Brain and quality of experience are important; for example, there is substantial evidence that animals raised in enriched environments have thicker cerebral cortices, indicating a higher density of synaptic connections, than animals whose levels of stimulation are restricted. The functions of the brain depend on the ability of neurons to transmit electrochemical signals to other cells, and their ability to respond appropriately to electrochemical signals received from other cells. The electrical properties of neurons are controlled by a wide variety of biochemical and metabolic processes, most notably the interactions between neurotransmitters and receptors that take place at synapses. Neurotransmitters are chemicals
The Stealers of Dreams typical. Then the Doctor is there, and asks to talk to him, go into the building and try to help. Once the Doctor gets inside, Jack fills him in on what's happening. Rose is in a room, still unsure of herself. The Doctor tells her about the microorganisms, how they feed off electrical activity, and seem to just love the neuroelectro-chemical signals put out by the right side of adult human brains. They create a feedback loop, which passes to the left side and causes a person to become 'fantasy-crazy.' He tells her that now that she understands what is