Neuro Test 3
"orexi"
"to eat"
do postganglionic neurons in the sympathetic and parasympathetic divisions use different neurotransmitters
both use Ach and only sympathetic uses NE
thoracic ganglion
contains cells that will constrict blood vessels, relax airways, and accelerate heart rates
what are corticotropes?
pituitary cells
hippocampus and amygdala
supply emotionally-relevant info to integrate autonomic responses with emotional state.
the arcuate nucleis and ghrelin
•NPY/AgRP neurons produce neuropeptide Y (NPY) and agouti-related peptide (AgRP) to stimulate appetite and lower metabolism, promoting weight gain. •POMC/CART neurons produce pro-opiomelanocortin (POMC) and cocaine- and amphetamine-related transcript (CART) to inhibit appetite and raise metabolism, promoting weight loss. •Ghrelin stimulates NPY/AgRP neurons, which increases appetite
cingluate cortex
(an emotion-processing cortical region) sends information regarding emotional state.
previous motherhood affects maternal behavior
-Female rats that never gave birth show a high latency to display maternal behavior if given orphaned rat pups. -Once pregnant & giving birth (the term primiparous indicates a first pregnancy), a female quickly displays maternal behavior. -Moreover - once a female has experience as a mother, she is more likely to display maternal behavior. How does this experiment work? -A female rat (in early puberty through early-mid adulthood) is exposed to a young, crying rat pup. -Prior to puberty, females behave maternally on the first day. -After puberty, pup exposure must be repeated 5-6 times (~1 hour daily exposure) to elicit maternal behavior. -Phenomenon of inducing maternal behavior in virgin animals is called concaveation. -Pregnant rats do not show maternal behavior except near the end of pregnancy (days 16 to 18 of the 22 gestation period) when they robustly respond to pups.
what are the major hypothalamic nuclei involved in appetite/feeding
-Lateral hypothalamus (LH) -Ventromedial hypothalamus (VMH) -Arcuate nucleus -Paraventricular nucleus (PVN)
celiac ganglion
-Liver - stimulates glucose production & release -Stomach, pancreas, small intestine - inhibits digestion -Adrenal gland (stimulates secretion of epinephrine, norepinephrine from adrenal medulla)
maternal behavior reduces stress response in pups
-Pups were either deprived of maternal care (DEP) or nondeprived (NDEP) -They were injected with ACTH. -Then circulating levels of cortisol were measured. -Maternal care reduced the increase in CORT levels at every time point examined.
What does the ANS regulate?
-Secretion of saliva, sweat, tears, mucus -Heart & blood vessels to control blood pressure and blood flow -Oxygen delivery (lung bronchi) -Digestion and metabolism (liver, GI tract, pancreas) -Kidney, urinary bladder, large intestine -Sex & reproduction -Interacts with body's immune system
What are the subdivisions of the ANS
-The sympathetic ANS -The parasympathetic ANS the divisions operate in parallel with generally opposing functions
fat cells and obesity
-Total number of fat cells increases during 3 general periods of life: Last trimester pregnancy, 1st year life, adolescence -Fat cells can increase in size (2-3x normal size) and number (up to ~75 billion) if an individual becomes obese -What happens to fat cell size and fat cell number when adults lose weight? Fat cells shrink to a smaller size than adipocytes of nonobese people, but number remains same.
what functions does peripheral vasopressin's regulate
-Water retention (acting on kidney) -Blood vessel constriction (increasing peripheral vascular resistance, which increases blood pressure) 1)Water deprivation in the body -> decreases blood volume, increases blood salt concentration -> peripheral sensors send info to hypothalamus. 2)Hypothalamus releases vasopressin (ADH). 3)Vasopressin acts on the kidneys to retain water, reduce urine production. 4)Less water lost in urine -> normalizes blood water levels (and salt concentration in blood).
What are the two broad forms or conditioned learning?
-classical conditioning -operant conditioning
sexual dimorphic nucleus of the pre-optic ares (SDN-POA)
-female rats given testosterone during a critical window have a masculinized SDN-POA -male rats that are gonadectomized (testes removed) during the critical window have female-like SDN-POA -this critical window is about embryonic day 18 to postnatal day 10
what are the major regions of the CNS that regulate the autonomic nervous system function?
-hypothalamus -amygdala -Brainstem
what does cortisol elicit in the brain and body?
-mobilizing energy stores -increasing arousal/vigilance -focusing attention -suppressing immune function
Projections of the parasympathetic nervous system
-ocularmotor nerve -facial nerve -glossopharyngeal nerve -vagus nerve -splanchic nerve
hormones involved in hunger
-orexin (hypothalamus) -ghrelin (stomach) -insulin (pancreas) -leptin (fat cells) -PYY increase (digestive tract)
What are the principal inputs to the hypothalamus?
-prefrontal cortex -cingluate cortex -hippocamous and amygdala -reticular formation and nucleus of the solitary tract -thalamus -hypothalamus -retina input
where do postganglionic cells of the sympathetic ANS innervate the vasculature and/or viscera
-superior cervical ganglion -thoracic ganglion -celiac ganglion -collateral ganglia
Neural control of male and female reproductive organs
1)Arousal: Stimulation of mechanoreceptors induces engorgement of external genitals (controlled by the parasympathetic nervous system). 2)Plateau: Further engorgement and release of lubricating fluids from the woman's vaginal wall and from the man's bulbourethral gland. 3)Orgasm: Sympathetic nervous system becomes activation, and in men this triggers muscles to push sperm through the vas deferens and out of the penis. Less is known about this process in women. 4)Resolution: the genitals drain of blood and some time must pass before orgasm can be initiated again.
