Dwell times between groups as a function of index of difficulty.

<p>Standard error bars included. Note: LN = large near, SN = small near, LF = large far, SF = small far. ** = p < .01, *** = p < .001.</p

Time after peak velocity between groups as a function of index of difficulty.

<p>Standard error bars included. Note: LN = large near, SN = small near, LF = large far, SF = small far. ** = p < .01.</p

Demographic and neurocognitive data across groups.

<p>Note: IQ (NART, National Adult Reading Test); CAG, cytosine-adenine-guanine (number of repeats >40 is full penetrance); UHDRS-TMS, Unified Huntington’s Disease Rating Scale-Total Motor Score (pre-HD, UHDRS-TMS≤5; symp-HD, UHDRS-TMS>5); DBS, Disease Burden Score (CAG-35.5) x age; YTO, Years to onset—estimation expressed as a countdown from current age to 0 = disease onset. YSO, Years since onset of symptoms.</p><p>Means and standard deviations (SD) provided.</p

Demographic and neurocognitive data across groups.

<p>Note: IQ (NART, National Adult Reading Test); CAG, cytosine-adenine-guanine (number of repeats >40 is full penetrance); UHDRS-TMS, Unified Huntington’s Disease Rating Scale-Total Motor Score (pre-HD, UHDRS-TMS≤5; symp-HD, UHDRS-TMS>5); DBS, Disease Burden Score (CAG-35.5) x age; YTO, Years to onset—estimation expressed as a countdown from current age to 0 = disease onset. YSO, Years since onset of symptoms.</p><p>Means and standard deviations (SD) provided.</p

Movement time variability between groups as a function of cue condition.

<p>Standard error bars included. *** = p < .001, between symp-HD and controls; ⁺⁺⁺ = p < .001, between symp-HD and pre-HD.</p

Movement time between groups as a function of index of difficulty.

<p>Standard error bars included. Note: LN = large near, SN = small near, LF = large far, SF = small far. ** = p < .01.</p

An illustration of the four configurations representing the four conditions and retrospective indices of difficulty.

<p>An illustration of the four configurations representing the four conditions and retrospective indices of difficulty.</p

Electrophysiological and behavioural results for participants in the Tapping Task 1 (cued and self-paced Conditions).

<p>Relative amplitude and latency are computed based on the difference in peak values between the negative peak occurring -50 to 100ms prior to the motor response, and the positive peak 100 to 300 ms post response. Peak amplitude represents the negative peak occurring around time of response (-150 to 200 ms). Independent samples t-tests used for differences between groups,</p><p>* <i>p</i> < .05,</p><p>** <i>p</i> < .01.</p><p>^a significantly different from controls,</p><p>^b significantly different from pre-HD.</p><p>Amplitude and latency by at Cz, averaged across groups. Standard deviations (SD) provided in parentheses.</p

Tapping Task 1 (cued and self-paced Conditions).

<p>Grand average Readiness Potential (RP) waveforms are shown at Cz for each of the control, pre-HD and symp-HD groups. (A) cued tapping. (B) Self-paced tapping. Time ‘0’ represents the time of motor response (right index finger button press).</p

Electrophysiological and behavioural results for participants in the Sensorimotor Integration Task 2.

<p>‘Peak amplitude’ refers to the maximum negative value in micro volts obtained within the early CNV or late CNV period, with early CNV defined as the period 550–750 ms following stimulus 1, and late CNV defined as the period in the 200 ms prior to stimulus 2. Area refers to the mean amplitude in micro volts during each respective CNV period, obtained separately for each electrode site, and is included to support peak amplitude. Independent samples t-tests used for differences between groups,</p><p>* <i>p</i> < .05,</p><p>** <i>p</i> < .01.</p><p>^a significantly different from controls,</p><p>^b significantly different from pre-HD.</p><p>Amplitudes of early and late CNV by group at Fz, Cz, and Pz. Standard deviations (SD) provided in parenthesis.</p