Male and female brain what constitutes the gender

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ppt on differences on between male & female brain....
Presented by my prof in physiology CME held in AJIMS.

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  • Preoptic area- involved in mating behaviour, Suprachiasmatic area- Circadian rhythym. Change of shape of SCN influences the connections it makes.
  • IPL found to be larger in Albert Einstein & other physicists.
  • Male and female brain what constitutes the gender

    1. 1. Male and Female Brain- What constitutes the gender difference Dr Supriya Hegde Aroor Associate Professor Dept of Psychiatry KMC Mangalore
    2. 2. Have you ever felt it so? • Why men & women think differently? • Why they behave differently in stressed situations? • Why they excel at different types of tasks? • Why do boys like to play with cars and trucks and superman? • Why there are sex differences in some diseases?
    3. 3. Outline • Anatomical differences. • Functional differences. • Biochemical differences. • Differences in Brain Maturation & Aging & Its causes. • Clinical implications.
    4. 4. Anatomical differences • Weight - Around 1130 cm3 in Women and 1260 cm3 in Men. • Male brains are about 10% larger than female brains. • Men's heads are also about 2% bigger than women's. • Even in early development a boy’s brain is between 12-20% larger than that of a girl. • Head circumference of boys is also 2% larger than that of girls.
    5. 5. Are females more capable of multi tasking?
    6. 6. Grey v/s White Matter • Grey matter- Men have approximately 6.5 times more grey matter than women. • White matter- Women have about 10 times more white matter than men. • Women have more of the white matter responsible for communication. • So, women have greater ability to do multitask.
    7. 7. Hypothalamus • Preoptic area - 2.2 times larger in men than in women and contains 2 times more cells. • Suprachiasmatic nucleus – In males it is shaped like a sphere whereas in females it is more elongated. • The strongest sex difference is found in the lateral and medial mamillary nucleus. • Differences also in Androgen Receptors in various areas.
    8. 8. Cerebral Hemispheres Male Brain • Enlarged frontal and occipital poles. • Thicker Right hemisphere. • Have a greater functional reserve. • Have larger Cerebellum. Female Brain • Greater cortical thickness in Temporal & Parietal regions • Thicker Left hemisphere. • More Neuropil. • Larger Anterior commissure & Mass Intermedia.
    9. 9. Other areas which are larger… Male Brain • Inferior Parietal Lobule (Lt > Rt in Rt handed male). • Amygdala. Female Brain • Orbitofrontal to Amygdala Ratio. • Limbic System. • Corpus Callosum. • Straight Gyrus. • Hippocampus. • Broca’s & Wernick’s area. • Lateral Ventricles (Lt > Rt).
    10. 10. Functional differences • Men & Women differ in the way they think !!!... • They differ in use of different parts of the brain to encode memories, sense emotions, recognize faces, solve certain problems and make decisions.
    11. 11. For Example…..
    12. 12. Functional differences Male Brain • Predominantly hard-wired for understanding & building systems. • Value more for power, politics, and competition. • When listening neurons on only one side of the brain are activated. • In interpretation of whole sentences, men use one side of brain. Female Brain • Predominantly hard-wired for empathy. • Value the development of altruistic, reciprocal relationships. • While listening neurons on both sides of the brain are activated. • In interpretation women use both sides of the brain.
    13. 13. Functional differences Male Brain • In stress, Increased blood flow to the right prefrontal cortex, responsible for “fight or flight”. • Men tend to be more logical emotionally. • Men navigate by using abstract concepts such as north and south or distances. Female Brain • There is increased blood to limbic system, which is associated with nurturing & friendly response. • Women tend to be more observant • Women navigate by talking about landmarks and things that can be seen or heard.
    14. 14. Functional differences Male Brain • In play, Engage in more rough-and tumble play. • Aggression, show more “direct” aggression such as pushing, hitting & punching. • Better at visual spatial abilities, quantitative problem solving, mental rotation and spatial perception. Female Brain • Engage in more nurturing games. • Show more “indirect”(or “relational” ) aggression. • Better in verbal memory tasks, verbal fluency tasks & in speed of articulation.
    15. 15. Functional differences Male Brain • Tend to be better in independence, dominance, spatial & mathematical skills, rank- related aggression. Female Brain • Show greater concern through more sad looks, sympathetic vocalizations and comforting. • Women were observed to show more comfort, even to strangers. • Can think logically and emotionally at the same time.
    16. 16. Do men & female differ in expression of emotions?
    17. 17. Emotions • Women – Faster and more accurate at identifying emotions. – Better at controlling their emotions. – More adept in encoding facial differences & changing vocal intonations. – Part of brain involved is large. – Use both hemispheres. • Men – Right hemisphere deals with emotions. – Males have a hard time expressing emotions.
    18. 18. Biochemical differences • Biochemically heterogeneous in regard to sex and brain region. • Seen mainly in the sensorimotor cortex and orbital frontal cortex. • Functional brain studies indicate sex differences in brain metabolism.
    19. 19. Sensorimotor cortex • Involved in sensory and motor processing, perception, and motor execution. • In female brain, increased NAA (N-acetyl Aspartate) is found. • NAA is localized within the neurons & is involved in synaptic processes. It can be considered a neuronal & axonal marker.
    20. 20. Functional brain studies • Cognitive activity resulted in increased blood flow to the cerebral hemispheres. • For Verbal task- Left hemisphere. • For Spatial task- Right hemisphere. • Men – Higher glucose metabolism - temporal-limbic regions and cerebellum. – Lower glucose metabolism - cingulate regions.
    21. 21. Serotonin • Function - Involved in gender-related behaviours and psychiatric conditions like aggression, eating disorders, depression, impulsivity or suicide. • Males – Synthesis is 52% higher than in females. – Higher 5 HT2 receptors, esp. in frontal & cingulate cortices. • Females – Higher 5 HT 1A receptors. • Importance – differences in prevalence of depression & anxiety.
