intro to neuro - exam ii

Are male and female brains the same?

Nope

What did patient C.V. show (baby)

he had constipation, could not hold his head up. He is believed to have some hormone deficiency that lead to problems in neurogenesis giving him microcephaly and also showed macroglossia (enlarged tongue)

Hormones vs Neurotransmitter

Hormones are working over a long distance while neurotransmitters are short distance. It's important to note that hormones act in a gradual fashion, essentially making more and more hormone as time goes by (long-term)

Do hormones work on a circadian clock? If yes, what is an example?

Some hormones do work using a circadian clock. A good example would be melatonin. The fact that it works on a circadian clock means that it is secreted at certain times of the day.

What type of feedback system is present in the endocrine system?

Negative feedback system

What are the two different types of hormones?

Tropic hormones and Releasing hormones

What are tropic hormones? Where are they released from?

These are hormones that affect *other* glands. These are released from the *anterior pituitary* (Example: TSH)

What are releasing hormones? Where are they released from?

These are released by the *hypothalamus* to regulate the release of tropic hormones from the pituitary. (Example: TRH)

If you had a high serum thyroid. You would expect your TSH levels to be....?

Low. (this makes sense since you have a negative feedback system. High thyroid levels would cause the body to inhibit TSH. Lower levels of TSH means that your body is working to reduce the amount of thyroid hormone produced.)

What are the hormones secreted by the Posterior pituitary?

Vasopressin and Oxytocin

What does Vasopressin do?

raises blood pressure and inhibits urine formation *(Vasopressin is also known as ADH or antidiuretic hormone)*

What does oxytocin do?

It is responsible for Maternal behavior/bonding.

What is the process by which tropic hormones are released from the Anterior pituitary?

1. Hypothalamic neurons synthesize releasing hormones.
2. Releasing hormones are then secreted into local blood vessels in order to go to the pituitary
3. These releasing hormones then act on the anterior pituitary releasing tropic hormones

What is necessary for the production of thyroid hormone?

Iodine

What happens when you do not have enough iodine?

Hypothyroidism develops

What does hypothyroidism/iodine deficiency lead to?

Formation of a *goiter*, which is the swelling of the thyroid gland. (In the case where you have a thyroid deficiency, your body is going to up-regulate the thyroid feedback loop in order to produce more thyroid hormone. This leads to the over-activation of the thyroid gland which leads to its swelling.)

What is Cushing's disease?

this results from long-term excess glucocorticoids. Individuals who have Cushing's disease tend to have depression and fatigue.

How many levels of sex determination do we have and what are they?

Chromosomal sex -\> Gonadal sex -\> Internal Sex organs -\> External sex organs -\> Brain sex -\> Gender identity -\> Gender preference

What are the two hypotheses for sexual orientation

Social influence hypothesis and Biological hypothesis

What does the social influence hypothesis emphasize

emphasizes that home environment and early seduction are causes of homosexuality. *Little support for this*

What does the biological hypothesis emphasize?

Most homosexuals report feeling different at a young age (4-5). They tend to show gender nonconformity Which essentially means that they engage in activities preferred by the other sex and they preferred having other sex friends.

Which birth order is most likely to develop homosexuality?

Last born

Is a hormonal influence likely?

Male homosexuals and heterosexuals tend to have the same testosterone levels so if there is a hormonal influence it is most likely to have occurred prenatally.

What are the two areas of the brain that are responsible for sexual orientation?

Sexually dimporphic nucleus (INH3) and Suprachiasmatic nucleus.

What is the INAH3 and how does it differ in homosexual individuals?

It is the third interstitial nucleus of the anterior hypothalamus. It is female sized *(smaller)* in homosexual men.

How does the Suprachiasmatic nucleus differ in gay men?

It is *larger* in gay men and tends to contain more vasopressin-secreting cells.

How does the anterior commissure differ in gay men?

It is *larger* in gay men.

Is a Gay man's verbal and spatial performance more similar to women or heterosexual males?

Women.

When does estrogen rise and why does it do so?

Rises before ovulation in order to promote non-human sexual behavior

What is the term used to refer to the time when a female is sexually receptive?

Estrus/heat

What is necessary for Male Copulation?

Androgens

What are the difference parts of a sexual response curve in both males and females?

Excitement phase (arousal) -\> In plateau arousal levels off -\> Orgasm -\> Resolution (this occurs when arousal levels fall and the body returns to normal)

If you were to look at the male brain during sex, what part would be activated

Ventral tegmental area (which we know to be responsible for addiction)

What hormone is released from the male brain during ejaculation?

