THE NEUROSCIENCE OF HANDWRITING

At a time when the validity and reliability of document examination is being closely scrutinized, Caligiuri (psychiatry, U. of California San Diego) and Mohammed, a forensic document examiner, explore the neuroscientific principles of normal and pathological hand motor control and handwriting for forensic documentation examination and legal professionals and researchers and discuss relevant theory and practice with examples from recent studies. They provide background on the fundamentals of motor control, with reference to handwriting; the fundamental principles of neuroanatomy and neurochemistry of hand motor control; theories of motor control and their application to handwriting research; common neurodegenerative diseases and their epidemiology, pathophysiology, and motor characteristics; common psychotropic medications for depression, bipolar disorder, and psychosis, their mechanisms of action, and why they are important in understanding motor behavior and handwriting; and the effects of the aging process on motor control and handwriting. The second section covers advances in the quantitative approach to signature authentication, mainly the kinematic approach to genuine, disguised, and forged signatures, and presents data from the authors' studies that tested specific hypotheses about whether a signature is authentic or forged, followed by a final section outlining their studies on the effects of medication and disease on handwriting, including progressive supranuclear palsy, neurological diseases, psychotropic medications, and substance abuse.