Hypothalamus functions: emotional & motivated behaviors
1. Fight-or-flight behavioral response to threatening stimuli or situations. 2. Motivated behaviors including feeding, sexual and other behaviors integral to promoting survival and reproduction. 3. Aggression, rage
hypothalamic control of sex steroid production
1. GnRH is synthesized in the hypothalamus 2. GnRH neurons release GnRH from their axons in the median eminence that migrate into the capillary bed. GnRH travels through the bloodstream to the anterior pituitary 3. GnRH binds to GnRH receptors on gonadotropes that release LH and FSH into the bloodstream 4. LH and FSH act on the gonads to stimulate steroid hormone production
What is the common pattern for most hormones of the hypothalamus-anterior pituitary complex
1. Parvocellular hypothalamic neurons project to the median eminence -> their hormones enter the hypophyseal portal blood supply. 2.These hypothalamus-secreted factors stimulate (or inhibit) anterior pituitary cells to release their hormones. 3.Hormones released into bloodstream.. 4.Target endocrine gland in the body is activated by the hormone. 5.Peripheral hormones in bloodstream feedback to hypothalamus to regulate its release (to make sure the system doesn't become overstimulated.)
hypothalamus functions: Basic physiological needs
1. Stress response (influencing blood flow to specific tissues, and by stimulating the secretion of adrenal stress hormones) 2. Ingestive behavior (feeding, drinking) 3. Blood pressure 4. Sleep-wake cycle, circadian function 5. Body temperature 6. Energy metabolism (via influence on feeding, digestion, and metabolic rate) 7. Reproduction (via hormonal control of mating, pregnancy and lactation)
Hormones bind to hormone receptors in order to induce changes in gene expression
1. hormones enter the cell 2. hormones bind to their respective receptors (androgen with AR and estrogen with ER) 3. the hormone-receptor complex binds to their respective response element (RE) and induce gene expression 4. Newly made mRNA is translated into new proteins which will change how the cell functions
can you answer these?
1.How can one define sex differences? 2.Be able to explain the HPG stress axis (GnRH -> LH and FSH -> sex steroid hormones and their downstream effects on brain and body) 3.What is the mechanism by which hormones affect molecular and cellular physiology? 4.What is the difference between organizational and activational effects of sex steroid hormones? What does "critical period" mean? 5.What are some of the ways that the HPG axis can change over the course of an adult human or adult animal lifespan? 6.What is CAIS and CAH? What has changed hormonally in glands and in the brain in these individuals? 7.How do androgens relate to aggressive behavior in humans?
the bodies stress response
1.Hypothalamic Pituitary Adrenal (HPA) stress axis (CRH -> ACTH -> cortisol) 2. Autonomic Nervous System ('fight or flight' physiological responses)
The basic hippocampal circuit
1.Information from the Entorhinal Cortex (EC) enters the hippocampus via the Perforant path, synapsing on Dentate gyrus (DG) cells. 2.The DG synapses onto CA3 cells via the Mossy fiber path. 3.Schaffer collaterals from CA3 synapse onto CA1 cells, which synapse onto different regions of EC.
preFrontal cortex & working memory - the delayed response task
1.Monkey is shown food placed in a well and covered (Cue). 2.A screen is lowered for a set period of time (Delay) and then lifted. 3.Monkey is shown the table and receives the food reward if it can recall the correct well. Panels B-D show neuronal firing in the prefrontal cortex during performance of the delayed response task. When the cue is given at the beginning of the task, information is "held" in the prefrontal cortex during the delay phase (i.e. the PFC neuron fires more rapidly during the delay). This is thought to then guide the monkey's behavior to help it choose the correct well during the response phase of the task.
can you answer these?
1.What are major subdivision of the hypothalamus? 2.What the major inputs/outputs of the hypothalamus? 3.A major aspect of hypothalamic function is its interaction with the pituitary; what are the different parts of the pituitary & what different functions do they each serve? 4.Be able to explain the HPA stress axis (CRH -> ACTH -> cortisol and its downstream effects on brain and body) 5.What are the effects of chronic stress on the body and behavior? On the brain?
can you answer these?
1.What are the four major stages of sex and what parts of the nervous system control those stages? 2.What are some of the ways that the HPG axis can change over the course of an adult human or adult animal lifespan? 3.How do androgens relate to aggressive behavior in animals and humans? 4.What are the types and categories of memory? 5.What is the difference between declarative and non-declarative memory? 6.What are the principles of conditioned learning? 7.What does the Morris Water Maze test? Can you understand a graph of results from the Morris Water Maze? 8.Where is the hippocampus located? What are the major neurons and areas of the hippocampus? How are they connected to each other?
can you answer these?
1.What is the posterior pituitary and how does it differ from the anterior pituitary? 2.What are the functions that oxytocin regulates? 3.What does maternal behavior look like in rats and how does it change with experience? 4.What are the effects of manipulating oxytocin signaling on maternal behavior? 5.What are the functions that vasopressin regulates? 6.What are the major differences between prairie voles and montane voles in their brains and in behavior? 7.What does manipulation of vasopressin do to courtship behavior in male voles?
can you answer these?
1.What is the role of the Lateral hypothalamus (LH), Ventromedial hypothalamus (VMH), and Arcuate nucleus in controlling hunger and satiety? 2.What is the role of NPY/AgRP and POMC/CART neurons in the arcuate in controlling hunger? 3.Where is ghrelin, orexin, PYY, and leptin made and what factors regulate their level of synthesis? 4.What is the effect of ghrelin, orexin, PYY, and leptin on feeding behavior? Where do they act in the brain? 5.How does mutations in leptin signaling affect weight gain? How would a mutation for leptin differ from a mutation for leptin receptor? 6.What is taste aversion? 7.What is anorexia?
can you answer these?
