effects of task instructions and target location on ... accident (cva; mathiowetz & bass-haugen,...
TRANSCRIPT
456� July/August 2008, Volume 62, Number 4
Effects of Task Instructions and Target Location on Reaching Kinematics in People With and Without Cerebrovascular Accident: A Study of the Less-Affected Limb
KEY WORDS• environment• movement• stroke• task performance and analysis
Keh-chung Lin, ScD, OTR, is Associate Professor and Chair, School of Occupational Therapy, College of Medicine, and Neurobiology and Cognitive Science Center, National Taiwan University, and Director, Division of Occupational Therapy, Department of Physical Medicine and Rehabilitation, National Taiwan University Hospital, Taipei.
Ching-yi Wu, ScD, OTR, is Associate Professor, Department of Occupational Therapy and Graduate Institute of Clinical Behavioral Science, Chang Gung University, 259 Wen-hwa 1st Road, Kwei-shan, Taoyuan, Taiwan 33302; [email protected]
Kwan-hwa Lin, PT, PhD, is Professor, Department of Physical Therapy, College of Medicine, National Taiwan University, Taipei.
Chein-wei Chang, MD, is Professor, Department of Physical Medicine and Rehabilitation, National Taiwan University Hospital, Taipei.
OBJECTIVE. We investigated how verbal instructions and target location interacted to influence reaching movement of the less-affected limb in participants with and without unilateral cerebrovascular accidents (CVAs).
METHOD. Using a counterbalanced repeated-measures design, 26 people with CVA and 24 age-matched healthy people performed the reaching tasks under 4 conditions formed by the crossing of verbal instructions (speed and accuracy emphasis) and target locations (ipsilateral and contralateral to the performing hand).
RESULTS. In the control groups, speeded instructions and ipsilateral reaches elicited significantly more preprogrammed movements than did accuracy instruction and contralateral reaches, respectively. Similar patterns of performance in response to task constraints were found in the CVA groups except for movement initiation in the right CVA group.
CONCLUSION. Instruction and locations interacted to constrain reaching movements in both control and CVA groups. The combination of speeded instruction and ipsilateral reach may optimize movement performance of the less-affected limb in stroke patients.
Lin, K.-C., Wu, C.-Y., Lin, K.-H., & Chang, C.-W. (2008). Effects of task instructions and target location on reaching kine-matics in people with and without cerebrovascular accident: A study of the less-affected limb. American Journal of Occupational Therapy, 62, 456–465.
Keh-chung Lin, Ching-yi Wu, Kwan-hwa Lin, Chein-wei Chang
Occupational�therapists�incorporate�different�types�of�task�constraints�into�prac-tice�schedules�when�designing�treatment�programs�for�people�with�cerebrovas-
cular�accident�(CVA;�Mathiowetz�&�Bass-Haugen,�2008;�Pendleton�&�Schultz-Krohn,�2006).�Task constraints�refer�to�limitations�imposed�on�purposeful�movement�(Trombly�Latham,�2008),�which�may�facilitate�desired�movement�organization�in�people�with�CVA� (Newell,� 1998;�Shumway-Cook�&�Woollacott,� 2007).�Two�general�sources�of�task�constraints�in�the�context�of�stroke�rehabilitation�have�been�identified:�augmented�information�(e.g.,�verbal�instructions�for�movement�prepara-tion�and�execution)�and�physical�demands�such�as�target�location�and�relevance�of�target�to�be�reached�(Lin,�Wu,�&�Trombly,�1998;�Ma�&�Trombly,�2004;�Newell,�1998;� Trombly� &� Wu,� 1999;� Wu,� Trombly,� Tickle-Degnen,� &� Lin,� 2000).�Appropriate�integration�of�verbal�instruction�and�target�location�may�be�used�to�optimize�movement�performance�by�people�with�CVA.�This�assumption�awaits�experimental�study�to�improve�knowledge�about�the�effects�of�task�constraints�on�movement�organization�during�goal-directed�reaching.�We�designed�this�study�to�investigate�how�verbal� instruction�and� target� location�may� interact� to� influence�movement�performance�by�people�with�and�without�CVA.
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The American Journal of Occupational Therapy� 457
Task Instructions and Reaching Kinematics
One�of�the�noted�examples�of�task�constraints�in�biomechani-cal� analysis�of�movements�would�be� the� trade-off�between�speed� and� accuracy� in� goal-directed� reaching� (Duarte� &�Freitas,�2005;�Fitts,�1954).�On�the�basis�of�the�speed–accuracy�paradigm,�previous�studies�of�the�effects�of�instruction�involved�healthy�people�(e.g.,�Rival,�Olivier,�&�Ceyte,�2003)�and�clini-cal�populations�such�as�people�with�Parkinson’s�disease�(Rand,�Stelmach,�&�Bloedel,�2000).�Research�on�people�with�CVA�is�needed�to�determine�the�effects�of�task�instructions�on�reach-ing�performance�during�motor�tasks.�Such�research�will�pro-vide�information�relevant�for�task-specific�practice�of�motor�actions�important�for�daily�occupations.
One� theme� of� the� speed–accuracy� research� (Adam,�1992;�Fisk�&�Goodale,�1984;�Rival�et�al.,�2003)�is�the�use�of� temporal� and� spatial� instructions� to� study� the� speed–�accuracy�trade-off�of�reaching� in�pointing�movements.�In�this�situation,�target�characteristics�(e.g.,�target�size,�distance)�and�the�environment�remain�constant,�and�the�emphasis�on�speed�and�accuracy�is�varied�by�changing�the�verbal�instruc-tions�to�the�task�performer.�These�instructions�involve�reach-ing�for�a�target�as�quickly�as�possible�or�as�accurately�as�pos-sible.�Several�studies�involving�healthy�adults�(Adam,�1992;�Fisk�&�Goodale,�1984;�Rival�et�al.,�2003)�and�people�with�Parkinson’s�disease�(Rand�et�al.,�2000)�have�indicated�that�with�speed�instructions,�participants�initiated�faster�and�pro-duced�more�efficient�reaching�movements�with�greater�force.�These�findings�suggest�that�the�speed–accuracy�information�provided�by�verbal�instructions�can�direct�a�person’s�atten-tion�toward�the�temporal�or�spatial�aspect�of�the�reaching�movement.�The�speed–accuracy�instructions�thus�influence�the�motor�planning�and�strategies�used�to�perform�the�task�(Fasoli,� Trombly,� Tickle-Degnen,� &� Verfaellie,� 2002;�Hermsdorfer� et� al.,� 1996;� Ma,� Trombly,� Wagenaar,� &�Tickle-Degnen,�2004).�
Speed-emphasized�tasks�demand�more�efficient�perfor-mance�of�the�task�in�the�temporal�domain�than�do�accuracy-emphasized�tasks,�and�they�demand�a�shorter�time�to�com-plete� the� task� and� require� more� ballistic-like� or� more�continuous�movements.�The�more�ballistic�reaching�move-ments�depend�more�on�advanced�motor�programming�(i.e.,�more�preplanning�of�the�reaching�movement)�and�less�on�direct�sensory�feedback,�as�reflected�by�less�time�for�move-ment� initiation� (shorter� reaction� time� [RT]),�higher� effi-ciency�of�movement�execution�(less�movement�time�[MT]),�and�greater�smoothness�during�performance�(fewer�move-ment�units� [MUs];�Haaland,�Prestopnik,�Knight,�&�Lee,�2004;�Milner,�1992;�Trombly,�1992).�To�complete�the�task�more�quickly,�the�performer�needs�greater�force�or�impulse�
at�movement�initiation�to�quickly�bring�the�hand�to�the�tar-get.�The�greater�force�or�impulse�at�movement�initiation�can�be�reflected�by�a�higher�amplitude�of�peak�velocity�(PV;�Ma�et�al.,�2004).
