Motor preparation in a memorised delay task

Exp Brain Res (2005) 166: 102108

DOI 10.1007/s00221-005-2348-0RESEARCH ARTICLEKimberlee Jordan Brian I. Hyland Jeery R. WickensJ. Greg AnsonMotor preparation in a memorised delay taskReceived: 26 April 2004 / Accepted: 7 March 2005 / Published online: 20 July 2005

Springer-Verlag 2005Abstract The eect on reaction time (RT) and movement time (MT) of remembering which one of several

targets to move to was investigated in 18 participants

who completed 416 trials in each task. On each trial,

participants moved their index nger from a central,

illuminated switch (the stimulus) to one of eight targets

located on the circumference of a 6 cm radius circle. A

visual cue (illumination of the target) informed the

participant of the appropriate target. In the memorised

delay task, the cued target was lit for 300 ms followed by

a variable (450750 ms) foreperiod during which the

participant was required to remember the location of the

target until the stimulus light was extinguished. In

the non-memorised delay task, the target remained lit

during the entire foreperiod (7501050 ms) until the

response was completed. At the go signal (stimulus

light extinguished) participants moved as quickly and

accurately as possible to the cued target. Both RT and

MT were signicantly (p<0.05) longer in the memorised

delay task. The increase in RT shows that remembering

which target imposed a greater load on motor preparation even though all the information needed for preparing the response was presented in the cue at the

beginning of each trial. The increase in MT raises the

possibility that movement execution was also programmed during motor preparation.Keywords Memory Reaction time Motor

preparationIntroductionThe eectiveness of motor preparation is often measured

by the speed and accuracy of movement initiation and

completion. The role of parameter specication in motor

preparation has been extensively studied in monkeys

(see, for example Evarts 1968; Georgopoulos et al. 1983;

Riehle et al. 1994) and humans (Rosenbaum 1983;

Larish and Frekany 1985; Lepine et al. 1989; Anson

et al. 2000). In these studies, the target is presented

continuously during motor preparation. However, in

many real-life situations, the correct target is not constantly indicated and has to be remembered during

preparation. The eect of having to remember the target

position has received scant attention.Smyrnis et al. (1992) conducted an experiment in