EXAM 3 Flashcards
idea that sensory feedback from our facial expressions can affect our mood
facial feedback hypothesis
process in which animals will work to provide electrical stimulation to particular brain sites, presumably bc the experience is rewarding
brain self-stimulation
collection of axons traveling in midline region of forebrain
medial forebrain bundle
region of forebrain that receives dopaminergic innervation from the ventral tegmental area, often associated with reward and pleasurable sensations
nucleus accumbens (NAc)
sudden intense emotion characterize by actions, such as snarling and biting in dogs, that lack clear direction
decorticate rage
loosely defined, widespread group of brain nuclei implicated in emotions that innervate each other to form a network
limbic system
region of cortex lying below the surface, within lateral sulcus, of the frontal, temporal, and parietal lobes
insula
composed of several psychological constructs, rooted in biology
arouses an organism toward desired goal which is the reason for action
motivation
examples of motivated behaviors
eating/drinking, sex/reproduction, sleep activity, curiosity/exploration, socializing, taking drugs, gambling, risk taking
core hedonic pleasure, rewarding-seeking behavior
composed of conscious pleasure and core hedonic (subcortical/ w/conscious awareness) pleasure
liking
motivation for reward, reward seeking behavior. Natural rewards elevate dopamine levels. Composed of conscious desires and incentive salience
wanting
- claims liking and wanting conscious mechanisms that likely involve cortical structure
- also have subcortical circuits, homologous with animals, below level of perceptual awareness
- believes that wanting and liking can be influenced by learning–associations, representations, and predictions about future rewards based on past experiences
- demonstrated that these psychological components are mediated by dissociable brain substrates
Berridge
“liking regions”
nucleus accumbens and ventral pallidum
“wanting regions”
ventral tegmentum
amygdala
ventral pallidum
nucleus accumbens
prefrontal and insular cortex -> incentive saliences processing
deep in brain-> nucleus accumbens, ventral pallidum, brainstem
-other candidates in cortex -> orbitofrontal, cingulate, medial prefrontal and insular cortices
-cortical regions involved in conscious awareness of pleasure/liking
hedonic pleasure mechanism location
dopamine pathways
1) mesolimbic
2) mesocortical
3)nigrostriatal
4)tuberhypophyseal
dopamine pathway with cell bodies in ventral tegmental area (VTA) and axons in nucleus accumbens
mesolimbic pathway
dopamine pathway with cell bodies in VTA and axons in prefrontal cortex, ventromedial prefrontal cortex
mesocortical pathway
dopamine pathway with cell bodies in substantial nigra and axons in striatum
nigrostriatal pathway
dopamine pathway within hypothalmus
tuberhypophyseal pathway
placed into these brain regions increases conscious subjective pleasure
conscious pleasure: OPIATES
orbital frontal cortex, anterior cingulate cortex, insular cortex/insula
conscious pleasure: CORTEX REGIONS
placed into these brain regions, increases subcortical subjective pleasure
core hedonic pleasure: OPIATES
NAc shell, ventral pallidum, periaqueductal gray (AG), amygdala
core hedonic pleasure: REGIONS
natural rewards
microdialysis
-less actions in female development
-default is female
-dont need estrogen secretion; natural process while testes must be turned on the other hand must be turned on in 2nd month of development
-estrogen needed for brain growth
development of sexual differentiation of females as indirect genetic effect
undifferentiated gonad -> chromosomal sex (XX vs XY) -> gonadal sex (ovaries vs. testes) -> sexual phenotype (vagina or penis)
normal sex differentiation (classic/simplistic model)
1)males inherit X and all its genes from Mom so any genes one X important for development in brain function come from mom
2) females have 2X-one is randomly expressing most cells
3)some cells express double dose of X
direct genetic effects in sexual dimorphism
XY
important b/c males have only 1 X and its from mom
-> sex-linked disorder prominent due to one faulty X
male chromosomes
XX
-one X is inactivated in most cells (Barr body)
-some cells use double dose of X
-some cells-X from mom, others- X from dad (random distribution
ex-phenomenon in calico cats mosaic-like patches
–all are female-> coats show X inactivation
female chromosomes
evidence that activational actions of hormones alone can change regions
-region of amygdala, the MePD, increases and decreases in size dependent on testosterone levels in males and females
