neurology Neurology (from el, νεῦρον (neûron), "string, nerve" and the suffix -logia, "study of") is the branch of medicine dealing with the diagnosis and treatment of all categories of conditions and disease involving the brain, the spinal ...

, the Bereitschaftspotential or BP (

German German(s) may refer to: * Germany (of or related to) ** Germania (historical use) * Germans, citizens of Germany, people of German ancestry, or native speakers of the German language ** For citizens of Germany, see also German nationality law **Ge ...

for "readiness potential"), also called the pre-motor potential or readiness potential (RP), is a measure of activity in the

motor cortex The motor cortex is the region of the cerebral cortex believed to be involved in the planning, control, and execution of voluntary movements. The motor cortex is an area of the frontal lobe located in the posterior precentral gyrus immediately ...

and

supplementary motor area The supplementary motor area (SMA) is a part of the motor cortex of primates that contributes to the control of movement. It is located on the midline surface of the hemisphere just in front of (anterior to) the primary motor cortex leg representa ...

of the brain leading up to voluntary muscle movement. The BP is a manifestation of cortical contribution to the pre- motor planning of volitional movement. It was first recorded and reported in 1964 by

Hans Helmut Kornhuber Hans Helmut Kornhuber (24 February 1928 – 30 October 2009) was a German neurologist and neurophysiologist. Biography Hans Helmut Kornhuber was born as the second of three children of Dr. med. Gertrud and Dr. Arnold Kornhuber. He grew up a ...

and

Lüder Deecke Lüder Deecke (; born 22 June 1938) in Lohe-Rickelshof, Germany is a German Austrian neurologist, neuroscientist, teacher and physician whose scientific discoveries have influenced brain research and the treatment and rehabilitation of neurologi ...

at the

University of Freiburg The University of Freiburg (colloquially german: Uni Freiburg), officially the Albert Ludwig University of Freiburg (german: Albert-Ludwigs-Universität Freiburg), is a public research university located in Freiburg im Breisgau, Baden-Württemb ...

Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwe ...

. In 1965 the full publication appeared after many control experiments.; Englisch translation:
PDF
(accessed October 21, 2016).

Discovery

In the spring of 1964

(then docent and chief physician at the department of neurology, head Professor Richard Jung, university hospital Freiburg im Breisgau) and

(his doctoral student) went for lunch to the 'Gasthaus zum Schwanen' at the foot of the Schlossberg hill in Freiburg. Sitting alone in the beautiful garden they discussed their frustration with the passive brain research prevailing worldwide and their desire to investigate self-initiated action of the brain and the will. Consequently, they decided to look for cerebral potentials in man related to volitional acts and to take voluntary movement as their research paradigm.Kornhuber, H.H.; Deecke, L. (1990). Readiness for movement – The Bereitschaftspotential-Story, ''Current Contents Life Sciences'' 33: 14. (Citation Classic
PDF
/ref> The possibility to do research on electrical brain potentials preceding voluntary movements came with the advent of the 'computer of average transients' (CAT computer), invented by Manfred Clynes, the first still simple instrument available at that time in the Freiburg laboratory. In the

electroencephalogram Electroencephalography (EEG) is a method to record an electrogram of the spontaneous electrical activity of the brain. The biosignals detected by EEG have been shown to represent the postsynaptic potentials of pyramidal neurons in the neocortex ...

(EEG) little is to be seen preceding actions, except of an inconstant diminution of the α- (or μ-) rhythm. The young researchers stored the electroencephalogram and

electromyogram Electromyography (EMG) is a technique for evaluating and recording the electrical activity produced by skeletal muscles. EMG is performed using an instrument called an electromyograph to produce a record called an electromyogram. An electromyog ...

of self-initiated movements (fast finger flexions) on tape and analyzed the cerebral potentials preceding movements time-reversed with the start of the movement as the trigger, literally turning the tape over for analysis since they had no reversal playback or programmable computer. A potential preceding human voluntary movement was discovered and published in the same year. After detailed investigation and control experiments such as passive finger movements the Citation Classic with the term ''Bereitschaftspotential'' was published.

Mechanism

The BP is ten to hundred times smaller than the α-rhythm of the EEG; only by averaging, relating the electrical potentials to the onset of the movement it becomes apparent. Figure shows the typical slow shifts of the cortical DC potential, called Bereitschaftspotential, preceding volitional, rapid

flexion Motion, the process of movement, is described using specific anatomical terms. Motion includes movement of organs, joints, limbs, and specific sections of the body. The terminology used describes this motion according to its direction relativ ...

