Tools of Discovery and Older Brain Structures Early observation into brain function could only work with head injuries that caused lesions. The three main tools for investigation are: Electro-Encephalogram or EEG Positron Emission Tomograph or PET Functional Magnetic Resonance Imagery or fMRI Of these three, the fMRI is king. See Fig. 5.3 (mp62, c2.14p63) an fMRI scan of a healthy individual compared with that of a schizophrenic.

Older Brain Structures Fig. 5.4 (mp63,c2.15p64) The brainstem and thalamus The brainstem, including the pons and medulla oblongata, is an extension of the spinal cord. The thalamus is attached to the top of the brainstem. The thalamus receives information from all the senses except smell. It also relays higher brain replies to the body. Smell, being separate from the other senses, is a good way to understand the evolution of the brain. It is a patch job: new structures are patched into old ones by mutation. For example, you cannot smell in your dreams. The reticular formation passes through both brain structures. It acts as a filter to incoming stimuli. The reticular formation enables arousal.

Older Brain Structures Fig. 5.7 (mp65, c2.18p66) The limbic (or ring) system sits between the evolutionary older parts and the cerebral hemisphere. Here is located the hypothalamus, which controls the pituitary gland. The hippocampus is the seat of short-term memory formation. It is the newest of the structures in the limbic system. The amygdala controls aggression and fear.

Older Brain Structures Olds and Milner (1975) located the reward centers in the hypothalamus. The most important of these is the nucleus accumbens, which is both a general dopamine-related reward system and will specific areas devoted to eating, drinking and sex. What do you think will happen if the reward center mutates, creating cross-connections between these areas, or making these areas much closer together? Deutsch (1972) and Hooper & Teresi (1986) discovered that humans can be calmed by electrical stimulation of specific areas of the hypothalamus, but not driven to a frenzy.

Older Brain Structures Memorize Figure 5.11 mp67, c2.22p68): It is a review of brain structures and their functions. Especially: The Amygdala, the Hippocampus, and the Hypothalamus. Most psychotherapy--whether medication, counseling or physiotherapy--is aimed at solving problems in these limbic areas.