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CHRONOMETRICSProcessing time and movement control
Introduction
We are opportunistic… We do as well as we can Things take time
How much time do things take? And what impact does this have on movement control And what impact might this have on brain
maturation/development?
Reflexes
The book balance task…
Ho-hum…Blindfold
Reflexes
The book balance task…
Hey!!Blindfold
Reflexes
The book balance task…
Hey!!Blindfold
What happens next?
Reflexes
The book balance task…
Hey!!Blindfold
Reflexes
The book balance task…
Whoa..Blindfold
Reflexes
The book balance task…
Phew…Blindfold
Reflexes
The book balance task…
Book added
EMG
Hand
Movement
M1 M2 M3
0 40 80 150Milliseconds
Reflexes
40ms (ish): M1 reflex 70ms (ish): M2 reflex 100ms (ish): triggered reaction 150ms ( big ish to this one): M3 – conscious
response
Wadman et al. 1979
Let’s ‘put the (time) pressure on’ these reflexes, and see what they do…
T1
T2
T3 T4
Normal EMG
EMG for blocked movement
Wadman et al. 1979
Biceps
0 (T1) T2 100(T3) T4 200 300
Triceps
EMG
UNDER THE SKINProcessing time for sensory information
Time Zero
Nothing is happening yet - everything is
connected, but there is no information flow about this movement
Time 2 - 50ms
Information about the first 10ms of
movement is available via M1 pathway.
M2, M3, TR pathways not yet
completed
Time 3 - 100ms
Information about the first 60ms of movement is
available via M1 pathway.
Information about the first 30ms of
movement is available via M2
pathway.
Time 4 - 175ms
Information about the first 135ms of
movement is available via M1 pathway.
Information about the first 105ms of
movement is available via M2
pathway.
Information about the very beginning of movement is just becoming available via
M3 pathway.
So what?
Time delay between current state and feedback regarding current state
Need for forward models An old example…
So what?
And a newer one…
So what?
And another…
Is the “forward” model learned?
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