Location ConstraintsThe� dimension� of� movements� studied� in� the� literature�related�to�the�speed–accuracy�instruction�is�limited�to�the�sagittal�plane.�It�remains�unclear�whether�those�effects�hold�true�in�other�spatial�planes.�In�addition,�target�location�is�another� important� constraint� to� consider� in�people�with�unilateral�CVA.�Previous�research�has�described�the�effects�of�the�laterality�of�the�target�position�on�movement�kine-matics�in�healthy�adults�(Fisk�&�Goodale,�1984;�Ghozlan,�1998;�Wu,�Lin,�Lin,�Chang,�&�Chen,�2005)�and�in�people�with�neurological� impairment� (Beer,�Dewald,�&�Rymer,�2000;� Castiello,� Bennett,� Bonfiglioli,� Lim,� &� Peppard,�1999;�Roy,�Kalbfleisch,�Bryden,�Barbour,�&�Black,�2000;�Trombly,�1993).�The�general�findings�suggest�that�ipsilat-eral reaches�(i.e.,�the�target�position�and�the�hand�used�to�reach�for�the�target�are�on�the�same�side)�were�more�efficient�in� movement� planning� and� execution� than� contralateral reaches (i.e.,�target�position�on�the�opposite�side�from�the�performing�limb).�Planning�and�execution�efficiency�were�reflected�by�RT�and�MT,�respectively.�Ipsilateral�reaches�are�also�more�preprogrammed�with�less�error�correction�(fewer�MUs),�more�forceful�(higher�PV),�and�more�accurate�than�contralateral�reaches.�The�information�on�targets�located�on�the�same�side�of�the�body�as�the�reaching�limb�is�processed�initially�in�the�same�hemisphere�that�controls�the�reaching�limb�(Barthelemy�&�Boulinguez,�2002).�The�advantage�for�reaches�made� into� the� ipsilateral� space�could�be�a�conse-quence� of� more� efficient� within-hemisphere� visuomotor�transmission�of�target�information�and�visual�feedback�from�the�reaching�limb�(Fisk�&�Goodale,�1984).�
One�alternative�explanation�for�the�ipsilateral�reaching�advantage�lies�in�biomechanical�factors.�Differences�between�ipsilateral�and�contralateral�reaches�could�be�accounted�for�by�differences�in�the�inertial�forces�operating�on�the�hand�for�movements�in�different�directions.�When�a�person�performs�abductive�movement�into�the�ipsilateral�space,�the�hand�path�direction�is�parallel�to�the�long�axis�of�the�upper�arm.�Such�ipsilateral�reaches�require�lower�inertial�loads�or�less�strength,�which�results�in�shorter�MT�and�higher�PV�than�contralat-eral�reaches,�in�which�the�hand�path�is�more�perpendicular�to�the�axis�of�the�upper�arm�(Carey,�Hargreaves,�&�Goodale,�1996;�Carey�&�Otto-de�Haart,�2001;�Trombly,�1993;�Wu�et�al.,�2005).�It�remains�unclear�whether�and�how�the�effect�of� location� constraint�may� interact�with� the� instructional�
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demand�to�constrain�targeted�movements�of�the�less-affected�limb�after�stroke.�
Study of the Less-Affected LimbAlthough�deficits�in�the�affected�limb�after�stroke�are�pro-nounced,�motor�deficits�may�also�appear�in�the�less-affected�limb� (Haaland� et� al.,� 2004;�Wetter,�Poole,�&�Haaland,�2005).�Reaching�movements�by�the�less-affected�limb�have�been�of� growing� interest� to� researchers� and�practitioners��(e.g.,� Hermsdorfer,� Blankenfeld,� &� Goldenberg,� 2003).�Therapists�working�with�people�with�stroke�often�teach�com-pensatory� strategies� using� the� less-affected� limb� for� fine�motor�activities�(Shumway-Cook�&�Woollacott,�2007).�In�addition,�recent�stroke�rehabilitation�literature�has�suggested�that�repetitive�training�involving�paired�movements�of�the�affected�and�less-affected�limbs�results�in�a�facilitation�effect�from�the�less-affected�limb�to�the�affected�limb�(Goble,�2006;�Whitall,�Waller,�Silver,�&�Macko,�2000).�Understanding�the�reaching�performance�of�the�less-affected�limb�in�response�to� task� constraints�may�provide� relevant� information� for�stroke�rehabilitation�that�involves�compensatory�training�of�the�less-affected�limb�or�practice�of�bilateral�movements.
Research Questions and HypothesesTo�clarify�the�effects�of�task�constraints�on�reaching�perfor-mance�of�the�less-affected�limb,�we�investigated�the�effect�of�task�instructions�and�target�location�on�reaching�in�people�with�left�and�right�CVA�(LCVA�and�RCVA,�respectively)�and�healthy�control�participants.�Specifically,�we�looked�at�reaching�kinematics�when�people�with�and�without�stroke�reached�for�an�ipsilateral�target�(i.e.,�the�target�ipsilateral�to�the�less-affected�hand�used�for�performance)�and�a�contra-lateral�target�(i.e.,�the�target�contralateral�to�the�responding�hand)�under�speed�and�accuracy�instructions.�Healthy�people�were�studied�to�provide�a�basis�on�which�to�establish�normal�patterns�in�task�performance�under�different�task�constraints�(Wu,�Trombly,�Lin,�&�Tickle-Degnen,�1998;�Wu�et� al.,�2000).�Studying�people�with�LCVA�and�RCVA�would�reveal�specific�movement�responses�to�task�constraints�and�provide�insights�into�the�role�each�hemisphere�plays�in�movement�organization�(Elliott�&�Carson,�2000;�Wu,�Wong,�Lin,�&�Chen,�2001).
The�four�experimental�conditions,�formed�by�the�cross-ing�of�task�instructions�(speed�and�accuracy�emphasis)�and�target� locations� (ipsilateral� and� contralateral� to� the� less-affected�hand�used�for�performance),�are�(1)�speed-empha-sized� reaching� for� an� ipsilateral� target� (SI),� (2)� accuracy-emphasized� reaching� for� an� ipsilateral� target� (AI),� (3)�speed-emphasized�reaching�for�a�contralateral�target�(SC),�
and� (4)� accuracy-emphasized� reaching� for� a� contralateral�target�(AC).�Participants�with�stroke�performed�the�reaching�tasks�with�their�less-affected�limbs.�
We�hypothesized� that,� for� people�with� and�without�stroke,�the�movement�would�be�more�programmed�(shorter�RT� and�MT,� fewer�MUs),�with�higher� force� generation�(higher�PV)�for�speed-emphasized�tasks�than�for�accuracy-emphasized�tasks�and�for�ipsilateral�reaches�than�for�contra-lateral�reaches.�Instruction�effects�were�further�proposed�to�override� location�effects,�based� in�part�on� the�findings�of�Adam�(1992)�and�Fasoli�et�al.�(2002)�that�speed–accuracy�or�instruction�effects�remain�robust�when�the�target�location�is�changed�or�when�different�task�conditions�are�performed.�That�is,�the�more�programmed�movements�with�higher�force�generation�would�be�elicited�by�the�testing�conditions�in�the�following�order:�SI,�SC,�AI,�and�AC.�We�also�predicted�that�differential� responses� to� task�manipulations�may� arise� in�accord�with�laterality�of�stroke�lesion.