-> we see change in amygdala in human males when they approach and pass puberty when testes turn on and start secreting testosterone
-> also true that unless male mice get chance to show rough-and-tumble play as juveniles, their MePD does not get large, remaining small like females
activational action of hormones and brain regions
1)regions of hypothalamus-LeVay studies
2)corpus callosum-different shape in female, may be related to differences in asymmetry between hemispheres of males and females (ex-males more lateralized in language)
3) differences in use of brain regions-> for some tasks, females use both hemisphere while men use only one
4) differences in structure and function of the amygdala-emotion regulation may be different in males vs. females
5)disproportionate representation of certain neuropsychiatric diseases between sexes
6)sex differences in regions of brain involved in reward
-both liking and wanting areas
-mPOA sends axons to VTA which then activate NAc and accessory olfactory bulb (AOB)
sexually dimorphic brain regions in humans
individuals have minimal 5-alpha reduces to convert testosterone to dihydrotestosterone
-while internal testes and duct system are male , external genitals which require dihydrotestosterone for development are feminine at birth
-@ puberty, when hypothalamus and pituitary secrete large quantities of GNRH, LH, FSH, the testes up regulates 5 alpha reductase activity and more dihydrotestosterone is produced
-> genitals grow and become masculine at puberty
-some remain female, but most live rest of lives as male
**When it was initially thought that these individuals proved that gender identity was fluid and could easily be altered, later research showed that these individuals were not raised as girls but as 3rd sex
–recognized as different and expected to become male at puberty
–thus, it is hard to disentangle environment and hormones from syndrome
Guevadoces / 5-alpha reductase deficiency
-these individuals have no androgen (testosterone) receptors and therefore cannot react to high levels of androgen their testes secrete
-born with female phenotype except for testes that do not descend due to lack of scrotum
–internal and external phenotype is otherwise female
-> v female behaviors and preferences with no evidence of masculinized behavior
**suggests that gender identity, sexual pref, and gender-related behaviors are not directly influenced by presence of Y chromosome
Androgen-Sensitivity Syndrome
-genetic abnormality in which an enzyme is missing from adrenal gland of fetus
–causes adrenal to fail to produce sufficient cortisol such that no negative feedback to hypothalamus (CRF) or pituitary (ACTH) occurs
-thus, lots of CRGF and ACTH are released and the adrenal is stimulated to produce excess androgens, including testosterone and dihydrotestosterone
-resulting levels are between normal male and female (intermediate)
-usually, individual born with masculinized genitals so often raised male due to masculine phenotype at birth
-others have feminizing genital surgery
–these individuals display more rough-and-tumble play, prefer male-type toys, and more typical behavior/pref than matched female relatives. Also are more likely to report homosexual fantasies. BUT have clear female identity
**data suggest that gender-related behaviors are influenced prenatally by high androgen levels and that sexual preference may also be influenced to some degree
-HOWEVER, gender IDENTITY may not be as readily influenced
adrenogenital syndrome
-BKGD: one twin’s penis was severely burnt at 8mo and was raised as girl until age 14. Underwent surgery and hormone therapy to live life as man, post-revelation of accident
**clinical case suggests that gender identity, sexual preferences, and gender-related behaviors are not easily reversed by environmental factors, at least after 1 year of age
-> boy raised as girl showed lots of rough-and-tumble play and did not like to do “what girls like to do”
Clinical Case of Twin Boys, One Raised as Girl
discovered a sexually dimorphic nuclei in hypothalamus of human brains
-in cluster of 4 regions of hypothalamus (INTERSTITIAL NUCLEI), 2 are sexually dimorphic, but not homologous with SDN of rats
-interestingly, in autopsy data of heterosexual men, homosexual men, and females, one of interstitial nuclei in homosexual men is small, like that of females
**Finding does NOT tell us anything about genes, hormones, or experiences leading to morphological difference in human brain that appear to be associated with male homosexuality (early or lack of hormone exposure? differential hormone exposure? AIDS exposure (autopsy!)? behavioral differences?)