1.Where is the hippocampus located? What are the major neurons and areas of the hippocampus? How are they connected to each other? 2.What is neurogenesis? Where does neurogenesis happen in the hippocampus? How are new neurons identified? 3.What is the relationship of hippocampal activity to space? 4.What are sharp-wave ripples? 5.What are the major findings of Patient HM? 6.What is the role of Prefrontal Cortex (PFC) in working memory? 7.What is an "engram" and where is it stored?
obesity
A disorder characterized by being excessively overweight. Obesity increases the risk for health issues like cardiovascular diseases, diabetes, hypertension, arthritis, and back problems.
does vasopressin plays a major role in aggressive behavior in male mice?
A mouse line with a mutated form of the vasopressin receptor (Avpr1b) is much less likely to show aggressive behavior. When the receptor is genetically added to the hippocampus, aggressive behavior is significantly recovered.
Hippocampus
A neural center located in the limbic system that helps process explicit memories for storage.
how does olfaction affect maternal behavior
A very famous lesion study showed how each of these regions plays a role in controlling maternal behavior. They lesioned either the olfactory bulb (OB), the vomeronasal organ (VN), or both regions together (VN-OB; VN + was a partial lesion of OB in virgin females and compared them to "sham" control groups, which had surgery but no lesion. Once recovered from surgery, each female was presented with foster pups. They found that lesioned females were more likely to show maternal care to the foster pups than the intact females. This shows that the olfactory system is necessary for inhibition of onset of maternal behavior in female rats.
What are the two main neurotransmitters used in the autonomic nervous system?
Acetylcholine (ACh) Norepinephine (NE)
Delayed Non-Match to Sample Task
After observing Patient H.M., scientists began lesion experiments to test hypotheses about the roles of specific parts of the temporal lobe in memory function. Delayed non-match to sample task is commonly used to test recognition memory: 1.Monkey learns to pick up an object to retrieve a treat beneath. 2.After getting a treat, the table is hidden for a short period. 3.When the table is shown again, it has two objects. a)'Match to sample' trial -> animal must pick the same item as before. b)'Non-match to sample' trial -> animal must choose the new object. Increasing the length of the delay makes this task harder
What are the two categories of hypothalamus functions?
Basic physiological needs and emotional and motivated behaviors
Medial Temporal Lobe Lesions dramatically impair animals' ability to perform the delayed non-match to sample task
Control monkeys (no lesion) learn the delayed non-match to sample task well (~90% correct choices even long delay). Monkeys with bilateral medial temporal lesions (akin to what was done to H.M.) show severe deficits, especially when the task is more difficult with long delays. This behavior suggests that the animals forgot the sample stimulus, especially with increasingly longer delays.
what is the first step in the hypothalmic-pituitary-adrenal (HPA) axis?
Corticotropin releasing hormone (CRH)
Vasopressin and oxytocin in dogs
Dogs with a history of aggressive behavior (case) have higher levels of circulating vasopressin than control dogs with no history of aggression. Dogs trained to be assistance dogs have higher levels of circulating oxytocin than pet dogs with no training for assistance.
Procedural Memory & habit learning
H.M.'s severe hippocampal lesion prevented him from forming new memories (part of declarative memory). His Episodic Memory was severely diminished but he still had Semantic Memory. Nevertheless, he was able to learn new habits and skills (even if he couldn't recall the process of learning/practicing those skills). Thus, H.M.'s procedural memory remained intact. Knowing the rules of Chess is an example of Semantic Memory
genetics and obesity
Identical twin studies reveal that body weight has a genetic basis.
In vivo recording of brain activity
Neuronal activity can be recorded by monitoring rapid changes in potential. This includes changes in potential just outside of the neurons. This is known as local field potential Multi-electrode array allows for simultaneous recording of local field potentials of 16 different places in the brain
Are both the anterior and posterior pituitary glands?
The anterior pituitary gland is an actual gland (as opposed to the posterior pituitary, which is essentially extension of the brain).
what is something the ANS and SMS do not have in common?
Unlike somatic motor system, ANS 'lower motor neurons' lie outside the CNS, within autonomic ganglia
what is the thalamus?
a 'relay station' that connects somatosensory system and motor system to the cortex.
what is the autonomic nervous system (ANS)?
a division of the peripheral nervous system that controls numerous involuntary physiological process of the body's internal organs, smooth and cardiac muscles
stress
a state of mental or emotional strain or tension resulting from demanding circumstances
declarative memory
ability to form memories of facts, events
what transmitter does the parasympathetic postganglionic neuron use?
acetylcholine (ACh)
retina input
also comes to the hypothalamus to contribute to circadian regulation.
mirror tracing tasks
assesses a person's procedural memory ability. •Uses visual & motor skills to learn a new motor skill •Task requires subject to trace the star while looking at hand only as a reflection in a mirror (panel A). •The task requires visual and proprioceptive feedback to control muscle movement. •Repeated trials à subject makes fewer errors, indicating learning has occurred. (Their brain forms a 'motor memory' of how to do the task). •Interestingly, H.M. could learn this task... although he couldn't recall doing the training...
posterior pituitary (neurhypophysis)
back portion; secretes the hormones oxytocin and vasopressin.
what are some body functions that fall under ANS control?
blood pressure heart rate digestion respiratory rate papillary response
what is something the ANS and SMS have in common?
both have 'upper motor neurons' that send commands to 'lower motor neurons'
how does chronic stress effect the brain?
chronic stress and cortisol treatment significantly reduces dendrite length in hippocampus, but recovery is possible (from a study)
anerexia nervosa
condition in which a normal-weight person (often an woman in teens to mid-20s) continuously loses weight but still feels overweight. Common symptoms: •Excessive weight loss •Self-starvation •Preoccupation with foods, progressing restrictions against whole categories of food •Anxiety about gaining weight or being "fat" •Denial of hunger •Consistent excuses to avoid mealtimes •Excessive, rigid exercise regimen to "burn off" calories •Withdrawal from usual friends
what does the autonomic nervous system do (ANS)?