Method
Participants
The�participants�with�stroke�were�recruited�from�two�medi-cal�centers,�and�stroke�location�was�identified�by�computed�tomography�or�magnetic�resonance�images�of�the�brain.�The�patients�were�able�to�understand�or�respond�to�directions�given�by�the�experimenter�and�had�no�clinical�signs�of�motor�apraxia�and�visuospatial�neglect.�They�had�no�history�of�prior�CVA�or�visual�deficit�that�would�prevent�participation.�The�participants� in� the� control� group�had�no�prior�history�of�neurological�or�psychiatric�disease,�determined�by�self-report.�All�participants�signed�informed�consent�forms�approved�by�the�Institutional�Review�Board�of�National�Taiwan�University�Hospital.�The�participants�with�CVA�used�the�less-affected�limb,�and�the�matched�control�participants�used�the�same�limb�as�did�the�participants�with�CVA.�
Materials and Instrumentation
The�target�object�was�a�desk�bell�with�a�diameter�of�9.65�cm�and�a�height�of�4.75�cm.�The�start�and�the�end�of�the�reach�event�were�determined�through�the�use�of�a�hand�switch�and�the�desk�bell.�Before�movement�initiation,�the�participant’s�hand�rested�on�a�switch.�The�beginning�of�movement�was�recorded�when�the�hand�moved�off�the�switch.�The�end�of�movement�was�obtained�when�the�participant�pressed�the�desk�bell.
A�six-camera�motion�analysis�system�(VICON�370�3–D;�Oxford�Metrics�Inc.,�Oxford,�England)�was�used�in�conjunc-tion�with�one�personal�computer�(IBM�clone)�to�capture�the�movement�of�the�marker�attached�to�the�styloid�process�of�
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The American Journal of Occupational Therapy� 459
the�ulna�during�reaching�to�press�the�bell�and�to�collect�two�channels�of�analog�signals�simultaneously.�The�analog�sig-nals,�connected�with�the�hand�switch�and�the�desk�bell,�were�used�to�determine�the�start�and�the�end�of�the�reach.�The�VICON�system�was�shown�to�accurately�and�reliably�mea-sure�distances� ranging� from�25�mm�to�500�mm�between�markers�statically�and�the�motion�of�markers�up�to�speeds�of�approximately�15�m�per�second.�This�precision�is�more�than�sufficient�when�measuring�motions�during�reaching�or�gait�(Bhimji,�Deroy,�Baskin,�&�Hillstrom,�2000).�This�system�was�calibrated�to�have�averaged�residual�errors�not�exceeding�3�mm�for�each�camera�before�data�acquisition.�As�the�par-ticipant�moved,�the�instantaneous�position�of�the�marker�was�digitized�at�a�sampling�rate�of�60�Hz.�After�data�acquisition,�we�used�the�VICON�system�analysis� software�to�save�the�three-dimensional�location�of�the�marker�together�with�ana-log�data�in�binary�format.�The�obtained�positional�data�were�digitally� low-pass� filtered� at� 5� Hz� using� a� second-order�Butterworth�filter�with�forward�and�backward�pass.
Design and Procedures
We�used�a�counterbalanced�repeated-measures�design.�Each�incoming�participant�was�randomly�assigned�to�one�of�four�sequences�for�executing�the�reaching�task:�SI–AI–SC–AC,�AI–SC–AC–SI,� SC–AC–SI–AI,� or� AC–SI–AI–SC� (see�Table�1).
During�the�experiment,�each�participant�sat�on�a�chair�40.00�cm�high�in�front�of�a�table�adjusted�to�5.00�cm�above�the�elbow.�The�participant’s�performing�hand�rested�on�a�pressure-sensitive�switch�that�was�located�on�the�edge�of�the�table�in�line�with�the�participant’s�midsagittal�plane.�Two�target� locations� were� used:� the� left� and� right� hemispace�located�on�a�meridian�45°�relative�to�the�start�position.�The�target�object�was�placed�38.00�cm�from�the�starting�position�for�each�task�location.�The�verbal� instruction�involved�an�emphasis�on�rapid�(i.e.,�as�quickly�as�possible)�or�accurate�(i.e.,�as�accurately�as�possible)�execution�of�the�experimental�task.�The�start�of�a�trial�was�prompted�by�a�randomly�timed�verbal�instruction,�“go,”�to�prevent�participants�from�expect-
ing�when�to�initiate�the�movement.�Under�the�speeded�con-ditions�(i.e.,�SI,�SC),�the�participants�missed�the�targets�in�some�trials,�and�these�were�not�included�for�analysis.�Each�participant�performed�three�successful�trials�for�each�condi-tion.�One�practice�trial�was�performed�before�the�participant�executed�the�task�for�each�condition.�
Data Analysis
We�used�an�analysis�program�coded�by�LabVIEW�(National�Instruments,� Inc.,�Austin,�TX)� to�process� collected�data.�Information�on�reaching�performance�including�RT,�MT,�MU,� and�PV�was� obtained.�We� conducted� the� analyses�separately�for�the�participants�with�LCVA�and�RCVA�and�for�the�healthy�control�participants.�To�test�the�effects�of�both� constraints,�we�used� contrast� analyses� (i.e.,� focused�analyses�of�variance�[ANOVAs])�in�which�specific�predic-tions�were�tested�by�contrasting�them�with�the�obtained�data�(Rosenthal�&�Rosnow,�1985).�We�first�performed�4��4�mixed�ANOVAs�for�each�dependent�variable�to�obtain�the�omnibus�F of�the�Sequence��Order�interaction.�There�was�one�between-subjects�factor,�sequence,�and�one�repeated�or�within-subjects�factor,�order,�in�this�mixed�ANOVA.�The�effects� of� the� task� constraints� (i.e.,� the�omnibus�F)�were�embedded�in�the�Sequence��Order�interaction�(Rosenthal�&�Rosnow,�1991).�This�practice�is�more�powerful�than�the�commonly�used�two-way�ANOVAs�with�repeated�factors�because�it�removes�the�confounding�effects�of�sequence�and�order�from�the�error�term.
We�then�obtained�the�focused�F�for�our�contrast�analysis�from�the�omnibus�F�as�follows:�Fcontrast�=�(r2)�(omnibus�Ftreatment�×�dfnumerator),�where� r2� is� the� square�of� the�correlation�between�the�contrast�weights�and�the�residualized�means�(Rosenthal�&�Rosnow,�1991).�For�the�present�study,�we� assigned� contrast� weights� numerically� reflecting� the�hypothesis.�For�example,�in�this�study’s�SI,�SC,�AI,�and�AC�conditions,�the�contrast�weights�for�predicting�the�trend�of�MT�were�–3,�–1,�1,� and�3,� respectively.�To� indicate� the�magnitude�of�the�effect�of�interest,�we�calculated�the�effect�size�r�for�each�dependent�variable�for�each�group�(Rosenthal�&�Rosnow,�1985).
