RESEARCH ARTICLE
Mohammad Ali Khoshnoodi Æ Rouzbeh Motiei-langroudi
Mohsen Omrani Æ Firouz Ghaderi-pakdell
Abdol Hossein Abbassian
Kinesthetic memory in distance reproduction task: importance of initial
hand position information
Received: 16 February 2005 / Accepted: 29 August 2005 / Published online: 30 November 2005

Springer-Verlag 2005
Abstract The role of the initial hand position in planning
and implementation of a goal-directed movement is a
matter of debate. We designed a non-visually guided
repetitive reaching movement task to investigate the role
of proprioceptive information of the initial or end hand
position in implementation of kinesthetic memory. The
experimental design consisted four experiments. Each
experiment consisted two phases: the training phase and
the test phase. In the training phase the subjects were
asked to learn and memorize the distance between start
and end points by moving their hands ten times between
them. In the test phase, the end point was removed, and
starting from the same initial position, the subjects were
asked to reproduce the memorized distance. In all
experiments, varied conditions called ‘‘mask phase’’
preceded the test phase: a 5-s delay in experiment 1,
shifting both initial and end points while keeping the
distance constant in experiment 2, shifting only the end
point, while keeping the initial point constant in exper-
iment 3 and shifting only the initial point and keeping
the end point constant in experiment 4. In comparison to
experiment 1 (which was considered as the control
group), no significant error in distance reproduction
occurred in experiment 3, while experiments 2 and 4
showed significant error. These findings mean that al-
though the distance information was available during
the mask phase of experiment 2, subjects could not
efficiently use this information to reproduce the distance.
The other two experiments suggest that this error was
caused by changing the initial hand position and not the
end point. We conclude that in a kinesthetic-guided
distance reproduction task, the initial hand position is
more important for implementation of distance memory
rather than the end point.
Keywords Initial hand position Æ Kinesthetic memory Æ
Motor planning Æ Proprioception
Introduction
Performing a goal-directed movement requires infor-
mation about the position of the object being reached
through sensory systems. In the course of processing the
spatial information, an internal representation is gener-
ated, based on which a feed-forward motor plan is
formed (Ghez and Krakuer 2000). The role of the initial
hand position in implementation of the motor plan has
been widely investigated, and whether or not the system
requires information of the initial hand position to
perform a goal-directed movement is a matter of debate.
Deafferentation studies were the first experiments
addressing this question. While some pioneer studies
suggested a key role for initial limb position information
for accurate pointing movements (Sherrington 1900),
later studies did not fully confirm these observations and
suggested that performing accurate movements was
possible in the absence of peripheral information, which
may code initial limb position (Lashley 1917). Based on
the latter results Polit and Bizzi (1979) have suggested
that the nervous system selects an equilibrium point as a
mechanical attractor which could be reached without
knowledge of the initial limb position (Polit and Bizzi
1979). However, the generality of this conclusion was
challenged by several experimental observations. Deaf-
ferented subjects, for instance, were unable to compen-
sate perturbations affecting the canonical posture of
their limbs (Desmurget et al. 1998).
There is evidence that information about initial limb
position may help to increase the accuracy of goal-di-
rected tasks (Ghez et al. 1995, 1990). Prablanc et al.
(1979) showed that vision of the hand in static position
Mohammad Ali Khoshnoodi, Rouzbeh Motiei-langroudi and
Mohsen Omrani had equally contributed to this work
M. A. Khoshnoodi (&) Æ R. Motiei-langroudi Æ M. Omrani
F. Ghaderi-pakdell Æ A. H. Abbassian
Institute for Studies in Theoretical Physics and Mathematics
(IPM), School of Cognitive Sciences (SCS), Tehran, Iran
E-mail: khoshnoodi@ipm.ir
Tel.: +98-21-22294035
Fax: +98-21-22280352
Exp Brain Res (2006) 170: 312–319
DOI 10.1007/s00221-005-0217-5

increased the accuracy of visually directed movements,
compared to the condition in which vision of the hand
was never allowed. Other studies showed that intro-
ducing conflicting sources of information about the
initial limb position caused a systematic error in reach-
ing tasks (i.e., introducing a new initial hand position by
displacing the visual information of the limb position
using a prism or virtual reality (Lateiner and Sainburg
2003; Rossetti et al. 1995) or by interfering the pro-
prioceptional information of the limb using tendon
vibration (Larish et al. 1984)). The interference between
location and distance information in a location repro-
duction task, which manifests itself as a systematic error
in the direction of the change of initial position, provides
further evidence for the role of starting position infor-
mation (Walsh et al. 1979; Imanaka and Abernethy
1992b). These experiments suggest that accuracy of
reaching arm movements is linked to the sensory
encoding of the initial state of the motor apparatus.
