Biological Bases of Behavior Flashcards

The proportion of variation in a trait across a population that can be attributed to genetic differences. It describes groups, not how much of one person's trait is genetic.

Identical (monozygotic) twins share nearly all their genes and fraternal (dizygotic) twins share about half, so greater similarity between identical twins on a trait points to a genetic influence.

By comparing adopted children with their biological and adoptive parents, they help separate genetic influences (shared with biological parents) from environmental ones (shared with adoptive parents).

As the product of natural selection: behaviors that helped ancestors survive and reproduce were more likely to be passed on (e.g., a preference for sweet, calorie-rich food).

The endocrine system sends hormones through the bloodstream, which is slower than neural signaling but produces longer-lasting, more widespread effects.

Under the direction of the hypothalamus, it releases hormones (such as growth hormone) that regulate the other endocrine glands.

Epinephrine (adrenaline) and norepinephrine, which raise heart rate, blood pressure and blood sugar for fight or flight. They also release the stress hormone cortisol.

Oxytocin, released by the pituitary gland.

Melatonin, which rises in darkness and helps regulate the sleep-wake cycle.

Ghrelin, secreted by an empty stomach, signals hunger. Leptin, secreted by fat cells, signals fullness and reduces appetite.

A drug or chemical that mimics a neurotransmitter or increases its effect at the receptor (e.g., morphine mimics endorphins).

A drug or chemical that blocks a neurotransmitter from activating its receptor (e.g., curare blocks acetylcholine receptors and causes paralysis).

It stops the sending neuron from reabsorbing a neurotransmitter, so more stays in the synapse for longer (e.g., SSRIs and serotonin).

They slow neural activity and body functions (e.g., alcohol, barbiturates, benzodiazepines), often by enhancing the inhibitory effect of GABA.

They speed up neural activity and arousal (e.g., caffeine, nicotine, cocaine, methamphetamine), many by increasing dopamine and norepinephrine activity.

Drugs that distort perception and evoke sensory images without sensory input (e.g., LSD and psilocybin).

They act as agonists at the brain's endorphin receptors, depressing neural activity and dulling pain (e.g., morphine, heroin, fentanyl).

The need for larger and larger doses to get the same effect, as the brain adapts to the drug's presence.

The discomfort and distress that follow stopping an addictive drug, often the opposite of the drug's effects (e.g., fatigue and low mood after stopping a stimulant).

The body's roughly 24-hour biological clock that regulates sleep, alertness and temperature. Light resets it through the suprachiasmatic nucleus of the hypothalamus.

Large, slow delta waves. NREM-3 is the deepest stage, the hardest to wake from, and when most growth hormone is released.

The eyes dart, the brain is as active as when awake, vivid dreams occur and voluntary muscles are nearly paralyzed, which is why REM is called paradoxical sleep.

Dreams are the brain's attempt to make sense of random neural activity that the brainstem generates during REM sleep (Hobson and McCarley).

Sleep, including dreaming, helps the brain sort, strengthen and store the day's memories.

A sleep disorder with sudden, uncontrollable attacks of sleepiness, sometimes dropping the person straight into REM sleep.