🧠 PSYCH100: unit 2

brain

primary organ of NS

spinal cord

a bundle of nerves that connect the brain to the body, contributes to movement

reflexes (involuntary)

pain hits spinal cord first, then to brain, brain creates feeling of pain

CNS

brain and spinal cord control everything

hypothalamus

Controls:

• hunger

• thirst

• body temperature

• sex drive

• hormones

• rewards

• homeostasis

Controls the pituitary gland.

Remember: Hypothalamus = keeping the body balanced.

hippocampus

helps protect explicit memories for storage

• Important for:

  • forming new memories

  • spatial memory

Damage → difficulty creating new memories.

cerebral cortex

control and info-processing center (perception, thinking, and language)

• ~22 billion neurons

ventricles

empty cavities (relative) in brain

neuroplasticity

existing neurons create new synapses

corpus callosum

• Large bundle of nerve fibers connecting the:

  • left hemisphere

  • right hemisphere

Allows communication between brain halves.

meninges

under bones, are membranes (thin many layers of tissue) that provide further protection for brain and spinal cord (like shrink wrap)

Weber’s law

The minimum difference needed to notice a change between two stimuli depends on the original intensity of the stimulus (a constant proportion, not a fixed amount).

Example:

• Easier to notice: 5 lbs → 10 lbs (100% increase)

• Harder to notice: 50 lbs → 55 lbs (10% increase)

Exam clue:
If they ask "which weight difference is easiest to detect?" → choose the one with the largest percentage change.

sensory neurons

carry info from outside/body back to CNS

motor neurons

carry CNS commands back to muscles & glands of body

interneurons

form bridges between sensory and motor neurons

brainstem

is the part of the brain containing the midbrain, pons, and medulla

• Directly branching is cranial nerves

medulla

is a brainstem structure located just above the SC

• like SC, contains large bundles of nerve fibers traveling to + from higher levels of brain

• Part of the hindbrain.

• Controls basic life functions:

  • breathing

  • heart rate

  • blood pressure

  • swallowing

Remember: Medulla = keeping you alive.

pons

are a part of the brainstem location between medulla and midbrain. Part of the hindbrain.

• “Bridge” between higher and lower portion of brain; especially connects cerebellum to rest of brain

• Coordinates movement and sleep

• Paralyze body while sleeping

• Helps regulate:

  • sleep

  • breathing

  • arousal

  • facial expressions

Remember: Pons = "bridge."

midbrain

part of brainstem between pons and cerebral hemispheres 

• Arousal, pain, temperature regulation

reticular formation

Network of neurons running through the brainstem.

• Controls:

  • arousal/alertness

  • mood

  • attention

  • consciousness

  • sleep-wake cycle

Remember: Reticular formation = "on/off switch" for arousal.

action potential

the electrical charge that travels down the axon of a neuron

resting potential

the neuron's resting electrical state when it is not firing. the inside of the neuron is more negative than the outside.

reuptake

molecules of neurotransmitter in the synaptic gap are returned to the axon terminal from which they were released

bottom up processing

starting with the sensory information and building up to a perception

Data-driven (your brain uses what it sees/hears first)

top down processing

using your past experiences, knowledge, expectations, and context to interpret sensory information

Concept-driven (your brain uses what it already knows)

PNS

Pathways that carry messages (nerves outside CNS; connects the body to CNS)

when nerves leave the protection of the skull or vertebral column and branch into the body, they are part of the PNS.

nerves

bundles of axons

axon

long part of the neuron that carries signals away from the cell body to other neurons, muscles, or glands

• “Sends” messages

Axon = Away

dendrites

Branch-like parts of a neuron that receive signals from other neurons and carry them toward the cell body.

• “Detect” incoming info

Dendrite = Detect incoming info

myelin sheath

a fatty protective covering around the axon that insulates it and speeds up nerve signal

“Makes it faster”

Myelin = myelin makes messages move faster

monism

Mind (consequences of brain activity) = brain (physical mass), no way to separate them

the mind is the result of brain activity

sensation

the process of detecting environmental stimuli or stimuli arising from the body.

perception

the process of interpreting sensory information.

transduction

the translation of incoming sensory information into neural signals.

sensory adaptation

the tendency to pay less attention to a nonchanging source of stimulation.

psychophysics

the study of relationships between the physical qualities of stimuli and the subjective responses they produce

absolute threshold

the smallest amount of stimulus that can be detected.

difference threshold

the smallest detectable difference between two stimuli.

vision

the sense that allows us to process reflected light.

cornea

bends/refracts light toward the retina.

pupil

forms an opening/hole in the iris that allows light into the eye

iris

colored part controls pupil size and amount of light entering

retina

contains rods, cones, and other visual neurons in its layers of cells. converts light into neural signals

lens

adjusts shape to focus light onto the retina.

rods

photoreceptors for dim light, black and white vision, peripheral vision

cones

photoreceptors for color vision, bright light, detailed vision

fovea (area of the retina)

processes best detailed vision. center area of the retina, contains many cones.

optic nerve

carries visual information from retina to brain.

optic tracts

pathways carrying visual information after the optic chiasm to the brain.

trichromatic theory (Young-Helmholtz theory)

We have three types of cones:

• red

• green

• blue

Different combinations create all colors.

opponent process theory (Hering)

Colors are processed in opposing pairs:

• red ↔ green

• blue ↔ yellow

• black ↔ white

Explains:

• afterimages

• why you cannot see "reddish-green"

depth perception

Ability to perceive distance and 3D space.

