Polite Dissent

The cingulate gyrus is part of the “limbic system” (but not, as the text implies, the entire system). Like most of the limbic system, it plays a major role in emotion, mood, and memory. More specifically, the cingulate gyrus seems to affect aggression, emotional response to pain, and the connection between the senses and emotions. Damage to the gyrus could affect any or all of these components.

Frontal lobe injuries can cause severe neurological symptoms up to and including paralysis. Other common symptoms include difficulty performing complex activities, an inability to focus on a task, lack of flexibility in thinking, and difficulties with problem solving.
Frontal lobe injuries can also have a severe effect on a person’s personality. The normal social responses are often blunted. Extreme emotional lability — switching rapidly from one mood to another — is common. The damage can also cause significant changes in behavior including pseudodepression and pseudopsycopathy. Sadie most likely is pseudopsychopathic, in which a person with a frontal lobe injury demonstrates immature behavior and marked lack of restraint, but without the mental/emotional symptoms that an actual psychopath has. Inappropriate sexual behavior has also been seen after frontal lobe injuries (though just as often a frontal lobe injury leads to a decrease in libido).

Temporal lobe injuries mainly affect memory and memory processing. Depending on the side of the brain injured, memory and processing of shapes and sounds can be compromised, or the use of words and language can be damaged. Aggression can be affected by temporal lobe injuries. Personality changes can also be seen, but not the type that Sadie is showing.

The amygdala is another part of the limbic system. It plays a role in emotional memories as well as converting short-term memories into long-term memories.

The hypothalamus is a particularly complex portion of the brain. Among other functions, it helps to regulate the autonomic nervous system and it plays a large role in hormone production and regulation. The hypothalamus affects hunger, blood pressure, heart rate, sexual arousal, and the sleep/wake cycle.