AP Psych Unit 1: Biological Bases of Behavior

Epigenetics is

the study of the effect of nurture on nature

The nervous system can be divided into

central nervous system - Brain and spinal cord

peripheral nervous system - all nerves outside of brain and spinal cord

The peripheral nervous system can be divided into

autonomic nervous system - involuntary functions

somatic nervous system - communicates sensory information through sensory neurons to the CNS and sends movement information from CNS to glands and muscles through motor neurons

Afferent vs Efferent

Sensory neurons, or afferent neurons, send signals to the brain (arrive at the brain).

Motor neurons, or efferent neurons, send signals from the brain (exit from the brain).

The autonomic nervous system can be divided into

sympathetic nervous system - controls fight-or-flight response

parasympathetic nervous system - “rest and digest”, calms the body after fight-or-flight

What is a neuron and what does it do?

Neurons are the building blocks of the nervous system, sending and receiving messages.

What are the parts of the neuron and how do signals move along these parts?

1. Dendrites branch out from the soma and receive signals to pass to the soma.

2. The soma is the body of the neuron, containing the nucleus. It decides what signals to send.

3. The axon carries the action potentials to the terminal. Some axons have a fatty myelin sheath which protects and insulates the axon, speeding up signals.

4. The axon terminal has terminal buttons where neurotransmitters can pass through the synapse/synaptic gap to other neurons.

5. When enough neurotransmitters lock into the dendrite of the postsynaptic neuron, the neuron fires.

All or none law

When it reaches the firing threshold due to neurotransmitters locking into its dendrites, the neuron fires once and at the same intensity each time.

What makes a neuron fire? Explain the process of depolarization

An inactive neuron is polarized and at resting potential (-60 mV).

When it releases an action potential down the axon, depolarization is caused by the change in electricity and creates a positive charge inside the neuron (+30 mV).

Refractory period

a very brief period immediately after firing when the neuron can’t fire again

Reuptake

The process of reabsorbing neurotransmitters in the synapse.

Two types of neurotransmitters and list 8 of the main ones

Excitatory - increases neurotransmitter activity (makes the next neuron more likely to fire)

Inhibitory - decreases neurotransmitter activity (makes the next neuron less likely to fire)

Glutamate, GABA (gamma aminobutyric acid), acetylcholine, dopamine, endorphins, epinephrine/adrenaline, norepinephrine, serotonin

Glutamate

the most abundant excitatory neurotransmitter

enhances memory by strengthening synaptic connections

GABA (gamma aminobutyric acid)

the most abundant inhibitory neurotransmitter

associated with various anxiety-related disorders

Acetylcholine + 1 related disorder

primarily excitatory

required for any physical movement, involved in learning and memory

Alzheimer’s disease is associated with low ACh activity

Dopamine + 2 related disorders

linked to pleasure and reward

involved in movement, attention and learning

Parkinson’s is associated with lack of dopamine. Schizophrenia is associated with excess dopamine.

Endorphins

natural painkiller, can create euphoric feelings

Epinephrine/Adrenaline

boosts energy, primary chemical in “fight-or-flight”

Norepinephrine/noradrenaline + 1 related disorder

involved in arousal, alertness, and heightened sensitivity to surroundings

heavily involved in sleep cycle

Depression is associated with low norepinephrine.

Serotonin + 1 related disorder

involved in mood, appetite, sleep, dreams

Depression is associated with low serotonin.

What do psychoactive drugs do? Two categories

Influence neurotransmitter activity, can lead to tolerance, physical dependence, and withdrawal

Agonists increase activity. Antagonists decrease activity.

Agonists + 5 Examples

Direct agonists mimic neurotransmitters to bind with receptors.

Heroin - endorphin, nicotine - acetylcholine, black widow venom - ACh

Indirect agonists block neurotransmitter reuptake (reuptake inhibitors).

Prozac - serotonin, cocaine - dopamine

Antagonists + 2 Examples

Antagonists inhibit neurotransmitter activity, often by binding to receptors to block the active site or by preventing the release of neurotransmitters.

