title: Neurological soft signs in schizophrenia: investigating motor overflow.
abstract: Investigation of neurological soft signs (NSSs) in schizophrenia may allow for a greater understanding of its underlying pathology. Motor overflow, involuntary movement occurring during voluntary movement, is a NSS thought to occur to a greater degree in schizophrenia. The aim of the current study was to replicate the only objective investigation which found enhanced motor overflow in schizophrenia and to further characterise its properties in a more systematic manner than previous research. The current study involved examining motor overflow production in 30 participants (15 with schizophrenia, 15 controls). Participants exerted 25 and 75% of their maximal force output, while overflow was monitored in the passive hand using linear variable differential transformer (LVDT) units. Patients with schizophrenia not only exhibited a significantly greater degree of motor overflow, compared to controls, they also exhibited a differential pattern of overflow production. Direct investigation of the cortical processes leading to motor overflow may provide a more complete understanding of the pathological relevance of motor overflow, and by extension NSSs, in schizophrenia.
authors.affiliation: Alfred Psychiatry Research Centre, The Alfred and Monash University School of Psychology, Psychiatry and Psychological Medicine, Melbourne, 3004, Australia. k.hoy@alfred.org.au
authors.forename: Kate E
authors.initials: KE
authors.lastname: Hoy
authors.forename: Nellie
authors.initials: N
authors.lastname: Georgiou-Karistianis
authors.forename: Maree
authors.initials: M
authors.lastname: Farrow
authors.forename: Paul B
authors.initials: PB
authors.lastname: Fitzgerald
mesh_terms: D000328:Adult; D001921:Brain / Q000503:physiopathology*; D039721:Diagnostic and Statistical Manual of Mental Disorders; D020820:Dyskinesias; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008297:Male; D011596:Psychomotor Disorders / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology*; D012559:Schizophrenia / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology*; D012720:Severity of Illness Index