ResultsThe�participants�in�this�study�included�26�people�with�uni-lateral�CVA�(18�men�and�8�women,�42–83�years�old,�mean�age�63.4�years)�and�24�age-matched�healthy�people�(7�men�and�17�women,�42–80�years�old,�mean�age�62.3�years),�who�were� right�handed�by� self-report.�Average� time� following�stroke�onset�was�2.62�months�(SD�=�3.12;�range�=�0.13−12.90�months).�Eleven�participants�with�RCVA�and�12�control�participants�used�their�right�limbs�to�perform�the�tasks;�15�
Table 1. A Counterbalanced Repeated-Measures Design
Sequence
Order
1 2 3 4
1 SI AI SC AC
2 AI SC AC SI
3 SC AC SI AI
4 AC SI AI SC
Note. Order refers to the order of administration of the treatment. SI = speed-emphasized reaching for an ipsilateral target; AI = accuracy-emphasized reaching for an ipsilateral target; SC = speed-emphasized reaching for a con-tralateral target; AC = accuracy-emphasized reaching for a contralateral target.
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participants�with�LCVA�and�12�control�participants�used�their�left�limbs.
Figures�1� through�4�present� the�means� and� standard�deviation�bars�associated�with�RT,�MT,�MU,�and�PV�under�each�experimental�condition�for�the�four�groups.�Table�2�shows�the�results�of�the�contrast�analyses.�For�both�control�groups�(one�group�using�the�left�hand�and�the�other�using�the�right�hand),�speeded�instructions�and�ipsilateral�reaches�elicited�more�preprogrammed�movements�than�did�accuracy�instruction�and�contralateral�reaches,�respectively.�Both�con-trol�groups�initiated�the�movement�faster�(shorter�RT)�and�performed�the�movement�more�efficiently�(shorter�MT)�and�smoothly�(fewer�MUs)�for�speed-emphasized�versus�accuracy-emphasized�tasks�and�for�ipsilateral�versus�contralateral�ones.�The�instructional�effects�overrode�the�target�location�effects�for�these�three�variables,�which�is�consistent�with�the�a�priori�hypotheses.�However,�a�scrutiny�of�the�raw�data�showed�that�the�direction�of�constraint�effects�on�force�generation�(PV)�was�not� fully� consistent�with� the�a�priori�hypothesis.�We�performed�a�post�hoc�analysis,�which� showed� that�higher�force�was�generated�for�speed-emphasized�versus�accuracy-emphasized�movements�and�for�ipsilateral�versus�contralat-eral�reaches.�Inconsistent�with�the�a�priori�hypotheses,�the�location�effects�overrode�the�instructional�effects�(Table�3).
Results� for� the� CVA� groups� using� the� less-affected�limb�showed�significant�and�large�effects�of�the�task�con-straints�for�all�variables�(RT,�MT,�MU,�PV)�for�the�LCVA�group�and�for�three�of�the�four�variables�(MT,�MU,�PV)�for� the� RCVA� group.� Nonsignificant� and� modest� task-constraint�effects�were�found�in�RT�for�the�RCVA�group.�Both� groups� showed� more� efficient� (shorter� MT)� and�smoother�(fewer�MUs)�performance�for�speed-emphasized�versus�accuracy-emphasized�movements�and�for�ipsilateral�
Figure 1. Performance by the healthy control group using the left hand as a function of task conditions. Mean and standard deviation bars are displayed.
RT = reaction time; MT = movement time; MU = movement unit; PV = peak velocity; SI = speed-emphasized reaching for an ipsilateral target; SC = speed-emphasized reaching for a contralateral target; AI = accuracy-emphasized reaching for an ipsilateral target; AC = accuracy-emphasized reaching for a contralateral target.
Figure 2. Performance by the healthy control group using the right hand as a function of task conditions. Mean and standard deviation bars are displayed.
RT = reaction time; MT = movement time; MU = movement unit; PV = peak velocity; SI = speed-emphasized reaching for an ipsilateral target; SC = speed-emphasized reaching for a contralateral target; AI = accuracy-emphasized reaching for an ipsilateral target; AC = accuracy-emphasized reaching for a contralateral target.
Figure 3. Performance by the LCVA group as a function of task condition. Mean and standard deviation bars are displayed.
RT = reaction time; MT = movement time; MU = movement unit; PV = peak velocity; SI = speed-emphasized reaching for an ipsilateral target; SC = speed-emphasized reaching for a contralateral target; AI = accuracy-emphasized reaching for an ipsilateral target; AC = accuracy-emphasized reaching for a contralateral target.
Figure 4. Performance by the RCVA group as a function of task condition. Mean and standard deviation bars are displayed.
RT = reaction time; MT = movement time; MU = movement unit; PV = peak velocity; SI = speed-emphasized reaching for an ipsilateral target; SC = speed-emphasized reaching for a contralateral target; AI = accuracy-emphasized reaching for an ipsilateral target; AC = accuracy-emphasized reaching for a contralateral target.
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The American Journal of Occupational Therapy� 461
versus�contralateral�movements.�Moreover,�the�instructional�effects�overrode�the�location�effects,�which�is�consistent�with�the�a�priori�prediction.
However,�the�raw�data�showed�that�the�effects�on�move-ment� initiation� (RT)� for� the�LCVA�group� and�on� force�generation�(PV)�for�both�groups�were�not�fully�consistent�with�the�a�priori�hypotheses.�We�conducted�post�hoc�analy-ses� of� the�data� for� the� stroke� groups.�Large� effects�were�obtained�in�favor�of�the�post�hoc�hypotheses�for�movement�initiation�in�the�LCVA�group�and�for�force�generation�in�both� groups� (Table� 3).� Speed-emphasized� conditions�required�less�time�to�initiate�the�movement�for�the�LCVA�group�than�did�the�accuracy-emphasized�conditions.�Target�location�did�not�affect�the�time�to�initiate�movement�in�this�group�under�either�type�of�task�instruction�(i.e.,�SI–SC;�AI–AC).�On�the�other�hand,�constraint�effects�on�force�genera-tion�were�found�for�the�RCVA�and�the�LCVA�groups.�Target�location�effects�overrode�the�instructional�effects,�in�which�ipsilateral�reaches�generated�higher�force�than�contralateral�reaches.�Speed�requirements�generated�higher�force,�relative�to�accuracy�demands,�for�either�type�of�reach.
Discussion
The�results�of�the�study�are�partially�consistent�with�the�a�priori� hypotheses� and� support� the�notion� that� task� con-straints� modulate� movement� preparation� and� execution�(Newell,� 1998;� Shumway-Cook� &� Woollacott,� 2007).�Healthy� people� used� more� programmed� movements� (as�suggested�by�RT,�MT,�and�MU)�with�higher�force�genera-tion� (higher� PV)� for� speed-emphasized� versus� accuracy-�emphasized� tasks� and� for� ipsilateral� versus� contralateral�movements.�The�instructional�effects�significantly�overrode�the� target� location� effects� on�movement� initiation� (RT),�efficiency� (MT),�and�smoothness� (MU)�but�not�on� force�generation�(PV).�We�found�similar�patterns�of�performance�in�response�to�task�constraints�in�the�CVA�groups�except�for�movement� initiation� in� the�RCVA�group.�Therefore,�we�concluded�that�the�integration�of�speeded�instruction�and�ipsilateral�reach�(SI�condition)�optimized�movement�execu-tion�for�healthy�adults�and�people�with�CVA.�A�major�deficit�of�people�with�CVA�in�response�to�task�constraints�lies�in�movement� initiation�because�we� found�no�differential� or�gradient�differences�in�RT�among�various�task�conditions.�However,�the�consistent�effects�of�task�constraints�on�move-ment� efficiency,� smoothness,� and� force� generation� in� the�healthy�participants�and�those�with�CVA�suggest�that�some�aspects�of�movement�kinematics�may�be�relatively�unaffected�by�stroke.
