Gender (see more on gender earlier in this volume)

. Sex refers to biology and anatomy, while gender refers to social expectations. Gender differences can be divided into genetic, neuroanatomical (investigating large structures in the brain) and behavioural.

. There are gender differences in the brain, eg

- the front and prefrontal cortex (controls much of our decision-making ability) is fatter in females

- there are sex differences in the limbic system (controls our emotional life and mediates some types of learning)

- significant differences in the amygdale (controls the generation of emotions and the ability to remember them). It is much larger in males and they favour the right hemisphere

- brain cells communicate via bio-chemicals, such as serotonin (key to regulating emotions and moods) which males synthesize over 50% faster than females.

NB Research is continuing on how important these differences in size and neurotransmitters are.

. Behavioural differences in type and severity of psychiatric disorders include

- males are impacted more by schizophrenia than females

- females are more likely to get depressed than males

- males exhibit more anti-social behavior than females

- females have more anxiety

- most alcoholics and drug addicts are male

- most anorexics are female

- females recall more emotional autobiographical events more rapidly and with greater intensity than males

- under stress, females focus on nurturing their offspring, ie tend and befriend, while men tend to withdraw

- females tend to use both hemispheres when speaking and processing verbal information; males focus on 1

- females tend to have thicker cables connecting the hemispheres

- female students are verbally more sophisticated than males

- female students are better at verbal memory tasks, verbal fluency and speed of articulation

- when female teenagers communicate with each other, they lean in, maintain eye contact and do a lot of talking to cement their relationship; male students never do this. They prefer to do things together physically to maintain their relationship

NB Need to be ware of social context in all these comparisons

. There as 2 X chromosomes in the female while only 1 in the male. The X carries an unusually large percentage of genes involved in brain manufacture eg higher cognitive functions such as verbal skills, social behavior, certain types of intelligence, etc.

. Females are more complex genetically. The female's X chromosome carries around 1,500 genes compared to less than 100 in the male's Y chromosomes

. Men and women's brains are differently structured and biochemically. Men have bigger amygdale and produce serotonin faster. The significance of this in unknown.

. Males and females respond differently to acute stress. Females activate the left hemisphere's amygdale which remember the emotional details; while males use the right amygdale which get the general gist.