controls all PNS-innervated tissues and body organs other than skeletal muscle
vagus nerve
cranial nerve 10, innervates: -Lung to constrict airways -Heart to slow heartbeat -Stomach to stimulate digestion -Pancreas to stimulate release of insulin and digestive enzymes -Small intestine to dilate blood vessels in gut
oculomotor neve
cranial nerve 3, leads to pupil constriction
facial nerve
cranial nerve 7, stimulated salivation
glossopharyngeal nerve
cranial nerve 9, stimulates salivation
Parasympathetic ANS
dedicated to long term bodily maintenance ('rest & digest').
what happens in the LH or VMH if lesioned or damaged
destroying th LH leads to and animal having no interest in eating destroying the VMH leads an animal to eat excessively (thereby developing extreme obesity)
Yerkes-Dodson law
dictates that performance increases with physiological or mental arousal, but only up to a point. When levels of arousal become too high, performance decreases.
sex divergence or latent sex difference
differences in endpoint only demonstrated under a challenging situation
Sexual dimorphism
different, separate endpoints
superior cervical ganglion
dilates pupils, inhibits salivation
taste adversion
eat something, have a bad experience, then don't try to eat it again
social behavior
encompasses a wide swath of behaviors whereby individuals interact with others and/or where individuals are required to interpret actions of others. ex: -Maternal/paternal behavior -Social interaction / exploration (with same-sex or opposite sex) -Courtship/ reproduction -Prosocial behavior (altruistic behavior intended to help others) -Aggression -Play behavior
sex difference
endpoint exists on a continuum and the averages differ between sexes
role of leptin
fat cells produce it and secrete it into the bloodstream, it works to suppress hunger by acting on receptors in the hypothalamus (e.g., arcuate nucleus)
leptin
fat cells release it and it decreases hunger
satiety
feeling of fulfillment or satisfaction
GnRH (gonadotropin-releasing hormone)
follicle-stimulating hormone (FSH) - production and maturation of gametes, production of estrogen luteinizing hormone (LH) -production and maturation of gametes, production of testosterone and estrogen
Conditioned learning
form of learning involving formation, strengthening, or weakening of an association between a stimulus
working memory
form of short-term memory where we temporarily hold information to guide decision making and behavior. •A key brain region involved in working memory function is the Prefrontal Cortex.
splanchinc nerve
from sacral spinal cord, innervates large intestine, bladdar, and reproductive organs
anterior pituitary (adenohypophysis)
front portion; secretes hormones that influence growth, sexual development, skin pigmentation, thyroid function and adrenocortical function (stress hormones).
What does the ANS innervate?
glands smooth muscle cardiac muscle
what in part drives sexual differentiation of the brain?
gonadal steroids early on in development, the male testes produce large quantities of testosterone. In the brain, the enzyme aromatase converts testosterone to estradiol (E2). The E2 acts on estrogen receptors to induce male-like changes to some brain areas
hypothalamus
has intrinsic sensory neurons (i.e. cells within hypothalamic regions that project to other hypothalamic nuclei) that respond to physiological stimuli, such as temperature, blood osmolality, or glucose.
working memory
hold and manipulate information in mind for seconds to minutes to achieve a goal
Immediate memory
hold ongoing experiences and information in mind for fractions of a second
What is the primary function of the hypothalamus
homeostasis. It uses hormones to coordinate autonomic, endocrine, and motor responses to fulfill the body's needs.
what are other experiences that impact maternal behavior?
how much maternal care offspring received in early life more licking and grooming when mother was a pup resulted in better maternal care from the mother to the new pups
where is GnRH synthesized
hypothalamus
arcuate nucleus
hypothalamus nuclei, contains and appetite controller governed by hormones, like insulin. relies on two sets of neurons with opposing effects: NPY/AgRP neurons and POMC/CART neurons, two main functions of these neurons: 1)Some projections stay in the arcuate and influence each other's activity. 2)Other projections leave the arcuate and make connections in other nuclei of the hypothalamus to modulate food intake, particularly: -Paraventricular nucleus (PVN) -Lateral hypothalamus (LH)
pyramidal cells
in the CA regions (CA1 and CA3); these are excitatory cells that use glutamate as a neurotransmitter
Where does ACTH circulate and what does it act on?
in the blood, acts on the adrenal grands to produce cortisol, epinephrine, and norepinephrine
where are preganglionic cells of the parasympathetic ANS located?
in the cranio-sacral regions (cransial nerve nuclei in the brain stem and sacral cord)
granule cells
in the dentate gyrus (DG)
grid cells
in the entorhinal cortex (EC), fire in a grid like pattern in a given area
place cells
in the hippocampus, fire at a particular place in an area
where are GnRH neurons located in primates and humans?
in the lower portions of the tuberal region of the hypothalamus
how does oxytocin stimulate uterine contractions
in the periphery, it induces uterine contractions to start labor or increase the speed of labor. because of this, if a women's labor is sluggish, they can be injected with synthetic oxytocin (pitocin) to stimulate or expedite labor
where are GnRH neurons located in rodents?
in the supraoptic region, primarily in the medial preoptic area
where are the preganglionic cells of the sympathetic ANS located?
in the thoracic-lumbar spinal cord
anterograde amnesia
inability to form new memories
collateral ganglia
innervates large intestine, bladder, reproductive organs
hunger
internal state of an animal seeking food
PPY
intestines release it and it decreases hunger
stress triggers the hypothalamus to secrete CRH where and what happens next?
into the anterior pituitary, these corticotropes then release adrenocorticotropic hormone (ACTH) into the blood stream
howcan bromodeoxyuridine (BrdU) be used?
