psych midterm 2

chapters 3, 4 & 5

glial cells functions

\-providing nutrition, healing and support for neurons

\-removing debris from brain

\-devouring dead cells

\-modulating the signaling of neurons (reducing or amplifying activity at synapses)

neurons

cells that receive, integrate and transmit info allowing communication in the nervous system

how do glial cells protect the brain

1. produce cerebral spinal fluid, cushions the brain
2. form the blood brain barrier
3. contribute to immune system of brain

how do neurons transmit info

1. resting potential
2. action potential
3. synaptic transmission
4. graded potentials

describe the action potential

* neuron become stimulated
* cause reversal of electrical potential
* channels in the cell membrane open and Na+ ions flow
* inside of cell go from -70mv to 30mv

absolute refractory period

minimum length of time after an action potential when another ap cant start

what influences speed of ap

axon size, the larger the faster, less resistance

benefits of gaps between myelin sheath

1. resting potential only needs to be maintained at gaps, saving energy
2. action potential can jump from gap to gap, increase speed

describe synaptic transmission

\-sending neuron releases chemical messengers into cleft

\-messengers attach to receptors on receiving neuron

\-binding of these messengers stimulate the receiving neuron

what happens when NT binds to receptor

voltage change occurs.

changes likelihood that the postsynaptic neuron will fire.

excitatory postsynaptic potential

increases likelihood of neuron firing, decreases negtvitity

inhibitory postsynaptic potential

decerases likelihood of firing, increases negativity inside

steps of synaptic transmission

1. synthesis
2. transportation and storage
3. release
4. binding
5. deactivation
6. autoreceptor activation
7. reuptake
8. degradation

spatial summation

combining excitatory and inhibitory inputs at different but close branches of the dendrite

temporal summation

process of combining excitatory and inhibitory inputs at the dendrites in rapid succession.

synaptic pruning

elimination of old synapses

agonist

mimics neurotransmitter action, fits into receptor site, result in PSP

antagonist

blocks action of neurotransmitterr, binds but doesnt fit site so blocks binding

neurotransmitters 4 common properties

1. synthesized in neuron
2. stored in synaptic terminals
3. released when neuron has ap
4. deactivated or removed from synapse

somatic nervous system

made of nerves that connect to voluntary skeletal muscles and sensory receptors

afferent nerve fibres

axons that carry info to the CNS

efferent nerve fibres

axons that carry info from CNS to the body

autonomic nervous system

made of nerves that connect to heart blood vessels smooth muscles and glands

sympathetic ns

fight or flight

parasympathetic ns

rest and digest

cerebrospinal fluid

nourishes the brain and provides a protective cushion for it

electroenecphalograph EEG

device that monitors electrical activity of brain overtime to show functioning of brain

transcranial magnetic stimulation

technique that permits scientists to temporarily enhance or depress activity in a specific area of the brain

brain 3 regions

1. hindbrain
2. midbrain
3. forebrain

hindbrain

has the cerebellum and 2 structures in lower brainstem: medulla and pons

midbrain

segment of brainstem between hindbrain and forebrain

integrates sensory processes like vision and hearing

reticular formation

helps with modulation of muscle reflexes breathing and pain perception.

role in regulation of sleep and arousal.

forebrain

largest and most complex

has thalamus, hypothalamus, limbic system and cerebrum

core of forebrain

made of thalamus, hypothalamus and limbic system

on top of brain stem

cerebrum

seat of complex thought, conciousness

cerebral cortex

wrinkled surface of the cerebrum, outer layer of brain

thalamus

relay station where all sensory info pass to get to cerebral cortex

hypothalamus

regulates basic biological needs

limbic system

network of structures involved in emotion, motivation and memory

corpus callosum

Bridge of fibres passing information between the two cerebral hemispheres

left hemisphere

language, speech, reading, writing

right hemisphere

spatial reasoning, visual recognition

four lobes

\-occipital

\-parietal

\-temporal

\-frontal

mirror neurons

neurons that are activated by performing an action or by seeing another animal perform the same action.

brain plasticity

brains ability to change in structure and function

how is brain plasticity stimulated

by experience through change in dendritic length, synapse formation and altered metabolic activity

proof of brain plasticity

1. experience sculpts features of brain structure
2. damage or destruction of brain tissue can lead to neural reorganization
3. adults brains can generate new neruons

split brain surgery

the corpus callosum is cut in half to reduce severity of epileptic seizures

sensation

stimulation of sense organs

perception

selection, organization and interpretation of sensory input

psychophysics

the study of how physical stimuli are translated into psychological experience

stimulus

a thing or event that evokes a response

synthesia

condition in which perceptual or cognitive activities trigger exceptional experiences

threshold

the point between detectable and non detectable energy levels

two types of threshold

absolute

difference

absolute threshold

the minimum amount of stimulation that can be detected

what does absolute threshold depend on

sensory capabilities

how much can stimulus be detectedd

50% of the time

Just noticeable difference

the smallest change in a stimulus intensity that is detectable

webers law

the size of JND is a constant proportion of the size of the initial stimulus

* whether u can detect change depends on original strength of stimulus
* as stimuli increase in magnitude, JND as well

signal detection theory

detecting sensory info is produced by both sensory processes and decision processes

detectability

measured in terms of probability and depends on decision making processes as well as sensory

what does signal detection theory attempt to do

account for the influence of decision making processes on stimulus detection

subliminal perception

registration of sensory input without conscious awareness

sensory adaptation

gradual decline in sensitivity due to prolonged stimulation

light

a form of electromagnetic radiation that travels as a wave moving

amplitude

height of wave

wavelength

distance between peaks

what does amplitude affect

brightness

what does wavelength affect

perception o colour

what does purity infleucne

perception of saturation or richness of colours

vision

filter that permits people to sense but a fraction of the real world

shorter wavelength

ultraviolet

longer wavelength

infrared

retina

channel light to the neural tissue that receives it

eye

\-housing neural tissue that receives light energy

\-channeling light towards the retina

cornea and lens job

form an upside down image of objects on the retina

lens

transparent eye structure that focuses the light rays falling on the retina

what process does the lens facilitate

accomodation

accomodation

when the curvature of the lens adjusts to alter visual focus

purity

number of different wavelengths mixed tog

cornea

where light enters the eye

iris

coloured ring of muscle consitrcts or dilates to change size of puppilp

pupil

regulates amount of light entering the eye

fovea

tiny spot in centre of retina containing only cones

optic disk

where optic nerve leaves eye, has blind spot

retina

absorbs light processes images and sends info to brain

retina job

absorbs light

processing images

sending visual info to brain

receptor cells

layer of cells closest to the back and responsible for detecting light

cones

* daylight and color vision
* most concentrated in fovea
* stubbier in shape
* about 6 million

rods

* night and peripheral vision
* most conc right outside fovea
* outnumber cones in periphery of retina
* elongated
* about 100 to 125 million

receptive fields

collection of rod and cone receptors that funnel signals to particular visual cell in the retina

close object

lens get fatter/rounder

far object

flat lense

eye movements

saccades

fovea

tiny spot in centre of retina that contains only cones; visual acuity is greatest

visual information processing 1

light striking the rods and cones triggers neural signals to move to bipolar cells

visual information processing 2

neural signals pass to ganglion cells

what do the axons of the ganglion cells form

optic fibres that make up the optic nerve

visual information processing 3

optic nerves travel to the optic chiasm