Pre-motion Positivity Research Articles

Event-related potentials of automatic imitation are modulated by ethnicity during stimulus processing, but not during motor execution

This study investigated neural processes underlying automatic imitation and its modulation by ethnically diverse hand stimuli (Black, White) using event-related brain potentials (ERPs). Automatic imitation relies on motor stimulus-response compatibility (SRC), i.e., response conflict caused by motoric (in)congruency between task-irrelevant hand stimuli and the required response. Our novel task aimed to separate two distinct neuro-cognitive processing stages of automatic imitation and its modulation by ethnicity: the stage of stimulus processing (i.e. perception), comprising presentation of stimulus ethnicity and SRC, and the stage of response execution (i.e. action). Effects of ethnicity were observed in ERPs of different stages of stimulus processing - during presentation of ethnicity (LPP) and SRC (N190, P3). ERPs at response execution, Pre-Motion Positivity (PMP) and Reafferent Potential (RAP), were only sensitive to congruency. The N190 results may index visual self-other distinction, while the neural timecourse of P3 and PMP variation could reflect a dynamical decision process linking perception to action, with motor initiation reflected in the PMP component. The PMP might further index motor-related self-other distinction regardless of ethnicity. Importantly, overt motor execution was not influenced by ethnically diverse stimuli, which suggests generalizability of the automatic imitation effect across ethnicities.

Pre-motion positivity during self-paced movements of finger and mouth

The present study investigated the role of pre-motion positivity in movement initiation and the reason why it is not reliably detectable in every study participant. Nineteen right-handed participants performed self-initiated simple movements of the right index finger and mouth while electroencephalography activity was recorded. Most of the participants showed a clear-cut pre-motion positivity with its characteristics varying as a function of the effector involved in the movement. The pre-motion positivity distribution was ipsilateral for finger movements and symmetrical for mouth movements. The results suggest that pre-motion positivity might represent a go-signal to initiate the movement and its occurrence might depend on movement initiation strategies.

What happens to the readiness potential when the movement is not executed?

The purpose of this study was to investigate and compare the movement-related brain potentials recorded from two groups of right-handed male study participants. One of the groups prepared for and conducted repetitive toe movements while the other prepared to carry out the same type of movement but finally did not execute it. The readiness potential, premotion positivity, motor potential and reafferent potential were recorded from 20 electroencephalogram electrodes. The most salient result was the greater readiness potential amplitude discovered in participants who ended up carrying out the movement, which indicates that the level of preparation in a repetitive task is greater when a final response is required. No group differences were found for the other potentials.

Brain potentials associated with voluntary manual tracking: bereitschaftspotential, conditioned premotion positivity, directed attention potential, and relaxation potential. Anticipatory activity of the limbic and frontal cortex.

Brain potentials associated with voluntary manual tracking: bereitschaftspotential, conditioned premotion positivity, directed attention potential, and relaxation potential. Anticipatory activity of the limbic and frontal cortex.

Force uncertainty of voluntary movement and human movement-related potentials

Five movement related potentials, the Bereitschaftspotential (BP), the pre-motion positivity (PMP), the motor potential (MP), the first negative potential during the movement (N1) and the late positive component (LPC) were recorded from human subjects performing right index finger flexions under conditions when the resistive forces (70 N cm or 10 N cm ) were predictable and when they were unpredictable. The BP was larger prior to the larger force in the certain condition. In the uncertain condition, the BP was similar to that associated with the larger force in the certain condition suggesting that the subjects tended to prepare for the heavy resistance when confronted with force uncertainty. The MP revealed enhanced negativity over the left parietal cortex when the force was unpredictable. The N1 was significantly larger during the high force movement, expecially in the uncertain condition. The results support the view that pre-movement compensation for force unpredictability does exist as reflected by the MP over the parietal areas.