Findings�for�both�control�groups�were�consistent�with�those�of�previous�studies�on�speed–accuracy�instruction�con-straints�(Adam,�1992;�Fasoli�et�al.,�2002;�Fisk�&�Goodale,�1984;�Rival�et�al.,�2003).�Speeded�instructions�and�ipsilateral�reaches� elicited�more�preprogrammed�movements� (faster�initiation� and�more� efficiency� and� smoothness)� than� the�accuracy�instruction�and�contralateral�reaches,�respectively.�This�study�extended�previous�research�by�showing�the�ben-efit�of�speeded�instruction�in�a�simple,�functionally�relevant�task.�The�instructional�effect�may�arise�because�the�demand�for� speed�can�direct� the�performer’s� attention� toward� the�temporal�organization�of�movement�and�activate�predomi-nantly� the� preprogrammed� strategies� (i.e.,� the� ballistic�
Table 2. Results of Contrast Analyses for the Study Groups
Dependent Variable
NL NR LCVA RCVA
FocusedF(1, 24) p
EffectSize r
FocusedF(1, 24) p
EffectSize r
FocusedF(1, 33) p
EffectSize r
FocusedF(1, 21) p
EffectSize r
RT 5.44 .015 .64 9.60 .025 .74 17.33 <.001 .78 1.87 .093 .45
MT 110.21 <.001 .97 65.10 <.001 .94 36.76 <.001 .88 46.95 <.001 .93
MU 9.91 .002 .74 14.07 <.001 .80 6.03 <.001 .60 8.46 <.001 .74
PV 9.80 .002 .74 7.82 .005 .70 13.31 <.001 .74 19.18 <.001 .86
Note. NL = controls using the left hand; NR = controls using the right hand; LCVA = participants with left cerebrovascular accidents; RCVA = participants with right cerebrovascular accidents; RT = reaction time; MT = movement time; MU = movement units; PV = peak velocity.
Table 3. Results of Post Hoc Contrast Analysis
Study Group andDependent Variable Post Hoc Hypotheses Effect Size r
NL
PV SI > AI >SC > AC 0.78
NR
PV SI > AI > SC > AC 0.85
LCVA
RT SI = SC < AI = AC 0.81
PV SI > AI > SC > AC 0.82
RCVA
PV SI > AI > SC > AC 0.94
Note. NL = controls using the left hand; NR = controls using the right hand; LCVA = participants with left cerebrovascular accidents; RCVA = participants with right cerebrovascular accidents; PV = peak velocity; RT = reaction time; SI = speed-emphasized reaching for an ipsilateral target; SC = speed-empha-sized reaching for a contralateral target; AI = accuracy-emphasized reaching for an ipsilateral target; AC = accuracy-emphasized reaching for a contralat-eral target.
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462� July/August 2008, Volume 62, Number 4
movements;� Hermsdorfer� et� al.,� 1996;� Ma� et� al.,� 2004).�Another�possibility�is�that�instructions�for�speed�versus�accu-racy�indicate�different�goals�to�be�accomplished.�Task�goal�has�been�shown�to�be�a�powerful�organizing�factor�in�simple�motor�tasks�(Lin�et�al.,�1998;�Shumway-Cook�&�Woollacott,�2007;�Trombly�&�Wu,�1999;�Wu�et�al.,�2000,�2001).�The�goal�of�reaching�quickly�may�organize�the�motor�system�to�perform�faster�and�more� smoothly� to�achieve� the� task�requirement,�whereas�the�goal�of�reaching�with�accuracy�possibly�directs�the�performer’s�attention�toward�endpoint�precision,�which�may�compromise�movement�efficiency�and�smoothness.
The�results�of�location�effects�on�movement�initiation,�efficiency,�and�smoothness�in�both�control�groups�agree�with�those�of�previous�research�(Fisk�&�Goodale,�1984;�Ghozlan,�1998;�Wu�et� al.,� 2005)�demonstrating� the� advantages�of�ipsilateral�reaches.�Such�advantages�possibly�lie�in�the�effi-ciency�of�intrahemispheric�processing�for�visuomotor�infor-mation�on�target�or�visual�feedback�from�the�reaching�limb�(Barthelemy�&�Boulinguez,�2002;�Fisk�&�Goodale,�1984).�Some�positron�emission�tomography�studies�(Carey,�Abbott,�Egan,�Tochon-Danguy,�&�Donnan,�2000;�van�Mier,�Tempel,�Perlmutter,�Raichle, & Petersen,�1998)�have�shown�greater�brain�activations�in�the�hemisphere�contralateral�to�the�hand�used�than�in�the�other�hemisphere�for�ipsilateral�reaches.�By�contrast,�comparable�brain�areas�were�activated�in�both�hemi-spheres�for�contralateral�reaches.�These�findings�further�sup-port�the�notion�of�the�advantage�of�intrahemispheric�process-ing�for�ipsilateral�reaches.�The�results�might�also�be�accounted�for�by�the�biomechanical�characteristics�of�the�movement.�As�mentioned�earlier,� inertial� force�operating�at� the�hand� for�ipsilateral� reaches�was� lower�than�for�contralateral� reaches.�Ipsilateral�reaches�may�engender�faster�movement�initiation�and�higher�movement�efficiency�than�contralateral�reaches�(Carey�et�al.,�1996;�Carey�&�Otto-de�Haart,�2001).
In�agreement�with�the�findings�of�Adam�(1992)�and�Fasoli�et�al.�(2002),�speed–accuracy�effects�overrode�location�effects.�This� study� extended� the� robust� effects�of� speed–accuracy�from�reciprocal�movements�to�simple�aiming�movements�and�from�the�sagittal�plane� to� the�spatial�planes� ipsilateral�and�contralateral�to�stroke�lesion.�This�may�be�because�the�nature�of�the�auditory�information�from�the�verbal�instruction�pro-vided�strong�constraints�that�captured�the�intrinsic�dynamics�of�the�performer’s�movement�system�and�overrode�the�effects�of�target�location�(Kail�&�Salthouse,�1994).
The�effects�of�task�constraints�on�force�generation�were�not�fully�consistent�with�the�a�priori�hypotheses.�The�control�participants� exerted�more� force� for� executing� the� task�of�speeded�and�ipsilateral�reaches�than�for�accurate�and�contra-lateral�reaches,�respectively,�supporting�the�notion�that�tasks�with�speeded�emphasis�and�ipsilateral�reaches�require�greater�inertial�force�or�impulse�at�movement�initiation�for�efficient�
movement�(Beer�et�al.,�2000;�Ma�et�al.,�2004;�Rand�et�al.,�2000;� Roy� et� al.,� 2000).� Inconsistent� with� the� a� priori�hypothesis,�location�effects�overrode�speed–accuracy�effects.�The�dominant�effects�of�target� location�suggest�that�force�generation�may�be�more�sensitive�to�within-hemisphere�pro-cessing�and�biomechanical�control�than�to�preprogrammed�strategies.