s of the right index finger. The vertical line indicates the instant of triggering t = 0 (first activity in the EMG of the agonist muscle). Recording positions are left precentral (L prec, C3), right precentral (R prec, C4), mid-parietal (Pz); these are unipolar recordings with linked ears as reference. The difference between the BP in C3 and in C4 is displayed in the lowest graph (L/R prec). Superimposed are the results of eight experiments as obtained in the same subject (B.L.) on different days. see Deecke, L.; Grözinger, B.; Kornhuber H.H. (1976) Note that the BP has two components, the early one (BP1) lasting from about −1.2 to −0.5; the late component (BP2) from −0.5 to shortly before 0 sec. The pre-motion positivity is even smaller, and the motor-potential which starts about fifty to sixty milliseconds before the onset of movement and has its maximum over the contralateral precentral hand area is still smaller. Thus, it takes great care to see these potentials: exact triggering by the real onset of movement is important, which is especially difficult preceding speech movements. Furthermore, artifacts due to head-, eye-, lid-, mouth-movements and respiration have to be eliminated before averaging because such artifacts may be of a magnitude which makes it difficult to render them negligible even after hundreds of sweeps.Grözinger, B.; Kornhuber, H.H.; Kriebel, J.; Szirtes, J.; Westphal, K.T.P. (1980). The Bereitschaftspotential preceding the act of speaking. Also an analysis of artifacts. pp 798–804 in Kornhuber H.H., Deecke L., eds., Motivation, motor and sensory processes of the brain: Electrical potentials, behaviour and clinical use. '' Progr Brain Res'' 54, Amsterdam, Elsevier. In the case of eye movements eye muscle potentials have to be distinguished from cerebral potentials. In some cases animal experiments were necessary to clarify the origin of potentials such as the R-wave. Therefore, it took many years until some of the other laboratories were able to confirm the details of Kornhuber & Deecke's results. In addition to the finger or eye movements as mentioned above, the BP has been recorded accompanying willful movements of the wrist, arm, shoulder, hip, knee, foot and toes. It was also recorded prior to speaking, writing and also swallowing.Huckabee, M.L.; Deecke, L.; Cannito, M.P.; Gould, H.J.; Mayr, W. Cortical control mechanisms in volitional swallowing: the Bereitschaftspotential. ''Brain Topogr''. 16: 3–17 (2003). The magnetoencephalographic (MEG) equivalent of the Bereitschaftspotential (BP), 'Bereitschafts(magnetic)field' (BF), or readiness field (RF) was first recorded in Hal Weinberg's laboratory at Simon Fraser University Burnaby B.C. Canada in 1982. It was confirmed that the early component, BP 1 or BF1, respectively was generated by the supplementary motor area (SMA), including the pre-SMA, while the late component, BP2 or BF2, was generated by the primary motor area, MI. A very similar event-related potential (ERP) component had earlier been discovered by the

British British may refer to: Peoples, culture, and language * British people, nationals or natives of the United Kingdom, British Overseas Territories, and Crown Dependencies. ** Britishness, the British identity and common culture * British English, ...

neurophysiologist

William Grey Walter William Grey Walter (February 19, 1910 – May 6, 1977) was an American-born British neurophysiologist, cybernetician and robotician. Early life and education Walter was born in Kansas City, Missouri, United States, on 19 February 1910, the ...

in 1962 and published in 1964. It is the contingent negative variation (CNV). The CNV also composes two waves; the initial wave (i.e., O wave) and the terminal wave (i.e., E wave). The terminal CNV has similar characteristics as the BP and many researchers have claimed that the BP and the terminal CNV are the same component. At least there is a consensus that both indicate a preparation of the brain for a following behavior.

Outcomes

The Bereitschaftspotential was received with great interest by the scientific community, as reflected by Sir John Eccles's comment: "There is a delightful parallel between these impressively simple experiments and the experiments of

Galileo Galilei Galileo di Vincenzo Bonaiuti de' Galilei (15 February 1564 – 8 January 1642) was an Italian astronomer, physicist and engineer, sometimes described as a polymath. Commonly referred to as Galileo, his name was pronounced (, ). He wa ...

who investigated the laws of motion of the universe with metal balls on an inclined plane".Eccles, J.C.; Zeier, H. (1980) ''Gehirn und Geist''. Zürich, Kindler. The interest was even greater in psychology and philosophy because volition is traditionally associated with human freedom (cf. Kornhuber 1984).Kornhuber, H.H. (1984). Von der Freiheit pp 83–112 in Lindauer M, Schöpf A, eds., Wie erkennt der Mensch die Welt? Grundlagen des Erkennens, Fühlens und Handelns. Geistes und Naturwissenschaftler im Dialog. Ernst Klett Stuttgart. The spirit of the time, however, was hostile to freedom in those years; it was believed that freedom is an illusion. The tradition of behaviourism and Freudism was deterministic. While will and volition were frequently leading concepts in psychological research papers before and after the first world war and even during the second war, after the end of the second world war this declined, and by the mid-sixties these key words completely disappeared and were abolished in the thesaurus of the American Psychological Association.Heckhausen, H. (1987). Perspektiven einer Psychologie des Wollens. pp 121–142 in Heckhausen, H. et al., eds., ''Jenseits des Rubikon: Der Wille in den Humanwissenschaften''. Springer, Berlin. The BP is an electrical sign of participation of the supplementary motor area (SMA) prior to volitional movement, which starts activity prior to the primary motor area. The BP has precipitated a worldwide discussion about

free will Free will is the capacity of agents to choose between different possible courses of action unimpeded. Free will is closely linked to the concepts of moral responsibility, praise, culpability, sin, and other judgements which apply only to ac ...

