Behavioral Neuro Exam 3

homeostasis

steady internal balance or equilibrium, maintenance of a constant internal environment

How does the homeostasis cycle work?

Balance is disturbed by biological needs (hunger and thirst), we are driven to fulfill those needs, need is satisfied and balance is restored

Motivation

activates and directs behavior toward a goal

What happens when homeostasis is compromised?

the nervous system first activates behavior by generating tension and discomfort in the form of drive states such as thirst and hunger

Relationship between surface-to-volume ratio and maintaining temperature

larger overall volume = more heat produced by metabolic activity = less energy to maintain body a constant temperature.

smaller overall volume = less heat produced by activity = more energy required to maintain constant body temp.

The role of ghrelin

Signals brain to stimulate appetite

How does ghrelin affect the body

Associated with the rewarding feeling that is associated with feeding, especially when food deprivation has been more severe.

Where is ghrelin found

pancreas and lining of the stomach

Where are ghrelin receptors found

the arcuate nucleus and the ventromedial hypothalamus

When are ghrelin levels highest ?

during fasting

When are ghrelin levels lowest?

after a meal

Function of the hypothalamus in regulating body temp

Acts as a precise thermostat.

Initiates compensation whenever core temperature deviates as little as 0.01 degrees from the ideal set point.

What happens if we experimentally alter the temperature of the hypothalamus itself?

Fever, hypothermia, heat stroke, hyperthermia

Body will respond to hypothalamus > external stimuli

How would you stimulate the release of water from cells in the body through osmosis?

increase salt/solute in exterior environment, causing water to move out of cells to balance solute concentrations.

What happens when you increase or decrease concentrations of sodium in extracellularfluid?

Water moves OUT of the cell.

Cell shrinkage.

What happens when you increase or decrease concentrations of sodium in intercelluarfluid?

Water moves IN to the cell.

Cell swelling.

What happens during hyponatremia?

Drinking too much water floods extracellular fluid faster than it can be excreted, resulting in a hypotonic solution. As a result of osmosis, water will leave the blood and enter the cells in an effort to equalize the concentrations, causing cells to swell and potentially burst.

Medical complications due to hyponatremia

Bloating, nausea, vomiting, cramps, disorientation.

Swelling of the brain can produce seizures, coma, and death.

How does neuropeptide Y (NPY) affect the body?

Initiates hunger and food seeking behavior, particularly during energy deficits.

How does orexin affect the body?

Stimulates wakefulness and increases food intake

What happens to metabolism when caloric intake is severely restricted?

Metabolism slows down as the body conserves energy, reducing the rate of calorie burning and promoting fat storage to maintain vital functions.

What is the mechanism for pyrogens in developing a fever?

they enter the brain in the preoptic area and reduce the firing rate of warm-sensitive neurons, which increases cold-sensitive neuron activity. This fools the system into thinking the body is too cold, and the hypothalamus responds by raising the temperature set point, causing a fever.

What does activity of cold-sensitive neurons lead to?

Greater production and retention of heat, increased heart rate, shivering, and other fever symptoms.

What is the function of aldosterone?

Signals kidneys to retain sodium rather than excrete it in urine.

Where in the body are glucagon and insulin produced?

In the pancreas

Glucagon

converts stores glycogen back into glucose

Insulin

helps store glucose as glycogen and assists in moving glucose from the blood supply into body cells.

What chemical is the main source of energy in the brain (used in PET scans)?

glucose

What is the role of leptin?

Regulates stored body fat.

When levels are high, feeding is suppressed.

How is the production of leptin different between humans and mice?

Obese humans produce substantial amounts and become resistant to it. Obese rodents are simply lacking the gene that allows for production, leading to missing feedback about high body fat and becoming obese.

Where would you find warm-sensitive cells in the brain?

Preoptic area (POA) of the hypothalamus, making up about 30% of the POA.

Where would you find cold-sensitive cells in the brain?

Posterior hypothalamus

Which biological gender produces more estrogens?

Females

What behaviors are associated with levels of oxytocin during pregnancy?

Maternal bonding behaviors such as gazing, affectionate touching of the infant, vocalizations, and positive mood.

Pair bonding.

What is the distinction between a Wolffian system and a Müllerian system?

One develops into female internal organs and one develops into male internal organs.

Wolffian system

develops into seminal vesicles, vas deferens, and prostate (male organs)

Mullerian system

develops into uterus, upper vagina and fallopian tubes (female organs)

Where is the SRY gene located?

It is found only on the Y chromosome.

what is special about the SRY gene?

It determines whether or not an embryo develops testes.

What are the chromosome configurations of Turner syndrome?

45,X

One X chromosome instead of the usual two.

What are the chromosome configurations of Klinefelter syndrome?