Oxytocin

If you were to look at the female brain during sex, what part would be activated?

Deep cerebellar nuclei. The orbitofrontal cortex will be inhibited.

What part of the brain is important during sex in both sexes?

Medial amygdala. (this is found in the temporal lobe and is involved in *sex, smell, aggression, and emotions*.

For males what is an important structure for sex?

Sexually dimorphic nucleus. It is located in the medial preoptic area and is about 2-3 times larger in males. The larger the size the more sexually active the male. It is important to note that it's size depends on prenatal exposure to testosterone.

For females what is an important structure for sex?

Ventromedial hypothalamus (which is responsible for putting females "in the mood")

What are the 2 neurotransmitters that are important for sexual behavior?

Dopamine and Serotonin.

What is responsible for the development of testes?

SRY gener which is the sex determining region on the Y chromosome. (Without this gene, an ovary forms)

In the case of Biological determination of gender, what are the two effects?

Organizing and Activating effects

Organizing effects vs Activating effects

Organizing effects occur prenatally or shortly after birth while activating effects happen at any time in life.

What is the main organizing hormone in human brain development?

Testosterone

What are the main differences between male and female brains?

Females tend to have a larger corpus callosum which correlates to the fact that women tend to have better cognitive skills than men. Males tend to show greater asymmetry in their brains (thicker right hemisphere in males than in females)

In what portions of the brain do women have a greater gray matter percentage?

Dorsolateral prefrontal cortex as well as the superior temporal gyrus.

How do female and male brains differ in their connectivity?

Males are better connected front to back while women are better connected left to right.
(females are better at multitasking while males are better at focusing on the task at hand)

What is high estrogen level associated with?

It is associated with a depressed spatial ability as well as enhanced speech and manual skill tasks.

What does testosterone in the 2nd trimester do?

It increases cerebral asymmetry by accelerating the growth of the right hemisphere.

What is enhances in androgenized girls?

Spatial ability (it is important to note that testosterone is associated with enhanced spatial abilities. Males who have low levels of testosterone tend to have a depressed spatial ability)

What to female to male transsexuals usually show?

They tend to have enhanced spatial abilities but decreased verbal fluency.

What part of a young girl's brain grows first and what is this brain region responsible for?

The frontal portion of the brain. This brain region is responsible for language, controlling aggression, and impulsivity.

What part of a young boy's brain grows first and what is this brain region responsible for?

The back portion of the brain. This part of the brain is responsible for visual spatial tasks (examples of such tasks are geometry and puzzle solving)

True or False? Gender is a dichotomy

False. Gender is a continuum rather than a dichotomy.

What do homeostatic systems do?

They use our behavior to keep things balanced.

What are the main homeostatic mechanisms?

Negative feedback

What is Hypovolemic thirst stimulated by?

low extracellular/intravascular volume

What is Osmotic thirst stimulated by?

high extracellular solute concentration

What is hypovolemic thirst stimulated by?

loss of water volume (it is important to note that the concentration does not change here)

What detects the initial drop in water volume and where are they located?

Baroreceptors (pressure receptors). They are found in blood vessels as well as the heart

What hormone is released due to hypovolemia?

Vasopressin AKA ADH (antidiuretic hormone) - released by the posterior pituitary

What is the relationship between diabetes insipidus and vasopressin?

vasopressin is not produced is not produced in individuals with diabetes insipidus. (This causes the kidney to send more urine to the bladder, which results in chronic thirst)

What is activated when blood volume is decreased?

Angiotensin cascade

What is the first step of the Angiotensin cascade?

Kidney releases *renin* which is an enzyme that allows the conversion of angiotensinogen into Angiotensin 1.

What are the 4 effects of Angiotensin 2?

Blood vessels constrict, Circumventricular organs trigger drinking, Vasopressin is released, and Aldosterone is released.

Where does Angiotensin 2 act in the brain?

It acts on the subfornical organ (hypovolemic thirst) in order to signal other brain sites to initiate drinking.

What responds to a rise in blood osmotic pressure?

Osmosensory neurons found in the anterior hypothalamus (OVLT) - Osmotic thirst

What do osmosensory neurons do when there is an increased osmotic pressure?

It causes the pituitary to release ADH

What is the main source of energy in our body?

Glucose

How is glucose stored and where is it stored?

