Lecture 15: grasping

Question 1

Reaching strategies are _____

speed?

Answer 1

executed very rapidly, as early as 90ms onset
up to 30% faster onset than fastest voluntary (Maki and Mcllroy)

Question 2

Grasping responses vary with

Answer 2

amplitude of perturbation
direction of perturbation
shown by Mcllroy and Maki

Question 3

what did Gage et al find in 2007

Answer 3

kinematics of upper limb grasp shared with voluntary reach to grasp

Question 4

Grasping can be enhanced by ______

Answer 4

instruction or explicit cueing
scovil et al 2007
room mounted on rollers
Some instructed about location of handrail in room
another condition is when handrail is highlighted with lights

Question 5

Does peripheral vision play a role in grasp responses

Answer 5

yes, seen in Scovil et. al. 2007
those with no cues who grasped handrail, less than 50 percent fixated on handrail beforehand

Question 6

Visuo-spatial map is developed ____ to the perturbation to achieve target-specific reactions

Answer 6

prior
Ghafouri et. al. 2004
even when vision is occluded during perturbation, used map from prior vision to grasp rail

Question 7

Central or peripheral field of view is

Answer 7

important for updating reaction for more accurate trajectory
Akram et al 2013

Question 8

The latency of reach depends on _____

Answer 8

predictability of grasp object
weaver and tokuno 2013
vision occluded before perturbation onset
predictable vs unpredictable handrail location (right vs either left or right)
less latency when predictable

Question 9

people are found to fall when____

Answer 9

they still have an object in their hands, despite options for grasping reactions (Robinovitch, 2013)

Question 10

holding an object in hand tended to _____

Answer 10

reduce the frequency of grasping response
Bateni et al

Question 11

Results from Van Ooteghem et al

Answer 11

nothing in their hands
1. object fixed to chair
2. 5cm diameter object
3. 10cm diameter object
response time increased when object got larger
as soon as something is in the hand, response time is delayed

Question 12

Komisar et al handrail locations

Answer 12

increasing handrail height decreases trunk pitch angle
subjects entered into a room, whole room translates forward or backward
prioritised grasp response

Question 13

_____ COP displacement for shoulder vs overhead rails

Answer 13

less
Sarraf et. al. 2014
really able to recover balance better with shoulder vs overhead handrail