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2.2.8 Sound localization-II
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来自 Peking University 的课程
Advanced Neurobiology II
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Perception: Auditory
与讲师见面
Chenjian LiProfessor
School of Life Sciences
Donggen LuoResearch Fellow
School of Life Sciences
Yan ZhangProfessor
School of Life Sciences, Peking University
Okay, first, let's take a look,
what kind of information can we use to locate a sound?
Like the bird catches the rat,
you need to actually locate this tiny there.
How can you make the location?
The one is the timing, last time shall we talk about.
So the timing will be, okay if a sound happened on my right side, of course,
the sound will come in through it, so the key through my right ear, right?
And then, my left side will receive the sound actually, by delay.
What's the delay?
It's the hair sights, right?
Okay, do a calculation, for
a typical human being, maybe it's a hat,
let's say, 20 centimeters this side.
And then, what's the delay,
maximum delay between the two sides of the sound?
20 centimeter the sound speed is the 340 meter per second.
Calculation, what's the delay?
0.05 media second, okay?
0.05 media second just
500 microsecond, right?
There's actually shorter than one
duration of the actual potential, right?
What is my one millisecond for
the action potential to time, quite impressive, right?
So we can detect the difference
between these 500 millisecond,
this already maximum, okay?
[FOREIGN] >> [INAUDIBLE]
>> [FOREIGN] 600 microsecond
difference is the maximum delay, okay?
Now, even the sound source
move to the middle side [FOREIGN]
there's no delay [FOREIGN] right?
[FOREIGN] The sound
coming from
this side, and
then you need first
this detection
organ here.
And then, you need to first all, go to this side, so we're about to make,
At the delay, to them,
the 600 microsecond
is the maximum [FOREIGN]
microsecond [FOREIGN].
A bird flying,
okay, across,
over your head,
and then the bird
make some sound
[FOREIGN] okay?
[FOREIGN]
This depends on this
information [FOREIGN]
for the horizontal
location we may
need depends on
take a time delay
[FOREIGN] okay?
[FOREIGN]
Okay?
Okay, so this is the time delay we can use to locate a target,
and also we can also use the intensity difference.
[FOREIGN] You
get shadow,
right?
[FOREIGN] This is also another cue for
the brain to interpret, where is the sound location?
Okay, so this information,
[FOREIGN] easy to calculate [FOREIGN].
You got information [FOREIGN] how can you use the neuromechanism?
[FOREIGN] 600 microsecond delay,
sometimes maybe only 10 or
20 microsecond delay [FOREIGN] to detect [FOREIGN].
If I ask you to design a device to achieve with
this location, you just use the time.
How can you achieve this one?
Of course, there is a comparison between the left and the right side, right?
[FOREIGN]
>> [INAUDIBLE]
>> [FOREIGN] Okay.
[FOREIGN]
Okay.
[FOREIGN] We talk about in the brainstem
already the input is too from one side
you can go to both sides, right?
[FOREIGN]
Responsible for
the auditory
detection device
[FOREIGN].
Okay, take a look, so this neural connection is from the left ear, okay?
So they are in the brain, in the brainstem, right now,
we have seven neurons, okay?
Seven neurons, of course, they sit at a different location, and
then this is neural pathway to make the connections.
This input to this one and of course,
this red one from the right ear, okay?
And also they make the connections,
that means each individual neuron,
we see simultaneously from the left and the right input, okay?
We know the action potential can travel
the axon of the spiral ganglion, right.
And if that the neuron, for example,
the sound is coming from the right side, what happen?
For this neuron, okay, take a look, for this neuron,
the first input we're coming from the right, right,
because there's actually about maybe 600 microsecond delay from the left.
And then this neuron will first receive input from right ear, okay?
How about the left input?
So this actually happened about 600 microsecond delay.
And that the same time that neuron propagation,
that go a long distance.
We have another delay over the action
potential propagation [FOREIGN]
microsecond [FOREIGN] microsecond later.
Okay, for the first ten those neurons
kill [FOREIGN] you got synchronization.
This is not a coincidence
detectors [FOREIGN] detection.
[FOREIGN]
Delay
[FOREIGN]
neuron
[FOREIGN].
So you have to show because actual potential to the propagation,
take your time [FOREIGN].
[FOREIGN]
Compensate
[FOREIGN]
detection
[FOREIGN]
difference.
[FOREIGN] This is actually,
in some animals people found this, maybe the,
the way actually to achieve some localization.
Let's take a look actually the sound localization for MSO [FOREIGN].
This is human for mammal connection, so this is actually from the ear,
okay, coming down the spinal ganglion and
then to the brainstem and how make this connection.
[FOREIGN] It's symmetric,
this symmetrical map here.
And from
this side
[FOREIGN]
intensity,
lie
detector,
and sound
[FOREIGN].
Okay, so for the last one so
[FOREIGN] deep in the location,
you can use time information.
Also use the intensity but for the vertical one,
right now [FOREIGN] you don't have any time difference.
[FOREIGN]
Information
[FOREIGN]
in many animals
[FOREIGN]
okay?
[FOREIGN]
Vertical
line
[FOREIGN].
