nervous sytem 2

Question 1

24: tonotopic organisation

Answer 1

starts at cochlea and sends information about sound to the Brain

Question 2

24: coding sound frequency - place code

Answer 2

auditory system keeping track of where info originated

Question 3

24: coding sound frequency - time code

Answer 3

firing a.p in auditory nerve fibres which synchronise with peaks of sound wave form

Question 4

24: auditory pathway - what does the auditory nerve connect to

Answer 4

connects cochlea to brain

Question 5

24: first synapse in auditory pathway

Answer 5

cochlear nucleus

Question 6

24: auditory pathway - midbrain auditory centre

Answer 6

inferior colliculus

Question 7

24: auditory pathway - thalamic auditory nucleus

Answer 7

medial geniculate body

(major synaptic stations in the pathways for information reaching auditory areas of cerebral cortex.)

Question 8

24: auditory pathway - temporal lobe

Answer 8

auditory cortex

Question 9

24: sound localisation - vertical plank vs horizontal

Answer 9

vertical - interactions of sound on the pinna (outer ear)

horizontal - interaural (between ears) differences in sound wave timing and intensity

Question 10

24: patients with little/ no cochlear function - activation (how?)

Answer 10

electrical activation of cochlear nerve fibres by electrode arrays in the cochlea

Question 11

24: cochlear implant (bionic ear) - induction coil

Answer 11

transmits signals across scalp and skull to implanted receiver

Question 12

24: cochlear implant (bionic ear) - microphone and processor

Answer 12

converts sound to electrical pulses

Question 13

24: cochlear implant (bionic ear) - electrode array in cochlea

Answer 13

activates nerve fibres arranged in frequency (high to low)

Question 14

25: eye - the cornea

Answer 14

refracts light to bring it into focus on the retina

Question 15

25: eye - lens

Answer 15

• responsible for accommodation

- adjust refractive properties to ensure objects are in focus

Question 16

25: eye - iris

Answer 16

• pigment determines eye colour

- muscles controlled by autonomic ns adjusts pupil diameter according to light levels + emotional signals

Question 17

25: eye - pupil

Answer 17

opening in centre of iris allows light entry

Question 18

25: eye - retina

Answer 18

layer at back of eye

e.g photoreceptors, bipolar cells, ganglion cells, nerve fibres

Question 19

25: eye - what happens as object is brought near to the eye

Answer 19

light rays need to be bent more to keep object in focus

Question 20

25: eye - focal length when lens is rounder

Answer 20

shorter focal length

Question 21

25: eye - role of ciliary muscles (distant vision vs near)

Answer 21

distant - less flattened for distant vision

near - rounded

Question 22

25: contraction of ciliary muscles

Answer 22

• allows Zonule of Zinn, to slacken
• lens expands
• lens more rounded

Question 23

25: emmetropic eye

Answer 23

focus light from a distant object on to retina

Question 24

25: myopia

Answer 24

short sighted

Question 25

25: myopic eye

Answer 25

- too much focal power for its length - lights rays converge infront of retina - cannot focus on distant objects

Question 26

25: hyperopia

Answer 26

long sighted

Question 27

25: hyperopic eye

Answer 27

- too little focal power for its length - light rays converge behind retina - cannot focus on close objects

Question 28

26: when its dark what do photoreceptors release

Answer 28

glutamate

Question 29

26: retinal ganglion cells

Answer 29

give rise to optic nerve fibres

Question 30

26: retinal processing: action of photoreceptors in response to light

Answer 30

- reduce neurotransmitter released | - excites or inhibits bipolar cells

Question 31

26: retinal processing: where do a.p first appear

Answer 31

ganglion cells

Question 32

26: off centre type vs on - light shone onto centre

Answer 32

off - inhibits ganglion cell | on - excites

Question 33

26: off centre type vs on - light shone onto surround

Answer 33

- excites ganglion cell | - inhibits

Question 34

26: organisation of cone ganglion cells

Answer 34

centre around organisation

Question 35

26: 2 types of cone ganglion cell centre surround organisation

Answer 35

- red (l) - green (m) | - blue - yellow

Question 36

26: here do fibres from nasal retina cross

Answer 36

cross at optic chiasm

Question 37

26: left eye temporal and right eye nasal

Answer 37

- go to left LGN and cortex | - represent right visual field

Question 38

26: right eye temporal and left eye nasal

Answer 38

- go to right LGN and cortex | - represent left visual field

Question 39

26: lateral geniculate body

Answer 39

- left - found on righit hemisphere | - projections from eye kept separate in different layers

Question 40

26: visual cortex

Answer 40

5 areas | V1 (primary visual cortex) to V5 (MT)

Question 41

26: primary visual cortex

Answer 41

- more cortical area to centre of vision | - receives info from retinas

Question 42

26: 2 processing streams in visual cortex

Answer 42

dorsal stream - action pathway | ventral stream recognition pathway