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Aim/Background (a review) Amygdala plays a role in sexual behaviour.

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Presentation on theme: "Aim/Background (a review) Amygdala plays a role in sexual behaviour."— Presentation transcript:

1 Hamann, Stephan 2005, Sex differences in the responses of the human amygdala.
Aim/Background (a review) Amygdala plays a role in sexual behaviour. Evidence: animal and human studies. Where: temporal lobe seizures near the amygdala. Specific sex differences in men and women. Evolutionary and sociobiological theories.

2 Hamann, Stephan 2005, Sex differences in the responses of the human amygdala.
Studies/Method: Non-human studies: Studies shows a difference between appetitive (smell olfactory) sexual behaviours which involves motivation to obtain a sexual reward i.e. desire or wanting. And consummatory (female rat is close) sexual behaviours which involve obtaining a reward i.e. copulation.

3 Hamann, Stephan 2005, Sex differences in the responses of the human amygdala.
Studies/Method: Lesions to the amygdala impaired the ability of male rats to respond to olfactory (smell) and other sexual cues from a respective female. Lesions to the female rats didn’t affect the sexual behavoiur at all. Localization of function and gender differences as this is not the case in female rats. Appetitive sexual motivation affected is crucial for male reproduction according to this study.

4 Hamann, Stephan 2005, Sex differences in the responses of the human amygdala.
Studies/Method: Human studies (drawn on previous animal studies): fMRI neuroimaging to examine sex differences in responses to appetitive visual sexual stimuli. Hypothesis was to compare men and women on their responses to visual sexual stimuli. Participants: 14 men and 14 women. Method: they viewed sexual arousing photographs, neutral photographs, or a control condition in which a blank screen with a cross was presented.

5 Hamann, Stephan 2005, Sex differences in the responses of the human amygdala.
Findings: Primary finding was that the amygdala and hypothalamus exihibited more activation in men than in womenwhen viewing the same sexually arousing visual stimuli. Especially in the left amygdala in men (localization of function). The findings were supported by a study using shorter versions of erotic films. This is a design more sensitive to rapid changes in amygdala activity, (Karama et al 2000). + the sex differences parallells with findings of prior animal studies. + Neuroimaging supports amygdala activity in other forms of appetitive motivation food, drugs etz.

6 Hamann, Stephan 2005, Sex differences in the responses of the human amygdala.
Clinical implications: Sex differences in the amygdala’s responses have been cited by several authors as a potentially important factor that may explain why some disorders are more common in men or women. Voyeurism is more prevalent in men than women which marks a preference to watch others undress or in a sexual relation. Typically begins in adolescense. Other disorders such as depression, posttraumatic stress, anxiety etz. Are more prevalent in women. Women tend to put more effort to memories and are somhow affected of them negative or positive. The same experience is seen in the sexual difference.

7 Hamann, Stephan 2005, Sex differences in the responses of the human amygdala.
Issues for discussion: Correlational study? p.29 What about the effects of different hormones on sexual responses? p.49 What about social experiences of men and women? Ethics? p.45 TOK box. Non-human research? fMRI? p.45 Localization of function? p.44-45

8 Rupp, H & Wallen K. (2008). Sex Differences in Response to Visual Sexual Stimuli: A Review
Aim/Background: This review discusses what is known about human sex differences in response to visual sexual stimuli and possible influences contributing to this sex difference Important to understand both cognitive, physiological, biological as well as a socio- cultural explenation.

9 Method: A review from studies of different academical disciplins.
Rupp, H & Wallen K. (2008). Sex Differences in Response to Visual Sexual Stimuli: A Review Method: A review from studies of different academical disciplins.

10 Rupp, H & Wallen K. (2008). Sex Differences in Response to Visual Sexual Stimuli: A Review
Findings: Reaches the same results that Hamann. Sexual visual stimuli may have a gender specific related effect. Western culture has given men more sexual freedom and constrained women more in the display of sexual motivation or interest in sexual material, a double standard that exists even to some degree today. Not only popular television, but also films used for sex education from 1990 to 2000 were found to portray a sexual double standard encouraging female passivity and caution.

11 Rupp, H & Wallen K. (2008). Sex Differences in Response to Visual Sexual Stimuli: A Review
Findings: That there are cultural differences in sexual attitudes suggests that social influences contribute to observed differences in sexual attitudes and behavior. Also, church attendance and identification with religion is correlated with decreased sexual permissiveness. If religious teachings stigmatize sexuality in women, this may influence women’ sexual attitudes and behaviors, and negatively bias their reported responses to sexual stimuli. differences between men and women in experience, gender roles, and feelings about sexuality may produce different subjective levels of arousal.

12 Rupp, H & Wallen K. (2008). Sex Differences in Response to Visual Sexual Stimuli: A Review
Conclusion: The sex differences observed in subjective sexual arousal to visual sexual stimuli are possibly the combined product of social and biological influences on cognitive processes that direct the perception and assessment of these stimuli. Based on how men and women differently regard these stimuli as positive and arousing, there will result in apparent differences in physiological and psychological responses. differences in response to visual sexual stimuli could be one example supporting the idea that the brains of men and women differ functionally in their environmental assessment to produce sexually differentiated behavioral response patterns.

13 Rupp, H & Wallen K. (2008). Sex Differences in Response to Visual Sexual Stimuli: A Review
Issues: Which importance should a socio- cultural explenation have in gender sexuality? What can Rupp/Wallen study add to the Hamann study?

