Solid State Detectors in Behavioral Studies

The use of small solid state detectors for behavioral studies is described. These detectors can be inserted in holders cemented to the skull of freely moving animals thus enabling the determination of uptake of radioactive matermal in an area of the brain. By injecting P32 labelled Na3PO4, the rate of incorporation of phosphate in the brain under different behavioral conditions such as sleep anesthesia, learning, etc. can be followed. The advantages of this method are the repeated measurements on the same animal, the use of live animals for both psychological and physiological studies, the possibility of kinetic and turnover studies in the brain, blood, and in principle, other organs. Using the uptake of P32 together with studies involving other isotopes such as the stable isotope O18, an estimate of the energyrequirements of the brain can be made. The detector is a lithium drifted silicon device mounted in an electroform nickel tube of 2mm O.D. and a wall thickness of ≤ 25 microns. The detector is coated with 3 microns of parylene and secured in the nickel tube with an RTV potting compound. The major components of the preamplifier are: an FET, a transistor, three resistors and three capacitors mounted behind the detector in the probe. Performance characteristics and results will be described.