1. Gender development Relationship to Brain Lateralisation

3. Brain lateralisation Brain lateralisation refers to the uneven distribution of tasks carried out by the hemispheres. Lateral Lateral means side. lateralised function Any function, e.g. language, which is found on one side of the brain is called a lateralised function. The brain is made up of two hemispheres that appear to be symmetrical. However it is known that each hemisphere is responsible for different functions. Which hemisphere is dominantWhich hemisphere is dominant?

6. Which side of the brain is directing this action?

7. Which side of the brain is working out this puzzle?

8. Which side of the brain is processing the phone conversation?

9. brain lateralisation Previously we learned that the development of the embryonic brain can be affected by the presence or absence of hormones in the womb. This may lead to brain lateralisation. male brains are more lateralised It is believed that male brains are more lateralised with specific functions being allocated to each hemisphere e.g. spatial skills in the right and language skills in the left. Functional differences may result from this including increased ability to manipulate objects in space. In evolutionary terms this would make males better hunters.

11. Female brains are less lateralised Female brains are less lateralised; their brains have a thicker connective band (corpus callosum) between the hemispheres. they use both sides for language and therefore have better communication skills This means they use both sides for language and therefore have better communication skills. In evolutionary terms this would make females better at socialising and therefore binding social groups together.

12. malesleft females bilateral brain activity In males, there is more left hemisphere activity during linguistic tasks, but in females there is usually bilateral brain activity during the same tasks. males rightfemales bilateral brain activity During spatial tasks, males show high levels of activity in the right hemisphere; whilst in females we are again more likely to see bilateral brain activity. corpus callosum is thicker in females Studies show that the corpus callosum is thicker in females and perhaps this explains why female brains are more bilateral, because the two hemispheres communicate more efficiently.

14. Test your Brain Sex You can do this by logging on to the following link and completing the test http://www.bbc.co.uk/science/humanbody/ sex/index_cookie.shtml http://www.bbc.co.uk/science/humanbody/ sex/index_cookie.shtml Have a go, you may be surprised by what you find out!

15. Sex differences in Brain Maturation during childhood and adolescence De Bellis et al, 2001

16. Aims three areas of the brain 1. To investigate three areas of the brain to find out if the volume of those areas changed over time from childhood to adolescence 2. To investigate whether there were differences in male and female brains

17. Procedure MRI Scanner

18. Magnetic Resonance Imaging (MRI) Can you recall how the MRI scan works?

19. (LINK) MAGNETIC RESONANCE IMAGING (LINK) MAGNETIC RESONANCE IMAGING (MRI) Put another way MRI detects signals produced by displaced radio waves in a magnetic field. It provides a detailed anatomical view of the brain. MRI scanning uses a strong magnetic field which affects some atoms. Protons Protons (positively charged particles) in hydrogen atoms in water behave like compass needles. The scanner’s electromagnet causes the protons to ‘point’ in the same direction. When radio waves are passed through the head the protons return to their original positions and this is detected by the scanner. Parts of the brain with more hydrogen atoms appear paler; those with fewer hydrogen atoms look darker.

20. Procedure Experimental method: cross sectional / lab- based The participants were healthy children and adolescents 61 males and 57 females Age range 6 to 17 years They advertised for Ppts in the local community Ppts underwent clinical evaluations to ensure no one had any mental disorders

21. Procedure no significant difference There was no significant difference in the groups in terms of: Ethnicity Socioeconomic status Handedness IQ

22. Procedure The majority of ppts showed above average IQ Males were significantly taller than females Fully informed consent was obtained from both the ppts and their parents Ppts received money for taking part

23. Questions What type of sampling method did De Bellis et al use? 1. Opportunity 2. Self-selected 3. Random 4. Stratified Answer Self selected

24. Questions Qu: Which items were there found to be no differences between the pps? Answers Ethnicity, Socioeconomic status, Handedness and IQ Ethnicity, Socioeconomic status, Handedness and IQ Qu: What difference was there between the groups? Answer Height Height

25. Procedure Prior to being scanned, pps underwent a desensitisation procedure in a simulation scanner – this reproduced the sights and sounds of the actual MRI to get pps used to the environment This meant they were more co-operative during the actual scan and led to an improvement in image acquisition

26. Procedure During the actual MRI scan ppts were able to watch videos of their favourite films Ppts were motivated to remain still by being allowed to see the images of their brain after scanning (if they moved they’d be blurry) No sedation was used!!! Scanning was supervised by a child/adolescent psychiatrist

27. Procedure The brain scans were read by people who did not know whether the scan was from a boy or a girl Question: Why was this important?

28. Questions Which ethical procedures did De Bellis et al follow? Answers: fully informed consent was obtained from both Pps and their parents fully informed consent was obtained from both Pps and their parents Procedures were put in place to ensure minimal discomfort/distress during the procedure i.e. being able to watch favourite film, not sedated, Child psychiatrist present - competence Procedures were put in place to ensure minimal discomfort/distress during the procedure i.e. being able to watch favourite film, not sedated, Child psychiatrist present - competence

29. Resultscorrelations Results – note they found correlations Scattergrams of cerebral volume solid lines = males dotted lines = Female

30. Results The older the ppts the less grey matter they had – especially males White matter and the corpus callosum both increased with age, more so for the boys

31. Conclusions They concluded that boys had faster changes than females as they aged They also said that the differences in the male and female brain could explain why males and females have different cognitive abilities  One of these reasons could be linked to hormones. Oestrogen delays pruning. Testosterone promotes myelination.

32. Questions What method did they use to analyse the data? Correlation Answer: Correlation Males showed faster changes than females True/false? True Answer: True

33. 1. With age the volume of grey matter decreased. 2. The corpus callosum and white matter volume increased. 3. It was at different rates for males & females What was found? GenderIncrease in White MatterIncrease in Grey Matter Increase in Corpus Callosum MaleIncreased by 45.1%Reduced by 19.1% 58.5% increase FemaleIncreased by 17.1%Reduced by just 4.7% 27.4% increase

34. The aim of this study was to look at differences in the function of the brain, based on different genders and ages. An MRI scan was used to observe white and grey matter volume over a period of time. 118 participants. 61 males and 57 females were used. Participants were children and adolescents, they were defined as healthy after undergoing medical checks for mental disorders. Volunteer sample (paper advert). Informed consent from each parent was obtained in writing. Before the experiment happened there was a trial run to practice. It consisted of a machine which replicated an MRI scanner. This was to enable the participants to understand what would happen in the real experiment. Furthermore it was hoped that it would train the participants to keep their head still. Participants were told in the experiment that images of their own brain would be shown to them at the end, however if they didn’t stay still the images would be blurred. Trained researchers using computer software looked at the results of each brain scan. include sufficient detail Describe – include sufficient detail

35. ✓ The participants were protected against psychological and physical harm because a professional neuroradiologist was in charge of each MRI scan, a psychiatrist also remained with the child or adolescent throughout. ✓ Reliability would be high because of the fact that participants kept their heads still so the images were clear and precise. ✓ validity is high because controls were in place e.g similar IQ X Low in generalisability as the participants were all of similar IQ scoring (at least 116) which may give different results to someone of lower IQ. X It’s possible that reliability and validity may be decreased due to difficulty of measuring white and grey matter X The study was cross-sectional instead of longitudinal which means that results could be increased significantly in reliability as participant variables would be identified and the change during growing up in both genders could be found and noted. Evaluation