Implicit and explicit aspects of sequence learning in pre-symptomatic Huntington's disease

M. F. Ghilardi, G. Silvestri, A. Feigin, P. Mattis, D. Zgaljardic, C. Moisello, D. Crupi, L. Marinelli, A. DiRocco, D. Eidelberg

Research output: Contribution to journalArticlepeer-review

40 Scopus citations


Learning deficits may be part of the early symptoms of Huntington's disease (HD). Here we characterized implicit and explicit aspects of sequence learning in 11 pre-symptomatic HD gene carriers (pHD) and 11 normal controls. Subjects moved a cursor on a digitizing tablet and performed the following tasks: SEQ: learning to anticipate the appearance of a target sequence in two blocks; VSEQ: learning a sequence by attending to the display without moving for one block, and by moving to the sequence in a successive block (VSEQ test). Explicit learning was measured with declarative scores and number of anticipatory movements. Implicit learning was measured as a strategy change reflected in movement time. By the end of SEQ, pHD had a significantly lower number of correct anticipatory movements and lower declarative scores than controls, while in VSEQ and VSEQ test these indices improved. During all three tasks, movement time changed in controls, but not in pHD. These results suggest that both explicit and implicit aspects of sequence learning may be impaired before the onset of motor symptoms. However, when attentional demands decrease, explicit, but not implicit, learning may improve.

Original languageEnglish (US)
Pages (from-to)457-464
Number of pages8
JournalParkinsonism and Related Disorders
Issue number6
StatePublished - Aug 2008
Externally publishedYes


  • Basal ganglia
  • Energy-saving strategy
  • Motor sequence
  • Reaching movements

ASJC Scopus subject areas

  • Neurology
  • Geriatrics and Gerontology
  • Clinical Neurology


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