14 Rapoport, J. 2001. Teenage brain: In progress.
Aim/Background: ”Use it or lose it” Neural connections and synapses that get exercised and are retained while that are don’t are lost. This is what animal studies so far have shown. Both genes and environment develops the brain in different directions. Later maturation of the brain, though science doesn’t know much about. What happens in adolescents within the brain?

15 Rapoport, J. 2001. Teenage brain: In progress.
Study/method: Longitudinell study of 145 children and adolescents. Following the same individual every two years during a long period. MRI imaging

16 Rapoport, J. 2001. Teenage brain: In progress.
Findings: They found an overproduction of gray matter in the frontal lobe cortex, the thinking part of the brain. The gray matter production brought neurons and their bransch-like extensions, just prior to puberty. The thickening peaks at age 11 for girls and 12 for boys. Other studies have suggested an increase early in life and pruning at around 18 month in the womb. Teens with schizophrenia showed a loss of four times as much gray matter than healthy teens. The area that was affected was the executive functioning such as planning, reasoning etz in the frontal lobe.

17 Rapoport, J. 2001. Teenage brain: In progress.
Findings: Interestingly the gray matter seems to grow from back to front the white matter seems to go the opposite direction and connecting brain regions, (Toga, A). The white matter begin growing in the frontal lobe and goes rearward and then subsides at the end of puberty. The white matter is a myelin layer of insulation which protects the fibres and connections in the brain and makes them more efficient (long distance connection). This growth can be seen between 6-13 , by the end the white matter reaches the parietal and temporal lobe and after it drops off sharply. Coinciding with a critical period for language learning.

18 Rapoport, J. 2001. Teenage brain: In progress.
Findings: The findings shows that the biggest difference between an young adult and a teen is the brains maturation and the white insulation protecting the gray matter (in the frontal cortex). This imply that the brains maturation means that the executive functioning and cogntive processes (language, reasoning) is more mature in a young adult than in a teen and more efficient.

19 Rapoport, J. 2001. Teenage brain: In progress.
Findings: Another series of experiment conducted by Yurgelun- Todd, scanned subjects brain activity (fMRI) while identified emotions looking at faces. The study Indicated that teens that did poorly on the test activated amygdala (fear, emotions, instincts) more than the frontal lobe.

20 Rapoport, J. 2001. Teenage brain: In progress.
Conclusions: The teenage brain differs rapidly from the adult brain. The brain grows in parallell direction.

21 Rapoport, J. 2001. Teenage brain: In progress.
Issues: What can we say abot the localization of the brain? Ethics within the research? The longtudinell research method: strengths and limitations? With this information what attitude should we have toward teens use of drugs and alcohol? Can it be more to harm than we first might belive?

22 Maguire, 1999 Navigation-related Structural Change in the Hippocampus of Taxi-drivers
Background: The hippocampus is a part of the brain located in the medial temporal lobe and making up part of the limbic system (emotions etz). Damage to the hippocampus is believed to result in severe memory deficits (such as, for instance, in patient H.M.) and neuroscientists know that it is involved in spatial memory. It has also been shown that the hippocampus can increase in size when needed, e.g. animals and birds have a greater hippocampal volume during seasons when navigational skills are important.

23 Maguire, 1999 Navigation-related Structural Change in the Hippocampus of Taxi-drivers
Aim: The study attempts to determine whether changes could be detected in the brains of humans who have extreme experience of spatial navigation.

24 Maguire, 1999 Navigation-related Structural Change in the Hippocampus of Taxi-drivers
Participants: Quasi-experiment which included sixteen male licensed cab drivers who had passed ‘the knowledge’ (navigational test necessary to receive taxi-driver license). All were right handed, and were aged between 32 and 62, with a mean age of 44. They had all been licensed at least 18 months, although the range was from 18 months to 42 years, with a mean 14.3 years. The control group consisted of scans selected from a database. All of the control group were healthy right handed males aged between 32 and 62. None of the control group were taxi-drivers.

25 Maguire, 1999 Navigation-related Structural Change in the Hippocampus of Taxi-drivers
Procedure: The brains of the taxi drivers were scanned using and MRI (magnetic resonance imaging) scan, focusing on the size and structure of the hippocampus.

26 Maguire, 1999 Navigation-related Structural Change in the Hippocampus of Taxi-drivers
Results: Using the MRI showed that the brains of cab drivers showed significantly increased size of the right and left posterior hippocampi, whereas the control group had relatively larger anterior hippocampi. No other differences were found between the brains of the two groups. The volume of the right posterior hippocampus showed a positive correlation with the length of time as a cab driver, the results were reversed when looking at the anterior hippocampus.

27 Maguire, 1999 Navigation-related Structural Change in the Hippocampus of Taxi-drivers
Conclusions: The results show that experience can affect the volume of structures of the brain, and that in particular the hippocampus is affected by navigational experiences.

28 Maguire, 1999 Navigation-related Structural Change in the Hippocampus of Taxi-drivers
Evaluation: MRI scans give a detailed view of the brain and safe and painless; The choice of cab drivers as a sample was good as they are a discrete group of people with specific knowledge and experience; However, this because this is a quasi-experiment (rather than a true experiment), bidirectional ambiguity or third factor influence is possible. The data collected was quantitative using precise equipment so there is unlikely to be any bias; Difficult to generalize to other groups with different types of experience


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