LeVay
found a sexually dimorphic nucleus in spinal cord that functions to control penile movement in rat
-turns out testosterone (not estradiol) is needed for male-like region to develop
-female rats given testosterone at birth have large regions in their spinal cord that control penile movement, even though they don’t have a penis
**brain sexual dimorphism can develop independent of functional output
Breedlove
showed that nuclei in songbird brain that control song are highly sexually dimorphic, just like behavior.
-females have tiny or nonexistent regions compared to large, well-developed regions in males
Nottebohm
sexually dimorphic nucleus of preoptic area is 3-5x larger in males than females due to testosterone
-giving female testosterone promotes axon growth but estradiol does not
-testosterone is converted to estradiol in female ovaries
R. Gorski study
1)Y -> SRY gene -> stimulates Sox9 gene on Chromosome 17
2)SRY gene expression leads to teste formation, which produces Leydig and Sertoli cells
3)Leydig cells produce testosterone, which leads to internal Wolffian duct system
-5-alpha reductase coverts testosterone to dihydrotestosterone, which leads to external male genitals
4)Sertoli cells produce Anti-Müllerian hormone, leading to the regression of female Müllerian duct system (disappearance of ovaries and Fallopian tubes)
-androgen receptors on X chromosome
development of sexual differentiation of males as indirect genetic effect
-males and females have different levels of androgens,estrogens, and somewhat different brain circuitry
-> if you give an adult female rat testosterone, it wouldn’t desire sex with other females (and vice versa with males and estrogen)
-clear sex differences in male and female brains, likely related to circuitry
-> sex differences in many neuro and psychiatric disorders (ex-females: Alzheimers, anxiety, depression, MS, anorexia. males: dyslexia, autism, Tourette’s)
Sexual dimorphism of brain composition
-conserved node
-sexually dimorphic
-social, sensory input
-stimulation from VTA and AOB
-widespread connections
-molecularly heterogenous
-periphery signals
dissection of medial preoptic area (mPOA) circuit
-in females, circulation of hormone leads to arousal behavior, such as Lordosis response (arched back)
-receptive field of skin and flank become very sensitive
-affects neurons at periaqueductal grey, ventromedial hypothalamus, medullary reticular formation, reticulospinal tract, spinal cord
-medulla acts as way station
estrogen
activation hormone most dominant in males
-kind of androgen
-more testosterone (above normal) does NOT increase sex drive in rats BUT removing source of testosterone (testes) via castration decreases sex drive
-sensory and motor system sensitivity
-converted to estrogen and act on mPOA and medial amygdala
- act on spinal neurons to augment reflex
-act on muscles, including erectile muscles
-receptors in ventral midbrain, acting as way station
-receptors in olfactory bulb vital for smell and for vomeronasal system
testosterone
long lasting effect of hormones (or other chemical) that alters that trajectory of development
-usually during early development
-influence synaptogenesis and cell death
-affect circuitry => long lasting
organizational effects of hormones
-short acting effect of hormones, drug, or other chemicals, usually at puberty and beyond
-like light switch
-hormones prime brain to modify processing of social info, such as opposite-sex mate cues and infant cues
-leads to development and turning on of behavior, return of reactivity to stimuli
activational action of hormones
-direct-encouraging sports in boys but not girls
-indirect-“mothering” may have different effect on biological males and females
early experiences as cause of sex differences and sexually dimorphic behaviors