it can be used to label newly synthesized data BrdU substitutes for thymidine in newly made DNA 1.Inject animals with BrdU, which incorporates into newly made DNA when cells are dividing. It washes out in about ~6hrs 2.Antibodies against BrdU will label DNA that contains BrdU. 3.BrdU will stay in daughter cells for the rest of that cell's life. This means you can birthdate a cell years later to the day!
vasopressin action in the brain
it influences certain types of behavior - particularly social bonding behavior. •Voles have been used to examine neurobiological factors that mediate social behavior (partner preference). •After mating, male and female voles display 'partner preference'. •Oxytocin mediates partner preference in female voles: -Infusing oxytocin (OT) into unmated female vole brain à partner preference (akin to what occurs post-mating). -Infusing an oxytocin receptor antagonist (OTA) into mated female vole brain BLOCKS partner preference. -Similar experiments in males had no effect. •Vasopressin mediates partner preference in male voles: -Infusing arginine vasopressin (AVP) into unmated male vole brain induced partner preference (akin to what occurs post-mating). -Infusing an AVP receptor antagonist into male mated vole brain BLOCKS development of partner preference. -Similar experiments in females have no effect.
What does the somatic motor system do (SMS)?
it innervates and controls skeletal muscle, voluntary movement
Is the hypothalamus comprised of sub-nuclei?
it is comprised of several sub-nuclei that each have distinct functions. These nuclei are can be grouped in three hypothalamic regions: 1. The Supraoptic region (anterior region that sits just above the optic chiasm) 2. The Tuberal region (middle region that sits above the infundibulum) 3. The Mammillary region (posterior region that sits above the mammillary body)
procedural memory
knowing how to do things (i.e. skills like riding a bike, learning a dance or how to play a musical instrument).
Interstitial nucleus of the anterior hypothalamus-3 (INAH-3)
larger in men than in women, and also perhaps larger in heterosexual men than in homosexual men
Parvocellular secretory cells
located in hypothalamus secrete hormones that travel to the anterior pituitary. These hormones trigger anterior pituitary cells to secrete hormones that are released into bloodstream to act on glands throughout the body.
retrograde amnesia
loss of memory prior to brain trauma
what does overexpression of Vasopressin receptors do to male montane voles (monogamus) and male prairie voles (promiscuous)?
makes male montane voles act more like male prairie voles
reciprocal projections
many brain regions that supply input hypothalamus get hypothalamic projections in return.
Estradiol treatment reduces cell death in the SDN-POA
masculinization of the SDN-POA is driven in part by estrodiol preventing loss of neurons via programmed cell death during the critical window
how is the stress response 'turned-off'?
negative feedback loop; cortisol can activate receptors in the hypothalamus to shut off this response •Cortisol circulates around the body and binds to corticoid receptors in the brain, including in the hypothalamus •This turns off secretion of CRH, and levels of overall cortisol in the body decrease
are there secretagogues in the posterior lobe of the pituitary
no
what brain region has control of appetite?
no single brain region has control of appetite but, the hypothalamus is important to regulation of metabolic rate, food intake, and body weight
What transmitter does the sympathetic postganglionic neuron use?
norepinephrine (NE), which often spreads far, even into the blood where it can circulate widley
posterior lobe, neurohypophysis
of the pituitary gland, is controlled by a different group of cells in the hypothalamus
what hormone promotes bonding of mother and child and maternal behavior?
oxytocin
maternal behavior and the role of oxytocin
oxytocin inducels a positive-feedback loop -> stimulating maternal care and social bonding, and, then -> positive feedback from experience promotes more oxytocin release 1. after giving birth, high oxytocin levels push a new mother to display maternal care 2. mother engaging in maternal care facilitates bonding with offspring 3. bonding enhances mom's oxytocin level further, -> promoting additional strong parental behavior 4. mother-offspring interactions stimulate offspring's oxytocin levels in short-term and can lead them to display high levels of parental care when they reach adulthood
What cells secrete corticotropin-releasing hormone and where are they located?
parvocellular cells of the paraventricular nucleus (PVN) of the hypothalamus in response to stress
Thalamus
sends some information to hypothalamus.
the role of oxytocin in social behavior
several forms of stimuli can trigger oxytocin release (olfactory, auditory, visual and physical stimuli) Through activation of oxytocin receptors in various parts of the brain, this peptide elicits a number of behavioral changes
Morris water maze task
spatial memory task for rodents 1.Rat is placed in a pool of cloudy water. 2.A small platform is submerged/hidden beneath the water. Once the rat finds it, the platform can be used to escape the water. 3.Normal rats quickly learn the platform location (based on visual cues in the room). They show reduced latency to find the platform with repeated trials.
ghrelin
stomach releases it and it increases hunger by stimulating NPY/AgRP neurons
Phineas Gage
suffered a lesion of the frontal lobe (particularly the prefrontal cortex) following a mining accident. Among his chief symptoms were difficulties with working memory, planning and organizing behavior.
Prefrontal cortex
supplies processed sensory information inform hypothalamic function.
what hormone organizes the developing brain to be more male-like?
testosterone
oxytocin
the 'love' hormone, important for social bonding and maternal behavior
what gene induces the biopotential gonad to turn into a testes
the SRY gene SRY promotes testicular formation, no SRY leads to female gonad development
what gene and on which chromosome induces testes development?
the SRY gene on the Y chromosome
Forgetting (disremembering)
the apparent loss or modification of information already encoded and stored in an individual's long-term memory. It is a spontaneous or gradual process in which old memories are unable to be recalled from memory storage. ) Different versions of the "heads" side of a penny. Despite innumerable exposures to this familiar design, few people are able to select the authentic version. Clearly, repeated information is not necessarily retained.
