Sensation and Perception - Final Exam

vestibular system

The sensory system that responds to gravity and keeps people informed of their body's location in space.

Can the vestibular systems be turned off?

No but they can fail to function properly

sense of balance

postural control by which weight is evenly distributed, allowing people to remain up and stable

linear motion

sense of moving forward or backward, linearly, not at an angle

angular motion

can be sensed when rotating head from side to side

tilt

current position of the head vs the body

vestibulo-ocular reflex (VOR)

vestibular system monitors head and body movement, and brain moves eye very quickly to compensate for these movements

Do all animals have vestibulo-ocular systems?

most do, some are more complex than other

What happens if an animal does not have much vestibulo-ocular system?

they must move their entire head/neck to compensate

How do you describe the position of the head?

in 3D Cartesian coordinate sytem

What are the 3 kinds of angular motion?

roll, pitch, and yaw

roll

tilt top of head from side to side

pitch

tip head forward and backward

yaw

look side to side

what are the 3 kinds of linear movement

X-axis, Y-axis, and Z-axis

X-axis

movement of head forward or backward

y-axis

movement of head from left to right

z-axis

movement of head up or down

For each of the 6 types of movement, how many directions are there?

2; pitch tilt and roll tilt

pitch tilt

tilting forward or backward

roll tilt

tilting left or right

vestibular organs

The set of five organs -three semicircular canals and two otolith organs- located in each inner ear that sense head motion and head orientation with respect to gravity.

semicircular canals

sense angular acceleration

otolith organs

sense linear acceleration

How do the semicircular canals work?

1. fluid rushes through the canals

2. pushes against the hair cells

3. based on the speed and direction of the fluid, we know where our head is

how do the otoliths (saccules and utricles) work?

1. tine stones in sacs in the inner ear

2. pushes against cells

3. changes in gravity, linear acceleration

T/F: each semicircular canal is oriented in the same plane

false, they are all in different planes

T/F: semicircular canals are full of fluid

true

How does angular acceleration play into semicircular canals

angular acceleration in a particular plane (x, y or z) causes that canal to rotate in acceleration direction

Does the fluid move in the semicircular canals when angular acceleration is applied?

yes, but it stays still for a moment

ampulla

components of the ear that sense fluid pressure

where are ampulla's located?

at the base of each semicircular canal

how does the ampulla work?

hair cells that work as mechanoreceptors are attached to fixed fibers. those hairs convert physical movement into electrical signals

what happens on the side of the canal where the fluid pushes?

hair cells bend toward the tallest hairs, the pressure increases, and the brain gets excited signal

What happens to the side of the canal where fluid pulls away?

hair cells bend away from the tallest hairs, the pressure decreases, and the brain gets quiet signals

mechanoreceptors

sensory receptors that are responsible to mechanical stimulation (pressure, vibration, movement)

T/F: when nothing changes, mechanoreceptors do not fire

false, hair cells release neurotransmitters at a constant rate

t/f: when hair cells bend, the change in hair cells deflection is proportional to the amount of voltage

true

As the hair is bent in one direction, what happens to the neurons?

the neuron fires more rapidly

what happens to the neuron if the hair gets bent in the other direction?

the neuron fires more slowly

how do we know the difference in direction?

the differences detected in the neuron firing rate of the hair cells

T/F: angular acceleration is confined to one side of the head

false, it affects both but in opposite directions

what happens when you tilt your head right?

the neurons on the right fire more rapidly and vice versa for the left side

what helps us know our current position in space?

otolith organs

otolith organs

mechanical structures that sense both linear acceleration and gravity; saccules and utricle

what are the hair cells of the otolith organs covered in?

gelatinous structure with crystals lined on top called the otoconia

T/F: larger accelerations move the otoconia more

true, the more acceleration the more deflection of hair cells

what are the tiny crystals of the otoconia called

otoconia

how does one figure out tilt?

by sensing the pressure on the membrane from the weight of the otoconia via hair cells

what does the otolith organs exhibit?

sustained sensation

sustained sensation

otoconia fall on a certain place and the hair cells continue to fire until your tilt changes

why do the hair cells in the otolith organs have high baseline firing?

the membrane flexes both ways; can fire more or less depending on direction of movement

is there a vestibular cortex?

no, the V1 name was already taken

how do vestibular inputs reach the cortex?

