Bimanual reaches with symbolic cues exhibit errors in target selection Jarrod Blinch, Brendan Cameron, Ian Franks, Romeo Chua School of Human Kinetics University of British Columbia motorbehaviour.wordpress.com

Research question Do bimanual reaches with more cognitive visuomotor control processes compared to more automatic control exhibit greater coupling? Do bimanual reaches with more cognitive visuomotor control processes compared to more automatic control exhibit greater coupling? Do bimanual reaches with more cognitive visuomotor control processes compared to more automatic control exhibit greater coupling? Do bimanual reaches with more cognitive visuomotor control processes compared to more automatic control exhibit greater coupling? Do bimanual reaches with more cognitive visuomotor control processes compared to more automatic control exhibit greater coupling?

Kelso, Southard, & Goodman, 1983 Define bimanual reach Two types of coupling: temporal, spatial Asymmetric movement Coupling during movement execution, what about coupling during movement preparation? Kelso, Putnam, & Goodman, 1979 Kelso, Southard, & Goodman, 1983

L S L L Symbolic cues Spatial cues Asymmetric movement Coupling during movement preparation Response selection or response programming, both measured by reaction time Symbolic cues Reaction times were longer for asymmetric movements compared to symmetric movements Reaction time cost for asymmetric movements RP or RS, if RP then any movement, regardless of the type of cue Spatial cues Equivalent RTs for symmetric and asymmetric movements So… Diedrichsen, Hazeltine, Kennerley, & Ivry, 2001

Reaction time cost with symbolic cues Coupling during movement preparation Increased processing demands on response selection Translate two different symbolic cues Assign a movement to each arm fMRI Increased processing in the medial frontal cortex Pre-Supplementary motor area and the rostral cingulate zone More cognitive-motor visuomotor processing compared to symmetric movements or spatial cues This increase in cognitive processing for symbolically-cued asymmetric movements creates coupling during movement preparation, but what about movement execution, specifically spatial coupling? Diedrichsen, Grafton, Albert, Hazeltine, & Ivry, 2006

Research question Do bimanual reaches with more cognitive visuomotor control processes compared to more automatic control exhibit greater spatial coupling?

L S Method 16 participants Spatial and symbolic cues Optotrak Cues: counterbalanced over two days

Replicated RT cost with symbolic cues and not spatial cues

Half of the trials from one participant Symmetric in blue, Asymmetric in red 14% of symbolic asymmetric movements had large trajectory modulations Spatial coupling or an online correction?

Symbolic, long-short, no modulations Symbolic, short-long, modulations Left arm (blue) to the long-distance target Velocity at 100 ms to examine what was programmed (before online control) Not coupling during movement execution, but rather online corrections to errors in target selection Also supported by delta reaction time

Discussion Increased cognitive processing for response selection with symbolically-cued asymmetric movements Coupling was also related to response selection Reaction time cost Errors in target selection Coupling is limited to the processes that require greater cognitive control Perhaps bimanual coupling is limited to the processes that require greater cognitive control Increased cognitive control for response selection leads to coupling during response selection We predict that experiments with spatial coupling likely had increased cognitive control to monitor movement execution, for example… In conclusion, bimanual coupling is limited to the processes that require greater cognitive control

Spatial coupling Franz, Zelaznik, Swinnen, & Walter, 2001 Swinnen, Lee, Verschueren, Serrien, & Bogaerds, 1997

Bimanual reaches with symbolic cues exhibit errors in target selection Jarrod Blinch, Brendan Cameron, Ian Franks, Romeo Chua School of Human Kinetics University of British Columbia motorbehaviour.wordpress.com

Movement time

Spatial

Symbolic

Delta reaction time (ms) Symbolic, no modulations Symbolic, modulations Long-Short -10.2 -0.4 Short-Long 0.6 -9.4 Delta reaction time Time difference for the left and right arms to begin their movements, negative is a left arm lead No modulations: large left hand head start of 10 ms for LS movements (handedness) With modulations: large left hand head start for SL movements

Online response selection