    22. 22. Differences in Neurotransmitter systems • Receptor affinity of glucocorticoids in females is half than in males. • Differences are reported in biochemical pathways pertaining to dopamine, and the interactions between them. • Women have a greater presynaptic dopamine synthesis and a lower D2 receptor affinity. • Women also have lower amphetamine- stimulated dopamine release and a greater dopamine transporter uptake.
    23. 23. Differences in Neurotransmitter systems • Women appear to have elevated basal, but decreased stimulated, striatal dopamine levels. • Levels of monoamine oxidase were significantly higher in several brain regions in women. • Genetic associations between COMT and various Psychiatric phenotypes frequently show differences between men and women. • Importance - May contribute to differential involvement in psychiatric disorders in men and women.
    24. 24. Differences in Brain Maturation & Aging • The brains of men and women are indeed different from birth. • But differences are subtle & might be found only among the synapses in brain structures. • MRI analysis suggest that females brain mature earlier than male brain. • Males age 6-17 years have been shown to display more prominent age-related decreases in grey matter and increases in white matter than females.
    25. 25. Differences in Brain Maturation & Aging • Adolescents’ brains undergo a substantial “pruning” or reduction in grey matter volume, this happens 2yrs earlier in females. • Girls reach puberty two years earlier than boys. • Prefrontal cortex develops earlier in girls compared to boys. • Areas of the brain involved in language and fine motor skills mature about six years earlier in girls than in boys.
    26. 26. Differences in Brain Maturation & Aging • Brain volume decreased with age among men, but hardly at all among women. • Greater decrements in brain volume occur with age in the frontal lobe than in the temporal lobe and in both regions it is greater in men. • Women are less vulnerable to age related changes in mental abilities.
    27. 27. Causes…. Genetic • Genes on the sex chromosomes determine the gender of the brain in two ways – Acting on the gonads to induce sex differences in levels of gonadal secretions that have sex-specific effects on the brain. – Acting in the brain itself to differentiate XX and XY brain cells. • Various studies performed identified different genes whose expression differed between male and female brain. • Two candidate genes are the two testis-determining factors (ZFY) and the master switch for differentiation of a testis SRY. • It was shown that SRY and ZFY are transcribed in the hypothalamus and frontal and temporal cortex of male.
    28. 28. Causes…. Sex hormones • During the development of the embryo in the womb, circulating hormones have a very important role in the sexual differentiation of the brain. • The presence of androgens in early life produces a “male” brain. In contrast, lack of androgens causes female brain. • Levels of circulating sex steroid hormones, during development and in adulthood, play a critical role in determining physiology and behaviour in adulthood.
    29. 29. Causes…. Evolution • Neurological substrate that forms the basis for complex cerebral asymmetries in Homo sapiens may have been established remarkably early in anthropoid evolution. • In ancient times, both sexes had very defined role that helped ensure the survival of the species. • Brain areas may have been sharpened to enable each sex to carry out their jobs. • Developing superior navigation skills in men may be better suited to the role of hunter, while preference for landmarks in female may have enabled them to fulfil the task of gathering food closer to home.
    30. 30. Causes…. Culture & Socialisation • Sex-determined differences appear in infancy and the gap widens as people mature. • Sex differences that grow larger throughout childhood are probably shaped by culture, lifestyle and training. • Studies on brain plasticity have shown that experiences changes brains structure. • During development synapses that are not used are eliminated. This is where experience plays an important role in wiring a young child's brain.
    31. 31. Susceptibility to Psychiatric Disorders • Many CNS-related disorders show sex differences in their incidence and/or nature. • Females have higher predisposition of Alzheimer's disease, Addiction, Major depressive disorder, Anxiety, Post-Traumatic Stress Disorder, Eating disorders. • Males have higher predisposition for Autism spectrum disorders, ADHD, Schizophrenia.
    32. 32. Susceptibility to Psychiatric Disorders • Also it is noticed that men with schizophrenia show significantly larger ventricles, whereas no such enlargement is seen in women with schizophrenia. • Symptoms of depression significantly increase the risk of developing AD in men, but not in women. • There is evidence that Rt hemisphere PFC lesions impair performance on decision-making task in men but not women, whereas Lt hemisphere lesions impair performance in women but not men.
    33. 33. Susceptibility to Psychiatric Disorders • Females are more sensitive to reinforcing effects of psychostimulants which account for rapid progression from initial use to drug dependence. • Different types of head injuries are more disastrous to one sex or the other. For e.g. frontal lobe injuries can be more detrimental to cognitive performance in women than men. • For stroke a woman may have rehabilitation options that the man may have more trouble, because the woman may be able to perform tasks using the other side of her brain. • Men may have more trouble with rehabilitation & may need to be checked more carefully before he can resume daily activities.
    34. 34. Conclusion • Male & Female brains show anatomical, functional and biochemical differences in all stages of life. • Sex differences need to be considered in studying brain structure and function. • Helps in in early diagnosis, precise treatment and management for neurological & psychiatric diseases. • Understanding development of normal brain and differences between the sexes is important for the interpretation of clinical imaging studies.

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