However, for the following reasons, uncertainties still
arise in attributing the obtained results to the change of
initial hand position: first, deafferentation may affect
end point specifications in addition to distortion of the
initial position information (Feldman and Levin 1995;
Feldman 1992); second, different movement strategies
might be used by deafferented patients compared to the
normal subjects (Feldman 1986); third, in experiments
not using deafferentation paradigm, it is the effect of
concurrent visual and proprioceptive information but
not the role of proprioception per se which has been
studied. Presence of concurrent visual information may
cause unpredicted effects such as conflicting visual and
proprioceptive information or providing allocentric cues
that may confound the results. A primary function of
proprioception is to detect unexpected events and to
initiate rapid compensatory responses. However, it has
become clear that proprioception has additional roles,
especially in the regulation of motor output during
unperturbed movements. Proprioceptive feedback con-
trols many aspects of the timing and magnitude of the
movement to ensure the appropriateness of the motor
pattern. In addition, proprioception has a predictive role
in updating motor commands as well as shaping the
properties of the internal representation in reaching
movements (Pearson 2000).
Pointing to or reaching a remembered target involves
transformation of the learned distance information into
an appropriate motor output, mediated by short-term
memory storage. It has been shown that kinesthetic cues
of both distance and location are used to recall a learned
non-visually guided movement (Hagman and Williams
1977). In other words, multiple kinesthetic cues establish
memorial representations of motor movements. In order
to investigate the nature of kinesthetic information that
is specified in performing reaching movements, varia-
tions of either distance- or position-reproduction tasks
have been typically employed. In both tasks, partici-
pants are required to produce movements from ran-
domly varying initial positions. The goal in distance
reproduction tasks is to produce movements having
constant amplitude, while the requirement in position
reproduction tasks is to terminate movements at a fixed
location. In most cases evidences indicate that in both
distance- and position-reproduction tasks, there is a
systematic pattern of undershooting and overshooting
the target, depending on the initial position of the limb
(Jaric et al. 1994, 1992; Bock and Eckmiller 1986; Ima-
naka and Abernethy 1992a; Ilic et al. 1998). However,
the effect of varying starting location on end point
accuracy has been shown to be less in position repro-
duction than distance reproduction tasks (Jaric et al.
1994; Khan et al. 2002). This interaction between loca-
tion and distance reproduction is mostly attributed to
interference of end point and distance information.
Regardless of controversies about the level in which this
interaction occurs, whether it happens at the level of
short-term memory or at the level of effector limb as a
result of an attractor equilibrium point, in all of these
studies the role of initial point information in retrieving
the short-term memory of distance was ignored and the
observed effect was attributed solely to end point
information interference. However it is possible that
changing the initial position could affect the implemen-
tation of the memorized distance, and therefore, the
observed biased error could not be confidently inter-
preted as the end point effect. Imanaka and Abernethy
(1992b) have illustrated that distance reproduction is
improved when participants are instructed to attend to
the initial locations of their movements and to take into
account changes in start positions from one trial to the
next (Imanaka and Abernethy 1992b). According to
Imanaka and Abernethy (1992b), participants could
better calibrate target positions in space by attending to
the changes in the start locations, which then facilitate
the reproduction of the required movement distance
from different initial positions. However, in a study
performed by Faineteau et al. (2003), subjects repro-
duced learned distances of straight and curvilinear paths
in an On-axis condition in which learned and repro-
duced movements were spatially aligned, and an Off-axis
condition in which they were displaced laterally. As
performance accuracy was not dramatically different
between the On- and Off-axis conditions, they concluded
that distance cues would seem to have played a more
important role than position cues in the execution of the
task.
Hence, we designed a task to investigate the role of
possible attributing kinesthetic cues, such as initial and
end point hand position, in the subject’s ability to
accurately reproduce a learned distance. As the aim of
the experiment was to investigate the effect of kinesthetic
information of initial and end positions of the effector
limb on short-term distance memory, a non-visually
guided repetitive distance reproduction task was de-
signed to prevent the possible interactions between vi-
sual and proprioceptive information. To obtain that, the
subjects had to learn a specific distance (as described
later) and reproduce it from the same initial point in
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