The�results� for�the�CVA�groups�were�consistent�with�those�for�the�control�groups�in�movement�efficiency,�smooth-ness,�and�force�generation,�suggesting�that�these�aspects�of�movement�kinematics�of�the�less-affected�limb�may�be�rela-tively�unaffected�by�stroke.�Moreover,�the�findings�on�move-ment�efficiency�and�smoothness�are�consistent�with�those�of�the�previous�studies�(Beer�et�al.,�2000;�Castiello�et�al.,�1999;�Roy� et� al.,� 2000).� The� deficits� of� people� with� CVA� in�response� to� task�constraints� (verbal� instruction�and� target�location)�occur�primarily�in�movement�planning.�The�LCVA�group� exhibited� shorter� time� for�movement�planning�or�preparation�under�speeded�instructions�than�under�accuracy�instructions�for�reaching�to�either�location.�By�contrast,�the�RCVA�group�did�not�demonstrate�significant�effects�of�task�constraints�on�movement�initiation.�A�possible�reason�for�differences�in�effects�of�task�constraints�between�the�LCVA�and�RCVA�groups�might�be� that� the� right�hemisphere� is�dominant�for�processing�visuospatial�or�positional�aspects�of�goal-directed�movements,�whereas�the�left�hemisphere�sub-serves�nonspatial� or�nonpositional� aspects�of�preplanning�(Haaland�et�al.,�2004;�Winstein�&�Pohl,�1995).�The�task�used� in� this� study� required�position� control� to� accurately�press�the�bell�under�either�type�of�instruction�and�scale�the�spatial� relationship�between� the� target� and� the�performer�(Heath,�Hodges,�Chua,�&�Elliott,�1998).�Accordingly,�once�the�right�hemisphere� is� lesioned,� the�ability� to�preplan�or�program�the�motor�act�for�a�visual�target�such�as�that�used�in�the�present�study�is�decreased,�and�the�pattern�of�RT�in�response� to� instructional� or� location� constraints� is�impaired.
A�scrutiny�of�the�kinematic�performance�between�the�control�and�the�CVA�groups�showed�that�the�participants�with�CVA�generally�produced� fewer�programmed�move-ments�(slower�movement�initiation,�less�movement�efficiency�and�smoothness)�with�lower�force�generation�than�the�con-trol�participants.�These�findings�suggest�that�occupational�therapy�for�stroke�should�consider�motor�deficits�of�the�less-affected� limb� (Haaland� et� al.,� 2004;�Kim,�Pohl,�Luchies,�Stylianou,� &� Won,� 2003;� Quaney,� Perera,� Maletsky,�Luchies,�&�Nudo,�2005; Wetter�et�al.,�2005).�This�consid-eration� is�necessary�because�compensatory�use�of� the� less-affected�limb�after�stroke�is�common�for�precision�tasks�in�daily�life�situations.�To�facilitate�enhanced�movement�per-formance,� occupational� therapists� may� incorporate� task�
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The American Journal of Occupational Therapy� 463
�constraints�(e.g.,�verbal�instructions�and�target�location)�into�practice�of�goal-directed�actions�by�people�with�CVA.
This� study’s�findings�may�have� implications� for� task-specific�practice�of�compensatory�use�of�the�less-affected�limb�after� stroke.�Task�demands� for� speeded�movement�or� for�ipsilateral� reach� might� facilitate� movement� efficiency,�smoothness,� and� force� generation.� The� combination� of�speeded�instruction�and�ipsilateral�reach�may�elicit�the�most�preprogrammed�movements�and�optimize�movement�per-formance�when�the�less-affected�limb�is�used�for�target�reach-ing.�The�speeded�instruction�might�have�greater�benefit�than�ipsilateral�reaches�for�enhancing�movement�efficiency�and�smoothness.�By�contrast,�if�generation�of�greater�force�is�the�goal,�use�of�the�less-affected�limb�for�practice�of�ipsilateral�reaches�might�be�more�advantageous�than�speeded�instruc-tions.�If�fast�response�to�the�task�demand�is�the�goal,�speeded�demands�may�be�helpful�for�people�with�LCVA�but�not�for�those�with�RCVA.
One�limitation�of�this�study�is�that�the�effect�of�stroke�severity�was�not�studied�and�warrants�future�research.�Future�research�may�also� investigate� the� response�patterns�of� the�more-affected�hand�in�response�to�the�constraints�to�update�motor�control�rehabilitation�interventions�for�clients�with�hemiplegia.�Additional� constraint� factors� are� relevant� for�study�to�elucidate�the�dynamic�interplay�between�task�con-straints�and�people�with�CVA.�Examples�are�task�difficulty�and� complexity� (e.g.,� target� size� and� task� distance;�Hermsdorfer�et�al.,�2003;�Kim�et�al.,�2003;�Ma�&�Trombly,�2004),�position�of�the�hand�relative�to�target�location,�pres-ence�of�distracting�objects,�and�motivational�relevance�of�the�motor�act�for�individual�performers.�Further�study�that�elu-cidates�these�issues�will�improve�understanding�of�the�orga-nization� of� aiming� movements� and� inform� task-specific�approaches�to�stroke�rehabilitation.
ConclusionsOur�findings� reveal� the� confluence�of� instructional� con-straints�of�speed–accuracy�and�target�location�during�reach-ing�movements�by�people�with�and�without�CVA.�The�study�demonstrated�that�instructions�for�speeded�reaching�for�an�ipsilateral� target� elicited� the�most�preprogrammed�move-ment.�Moreover,�some�aspects�of�movement�performance—such�as�movement�efficiency,�smoothness,�and�force�genera-tion� of� the� less-affected� limb� in� response� to� the� task�constraints—may� be� relatively� unaffected� by� unilateral�stroke.�The�RCVA�group,�but�not�the�LCVA�group,�failed�to� respond� to� the� instruction� and� location� constraints� in�movement�preparation�during�the�desk�bell�task.�The�dif-ferential� responses� to� task� constraints� in� the�hemispheric�groups�suggest�that�the�right�hemisphere�may�be�responsible�
for�the�programming�and�planning�of�motor�acts�involving�space�coding.�Such�information�might�facilitate�rehabilitative�treatment�planning�for�the�less-affected�limb�that�incorpo-rates�constraint�factors�into�compensatory�strategy�practice.�Therapeutic�activities�that�involve�instructional�demands�for�fast�movement�and�ipsilateral�reaches�may�be�used�to�facili-tate�movement�efficiency,�smoothness,�and�force�generation�of� the� less-affected� limb.�Further� research�may�also� study�whether�practice� on� these� activities�may� enhance�perfor-mance� of� the� affected� limb� during� bilateral� movements�involving�both�upper�limbs�(e.g.,�opening�a�drawer�with�the�affected�hand�and�retrieving�a� target�object�with� the� less-affected�hand;�Wu,�Lin,�Chen,�Chen,�&�Hong,�2007).� s
AcknowledgmentsWe� thank� the� research� therapists� at� National� Taiwan�University�Hospital�for�their�assistance�and�the�anonymous�reviewers�for�their�insightful�comments�on�this�article.�This�project� was� supported� by� the� National� Science� Council�(NSC�91-2314-B-002-080�and�NSC�92-2314-B-002-139)�and�the�National�Health�Research�Institutes�(NHRI-EX93-9103EC�and�NHRI-EX94-9103EC)�in�Taiwan.
