A Review of Techniques for Detection of Movement Intention Using Movement-Related Cortical Potentials <s> Contingent Negative Variation. <s> In the title of the first report about the Contingent Negative Variation (CNV) two things are suggested: The CNV is a sign of “sensori-motor association” and the CNV is an index for “expectancy” (Walter et al., 1964). In other words, the CNV reflects processes, which are, at first sight, quite different from the processes discussed in the other chapters in this book. Why then is it important to add a “deviant” chapter to this book? There are two reasons. First, the CNV is also a movement-preceding negativity (MPN), just as the Readiness Potential (RP). The RP reflects processes involved in the preparation of voluntary movements, and the CNV reflects processes involved in the preparation of signaled movements. In other words the RP and the CNV are both reflections of anticipatory behavior, at least as far as the motor system is involved. Moreover it doesn’t seem too difficult to put up a case for the view that most of our motor activity is elicited by the presence of some kind of stimuli, rather than being “voluntary”. This being a sufficient reason for a chapter on the CNV, there is a second reason. Anticipatory behavior is not restricted to the motor system; it involves attention to the surrounding and to stimuli, which are relevant for our ongoing behavior. This becomes clear in a simple paradigm such as the forewarned reaction time task, used to elicit a CNV. In such a paradigm, a warning signal (WS) alerts the subject to an upcoming imperative signal (RS) to which the subject has to respond, e. g. by pressing a button. The consequence is that the CNV is a MPN, confounded by activity related to anticipatory attention for the response signal (RS). This causes serious difficulty for the interpretation of the CNV. I will discuss later on a paradigm in which Separation in time of motor preparation and anticipatory attention is possible. The latter function is reflected in a second category of anticipatory slow waves: the Stimulus Preceding Negativity (SPN). <s> BIB001 </s> A Review of Techniques for Detection of Movement Intention Using Movement-Related Cortical Potentials <s> Contingent Negative Variation. <s> In this study we summarize the features that characterize the pre-movements and pre-motor imageries (before imagining the movement) electroencephalography (EEG) data in humans from both Neuroscientists' and Engineers' point of view. We demonstrate what the brain status is before a voluntary movement and how it has been used in practical applications such as brain computer interfaces (BCIs). Usually, in BCI applications, the focus of study is on the after-movement or motor imagery potentials. However, this study shows that it is possible to develop BCIs based on the before-movement or motor imagery potentials such as the Bereitschaftspotential (BP). Using the pre-movement or pre-motor imagery potentials, we can correctly predict the onset of the upcoming movement, its direction and even the limb that is engaged in the performance. This information can help in designing a more efficient rehabilitation tool as well as BCIs with a shorter response time which appear more natural to the users. <s> BIB002
CNV is a slow negative wave that originates in the interval (1-1.5 s) between a "Warning" and a "Go" stimulus  . It shows expectancy for an imminent signal and preparation for execution of a response. In other words, CNV reveals preparation for signaled movements and is an indicator for anticipation. The earlier part of the CNV is generated in response to a "Warning" cue and has maximum amplitude over the frontal cortex reflecting phase of the movement, whereas the later or terminal CNV, reflecting preparation for a motor response, begins around 1.5 s before the "Go" cue and has maximum amplitude over the motor cortex BIB002 BIB001 . The later part of CNV happens even if the subject responds at the time he anticipates the "Go" stimulus  .