Principles of Stereotaxy in Small Animals

Abstract

Under the methods of background research to study neuronal communication in the central nervous system (CNS) connected to its vital functions, learning and degenerative processes are techniques that enable in vivo stimulation and determination of neurotransmitters and second messengers in the brain of small animals, mainly rats and mice.

In distinct brain areas, the collection of samples, measurement of signaling molecules, and recording responses to manipulation from and in the brain area of interest can be reached by various techniques. The distinct brain area is reached using brain coordinates that are documented in brain maps of these rodents. For this purpose, the head of an anaesthetized animal is fixed in a stereotaxic frame and either a microdialysis probe or an amperometric sensor, a modified push–pull cannula (PPC), a cannula for intracerebroventricular- (i.c.v.) and micro-injections, or electrodes are inserted stereotactically with skull-flat orientation. A microdrive is used for the exact insertion of the device into the brain tissue or brain ventricle through a hole in the skull. The experiment may be carried out in anesthetized or conscious, freely moving animals. At the end of the experiment the brain is removed from the skull of the sacrificed animal—prior anesthetized if the experiment was carried out on a conscious animal—and kept in order to validate histologically correct localization of the inserted device.