Glucose is stored as glycogen in the liver (short-term)

What happens during glycogenesis?

It converts glucose into glycogen using the hormone insulin (released by the pancreas)

What are lipids used for?

Long term energy storage in fat tissue

What 3 things regulates food intake?

External factors, Central signals, and Peripheral signals.

What does leptin deficiency lead to?

Obesity. Leptin deficiency leads to a falsely low report of body fat which causes animals to eat. (Fat cells produce and secrete leptin) - it is important to note that leptin has a negative feedback mechanism which is what causes you to overeat.

Where is Ghrelin released from and what is it responsible for?

It is released by stomach endocrine cells and it works as an appetite stimulant. (Rises during fasting and drops after eating)

Some obese people have elevated ghrelin levels, what is the most likely diagnosis for these individuals?

Prader- Willi syndrome (These people are always starving)

What is the hunger control center? And what are the two divisions of this center?

Hypothalamus. The two divisions are Lateral hypothalamus and Ventromedial thalamus

What do lesions in the lateral hypothalamus lead to?

Lesions here lead to a refusal to eat

What do lesions in the ventromedial hypothalamus lead to?

Lesions here lead to overeating and hence obesity.

What do VMH lesioned animals exhibit?

They overeat till they become obese. The weight stabilizes and is maintained after food manipulations (you create a new set point)

What do LH lesioned animals exhibit?

They stop eating for some time but eventually start eating again. Once they resume they are stabilized at a new lower level.

There are two sets of neurons in the hypothalamus that have opposing effects, what are they?

NPY/AgRP neurons and POMC/CART neurons.

What do NPY/AgRP neurons produce? And what do they do?

Neuropeptide Y and agouti-related peptide. They stimulate appetite and lower metabolism which leads to weight gain.

What do POMC/CART neurons produce? And what do they do?

pro-opiomelanocortin and CART. They inhibit appetite and raise metabolism which leads to weight loss.

Leptin inhibits the secretion of what?

AgRP

Which psychiatric disorder has the highest mortality rate?

Anorexia Nervosa

What is the main characteristic of Anorexia nervosa?

Refusal to maintain body weight

What is the main characteristic of Bulimia?

Recurrent binge eating

When looking at the brain of teenage girls with anorexia what does one notice?

Larger insula and larger oribitofrontal cortex.

When looking at treatments for obesity what are 3 things that obese individuals can do in order to lose weight effectively?

Eat less, Modify behavior and Exercise

Do obese individuals share characteristics with individuals suffering from addiction? If yes, what do they share?

Yes they share several characteristics. These include, *fewer D2 receptors associated with lower prefrontal lobe metabolism, peptides that induce eating target dopamine neurons* ( it is important to note that anti-addiction drugs are somewhat effective in weight loss which signifies that obesity and addiction are relatively similar)

What does the Basal Metabolic rate measure?

It measures the amount of energy required to fuel the brain/body as well as maintain body temperature.

True or False? A high BMR is associated with problems in dieting.

False. Of women on a diet, studies showed that 1/3 of those who failed at dieting had a *low BMR*

Is BMR only dependent on genetics or are there other factors?

Heredity accounts for 40% of a persons BMR *BUT* spontaneous activity can also increase BMR.

What is a long lasting treatment of weight loss? And how does this work.

Gastric bypass surgery. This surgery leads to lower levels of ghrelin and increases in PYY and GLP-1 which essentially reduce hunger.

When looking at patient Bob, he reported that he doesn't care anymore signifying some emotional disorder. What is patient Bob suffering from?

Diffuse Axonal injury (DAI) - this is found in most head trauma cases. Relatively common. Bob damaged his orbitofrontal cortex.

What is an emotion?

It is an increase or decrease in physiological activity that is accompanied by feelings that are characteristic of that emotion.

When looking at the model of emotion what are the different steps?

Stimulus-\>Appraisal-\>ANS, behavior, emotional expression, emotional feelings-\>Appraisal (danger!) - It is important to realize that in the diagram given in class it shows that *ANS arousal* can gives rise to a Behavior, Emotional expression and Emotional feelings

How many universal emotions (facial expressions) are there and what are they?

8. Anger, Sadness, Happiness, Fear, Disgust, Surprise, Contempt, Embarrassment. The fact that these emotions are shared across cultures shows that these emotions are biological in nature.

In the case where you hear something funny what system activates your laughter/happiness?

Limbic system

In some cases where you really want to laugh but you don't (suppress) what system is at play?

Frontal cortex