ReferencesAdam,�J.�J.�(1992).�The�effects�of�objectives�and�constraints�on�
motor� control� strategy� in� reciprocal� aiming� movements.�Journal of Motor Behavior,�24,�173–185.
Barthelemy,�S.,�&�Boulinguez,�P.�(2002).�Manual�asymmetries�in�the�directional�coding�of�reaching:�Further�evidence�for�hemis-patial�effects�and�right�hemisphere�dominance�for�movement�planning.�Experimental Brain Research, 147,�305–312.
Beer,�R.�F.,�Dewald,�J.�P.�A.,�&�Rymer,�W.�Z.�(2000).�Deficits�in�the�coordination�of�multijoint�arm�movements�in�patients�with�hemiparesis:�Evidence� for� disturbed� control� of� limb�dynamics.�Experimental Brain Research, 131,�305–319.
Bhimji,�S.,�Deroy,�A.�R.,�Baskin,�E.�S.,�&�Hillstrom,�H.�J.�(2000).�Static�and�dynamic�accuracy�of�the�VICON�370�3-D�kine-matic�system.�Gait and Posture, 11,�130.�
Carey,� D.� P.,� Hargreaves,� E.� L.,� &� Goodale,� M.� A.� (1996).�Reaching� to� ipsilateral� or� contralateral� targets:� Within-�hemisphere�visuomotor�processing�cannot�explain�hemispatial�differences� in�motor� control.�Experimental Brain Research, 112,�496–504.
Carey,�D.�P.,�&�Otto-de�Haart,�E.�G.�(2001).�Hemispatial�differ-ences�in�visually�guided�aiming�are�neither�hemispatial�nor�visual.�Neuropsychologia,�39,�885–894.
Carey,�L.�M.,�Abbott,�D.�F.,�Egan,�G.�F.,�Tochon-Danguy,�H.�J.,�&�Donnan,�G.�A.�(2000).�The�functional�neuroanatomy�and�long-term�reproducibility�of�brain�activation�associated�with�a�simple�finger�tapping�task�in�older�healthy�volunteers:�A�serial�PET�study.�NeuroImage, 11,�124–144.
Castiello,�U.,�Bennett,�K.,�Bonfiglioli,�C.,�Lim,�S.,�&�Peppard,�R.�F.�(1999).�The�reach-to-grasp�movement�in�Parkinson’s�
Downloaded From: http://ajot.aota.org/pdfaccess.ashx?url=/data/journals/ajot/930098/ on 07/07/2018 Terms of Use: http://AOTA.org/terms
464� July/August 2008, Volume 62, Number 4
disease:�Response� to�a� simultaneous�perturbation�of�object�position�and�object� size.�Experimental Brain Research,�125,�453–462.
Duarte,�M.,�&�Freitas,�S.�M.�(2005).�Speed-accuracy�trade-off�in�voluntary�postural�movements.�Motor Control,�9,�180–196.
Elliott,�D.,�&�Carson,�R.�G.�(2000).�Moving�into�the�new�millen-nium:�Some�perspectives�on�the�brain�in�action. Brain and Cognition,�42,�153–156.
Fasoli,�S.�E.,�Trombly,�C.�A.,�Tickle-Degnen,�L.,�&�Verfaellie,�M.�H.�(2002).�Effect�of�instructions�on�functional�reaching�in�persons�with�and�without�cerebrovascular�accident.�American Journal of Occupational Therapy, 56,�380–390.
Fisk,�J.�D.,�&�Goodale,�M.�A.�(1984).�Differences�in�the�organiza-tion�of�visually�guided�reaching�to�ipsilateral�and�contralateral�targets. Behavioural Brain Research, 12,�189–190.
Fitts,�P.�M.�(1954).�The�information�capacity�of�the�human�motor�system�in�controlling�the�amplitude�of�movement.�Journal of Experimental Psychology,�47,�381–391.
Ghozlan,�A.�(1998).�Stimulus-response�compatibility�and�position�of�the�hands:�Nonadditive�effects.�Perceptual and Motor Skills,�86,�843–850.
Goble,�D.�J.�(2006).�The�potential�for�utilizing�inter-limb�cou-pling�in�the�rehabilitation�of�upper�limb�motor�disability�due�to�unilateral�brain�injury.�Disability and Rehabilitation, 28,�1103–1108.
Haaland,�K.�Y.,�Prestopnik,�J.�L.,�Knight,�R.�T.,�&�Lee,�R.�R.�(2004).�Hemispheric� asymmetries� for�kinematic� and�posi-tional�aspects�of�reaching.�Brain,�127,�1145–1158.�
Heath,�M.,�Hodges,�N.,�Chua,�R.,�&�Elliott,�D.�(1998).�On-line�control�of�rapid�aiming�movements:�Unexpected�target�per-turbations�and�movement�kinematics. Canadian Journal of Experimental Psychology,�52,�163–173.
Hermsdorfer,�J.,�Blankenfeld,�H.,�&�Goldenberg,�G.�(2003).�The�dependence�of�ipsilesional�aiming�deficits�on�task�demands,�lesioned� hemisphere,� and� apraxia.� Neuropsychologia,� 41,�1628–1643.�
Hermsdorfer,�J.,�Mai,�N.,�Spatt,�J.,�Marquardt,�C.,�Vetkamp,�R.,�&�Goldenberg,�G.�(1996).�Kinematic�analysis�of�movement�initiation�in�apraxia.�Brain,�119,�1575–1586.
Kail,�R.,�&�Salthouse,�T.�A.�(1994).�Processing�speed�as�a�mental�capacity. Acta Psychologica,�86,�199–225.
Kim,�S.�H.,�Pohl,�P.�S.,�Luchies,�C.�W.,�Stylianou,�A.�P.,�&�Won,�Y.� (2003).� Ipsilateral� deficits� of� targeted�movements� after�stroke.�Archives of Physical Medicine and Rehabilitation, 84,�719–724.
Lin,�K.-C.,�Wu,�C.-Y.,�&�Trombly,�C.�A.�(1998).�Effects�of�task�goal�on�movement�kinematics�and�line�bisection�performance�in�adults�without�disabilities.�American Journal of Occupational Therapy, 52,�179–187.
Ma,�H.-I.,�&�Trombly,�C.�A.�(2004).�Effects�of�task�complexity�on�reaction�time�and�movement�kinematics�in�elderly�people.�American Journal of Occupational Therapy, 58,�150–158.
Ma,�H.-I.,�Trombly,�C.�A.,�Wagenaar,�R.�C.,�&�Tickle-Degnen,�L.�(2004).�Effect�of�one�single�auditory�cue�on�movement�kine-matics�in�patients�with�Parkinson’s�disease.�American Journal of Physical Medicine and Rehabilitation,�83,�530–536.
Mathiowetz,�V.,�&�Bass-Haugen,� J.� (2008).�Assessing� abilities�and�capacities:�Motor�behavior.�In�M.�V.�Radomski�&�C.�A.�Trombly�Latham�(Eds.),�Occupational therapy for physical
dysfunction� (6th� ed.,� pp.�186–211).�Baltimore:�Lippincott�Williams�&�Wilkins.�
Milner,�T.�E.�(1992).�A�model�for�the�generation�of�movements�requiring�endpoint�precision.�Neuroscience,�49,�487–496.