Botox - ACh, Thorazine - doparmine

4 main categories of psychoactive drugs and examples

Depressants - slow/inhibit the CNS (alcohol - GABA agonist)

Opiates/opioids - endorphin agonists (heroin, oxycodone, fentanyl)

Stimulants - increase activity in the sympathetic nervous system (caffeine - adenosine antagonist which stimulates dopamine release, cocaine)

Hallucinogens/psychedelics - alters mood/thinking and creates sensory and perceptual distortions (THC/tetrahydrocannabinol)

4 parts of the Hindbrain

1. Medulla oblongata - located in brainstem, vital to survival functions and autonomic functions (heart rate, breathing, blood pressure)

2. Pons - connects the brainstem and cerebellum, coordinates movements on each side of body, involved in sleep

3. Reticular formation/reticular activating system (RAS) - set of nerves running through medulla and pons, vital in survival functions (attention, arousal, alertness)

4. Cerebellum - coordinated sequences of movement, balance and equilibrium, implicit memory

What is the midbrain?

Nerve system connect higher and lower portions of the brain

Relays information between brain, eyes, and ears

Helps integrate visual and auditory senses

What is the limbic system? + four parts

A set of structures in the forebrain, involved in emotion, motivation, learning, and memory

1. Thalamus - located in center of brain, receives and sorts sensory information (except olfactory) and sends to other parts for interpretation

2. Hypothalamus - small area under thalamus, involved in regular functions like “fight-or-flight”, feeding, fornication

3. Amygdala - two small almond-shaped structures, involved in emotions like aggression/fear/anger, involved in highly emotional memories

4. Hippocampus - converts short-term memory to long-term, processes declarative and spatial relationship memory

What is the cerebral cortex? + 4 lobes and parts

The outermost layer of the brain

Each hemisphere has four lobes

1. Frontal - prefrontal cortex (high-level cognitive functions), primary motor cortex (voluntary movement)

2. Parietal - somatosensory cortex (sense of touch, contralateral)

3. Occipital - primary visual cortex (sense of sight)

4. Temporal - primary auditory cortex (sense of hearing), auditory association cortex (integrates auditory perception)

Two areas of the brain for language + related disorders

The two hemispheres are mostly mirrored except these areas

1. Broca’s area - frontal lobe, creating expressive speech

2. Wernicke’s area - temporal lobe, understanding language

Damage to either area can cause Broca’s aphasia/expressive aphasia or Wernicke’s aphasia

Brain lateralization

Some brain functions are lateralized to either hemisphere, such as language

Long-term potentiation (LTP)

A type of structural neuroplasticity that causes neutral pathways to physically change and become more efficient when a neuron network fires repeatedly.

6 types of brain scan technology

1. Computerized Tomography (CT) - X-ray images combine to show detailed body structures

2. Magnetic Resonance Imaging (MRI) - magnetic fields and radio waves show detailed anatomy

3. Functional MRI (fMRI) - detects changes in blood flow and oxygen levels

4. Electroencephalography (EEG) - electrodes on scalp record electrical activity

5. Positron Emission Tomography (PET) - detects radioactive glucose tracer in active brain areas

6. Magnetoencephalography with Source Imaging (MSI) - measures magnetic fields produced by brain activity to pinpoint brain function

4 Stages of the Sleep Cycle

When awake - beta waves

1. NREM 1 - alpha waves, 10 min, Brain still active and response to sensation

2. NREM 2 - theta waves

3. NREM 3 - Delta waves, deepest sleep stage, night terrors, somnambulism

4. REM - beta waves, brain active like when awake, large muscles paralyzed, memory consolidation

NREM recovers the body, REM recovers the mind

3 Sleep Theories

1. Restoration theory - restore energy, hormones, and neurotransmitters during NREM; growth and development occurs; repair muscles and brain tissue; deplete accumulated chemicals (adenosine, cortisol)

2. Memory consolidation theory (cognitive or information processing theory) - memory consolidation occurs during REM

3. Energy conservation theory - survival tactic that saves energy and minimizes risks

Sigmund Freud’s Dream Theory

Manifest content - you are consciously aware of

Latent content - hidden meaning

Dreams are a product of the unconscious mind.