47, XXY

Males have an extra X chromosome.

What physical traits are correlated with prenatal androgen exposure?

Ambiguous external genitalia, engage in more male-interest play, more likely to report bisexual or lesbian, more likely to show interest in male-dominated fields.

What are the functions of the Luteinizing Hormone?

Signals male testes to produce testosterone

Regulates menstrual cycles

What are the functions of the Follicle Stimulating Hormone?

Stimulates development of eggs in the ovaries and sperm in the testes

What structure in the brain releases Luteinizing Hormone and Follicle Stimulating Hormone?

Anterior pituitary gland

What is the cause of Androgen Insensitivity Syndrome?

A defective gene produces abnormal androgen receptors. As a result, the fetus' tissues are blind to the presence of androgens.

What is the result of Androgen Insensitivity Syndrome?

Shallow vagina due to the wolffian system failing to develop. Lack of ovaries, fallopian tubes, or uterus.

What can trigger a fluctuation of testosterone production in men?

Anticipation of a competition / observing a competition

What information is contained in body odors that may signal attractiveness?

immune system information

Which hormone is correlated with romantic love?

oxytocin

Which hormone is correlated with sexual desire?

testosterone

EEG signals for the stage 1 of sleep

similar to awake EEG

theta rhythms

EEG signals for the stage 2 of sleep

Sleep spindles and K-complexes

Sleep spindles

short bursts of brain waves detected in stage 2 sleep (NREM)

K-complexes

a brief burst of brain activity consisting of single delta waves occurring during stage 2 NREM sleep, reflects the brain efforts to keep us asleep while continuing to monitor the external environment

EEG signals for the stage 3 of sleep

appearance of delta waves

awakening is difficult and disorienting

delta waves

largest, slowest, most synchronized waveform of the sleeping state

theta waves

characterize lighter stages of sleep, can serve as a signal for a severe need for sleep

EEG signals for the stage 4 of sleep

delta waves present about half the time

desynchronous neural activity

brain activity associated with independent action of many neurons and alertness

synchronous neural activity

brain activity associated with neurons firing in unison and deep sleep

What is the state of the raphe nuclei during REM?

Inactive

What is the state of the raphe nuclei during NREM?

Less active

What is special about RGC's that form the retinohypothalamic pathway?

They do not process information about visual images. They provide light information that is necessary to maintain circadian rhythms.

What happens during a phase shift?

Shift in activity in response to a synchronizing stimulus (e.g. light to dark)

how does jet jag demonstrate a phase shift?

Our bodies are used to going to bed at a certain time and waking up at a certain time, flying across the country shifts our bodies to different time zones.

Insomnia symptoms

trouble falling asleep, many awakenings + difficulty falling back asleep

What is REM sleep paralysis?

an inability to move muscles during REM sleep

Typical sleep cycle

Awake -> stage 1 -> stage 2 -> stage 3 -> stage 4 -> stage 3 -> stage 2 -> stage 1 / rem and all over again

Characteristics of a typical sleep cycle

Avg 7-8 hours

45-50% is stage 2

20% is rem

cycles last 90-110 mins

Early cycles consist of more stage 3 and 4

Later cycles consist of more REM

What is the role of serotonin in REM?

Highest during waking, drops off during NREM, and very low during REM.

Initiates and regulates

When is growth hormone released into the blood stream during sleep?

Stage 4

Which important hormone is released by the pineal gland in response to darkness?

melatonin

CLOCK

circadian locomotor output cycles

PER

period

TIM

timeless

Step one of CLOCK, PER, TIM cycle

lowest levels of per and tim activate clock which triggers the production of per and tim

*After dawn

Step two of CLOCK, PER, TIM cycle

Levels of per and tim rise

*Around noon

Step three of CLOCK, PER, TIM cycle

Higher levels of per and tim inhibit clock, resulting in decreased production of per and tim

*Mid afternoon

Step four of CLOCK, PER, TIM cycle

highest levels of per and tim, new production ceases

*After dusk

Step five of CLOCK, PER, TIM cycle

Per and tim disintegrate, levels start dropping

*After midnight, during sleep

What are the stimuli involved in the circadian rhythm?

Light, dark, external temp, food

What are the behaviors involved in the circadian rhythm?

sleep wake cycle, body temp, activity levels, cortisol secretion

The role of the suprachiasmatic nucleus in the circadian rhythm

Internal master clock

Maintains internal timing system (e.g., when to eat and sleep), which in turn maintains the circadian rhythm

What is the DMN?

The default mode network, or the normal brain pathway

when is DMN active?

when we are in a passive state, not focused on a particular task

When do sleep spindles and K-Complexes appear?

stage 2

Describe the developmental changes in sleep over the lifespan

As we grow older, we need less sleep.