Components of the movement-related cortical potential and their scalp topography

In order to clarify the significance of the various components of the movement-related cortical potentials, scalp-recorded potential changes associated with voluntary, self-paced middle finger flexion and extension were studied by an opisthochronic averaging program in 14 normal right-handed subjects. Topographical study, based on 14 simultaneously recorded and averaged EEG channels, enabled us to identify at least 8 components; 4 pre-motion and 4 post-motion. The pre-motion components are the Bereitschaftspotential (BP) (a symmetric early negative shift), NS′(−500 to −90) (a negative slope maximal over the contralateral precentral region and culminating in N−90 ipsilaterally), P−50 (corresponding to the pre-motion positivity, PMP), and N−10 (probably corresponding to the motor potential, MP). The post-motion components include N+50 (a sharp negative post-motion activity over the contralateral frontal region), P+90 , and N+160 (presumably representing sensory functions) and P+300 (a large positivity maximal over the contralateral precentral region but widely distributed).

Comparison of Bereitschaftspotential, Pre-motion Positivity and Motor Potential Preceding Voluntary Flexion and Extension Movements in Man

This chapter discusses comparison of bereitschaftspotential, pre-motion positivity and motor potential preceding voluntary flexion and extension movements in man. That the precentral motor cortex is involved in control of movement rather than of individual muscles is an early concept. Recent results in primates suggest differences between flexion-related and extension-related motor cortex cells. Through the intact human skull, 3 different potentials can be recorded preceding voluntary finger movement, Bereitschaftspotential (BP), pre-motion positivity (PMP), and motor potential (MP). The MP is defined as an additional negativity starting on average 60msec prior to the first muscle action potential occurring in bipolar contralateral versus ipsilateral precentral leads. The MP is thought to reflect activation of the precentral motor cortex while generating the pyramidal tract volley. If this is true, the MP should share certain characteristics observed in recordings of single neurons in animals, including differences between flexion-dependent and extension-dependent motor cortex cells. The results suggest that the early preparatory process of the BP in the foreperiod of a voluntary movement is not basically different whether it precedes index finger flexion or extension of equal size.

Cerebral Potentials prior to various Force Deployments

Publisher Summary This chapter discusses cerebral potentials prior to various force deployments. Three different cerebral potentials can be recorded from the human scalp preceding a unilateral voluntary movement: (1) bilateral slow negativity (Bereitschaftspotential, BP), (2) a short bilateral pre-motion positivity (PMP) and, (3) a short negative motor potential (MP) over the contralateral precentral motor area. A complex positive-negative wave after movement onset can also be recorded. The present results show that the BP amplitude prior to isometric deployments varies as a function of the force amplitude: over all electrode positions investigated the BP amplitude is higher prior to large than to small isometric force pulses. The difference is highly significant over the precentral cortex (2P

Cerebral potentials preceding unilateral and simultaneous bilateral finger movements

Cerebral potentials preceding voluntary bilateral simultaneous finger movements were investigated in 19 right-handed young adult subjects, and were compared with unilateral right-sided finger movements within the same experiment. With bilateral movements, the Bereitschaftspotential (BP) was not symmetrical or larger over the dominant hemisphere, but surprisingly, it was larger over the minor hemisphere. The BP averaged −3.66 μV (S.D. 1.96) over the left precentral region and −4.82 μV (S.D. 3.73) over the right precentral region in this condition. The difference was significant at 2 P < 0.01. This difference was pronounced in precentral leads but very small and almost missing in parietal leads. The pre-motion positivity (PMP) was well developed and even larger with bilateral than with unilateral (right-sided) movements. At the vertex it averaged +1.33 μV (S.D. 4.16) with bilateral movements and only +0.15 μV (S.D. 1.42) with right-sided unilateral movements (2 P < 0.05). With bilateral movements the PMP could be observed in any record, but with unilateral movements it was missing at the left precentral lead, in accordance with previous publications (Deecke et al. 1969, 1976). The motor potential (MP), measured in a bipolar record from left and right precentral leads, was larger with unilateral (−1.25 μV, S.D. 1.33) than with bilateral movements (−0.36 μV, S.D. 0.92). Onset time differences of the BP preceding unilateral and bilateral movements were very small. However, there was a tendency towards earlier onset with unilateral than with bilateral movements (1031 msec, S.D. 358, as compared with 951 msec, S.D. 305). The averaged EMG revealed differences in movement onset. Muscular contraction tended to be earlier in the right than in the left m. flexor indicis in our right-handed subjects, on the average by 16 msec (S.D. 15). With unilateral right-sided movements, the left m. flexor indicis was not silent but showed an abortive mirror activity in the EMG, without visible movement. This activity occurred on the average 50 msec (S.D. 39) later on the non-moving side.

