Todocumentthequalityofmotorperformance,fourmagnetic
trackingsensorswereplacedontheinfant:onesuperficialtothe
styloidprocessoftheradiusoneachwrist,oneontheposterior
and prominentpartofthecervicalvertebra7(c7)andoneona
headband withthesensorcenteredontheforehead.Thesesensors
FIGURE 1|Schematicrepresentationofinfantchairattachedto
externalsupportdeviceat(A)thoracicand(B)pelviclevelsoftrunk
support.
wereusedtotrackarmandheadmovements.Priortostarting
the reachingtest,thepositionoftheleftandrighttragus,the
medial/lateralandanterior/posteriorpointsoftheexternalsup-
port(pelvicorthoracic)andsternalnotchwererecorded.This
allowedestimationofthelocationoftheheadcenterofmass
using thecenterofthedistancebetweenthemidpointofthe
twotragusmarkersandtheheadsensor.Thecenterofthetrunk
regionbeingevaluatedwasestimatedasthemidpointbetweenthe
sternalnotchandC7,andthecenteroftheexternalsupportwas
calculatedasthemidpointofthetwovectorscreatedbytheante-
rior/posteriorandmedial/lateralmarkersoftheexternalsupport.
Positiondataofallfoursensorswerereferencedtothecenterof
the externaltrunksupport.