was not attenuated by vagotomy. Aminophylline, an inhibitor of cAMP breakdown, had no effect on intake when injected into the portal vein (2500-10000 micrograms) and the depressing effect of 200 micrograms epinephrine was not modified by simultaneous injection of 10000 micrograms aminophylline. It is concluded that epinephrine acts on the liver to suppress intake via a vagally-mediated pathway, but that the mechanisms of action are not known.

A role for the liver in the effects of glucagon on food intake in domestic fowl

Adolescent cockerels of an egg-laying strain were prepared with catheters into the hepatic portal vein (HPV) and offered a standard poultry ration ad lib. Injection of 10, 100 and 1000 micrograms of bovine glucagon into the HPV caused a depression in intake which was significantly different from the control from 60 to 90 minutes after injection and was related to the logarithm of the dose. In birds prepared with HPV and jugular vein catheters, 1000 micrograms of glucagon had a similar depressing effect on intake irrespective of route of administration. In cockerels vagotomised at the level of the proventriculus, doses of glucagon up to 1000 micrograms injected into the HPV had no significant effect on intake. When vagotomised and sham-operated birds, in direct comparison, were injected with 0, 5 and 50 micrograms glucagon, there was s significant depression with both doses in the sham-operated cockerels but no effect in those which were vagotomised. However, the vagotomised birds had low control food intakes and the data obtained from them must be interpreted with caution. The conclusion is drawn that glucagon affects liver metabolism to influence the information transmitted via the vagus nerves to the central nervous system circuits involved in the control of feeding.