Voluntary finger movement in man: cerebral potentials and theory.

Three different brain potentials preceeding voluntary rapid finger flexion can be recorded from the skull surface by time reversed averaging. The early cortical activity preceding unilateral movement is bilateral and widespread (Bereitschaftspotential, BP). The same applies for the second potential (pre-motion positivity, PMP). Only the third potential (motor potential, MP) is unilateral and restricted to the contralateral motor cortex. In a total of 87 experiments with 39 subjects, the BP started on the average 750 ms (SD 360, SE 38.5) prior to rapid finger flexion. Its largest amplitude was found mid-parietally and averaged-5.3 μV (SD 2.32, SE 0.4). Such amplitudes were found with averages of 800 and more movements per experiment. However, at the beginning of an experiment the BP is larger. Preceding finger movement, the BP was found bilaterally over the parietal and precentral cortex and over the midline. Over the frontal cortex, either no potential or positivity was recorded. In normal subjects, the BP always begins bilaterally and symmetrically. At parietal leads, it remains bilaterally-symmetrical. A slight contralateral preponderance begins about 400 ms prior to movement only over motor cortex, which becomes statistically significant at 150 ms. When comparing the parietal BP amplitude with the precentral amplitude on the ipsilateral side, where no superposition of the MP occurs, there is more negativity parietally than precentrally, although the parietal skull is about 11% thicker than the precentral. The BP is a negative shift of the cortical DC potential probably representing a preparatory process in the dendritic network of those cortical areas that are involved in the intended movement. The PMP is the next potential occurring 90---80 ms ( $$\bar x = {\text{87}}$$ , SD 34.2, SE 2.95) prior to the first action potential in the contracting muscle (EMG). It was found in 85% of our subjects. The PMP has at its maximum, mid-parietally, a mean amplitude of +1.7 μV (SD 1.6, SE 0.28). Like the BP, the PMP is bilateral and widespread in parietal and precentral leads of both sides and in the midline with a maximum at the anterior parietal region, despite the parietal skull being thicker than precentral. The short and the relatively constant onset time suggests that the PMP might reflect cortical activity (motor command) related to initiation of the tactually guided rapid finger movement under study. The MP starting 60---50 ms ( $$\bar x = {\text{54}}$$ , SD 19.4, SE 3.1) prior to first activity in the agonist EMG is the last potential to occur and is the only unilateral potential: its localisation is limited to the hand area of the motor cortex contralateral to the moving finger. In bipolar recordings, contralateral versus ipsilateral precentral or contralateral precentral versus vertex, it appears as a sharp additional negativity. This additional negativity averaged-1.3 μV (SD 0.64, SE 0.08). The MP reflects the motor cortical activity immediately preceding the movement. After movement onset, a complex potential is recorded, that is also seen with passive finger movement, largely representing a somatosensory (proprioceptive) evoked response. The possible meaning of the movement-related potentials is discussed in relation to a theory of central motor function.

Distribution of readiness potential, pre-motion positivity, and motor potential of the human cerebral cortex preceding voluntary finger movements.

Potentials recorded from the scalp of human subjects preceding voluntary finger movements may be devided into 3 components: 1. a slowly increasing surface negative readiness potential which starts about 850 msec before movement and is bilaterally symmetrical over the pre- and post-central region with a maximum at the vertex; 2. a pre-motion positivity which is also bilaterally symmetrical and starts about 86 msec before the onset of EMG; 3. a surface negative motor potential which starts about 56 msec before the onset of movement in the EMG and has its maximum over the contralateral precentral hand area.