Activation-Synthesis Model/Biological & Information Processing Theories

Dreams help with memory consolidation

3 Sleep disorders

1. Insomnia - inability to fall asleep or stay asleep (for at least a couple weeks)

2. Sleep apnea - trouble breathing, snoring, not feeling rested

• Obstructive sleep apnea, central sleep apnea, complex sleep apnea (both)

3. Narcolepsy - genetic, uncontrollable “sleep attacks”

Absolute Threshold

minimum amount of stimulus required to detect a sensation 50% of the time

Difference Threshold and Weber-Fechner Law

minimum difference/change between two stimuli required to detect the change

In order to notice the difference, the stimuli must differ by a constant percent rather than a constant amount.

Sensory Adaptation vs Habituation

Sensory adaptation is decreased sensitivity to constant stimuli.

Habituation is decreased response to constant stimuli (the stimuli is still detected).

Parts of the Eye + 1 Disorder

The lens in the front focus images onto the fovea, which is the center of the retina, the back of the eye.

Cones concentrated around the fovea detect color and detail. Rods spread over the retina detect light intensity and can work in dark environments. These are photoreceptors.

Ganglion cells receive the final visual output from the retina. Their axons form the optic nerve, which connects to the brain. Because there are no receptor cells where the optic nerve leaves the eye, there is a blind spot there.

Color blindness is the inability to detect color(s), often due to malfunction of cone cells.

Two Color Theories + Afterimage

Trichromatic theory - Three types of cones (S-cone for blue, M-cone for green, L-cone for red) fire at ratios which the brain interprets as different colors.

Opponent processing theory - Colors are processed in pairs (red-green, yellow-blue, black-white) and detecting one color inhibits the other in the pair.

• Afterimages occur when neural circuits processing certain colors are overloaded, causing a color “rebound”.

Parts of the Ear (Outer, Middle, Inner)

Outer - pinna focuses sound into ear hole, ear canal carries sound to ear drum

Middle - ear drum/tympanic membrane vibrates, the three ossicles attached to the ear drum (hammer/malleus, anvil/incus, stirrup/stapes) send the sound waves to the inner ear

Inner - fluid-filled cochlea contains the organ of corti and cilia on the membrane convert sound to nerve impulses

Sound Theories

1. Place theory - hair cells at the base of the cochlea detect higher pitches than hair cells near the top of the cochlea, so the brain determines pitch based on the location in the cochlea where the hair cells were activated

2. Frequency theory - auditory nerves fire at a rate corresponding to the sound wave

• Volley theory suggests that auditory nerves work together and fire in a staggered manner for higher pitches

Sound Localization

The brain can determine direction and distance of sounds through various cues, including auditory disparity (the difference in signals between the two ears).

2 Types of Deafness

Conduction deafness - sound can’t reach the inner ear due to malfunction in outer or middle ear

Neurological deafness/Sensorineural hearing loss - cochlea does not send the correct signals to the brain

Olfaction

There are hundreds of different olfactory receptor neurons in the mucus membranes of the nose. Their axons group at the olfactory bulb in the brain. The ratio for signals from the receptors determines what smell is perceived.

Smell bypasses the thalamus, unlike other senses.

Gustation

Thousands of papilla, bumps on the tongue, each have hundreds of taste buds. Taste buds have receptors that detect salty, sour, sweet, bitter, and umami. More than five tastes can be perceived due to interactions with the olfactory sense.

Embodied Cognition

The body helps the brain process information constantly, rather than just collecting information.

Kinesthetic awareness

Awareness of how the body moves and where each body part is

Vestibular System & Motion Sickness

Creates the sense of balance

Motion sickness is caused by disparity between the vestibular and visual senses.

Gate Control Theory of Pain

There is a limit to how much pain can go from the body to the brain. The spinal cord can control which pain signals get to the brain.