Newell,�K.�M.�(1998).�Therapeutic�intervention�as�a�constraint�in� learning� and� relearning�movement� skills. Scandinavian Journal of Occupational Therapy,�5,�51–57.
Pendleton,�H.�M.,�&�Schultz-Krohn,�W.� (2006).�The�occupa-tional�therapy�practice�framework�and�the�practice�of�occupa-tional�therapy�for�people�with�physical�disabilities.�In�H.�M.�Pendleton�&�W.�Schultz-Krohn�(Eds.),�Pedretti’s occupational therapy: Practice skills for physical dysfunction� (6th� ed.,� pp.�1–16).�St.�Louis,�MO:�Mosby.
Quaney,�B.�M.,�Perera,�S.,�Maletsky,�R.,�Luchies,�C.�W.,�&�Nudo,�R.�J. (2005).�Impaired�grip�force�modulation�in�the�ipsile-sional� hand� after� unilateral�middle� cerebral� artery� stroke.�Neurorehabilitation and Neural Repair, 19,�338–349.
Rand,�M.�K.,�Stelmach,�G.�E.,�&�Bloedel,�J.�R.�(2000).�Movement�accuracy� constraints� in� Parkinson’s� disease� patients.�Neuropsychologia,�38,�203–212.
Rival,�C.,�Olivier,�I.,�&�Ceyte,�H.�(2003).�Effects�of�temporal�and/or�spatial�instructions�on�the�speed–accuracy�trade-off�of�pointing�movements�in�children.�Neuroscience Letters, 336,�65–69.
Rosenthal,�R.,�&�Rosnow,�R.�L.�(1985).�Contrast analysis: Focused comparisons in the analysis of variance.�Cambridge,�England:�Cambridge�University�Press.
Rosenthal,�R.,�&�Rosnow,�R.�L.�(1991).�Essentials of behavioral research: Methods and data analysis� (2nd� ed.).�New�York:�McGraw-Hill.�
Roy,�E.,�Kalbfleisch,�L.,�Bryden,�P.,�Barbour,�K.,�&�Black,� S.�(2000).�Visual� aiming�movements� in�Alzheimer’s� disease.�Brain and Cognition,�43,�380–384.�
Shumway-Cook,�A.,�&�Woollacott,�M.�H.�(2007).�Motor control: Translating research into clinical practice�(3rd�ed.,�pp.�3–20).�New�York:�Lippincott�Williams�&�Wilkins.
Trombly,�C.�A.�(1992).�Deficits�of�reaching�in�subjects�with�left�hemiparesis:�A�pilot�study.�American Journal of Occupational Therapy, 46,�887–897.
Trombly,�C.�A.�(1993).�Observations�of�improvement�of�reaching�in�five� subjects�with� left�hemiparesis.� Journal of Neurology, Neurosurgery, and Psychiatry, 56,�40–45.
Trombly�Latham,�C.�A.� (2008).�Occupation:�Philosophy� and�concepts.� In�M.�V.�Radomski�&�C.�A.�Trombly�Latham�(Eds.),�Occupational therapy for physical dysfunction�(6th�ed.,�pp.�339–357).�Baltimore:�Lippincott�Williams�&�Wilkins.
Trombly,�C.�A.,�&�Wu,�C.-Y.�(1999).�Effect�of�rehabilitation�tasks�on�organization�of�movement�post�stroke.�American Journal of Occupational Therapy, 53,�333–344.
van�Mier,�H.,�Tempel,�L.�W.,�Perlmutter,�J.�S.,�Raichle,�M.�E., & Petersen,�S.�E. (1998).�Changes�in�brain�activity�during�motor�learning�measured�with�PET:�Effects�of�hand�of�performance�and�practice.�Journal of Neurophysiology,�80,�2177–2199.�
Wetter,�S.,�Poole,�J.�L.,�&�Haaland,�K.�Y.�(2005).�Functional�impli-cations�of� ipsilesional�motor�deficits� after�unilateral� stroke.�Archives of Physical Medicine and Rehabilitation,�86,�776–781.
Whitall,�J.,�Waller,�S.�M.,�Silver,�K.�H.�C.,�&�Macko,�R.�F.�(2000).�Repetitive�bilateral�arm�training�with�rhythmic�auditory�cue-ing�improves�motor�function�in�chronic�hemiparetic�stroke.�Stroke, 31,�2390–2395.
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The American Journal of Occupational Therapy� 465
Winstein,�C.�J.,�&�Pohl,�P.�S.�(1995).�Effects�of�unilateral�brain�damage�on� the� control� of� goal-directed�hand�movements.�Experimental Brain Research,�105,�163–174.
Wu,�C.-Y.,�Lin,�K.-C.,�Chen,�H.-C.,�Chen,�I.-H.,�&�Hong,�W.-H.� (2007).�Effects� of�modifi�ed� constraint-induced�move-ment�therapy�on�movement�kinematics�and�daily�function�in�patients�with� stroke:�A�kinematic� study�of�motor� con-trol�mechanisms.�Neurorehabilitation and Neural Repair, 21,�460–466.
Wu,�C.-Y.,�Lin,�K.-C.,�Lin,�K.-H.,�Chang,�C.-W.,�&�Chen,�C.-L.�(2005).�Effects�of�task�constraints�on�reaching�kinematics�by�healthy�adults.�Perceptual and Motor Skills, 100,�983–994.
Wu,�C.-Y.,�Trombly,�C.�A.,�Lin,�K.-C.,�&�Tickle-Degnen,�L.�(1998).�Effects�of�object�affordances�on�reaching�performance�in�persons�with�and�without�cerebral�vascular�accident�(CVA).�American Journal of Occupational Therapy, 52,�447–456.
Wu,�C.-Y.,�Trombly,�C.�A.,�Tickle-Degnen,�L.,�&�Lin,�K.-C.�(2000).�A�kinematic�study�of�contextual�effects�on�reaching�performance�in�persons�with�and�without�stroke:�Infl�uences�of� object� availability.� Archives of Physical Medicine and Rehabilitation, 81,�95–101.
Wu,�C.-Y.,�Wong,�M.-K.,�Lin,�K.-C.,�&�Chen,�H.-C.�(2001).�Effects�of�task�goal�and�personal�preference�on�seated�reaching�kinematics�after�stroke.�Stroke, 32,�70–76.
Adults With Stroke (AOTA Practice Guidelines) By Joyce Sabari, PhD, OTR, FAOTA; Series Editor: Deborah Lieberman, MHSA, OTR/L, FAOTA �
Each�year,�as�many�as�700,000�people�in�the�United�States�
experience�a�new�or�recurrent�stroke,�and�more�than�500,000�survive.�
Over�a�million�of�those�survivors,�however,�report�diffi�culties�related�to�the�
functional�limitations�that�can�result�from�this�life-changing�experience.�
The�new,�evidence-based�Adults With Stroke (AOTA Practice Guidelines)�
details�the�signifi�cant�contribution�of�occupational�therapy�in�treating�adults�
dealing�with�these�limitations.�Appendixes�include�other�valuable�resources�such�as�
CPT(TM)�codes�related�to�occupational�therapy�for�stroke�survivors.�
Order #2211 Member Price: $39.00 Non-Member Price: $55.00 ISBN: 978-1-56900-263-6
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