Quiz #3: Unraveling Brain

Identify the brain regions used to assess risk and maximize net gains (by name and in a diagram).

the ventromedial prefrontal cortex is used to assess risk and maximize net gains

Utilize understanding of Iowa gambling task to analyze new patient cases of impulsivity.

patients with bilateral lesions of the ventromedial prefrontal cortex opt for choices that yield high immediate gains in spite of higher future losses (myopia for the future)

Distinguish impulsive action from impulsive choice (by definition and by the rat gambling task).

impulsive action: failure to inhibit an inappropriate response
- test whether rats touch screen prematurely

impulsive choice: impulsive decision-making by choosing small immediate rewards over more beneficial delayed rewards
- test rats' choice response preferences

Predict how risk-averse and risk-seeking rats perform on the rat gambling task.

risk-averse rats quickly develop a pattern of preference for P2 (display less impulsive choice)

risk-seeking rats do not stabilize a preference for P2 (display more impulsive choice)

Describe how drugs of abuse affect the mesolimbic pathway.

drugs of abuse trigger abnormally large surges of dopamine in the nucleus accumbens

Describe how the brain changes after repeated drug use.

- the brain enhances its reactivity to drug cues
- the brain reduces its sensitivity to non-drug rewards
- drugs interfere w/ the brain's capacity to exert self-control
- drugs render the brain more sensitive to stressful stimuli & dysphoria

Contrast stimulant-induced dopamine changes in long-time, active cocaine abusers from dopamine changes in normal controls.

stimulant-induced dopamine increases are blunted in active cocaine abusers, but cravings continue & are stronger in cocaine abusers than control

cocaine addicts crave more and more cocaine, seeking to regain lost dopamine signaling

Articulate how brain wave patterns change during sleep stages.

each sleep stage has representative brain wave patterns

go through cycle 4-5x a night (as you stay asleep longer, duration of REM sleep increases and onset of REM comes earlier)

stage 1: transition from waking to sleeping; irregular waves with occasional alpha waves

stage 2: transition from lighter to deeper sleep; sleep spindles (waves with alternating periods of calm and flashes of intense activity) appear

stage 3: deeper sleep; slow-wave sleep begins with EEG shows 20% of brain waves are delta waves

stage 4: deepest sleep; begins when 50% of waves are delta waves; about 40 minutes later, delta waves begin to disappear

REM sleep: shortly after the sleeper returns to Stage 1, REM period begins; sleeper may be easily awakened before and after REM period

Name the technique that is typically used to identify stages of sleep.

EEG

Distinguish brain regions which regulate sleep from brain regions which are observed by EEG.

EEG detects brain activity on the outer rim of the brain

sleep is regulated by the hypothalamus

Compare and contrast the circadian process and homeostatic process which regulate sleep.

circadian process: causes sleepiness at defined times in response to environmental cues (24 hr body clock)

homeostatic process: causes sleepiness in proportion to time spend awake (builds sleep drive the longer we're awake)

Recognize day-to-day signs of sleep deprivation.

- irritability
- cognitive impairment
- memory lapses/loss
- impaired moral judgment
- severe yawning
- hallucinations
- symptoms similar to ADHD
- impaired immune system
- increased heart rate variability
- risk of heart disease
- decreased reaction time & accuracy
- tremors
- aches

Describe how hippocampal place cell activation can be used to determine if memories are replayed during sleep.

place cells in the hippocampus are activated at specific places in a map

the order in which neurons are activated when the mouse crawls in the maze is the order in which neurons are activated during slow wave sleep

Identify which brain regions have sustained damage in patients in the vegetative state (by name and by diagram).

cerebellum & cortex

Distinguish the vegetative state, minimally conscious state, locked-in syndrome, coma, and brain death by the behavior exhibited by people in these states.

vegetative state: paradoxical combo of wakefulness without awareness
- exhibit sleep-wake cycles
- open their eyes in response to stimulation

minimally conscious state: wakefulness with minimal awareness & responsiveness
- sustain gaze at moving target
- reach for offered objects
- speak a few words
- express appropriate emotional reactions to stimuli

locked-in syndrome: full wakefulness & awareness but nearly completely paralyzed
- don't have any voluntary movement of limbs, face, throat, and horizontal eye movement
- can move eyes up and down and blink

coma: neither wakeful not aware
- immobile with eyes closed
- unresponsive
- in a transient/unstable state

brain death: irreversible loss of brain function

List 4 criteria used to diagnose people for total brain failure.

1. exclude reversible causes
2. no motor function
3. no brain stem reflexes
4. conduct apnea test (should not gasp for air)

List 2 tests that can be used to confirm total brain failure.

EEG measurement of brain activity

radioactive tracer to examine blood flow into brain (PET scan)

Describe how PET scans detect brain activity.

glucose tagged with radioactivity stays in parts of the brain that need more energy

Rank a young, old, and Alzheimer's brain for ventricle size and brain tissue volume.

ventricle size (largest --> smallest):
- someone w/ Alzheimer's --> elderly w/o Alzheimer's --> normal adult

brain tissue volume (largest --> smallest):
- normal adult --> elderly w/o Alzheimer's --> someone w/ Alzheimer's

Identify the initial brain areas affected in Alzheimer's disease, Huntington's disease, and Parkinson's disease.

Alzheimer's: gradual loss of brain structure & function, beginning with area around hippocampus

Huntington's: degenerated inhibitory neurons in cortex & striatum (brain region that neighbors & works with the substantia nigra)

Parkinson's: characterized by loss of dopaminergic neurons in substantia nigra

Describe how a person with Alzheimer's disease, Huntington's disease, or Parkinson's disease behaves.

Alzheimer's: living with memory loss & behavioral disturbances

Huntington's: characterized by chorea (jerky involuntary movements)

Parkinson's: PD patients exhibit resting tremor, postural instability, & gait disturbances

Name cellular events occurring in the brains of those affected by Alzheimer's disease, Huntington's disease, or Parkinson's disease.

Alzheimer's: characterized by extracellular amyloid beta plaques & intracellular tau tangles in neurons
- having APOE4 allele increases risk of Alzheimer's

Huntington's: mutant Huntingtin (Htt) protein aggregates in neurons

Parkinson's: display Lewy bodies & alpha-synuclein fibrils at the cellular level

Recall the mutations that occur on the DNA and protein level that cause Huntington's disease.

CAG repeats predict the disease
- CAG codes for Glutamine (Gln)
- 0 CAG repeats in protein (no CAG on protein level)