through the thalamus

vection

illusory sense of motion produced when you are not moving, but the visual cues suggest that you are; vision + vestibulation

what works together to keep people from falling over?

muscles, vision and the vestibular system

T/F: VORs have an indirect connect from the organ to vision

false

motion sickness

results from a disagreement between motion and orientation provided by vision

car sickness and getting sick using VR

vestibular system says you are moving but the eyes say you are staying still

what is an evolutionary response to being poisoned?

vomiting

T/F: humans are accurate at estimating their own tilt

true, even in the dark they can tell their oritentation

rotation perception accuracy

upon starting rotation, we can sense it really well but after a minute you slow down. eventually you do not sense rotation anymore

what happens in the vestibular system when a person stops spinning?

it tells you you are spinning in the opposite direction which causes dizziness

sensory integration

perception of motion, tilt, etc are derived from a combo of vestibular organs and vision

how does one create a mental representation of space?

vision + vestibular system, and memory

Mal de Debarquement Syndrome

Swaying, rocking, or tilting perceptions felt after spending time on a boat or in the ocean

Aftereffect of adapting to the rocking motion of the ocean

"Getting your sea legs"

Usually goes away after a few hours, but some people experience it continuously, causing problems

Menieres Syndrome

a rare chronic disease in which the amount of fluid in the inner ear increases intermittently, producing attacks of vertigo, a fluctuating hearing loss (usually in one ear) and tinnitus

kinestesia

perception of the position and movement of our limbs in space

proprioception

perception mediated by kinesthetic and internal receptors

somatosensation

collectively, sensory organs from the skin, muscles, tendons, joints, and internal receptors

T/F: touch perception only includes mechanical perception

false, it involves many different types including mechanical pressure, pain, hot/cold, etc.

what is the difference between the skin of those who are hairless and hairy?

those without hair have thick skin where those who are hairy have thin skin

Touch receptors are mostly ____________

mechanoreceptors

What do touch receptors respond to?

mechanical movement in the skin (vibration, stretching, pressure)

mechanoreceptors

embedded in epidermis and dermis of skin

what are the 3 criteria of touch receptors?

1 - Type of stimulation to which the receptor responds

2- Size of the receptive field

3 - Rate of adaptation

Merkel (SA I) Receptors

detect steady pressure

Ruffini "(SA II) Receptor

detect skin stretch

Meissner (FA I)

detect light vibrations

Pacinian (FA II)

detect deep vibrations

thermoreceptors

respond to changes in temperature; made of warmth and cold fibers

nocireceptors

pain receptors; some are myelinated and some are not

what happens when nocireceptors are not myelinated

there is a slower pain response

where do thermoreceptors exist?

in the hypothalamus to measure blood temperature

what is the roadmap of receptors to the brain?

all the receptors send axons from the skin to the spinal column

the touch sensation can travel as far as 2 meters from the skin to the brain

what are the two pathways from the spine to the brain

spinothalamic pathway and the dorsal column medial lemniscal pathway

spinothalamic pathway

information about skin temperature and pain

dorsal column medial lemniscal pathway

information from skin, muscles, joints and tendons

somatopical representation

- terminate in the primary sensory cortex

- body is somatically represented in the brain

- adjacent areas on skin connect to adjacent areas in the brain

homunculus

maplike representation of regions of the body in the brain

kinesthetic perception

the proprioceptive sense that tells us where the parts of the body are with respect to one another

where are kinesthetic receptors located

Joints, muscles, and tendons

body image

creates a distortion in our perception of our own bodies

rubber hand illusion

when visual cues are congruent with tactile cues, we perceive that it comes from one stimulus

phantom limb

sensation perceived from a physically amputated limb of the body

why do people feel phantom limbs?

parts of the brain are listening to missing limbs but are not fully aware of the missing connection

re-mapping causing phantom limb

unused cortex from the missing limb start to be associated with other parts of the body which leads to feeling a missing limb

neural plasticity

the ability of neural circuits to undergo changes in function and organization as a result of previous activity

Pascaul-Leone and Hamilton 2001 experiment

- blindfolded participants for 5 days

- day 1: one S1 in the left hemisphere was activated

- day 5: S1 activation had decreased and V1 activation increased

nociceptors

sensory neurons that detect potentially damaging stimulation