Summary
Summary 2.4 Problem 9
- Course
- Institution
- Book
Summary of p9 for perception
[Show more]
Connected book
Book Title:
Author(s):
- Edition:
- ISBN:
- Edition:
Seller
Follow
ebru1365
Reviews received
Content preview
Problem 9 – WolfeThe vestibular organs are a set of specialized sense organs located in the inner ear next to the
cochlea
- senses of tilt and self-motion contribute our sense of spatial orientation
Problems with spatial orientation:
- dizziness: any form of spatial disorientation with or without instability
- vertigo: sensation of rotation or spinning
- spatial disorientation: impairment of spatial orientation
- imbalance: unsteadiness
Our spatial orientation is based on 3 sensory modalities:
- angular motion: rotation motion
- linear motion: translational motion
- tilt: head inclination with respect to gravity
The 3 stimulation energies are sensed by 2 types of vestibular sense organs:
- semicircular canals
o sense angular acceleration (change in angular velocity)
- otolith organs
o transduce both linear acceleration (change of linear velocity) and gravity (provide
contribution to sense of head tilt)
Each of the 3 spatial orientation modalities include 2 qualities: amplitude & direction
1) amplitude:
o rotation motion can be perceived as having high amplitude (vigorously shaking
head) or low amplitude
o translational motion can be perceived as having high velocity (car speeding on
highway) or low velocity
o tilt can be perceived with small amplitudes (nodding head) or large amplitudes
(hang upside down)
2) direction:
- coordinate system: x-axis always points forward, y-axis always point to left ear, and z-axis
always points out the top of the head
- these 3 directions define our sense of angular motion
The head can rotate 3 ways (angular):
- with a roll of angular velocity (a) on x-axis
- with a pitch angular velocity (b) on y-axis
- with a yaw angular velocity (c) on z-axis
, There are also 3 directions for our sense of linear motion (translational):
- stepping forward or backward along x-axis
- sliding left or right along the y-axis
- translating up or down along the z-axis
Each orientation has 2 tilt directions:
- a pitch tilt forward or backward (a)
- roll tilt to left or right (b)
- 3rd direction would be yaw rotation but this wouldn’t cause change in the head with
respect to gravity
The vestibular system
- the inner ear has one vestibula labyrinth and each vestibular labyrinth includes 5 sense
organs: three semicircular canals that sense rotational motion and 2 otolith organs that
sense gravity and linear acceleration
- both organs respond to changes in velocity: acceleration
- the vestibular system is principally sensitive to changes in motion, constant motion doesn’t
result in signals
Hair cells: mechanical transducers
- hair cells act as mechanoreceptors in each of the 5 vestibular organs
> head motion causes hair cell stereocilia to deflect
> stereocilia deflection causes a change in the hair cell voltage
> when a hair cell bends toward the tallest stereocilia the hair cell voltage becomes less
negative – also called depolarization
> changes in hair cell voltage: called receptor potential are proportional to the bending of
the hair cell bundles and control the rate at which hair cells release neurotransmitters
> the change in hair voltage increases neurotransmitter release and increases action
potential rate called excitation
> afferent neurons carry the action potentials to the brain
> if the hair cell is bent away from the tallest stereocilia, the cell potential becomes more
negative (hyperpolarization) causing a decrease in neurotransmitter release thus decrease
in action potential (inhibition)
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through EFT, credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying this summary from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller ebru1365. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy this summary for R89,84. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
73314 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy summaries for 14 years now