alpha particles, and so forth, that had been accelerated to high
velocities in a cyclotron, they found that ever heavier elements
could be formed. And thus the periodic table was extended into the
transuranium region: neptunium, plutonium, americium, curium,
berkelium, californium, einsteinium, fermium, mendelevium—el-
ements 93,94, 95,96, 97, 98,99, 100, 101—all were discovered at
UC Berkeley during the 1940s and 1950s, most of them using the
cyclotron to smash atoms into one another at very high velocity.A PET scan is a complex and expensive process. Highly unstable ra-
dioactive chemicals must be generated on the spot using a cyclotron.
The radioactive atoms must then be chemically incorporated into
glucose, or water, or a particular neurotransmitter-like labeling mol-
ecule, to be administered to the PET-scan subject. The injection is per-
formed and the measurement of gamma rays resulting from positron-
electron annihilation is conducted. And it all needs to be done rapidly,
before a substantial amount of the short-lived radioactive chemicals
decay away. And another important thing—a person undergoing a
PET scan receives injections of radioactive material, a significant toxic
exposure. All this contributes to PET scanning being used only in lim-
ited ways.
PET may be used to generate a map of neural activity in the brain
under various conditions. Such a map can be constructed based on
either glucose use (as measured by the accumulation of radioactive
fluorinated glucose) or blood flow (as measured by flow of radioactive
water). By using radioactive glucose, estimates can be made regarding
the brain’s total energy consumption. This shows that a great deal of
energy use and neural activity occurs in the brain at all times. When
you are sitting in the dark, eyes closed, no sound, not moving, not