Neurogenisis
the birth, migration, and integration of new neurons into the adult brain
How does the brain decide whether to initiate eating?
the brain integrates insulin and blood glucose levels with other information to decide to eat
how does the anygdala help regulate the autonomic nervous system functions?
the central nucleus of the amygdala (CeA) contributes to parasympathetic outflow
where is neurogenisis in the hippocampus restricted to?
the dentate gyrus (DG)
satiety signals
As food fills the stomach. stretch receptors provide signals to hypothalamus. Other hormone from the gut and fat slow feeding. These signals are sent to the hypothalamus to indicate a feeling of fullness and satisfaction.
orexigenic signals
Blood glucose levels are monitored by receptors in the stomach, liver, and intestines. Hormones released from the gut act on the brain. These signals are sent to the hypothalamus to indicate hunger. Food seeking increases.
neurogenesis in the adult human hippocampus
Cancer patients were given BrdU to assess tumor growth. Years later, these patients died. Neurons with BrdU positive nuclei we found in the dentate gyrus. The adult human hippocampus is the only brain area known to undergo neurogenesis.
Hippocampal place cells are neurons that fire when an animal is located in a particular place in a familiar space
Each dot (and click noise) represents an action potential of a neuron. The different colors represent different locations on the multielectrode array, and thus different parts of hippocampus are active at different parts of the arena. Neurons selectively respond in particular places in the arena. Thus they are known as hippocampal place cells. Activity of hippocampal place cells can be arranged in the order of location as they travel through a maze. This suggests that activity rolls through hippocampus as they travel through space, which means that activity in the hippocampus represents a map. Hippocampal Place cells rapidly repeat the pattern of firing right before the begin the maze and the reverse pattern when they finish the maze This rapid repeat of the map activity is necessary for mice to maintain these memories. This repeat of activity is known as sharp-wave ripples.)
how do we form long-term memories?
Engram •Physical changes in brain wiring (D in efficacy of synaptic connections, growth / refinement of synaptic connections) to accommodate memory storage.
Types of memory
Memory can be categorized on timeframe for when it is retained and used: -Immediate memory -working memory -long-term memory
Congenital adrenal hyperlasia (CAH) females
Note that boys can be born with CAH, but that they tend to have problems with cortisol control. Also, like in CAH females their adrenals are making testosterone, but this is less of an issue because they are genetic XY. •Inherited genetic disorder •Patients lack 21-hydorxylase, an enzyme the adrenal glands use to produce adrenal hormones •Affects production of glucocorticoids, mineralocorticoids and androgens •Females with CAH are often born with enlarged clitoris •Majority of females with CAH identify as female, but 5% report gender dysphoria •About 5.8% have same-sex partners, and studies show that anywhere between 20-47% of CAH females have homosexual fantasies. •They have a tendency to show preference for "boy toys" and roughhouse behavior •Act like "tomboys", Draw like boys •Perform better on tasks that involve mental rotation
Testosterone and aggression/conflict
Students who had lived in the South for a period of at least 6 years were considered southern. The South was defined as census divisions 5, 6, and 7. This includes the states of Delaware, Maryland, West Virginia, Virginia, North Carolina, South Carolina, Georgia, Florida, Kentucky, Tennessee, Alabama, Mississippi, Arkansas, Oklahoma, Louisiana, and Texas. In this experiment students from Washington, DC and from towns we could identify as its immediate suburbs were excluded, because DC is probably not representative of either northern or southern culture. All other students were considered northern.
Where are long-term memories stored? Searching for the engram
Studies of H.M. showed that the hippocampus is critical for forming memories. But, many of his long-term memories (formed prior to surgery) remained in tact. This suggested that long term memory storage occurs elsewhere in the brain. Cerebral cortex is likely the major long-term repository for declarative memories. Rats received various sizes of cerebral cortical lesions (very slight à very large) à then evaluated ability to learn to run mazes of varying difficulty. Location of the cortical lesion didn't seem to affect memory function. Rather, extent of tissue destruction and difficulty of the task had the greatest effect on maze performance. This suggested that storing declarative memories depends on a distributed cortical network that is seriously impaired only when large portions of it are destroyed.
The striatum and procedural memory
Studying role of striatum in procedural learning. Rats trained to perform two types of the radial arm maze task. (A) Phase one: 'Standard Radial Arm Maze Task' where all arms are baited with food. This tests declarative memory; to efficiently obtain all food, the rat must remember which arms it explored and not repeat arms. Hippocampal lesions impair this task, but striatum lesions have no effect. (B) Phase two: modified Radial Arm Maze Task where lights illuminate above arms baited with food. Rats learned association of illuminated light + food; only go down those arms to retrieve food. (Learn procedure / habit to follow in order to receive the food reward.) This tests procedural memory; to efficiently obtain food, the rat must remember the habit/rule to follow: "enter only the lighted arms". Striatal lesions impair rats on this task, but hippocampal lesions have no effect.
Principle efferent (output) from hypothalamus
The hypothalamus has many reciprocal projections. Such projections include hypothalamic outputs to: •Prefrontal cortex, septum, cingulate cortex •Hippocampus •Amygdala •Periaqueductal gray •Brain Stem •Spinal Cord
What is the hypothalamus?
