Congenital unilateral absence of the hand (amelia) completely deprives individuals of

Congenital unilateral absence of the hand (amelia) completely deprives individuals of sensorimotor experiences with their absent effector. in PGS vs. OGS. For the absent hand we compared PGS responses Col4a6 with OGS responses for the intact hand that had been phase shifted by 180° thereby accounting for mirror symmetrical biomechanical constraints of the two limbs. Like controls amelic individuals displayed a consistent preference for less awkward grips in both OGS and PGS. Unexpectedly however they were slower and less accurate for PGS based on We conclude that direct sensorimotor experience with hands may be important for the typical development or refinement of effector-specific internal representations of limb. while reporting which side (“pink” or “tan”) of the stimulus their thumb would contact if they were to grasp the object using the Flupirtine maleate specified hand and the most natural precision grip. Participants reported this response by speaking the appropriate color name into a microphone and the experimenter recorded the chosen color. Microphone input was used only to determine the onset of the vocal response. Response time (RT) was defined as the time from stimulus appearance to start of vocal response. Participants were instructed to respond as quickly and accurately as possible; instructions did not include any mention of imagery or imagination. All participants performed PGS separately with the absent and intact hands. For adult participants who performed Task 2 (PGS) first they were presented with 5 OGS trials to familiarize themselves with the precision grasping movements and with the stimuli. During this familiarization session the stimulus appeared at orientations not used during the main task. Child participants received no familiarization session. In addition all participants performed 10 practice PGS trials before beginning data Flupirtine maleate collection. Similar to Task 1 the PGS task comprised a single session of 192 trials divided into 4 blocks of 48 trials each (Child participants: 96 trials 8 blocks of 12 trials each). Hand varied between trials counterbalanced within each block. Thus Condition 2 entailed Flupirtine maleate 8 trials of each combination of 12 stimulus orientations * 2 hands. Each PGS trial followed the structure of OGS trials with three exceptions (Fig. 2B). First each trial began with a hand choice cue of 1000 ms duration in the form of an arrow pointing either left or right to indicate the hand used in the current trial. Second there was no key-return period. Third the stimulus window lasted up to 8000 ms. Trials were Flupirtine maleate aborted if the participant moved either hand off the rest key at any time. 2.5 Data collection Flupirtine maleate and analysis Trials with OT MT or RT more than two standard deviations from the within-participant means were eliminated from the analyses; this eliminated 6.0% of OGS trials and 4.9% of PGS trials. Outlier rate did not differ between groups in either task (> 0.3). Repeated-measures analyses of variance (ANOVA) were performed on participant means as described later in the text with all post-hoc comparisons carried out via Tukey’s HSD test. Correlations were calculated using Pearson’s when the assumptions were met. The nonparametric measure of Kendall’s was also used because of its robustness in the presence of small sample sizes and outliers. Differences between correlations were tested for statistical significance by using Fisher’s < 0.001 in all cases). Note that this strong inverse relationship between grip preferences and awkwardness arose even though we calculated the two measures from different populations (choice likelihoods from amelic participants and matched controls awkwardness ratings from na?ve healthy young adult participants). Furthermore OGS grip preferences with the intact hand were nearly identical across Flupirtine maleate groups (< 0.0001). Fig. 3 OGS choice likelihood for each thumb placement. All OGS data from intact hand mirror-reversed to produce absent hand data; see Section 2 for details. Congruence between high choice likelihood and low awkwardness demonstrates selection of non-awkward ... Despite the absence of movements (and associated feedback) in PGS both groups’ grip preferences still showed a strong negative correlation with rated awkwardness consistent with previous work in healthy adults (Johnson 2000 Jacobs et al. 2010 Martin et al. 2011 densely hemiplegic stroke patients (Johnson 2000 Johnson et al. 2002 and traumatic amputees (Philip and Frey 2011 The correlation between PGS choice likelihood and awkwardness for controls was ?0.879 for the absent hand (< 0.0001) and ?0.814 for the intact hand.