(cf. the closing chapter in the book "The Bereitschaftspotential").Deecke, L.; Kornhuber, H.H. (2003). Human freedom, reasoned will, and the brain. The Bereitschaftspotential story. In: M Jahanshahi, M Hallett (Eds.) ''The Bereitschaftspotential, movement-related cortical potentials''. Kluwer Academic / Plenum Publishers pp. 283–320. As said above, the activity of the SMA generates the early component of the Bereitschaftspotential (BP1 or BP early). The SMA has the starting function of the movement or action. The role of the SMA was further substantiated by Cunnington et al. 2003, showing that SMA proper and pre-SMA are active prior to volitional movement or action, as well as the cingulate motor area (CMA). This is now called ‘anterior mid-cingulate cortex (aMCC)’. Recently it has been shown by integrating simultaneously acquired EEG and fMRI that SMA and aMCC have strong reciprocal connections that act to sustain each other’s activity, and that this interaction is mediated during movement preparation according to the Bereitschaftspotential amplitude. EEGs and EMGs are used in combination with Bayesian inference to construct

Bayesian network A Bayesian network (also known as a Bayes network, Bayes net, belief network, or decision network) is a probabilistic graphical model that represents a set of variables and their conditional dependencies via a directed acyclic graph (DAG). Bay ...

s which attempt to predict general patterns of Motor Intent Neuron

Action Potential An action potential occurs when the membrane potential of a specific cell location rapidly rises and falls. This depolarization then causes adjacent locations to similarly depolarize. Action potentials occur in several types of animal cells, ...

s firing. Researchers attempting to develop non-intrusive

brain–computer interface A brain–computer interface (BCI), sometimes called a brain–machine interface (BMI) or smartbrain, is a direct communication pathway between the brain's electrical activity and an external device, most commonly a computer or robotic limb. B ...

s are interested in this, as are system analysis, operations research, and epistemology (e.g. the Smith predictor has been suggested in the discussion).

BP and free will

In a series of experiments in the 1980s,

Benjamin Libet Benjamin Libet (; April 12, 1916 – July 23, 2007) was an American neuroscientist who was a pioneer in the field of human consciousness. Libet was a researcher in the physiology department of the University of California, San Francisco. In 2003, ...

studied the relationship between conscious experience of volition and the BP e.g. and found that the BP started about 0.35 sec ''earlier'' than the subject's reported conscious awareness that "now he or she feels the desire to make a movement." Libet concludes that we have no

in the initiation of our movements; though, since subjects were able to prevent intended movement at the last moment, we do have the ability to veto these actions ("free won't"). These studies have provoked widespread debate. In 2016, a group around

John-Dylan Haynes John-Dylan Haynes (born 1971) is a British-German brain researcher. Haynes studied psychology and philosophy at the University of Bremen from 1992 to 1997. In 2003 he received his doctorate from the Institute of Biology in Bremen. After researc ...

in Berlin (Germany) determined the time window after the BP in which an intended motion could possibly be cancelled upon command. The authors tested whether human volunteers could win a "duel" against a BCI (

) designed to predict their movements in real-time from observations of their EEG activity (the BP). They aimed to determine the exact time at which cancellation (veto) of movements was not possible anymore (the point of no return). The computer was trained to predict by means of the BP when a proband would move. The point of no return was at 200 ms before the movement. However, even after that, when a pedal was already set in motion, the subjects were able to reschedule their action by not completing the already started behavior. The authors pointed out in their report that cancellation of self-initiated movements had already been reported by Libet in 1985. Thus, the new achievement was a more precise determination of the point of no return. Methodological concerns regarding how readiness potentials are identified and measured have raised doubts about the readiness potential's validity, as well as its implications for the existence of free will. Specifically, the wave of the readiness potential may arise from a biased ensemble of "random" background brain waves, producing an apparent pattern without clear causal connection to movement planning and execution. https://www.cell.com/trends/cognitive-sciences/fulltext/S1364-6613(21)00093-0

Applications

An interesting use of the Bereitschaftspotential is in

(BCI) applications; this signal feature can be identified from scalp recording (even from single-trial measurements) and interpreted for various uses, for example control of computer displays or control of peripheral motor units in spinal cord injuries. The most important BCI application is the 'mental' steering of artificial limbs in amputees.

References

External links

* http://www.cmds.canterbury.ac.nz/documents/huckabee_swallowing.pdf * http://www.cs.washington.edu/homes/rao/shenoy_rao05.pdf * {{EEG Somatic motor system History of neuroscience Brain–computer interfacing Motor control Electroencephalography Evoked potentials