The hypothalamus is part of a brain region called the diencephalon. It is situated below the thalamus & is connected to the pituitary gland, which works together with the hypothalamus to control hormone release in the body.
obesity and mortality
The risk of death dramatically increases with progressively increased weight (BMI), particularly in men.
sensory factors affect maternal behavior
The orphaned pup 'concavetion' experiments showed that repeated exposure to rat pups can induce maternal behavior (both in virgin females and females that had prior maternal experience). An important stimulus that drives such behavior is the pups themselves: -Pups emit vocalizations to elicit care -Pups exhibit a certain smell, warmth (if healthy), which can induce care -Pups must also root around & push against a rat mother's belly to elicit her nursing crouch reflex.
oxytocin and social behavior
There are reports showing genetic variation of the oxytocin receptor that co-vary with empathy and anxiety. These genetic differences likely convey functional differences and appear to predict distinct behavioral phenotypes.
who is the most famous neuroscience case study that helped us to understand neurological mechanisms of memory?
patient H.M. he experienced severe epilepsy from age 10 onwards. his condition worsened with age, so at age 27, neurosurgeons removes a significant portion of his medial temporal lobe, including massive removal of his hippocampus H.M. exhibited deficits in a number of aspects of memory function: a)After his surgery, H.M. worked with some doctors for 50+ years to study the effect of his lesion. In spite of this long relationship, they had to introduce themselves to him every single time they met because he could not remember who they were. b)In general H.M. would forget events almost as quickly as they occurred. With repetition he could remember a number for a short time, but if he were distracted, he would forget the H.M. experienced deficiencies in declarative memory. Interestingly, other types of memory remained in tact for H.M. : •Procedural memory •Working memory
Pituitary Gland
pea-sized structure attached to base of the brain that is the body's main endocrine gland.
What stressors activate the hypothalmic-pituitary-adrenal (HPA) axis?
physical and psychological stressors
engram
physical embodiment of a long-term memory in neuronal machinery
what are the neurons in the autonomic ganglia called?
postganglionic neurons
what are postganglionic neurons stimulated by?
preganglionic neurons in the spinal cord or brain stem
What cells release ACh
preganglionic neurons in the sympathetic and parasympathetic divisions of the ANS
magnocellular secretory cells in the hypothalamus
produce and secrete the neurohormones oxytocin and vasopressin directly into the blood stream
NPY/AgRP neurons
produce neuropeptide Y (NPY) and agouti-related peptide (AgRP) to stimulate appetite and lower metabolism, promoting weight gain.
POMC/CART
produce pro-opiomelanocortin (POMC) and cocaine- and amphetamine-related transcript (CART) to inhibit appetite and raise metabolism, promoting weight loss.
Orexin
produced in lateral hypothalamus (LH) and it increases appetite and food intake by suppressing inhibitory post-ingestive feedback
reticular formation and nucleus of the solitary tract (brainstem region)
provide information re. arousal and visceral information
Vasopressin (antidiuretic hormone- ADH)
regulates blood volume and salt concentration of the blood. cells that make vasopressin sense changes in blood tonicity so they can release more vasopressin upon water loss. vasopressin increases water resorption in the kidney
the effects of temporal lobectomy
removal of the temporal lobe did not affect H.M's sensory perception, intelligence, or personality. however, the temporal lobe legion did produce profound and debilitating anterograde amnesia
long-term memory
retain information for days, weeks, or even a lifetime. Information that is very significant in intermediate or working memory can enter into long-term memory via rehearsal or practice (memory consolidation), although most is forgotten
how does the brainstem help regulate the autonomic nervous system functions?
the locis coerculus, rostral and caudal ventrolateral medulla and serotonergic cells of the pontine and medullare raphe contribute to sympathetic outflow
how does the hypothalamus help regulate the autonomic nervous system functions?
the paraventricular nucleus (PVN) is especially important, it projects to the brainstem to influence autonomic outflow
Principal neurons and their dendritic arbors in the hippocampus
three major cell types in the hippocampal formation: -pyramidal cells -granule cells -local circuit interneurons
Local circuit interneurons
throughout all regions (generally these are inhibitory neurons that use GABA)
true or false: much of the autonomic nervous system function operates by visceral reflexes
true. Subconscious sensory signals from visceral organs enter spinal cord, brainstem or hypothalamus -> triggers subconscious reflex back to visceral organ to control activity. ex: baroreceptor reflex •Baroreceptors are located in the carotid sinus and aortic arch. •When they detect too much (or too little) stretch (due to elevated or decreased blood pressure, respectively), signals -> brainstem. •A descending signal travels back down -> sympathetic nervous system (via the vagus nerve) •This signal regulates blood pressure by controlling heart rate, strength of heart contractions, and diameter of blood vessels.
classical conditioning
two stimuli are repeatedly paired; a response first elicited by the second stimulus -> eventually elicited by the first stimulus alone Most famous example of classical conditioning is Pavlov's dog experiments. Before conditioning occurs, dog is exposed to: 1)Unconditioned stimulus (US) - sight or smell of food, 2)Conditioned stimulus (CS) - a ringing bell. Seeing/smelling the food à salivation (unconditioned response - UR) Hearing the bell -> nothing at first With training (conditioning), the bell (US) was repeatedly paired with food presentation (CS). After this conditioning period, CS alone (bell) could elicit salivation response (now called the 'conditioned response' - CR).
operant conditioning
type of learning where behavior is controlled by consequences (i.e. positive reinforcement increases probability of certain behavior whereas negative reinforcement decreases probability of a behavior) learning to associate a particular act/operation with a particular consequence (could be a positive outcome such as reward or a negative outcome, such as a foot shock). B.F. Skinner's experiments taught pigeons to lever press for food reward. This approach is widely used in many types of animals in a test apparatus often referred to as a "Skinner box" (shown at left with a rat). The 'Skinner box' is outfitted with various environmental cues (lights, sound-producing speakers) as well as a device to activate (such as a lever). •Experimental animals may initially press the lever by accident. •After multiple experiences of pushing the lever and receiving a reward à animals begin to form an association between the two events (i.e. "hey, pressing this lever gets me food; Cool!"). •Consequently, they will increase the probability of pressing the level to receive more reward.
Sympathetic ANS
usually most active during crisis (real or perceived), mobilizing energy stores, preparing an organisms for 'fight-or-flight' reactions.
Cognitive differences between men and women
women tend to preform better at word-related tasks, men tend to preform better at spatial and metal rotation tasks
Delayed response task
working memory task used in non-human primates (modified versions in rodents).
