The Effect Of Odor Stimuli On A Reach-to-grasp Task

In a sensorimotor control system,sensory information affects body movement.Recent evidence suggests that target-relevant sensory stimuli(i.e.,visual,auditory,and olfactory)can play important roles in the motor system.However,little is known about the effects of odor stimuli on reaching and grasping movements.In this research,we investigated whether odor stimuli affect hand movements in different visual loops.29 Participants(14 men and 15 women,average age: 23.0±1.7)received an odor stimulus and then reached toward the target with one of two grips: a precision grip for a small object or a power grip for a larger object.We recorded the kinematics data by a three-dimensional video motion capture system.In the first part,we aimed to find out the effect of odor stimuli on the hand performance.The reaction time of consistent odor stimuli was significantly shorter than the inconsistent odor stimuli [(357.71±137.33)ms vs.(386.35±151.68)ms],and also shorter then the air stimuli [(357.71±137.33)ms vs.(399.52±158.48)ms].In addition,visual feedback influenced the results.The movement duration in closed loop was faster than in open loop [(2547.59±653.42)ms vs.(2676.66±698.78)ms].And when the odor stimuli was incongruent with the size of the target,an interference effect was apparent on the maximum aperture time.It was longer than air stimuli [(1215.76±499.61)ms vs.(1127.21±428.00)ms].In the second part,we tried to determine how odor stimuli affect hand movements at different time periods.The grip aperture was sliced into 10 stages with 2s after hand movement started.We matched the type of odor stimuli with visual loops.In a power grip task,there is a significant difference at the first time period between 2 types of odor in closed loop and open loop [closed loop: consistent odor(61.57 ± 20.95)mm,inconsistent odor(59.30±20.66)mm open loop: consistent odor(61.72±21.52)mm,inconsistent odor(59.22±19.81)mm ].When the odor stimuli was inconsistent with the target,the grip aperture was larger at the fourth time period in closed loop than in open loop [(93.50±20.31)mm vs.(89.68±23.54)mm].When the odor stimuli was replaced by odorless air,visual feedback affect the aperture at the second time period [closed loop vs.open loop:(85.44±25.30 mm)vs.(81.43±25.92)mm].In a precision grip task,the result was different at the second time period in open loop [consistent odor vs.inconsistent odor:(71.69±23.70)mm vs.(77.47±24.71)mm].But in closed loop,the difference existed at the third time period [consistent odor vs.inconsistent odor:(71.94±21.55)mm vs.(75.55±22.49)mm].The present research suggested that odor stimuli could affect the reach-to-grasp movement.The consistent odor stimuli affect the plan and control of grasping and it occurs at the early stage.