lecture 18

Question 1

tonotopic theory

Answer 1

hair cells in cochlea code frequency as a function of location on basilar membrane

base: high frequency waves
apex: low frequency waves

Question 2

tonotopic representation

Answer 2

basilar membrane representation if mirrored in cochlear nucleus and maintained to cortex

Question 3

what does tonotopic theory not explain

Answer 3

how sounds below 200Hz are coded

- range stimulates all cells at apex of basilar membrane

Question 4

temporal theory (frequency theory)

Answer 4

rate of firing is proportional to frequency

• below 1000Hz neuron phase locks
• above 1000Hz populations of neurons fire in sequence

Question 5

place and temporal theories

Answer 5

100 - 10000 Hz is temporal
1000-4000Hz is temporal and place
4000-20,000Hz is place

Question 6

hypothesis for detecting loudness

Answer 6

firing rate hypothesis: greater the amplitude of the incoming sound waves the higher the firing rate of bipolar cells in occhlea

Question 7

strategy 1 for detecting location: interaural time difference

Answer 7

neurons in brainstem compute difference in sound waves arrival time at each ear
- happens in medial superior olive

Question 8

strategy 2 for detecting location: interaural intensity difference

Answer 8

detect differences in loudness at each sound

• head acts at an obstacle to high frequency sounds
• louder on one side of head than other
• happens in lateral superior olive and trapezoid body

Question 9

ventral/dorsal streams of auditory system

Answer 9

ventral- auditory object recognition that decodes spectrally complex sounds and their meaning
dorsal- audition for action that integrates auditory and somatosensory info to control speech production

Question 10

evidence that language is uniform

Answer 10

1. language is universal in humans
2. humans learn language early in life and without effort
3. languages have many structural elements in common (syntax and grammer)
   - must be a language centre in brain for processing language

Question 11

brocas area

Answer 11

anterior speech area in left frontal lobe that functions with motor cortex to produce movements needed for speaking

Question 12

wernickes area

Answer 12

posterior speech area at the rear of left temporal lobe that regulates language comprehension

Question 13

arcuate fasiculus

Answer 13

tract for connecting wernickes and brocas area

Question 14

aphasia

Answer 14

inability to speak despite having normal comprehension or intact vocal mechanisms or inability to compreheind despite normal speech and hearing

Question 15

brocas aphasia

Answer 15

inability to speak fluently despite normal comprehension

Question 16

wernickes aphasia

Answer 16

inability to understand even though production is intact

Question 17

wilder penfield

Answer 17

used weak electrical current to stimulate brain surfaces ando bserved A1 produced pure ringing sounds whereas furthur away produced interpretive sounds (crickets, doorbells)

Question 18

observations as a result of PET

Answer 18

all incoming auditory info first analyzed at A1
complex auditory info analyzed in secondary auditory arae
phonetic discrimination activates brocas