Psychogenic Movement Disorders, Bereitschaftspotential, and Event-Related Potentials
A 22-year-old male patient is suffering from jerky movements in his right upper leg since 2 years. These movements only occur during rest and never during action, but are otherwise position-independent. The frequency and duration of these movements have gradually increased over time and now they occur approximately once every 10 s. The frequency increases further as a result of stress or sleep deprivation. The patient reports that he can not willingly suppress the movements. Thinking that there may be an epileptic origin of the movements, antiepileptic medication has been tried in the past but to no avail.
KeywordsIndependent Component Analysis Independent Component Analysis Contingent Negative Variation Lateralized Readiness Potential Ocular Artifact
Direct current (in contrast to alternating current [AC]): unidirectional flow of electric current. Also known as the constant, zero-frequency, or slowly varying local mean value of a current.
Arising from within (the brain).
Opposite from endogenous: coming from outside (the brain).
Decrease in response to a stimulus after repeated regular exposure to that stimulus over a duration of time.
Constructing new datapoints within the range of existing data points according to a mathematical method (e.g., linear, polynomial or spline interpolation).
In mathematics a linear operation f is an operation that obeys the following two criteria: f(x + y) = f(x) + f(y) and f(ax) = af(x) where a is a scalar.
Sudden, quick, shock-like, single, or repetitive involuntary movements without loss of consciousness.
Executing a calculation or an operation on a dataset while this dataset is being recorded (in contrast to offline analysis).
Affecting or relating to an organ, of physiological origin.
Neurological syndrome characterized by tremor, hypokinesia (slow or decreased movement), rigidity (increased muscle tension when moved passively), and postural instability. This syndrome is found in Parkinson’s disease, but also e.g., in corticobasal degeneration and progressive supranuclear palsy.
Sign: positive or negative.
Relating to the spinal cord and specifically, denoting those nerve cells and their fibers that connect the different segments of the spinal cord with each other. Propriospinal myoclonus: jerks of the trunc and/or limbs, usually due to a generator in the spinal cord. Typical is a delay of the jerk in the different involved parts of the body consistent with the distance traveled by the electric signal along the slow conducting propriospinal nerve fibers.
Disease for which no structural or anatomical abnormality can be identified (in contrast to an organic disease).
A signal is rectified by retaining all positive values and by replacing all negative values by positive values of the same size.
As in: topographic (brain) mapping. Spatial variations in scalp voltage, often plotted in two dimensions in a top view of the head.
Online Sources of information
- http://http:\crbooks.google.co.uk. Evoked potentials in Clinical Medicine, edited by K.H. Chiappa and published by Lippincott-Raven, 1997. Of particular interest is Chapter 15 Endogenous event-related potentials, by B.S. OkenGoogle Scholar
- http://en.wikipedia.org/wiki/Bereitschaft_potential. Overview of the origin and derivation of the BP
- http://www.cis.hut.fi/projects/ica/book/intro.pdf. Introduction to the more mathematical concepts of ICA from the book by Hyvärinen A, Karhunen J and Oja E. (2001) Independent Component Analysis, Wiley
- Jahanshahi M, Hallett M (eds) (2003) The Bereitschaftspotential. Movement-related cortical potentials. Kluwer Academic, New YorkGoogle Scholar
- Handy TC (ed) (2005) Event-related potentials. A methods handbook. MIT Press, CambridgeGoogle Scholar
- Luck SJ (2005) An introduction to the event-related potential technique. MIT Press, CambridgeGoogle Scholar