WEEK 6: 6.2 Special Senses Flashcards
What is the labelled lines principle?
The specific pathway that transmits information about a specific modality is a ‘labelled line’. Stimulation of a labelled line only produces a sensation of its modality, no matter what type of energy produces the action potentials
What are the steps involved in vision: eye
- Light waves pass through the cornea (a clear protective outer layer)
- light waves pass through the pupil (a small opening in the eye surrounded by the iris which regulates the amount of light entering the eye.
- light waves pass through the lens
- light waves as projected onto the retina, which contains all of the receptor cells
What receptors do light activate?
Photoreceptors, located within the retina of the eye
What are two different types of photo receptors
- Rods (monochromatic & low visual acuity)
- Cones (mediate colour vision, high visual acuity)
What happens once light information is processed within the retina photoreceptors?
this visual info is passed onto bipolar nerve cells -> ganglion cells (their axons form optic nerve)
What is the centre of the retina called
Macula, in which the fovea is the pit inside the macula that contains only cones
What is the ratio of rods to cones in the periphery of the retina?
Higher ratio of rods to cones
What is the blindspot called in the retina?
Optic disc
Image on the retina is ___ and ___
inverted and reversed
What is the optic nerve formed from?
axons and ganglion cells
optic nerve joins with an opposite optic nerve to form the
optic chiasm
What occurs in the optic chiasm
The partial crossing of optic nerve fibres, in which medial nasal retinal fibres cross whilst lateral temporal retinal fibres do not crosss
Axons from the optic tract terminate in the?
thalamus (in a region called lateral geniculate nucleus)
as the axons leave the thalamus, they form optic ___
radiations
After forming optic radiations, the axons then terminate in the
primary visual cortex
Where is the primary visual cortex located?
above the calcarine sulcus in the occipital lobe
What are the two different streams in which further processing of information happens in visual association areas?
- What stream: towards temporal cortex that recognises what an object is
-Where stream: Towards the parietal cortex that allows for recognition of where an object is
What 3 parts can the ear be divided into?
The external ear, middle ear and inner ear
What is the external ear’s function?
Sound collection , localising sound
What is the middle ear’s function?
impedance matching between outer ear (air) and inner ear (liquid)
What is the inner ear’s function?
signals are analysed and transduced
What are the sensory receptors in the inner ear essential for hearing?
hair cells
What is the function of hair cells?
to convert sound vibrations into electrical signals
Describe the steps in which hair cells work?
- sound enters the ear, travels through the ear canal, hits the eardrum and causes it to vibrate
- vibrations are transmitted through ossicles, middle ear bones, to the cochlea in the inner ear
- inside the cochlea, sound vibrations create waves in fluid-filled chambers
- these waves move to the basilar membrane, causing hair cells sitting on it to bend
- when hair cells bend, they generate electrical signals sent to the brain via the auditory nerve
- the brain interprets these signals as sound