Does hippocampal legions interfere with spatial memory?
yes
Is running just as effective at increasing neurogenesis in the hippocampus as an enriched environment?
yes
can experience enhance neurogenisisn in the hippocampus?
yes more huppocampal neurons in adult mice living in enriched environment then in a standard cage
the neurobiology of the stress response
•Acute increases in cortisol is important to instigate actions, such as fight-or-flight. However, chronic stress/elevated cortisol can elicit adverse effects: -Hypertension, cardiovascular disease -Immunosuppression -Insulin resistance -Emotional disorders (anxiety, depression)
therapeutic use for ghrelin?
•Because of observations of altered ghrelin levels (and ghrelin function) in obese individuals, the idea of blocking ghrelin signaling with GHS-R antagonists is of interest as a means of preventing obesity. •It has been demonstrated that vaccinating rats against ghrelin can reduce weight gain. •It remains to be shown whether blocking ghrelin signaling is a viable long-term obesity therapy for humans. •Ghrelin agonists might be useful in the treatment of specific patient groups with anorexia. Interestingly, ghrelin levels can also be influenced by environmental factors... such as how much (or little) sleep an individual typically gets.
examining mating in two species of voles: •Prairie vole (monogamous) vs. •Montane vole (promiscuous)
•Besides distinct social/mating behaviors, Montane vs. Prairie voles exhibit disparate patterns of oxytocin and vasopressin receptors in brain. •This finding suggests that oxytocin/vasopressin differences underlie their distinct social behaviors.
emotional influences on eating
•Food sensory input can activate the brains 'Reward' system as well as 'Disgust' system •Negative emotions: -Fear, sadness, anger can disrupt eating -Sometimes increases and sometimes decreases eating
hormones that affect maternal behavior-oxytocin
•In this experiment, virgin females received injections into their brain of either oxytocin (OXY) or a control substance (EB-only). •Within one hour, oxytocin-treated rats were more likely to display maternal behavior. •OXY treated rats had a shorter latency to show maternal behavior. Blocking oxytocin action by injecting oxytocin antagonists into the brain can impede maternal behavior: •Increasing latency to retrieve pups and decreasing # of pups retrieved •Decreasing time a mother spends performing pup-related behaviors •Increasing time mother engages in non-maternal behaviors (like exploring her cage). Mice that have a genetic deletion of the oxytocin receptor will show deficient maternal care (here showing high levels of pup abandonment).
fat cells number and size
•Increases in adipose tissue occurs in two ways: 1.Fat cell hypertrophy (get larger in size) 2.Fat cell hyperplasia (increase in amount of cells)
Testosterone "organizes" the developing brain to be more male-like
•Lesion of the SDN-POA in male rats. These lesions are hard, and there is variation in how much of the SDN-POA gets destroyed. Thus, in this study the categorize them with SDN-POA destroyed > 50% and < 50%. •They let animals recover and present them with females. •They observed a series of sexual behaviors from the males. Lesioned males showed lower frequency of sexual behaviors. •The graph on left shows the median amount of time it took before ejaculation occurred in 30 min (1800 seconds) with a female. The median value for lesion groups was 1800, which means ejaculation did not occur.
the arcuate nucleus and PYY
•NPY/AgRP neurons produce neuropeptide Y (NPY) and agouti-related peptide (AgRP) to stimulate appetite and lower metabolism, promoting weight gain. •POMC/CART neurons produce pro-opiomelanocortin (POMC) and cocaine- and amphetamine-related transcript (CART) to inhibit appetite and raise metabolism, promoting weight loss. •PYY, acts mainly by inhibiting NPY/AgRP neurons (reducing appetite, which is in opposition to effects of ghrelin).
the arcuate nucleus and leptin
•NPY/AgRP neurons stimulate appetite and lower metabolism, promoting weight gain. •POMC/CART neurons inhibit appetite and raise metabolism, promoting weight loss. •Leptin activates POMC/CART neurons and inhibits NPY/AgRP neurons, so leptin works to suppress hunger. •Leptin's effects on the arcuate are long-lasting.
role of PPY
•Peptide Tyrosine Tyrosine •Small peptide produced by the small intestine •from cells in the ileum and colon •Has low baseline levels that increase quickly when eating •Increased PYY levels -> decrease appetite •High doses of PYY have been reported to cause conditioned taste aversion in animals and nausea in humans. •Receptors located in the arcuate nucleus and vagus nerve input to the brainstem
ghrelin
•Peptide hormone released from cells in the stomach •Increases during fasting and decreases after a meal •Increased ghrelin levels -> produce increased appetite •Receptors located in multiple brain areas: arcuate nucleus, lateral hypothalamic area, nucleus accumbens, ventral tegmental area •Treating rats with ghrelin acutely stimulates food intake and growth hormone release; chronic ghrelin administration causes weight gain. •Intravenous infusion or subcutaneous injection of ghrelin to humans increases feelings of hunger as well as food intake. •Obese individuals •have low baseline levels •levels do not drop after a meal so no signal for "just ate a meal"
cognitive influences on eating
•Sensory (Taste & Odor, Visual aspects) •Memory •Early childhood eating habits •Food preferences generally •Cultural influences
the lateral hypothalamus (LH)
•Stimulating the lateral hypothalamus (LH) brings on hunger. •Low blood glucose levels -> stimulates the LH to produce / release the hormone orexin, which triggers eating.
the ventromedial hypothalamus (VMH)
•Stimulating the ventromedial hypothalamus (VMH) depresses hunger.
Complete androgen insensitivity syndrome (CAIS)
•They are genetic males (XY chromosome), but they have a mutation in the androgen receptor. •CAIS individuals are phenotypically female and identify as female •They have testes that are either internalized or located in the labia. They have a shallow vagina but no ovaries. •They develop breasts/hips at puberty •Reproductively infertile •Low percentage body fat, no body odor, no secondary hair growth, no acne