Uses:

• binocular cues

• monocular cues

retinal disparity

A binocular depth cue.

• Each eye sees a slightly different image.

• Brain compares differences to judge distance.

Closer objects = bigger difference between eyes.

primary visual cortex (area in occipital lobe)

• Located in the occipital lobe.

• First cortical area that processes visual information.

cochlea

the structure in the inner ear that contains auditory receptors.

basilar membrane

• Structure inside the cochlea.

• Vibrates differently depending on sound frequency.

Important for pitch perception.

organ of Corti

• Contains hair cells.

• Converts sound vibrations into neural signals.

somatosensation

Sense of the body:

• touch

• pressure

• temperature

• pain

• body position

gate theory of pain

Pain signals can be increased or blocked by a "gate" in the spinal cord.

• Touch signals can reduce pain signals.

Example:
Rubbing an injured area can decrease pain.

auditory nerve

nerve carrying sound information from the cochlea to the brain.

vestibular system

the system in the inner ear that provides information about body position and movement.

olfaction

the sense of smell

gustation

the sense of taste

papillae

small bumps on the tongue that contain taste buds.

taste bud

a structure found in papillae that contains taste receptor cells.

olfactory nerve

• Cranial nerve responsible for smell.

• Carries odor information from nose to brain.

olfactory bulb

• Brain structure that first processes smell information.

Important: Smell is the only sense that does not first go through the thalamus.

pinna

• Outer visible part of ear.

• Collects sound waves and directs them into ear canal.

tympanic membrane

(Eardrum)

• Vibrates when sound waves hit it.

• Transfers vibrations to middle ear bones.

sympathetic NS

fight or flight

Activates body during stress:

• increases heart rate

• dilates pupils

• releases energy

parasympathetic NS

rest and digest

Calms body:

• slows heart rate

• promotes digestion

• conserves energy

enteric NS

Controls:

• digestive system

• movement of intestines

• digestion processes

Sometimes called the "second brain."

endocrine system

System of glands that releases hormones into the bloodstream.

Controls:

• growth

• metabolism

• stress responses

• reproduction

glia

Support cells for neurons.

Functions:

• protect neurons

• provide nutrients

• remove waste

• create myelin

cell body

Main part of neuron containing:

• nucleus

• organelles

Maintains the neuron's life.

somatic NS

Controls:

• voluntary movements

• skeletal muscles

• sensory information from skin, muscles, joints

Example: Moving your arm.

autonomic NS

Controls automatic body functions:

• heart rate

• digestion

• breathing rate

• glands

Divided into sympathetic and parasympathetic.

amygdala

fear, emotion, aggression

prefontal cortex

Front part of frontal lobe.

Responsible for:

• impulse control

• planning

• judgment

• personality

• complex decision-making

cerebellum

Cerebellum

• Located at the back of the brain.

• structure attached to the brainstem

• Responsible for:

  • balance

  • voluntary movement

  • judgment of time

  • emotional control

  • nonverbal learning and memory

  • coordination

  • fine motor movements

Example: Riding a bike, catching a ball.

• One of first structures in brain to be affected by alcohol 

thalamus

• The brain's sensory relay station.

• Sends most sensory information to the cerebral cortex.

Exception:

• Smell bypasses the thalamus initially.

Remember: Thalamus = traffic controller.

sensory control center, gateway to cortex

• Directs sensory messages to the cortex

• Transmits replies to the cerebellum and medulla

basal ganglia

• Group of structures involved in:

  • movement control

  • habit formation

  • procedural learning

Damage can contribute to Parkinson's disease.

neuron doctrine

• The idea that the neuron is the basic building block of the nervous system.

• Neurons are separate cells that communicate with each other through signals.

• Proposed by Santiago Cajal.

Remember: Nervous system = made of individual neurons, not one continuous network.

cingulate cortex

• Involved in:

  • emotion regulation

  • attention

  • decision-making

  • pain processing

nucleus accumbens

• Part of the reward system.

• Involved in:

  • pleasure

  • motivation

  • reinforcement

  • dopamine reward pathways

Remember: "I want that" system.

frontal lobe

Controls:

• planning

• reasoning

• personality

• decision-making

• voluntary movement

Contains the prefrontal cortex.

parietal lobe

Controls:

• touch

• body sensations

• spatial awareness

occipital lobe

Controls:

• vision

Contains the primary visual cortex.

temporal lobe

Controls:

• hearing

• language comprehension

• memory

lateralization

our left and right hemispheres serve differing functions

wavelength in light

Distance between the peaks of waves; determines hue/color.

• Short wavelength = blue/violet

• Long wavelength = red

wavelength in sound

Determines frequency/pitch.

• High frequency = high pitch

• Low frequency = low pitch

hue

The perceived color of light (blue, green, red); determined by wavelength.

amplitude

Height of a wave; determines the strength/intensity of a stimulus.

amplitude in light

Determines brightness/intensity.

• Higher amplitude = brighter

• Lower amplitude = dimmer

amplitude in sound

Determines volume/loudness.

• Higher amplitude = louder

• Lower amplitude = softer

acetylcholine

neurotransmitter

• Movement 

• Memory

norepinephrine

neurotransmitter

• Arousal, alertness

dopamine

neurotransmitter

• Movement, planning, reward

serotonin

• Mood, appetite, sleep