Temporal Coding

Question 0

Rate

Answer 0

another physical feature of Basilar Membrane is that the input frequency affects the RATE at which the membrane vibrates

e. g. when you play a sound of 500 Hz, the whole membrane moves up and down 500 times per second
e. g. when play sound of 3000 Hz, the whole membrane moves up and down 3000 times per second

Question 1

Temporal Coding

Answer 1

or Frequency Theory

for frequencies < 4kHz

Question 2

NOTE: Membrane moves (is displaced) FARTHER at some places places than others, BUT…

Answer 2

…at the SAME RATE thru-out

Question 3

Auditory System can also use _____ to code for frequency

Answer 3

RATE of Action Potentials along Auditory nerve to code for frequency

Question 4

We can discriminate between frequencies ____

Answer 4

VERY WELL

up to about 4000 Hz

Question 5

Spiral Ganglions are limited…

Answer 5

… to firing at most 1000 times/second because of their REFRACTORY PERIOD

Question 6

How can Timing Code be used for frequencies above 1000 Hz if no cell can fire faster than 1000 times/second?

Answer 6

the VOLLEY PRINCIPLE

Question 7

the Volley Principle

Answer 7

one cell can’t but several working in concert can fire faster than 1000Hz

another example of Across Fiber Coding

e.g. for a 3000 Hz tone => a volley of activity from one subset of Spiral Ganglions is followed, 1/3000 sec later, by a volley from another subset (while first subset is recovering), followed by another, etc. etc.

this activity is Phase locked, and as a result these volleys occur at a rate that corresponds to the rate of the input frequency

Question 8

Phase Locked

Answer 8

the Ganglions can only fire at the same phase (e.g. peak) of the input frequency