Academic literature on the topic 'LRP: Lateralized Readiness Potential'

AbstractWillfully not responding to auditory stimuli hampers accurate behavioral measurements. An objective measure of covert manual suppression recorded during response tasks may be useful to assess the veracity of responses to stimuli.To investigate whether the lateralized readiness potential (LRP), an electrophysiological measure of corticomotor response and suppression, may be of use in determining when participants hear but do not respond to pure tones.Within-subject repeated measures with a Go–NoGo paradigm.Five males and five females (mean age = 38.8 years, standard deviation = 8.8) underwent electrophysiology testing. All had normal hearing, except one.Participants were tested in a condition where they consistently responded to tonal stimuli, and in a condition where intensity cued whether they should respond or not. Scalp-recorded cortical potentials and behavioral responses were recorded, along with a question that probed the perceived effort required to suppress responses to the stimuli.Electrophysiology data were processed with independent component analysis and epoch-based artifact rejection. Averaged group and individual LRPs were calculated.Group averaged waveforms show that suppressed responses, cued by NoGo stimuli, diverge positively at approximately 300 msec poststimulus, when compared with performed (Go) responses. LRPs were comparable when Go responses were recorded in a separate condition in which participants responded to all stimuli, and when Go and NoGo trials were included in the same condition. The LRP was not observed in one participant.Subsequent to further investigation, the LRP may prove suitable in assessing the suppression of responses to audiometric stimuli, and, thereby, useful in cases where functional hearing loss is suspected.

This article explores the contribution of differences in motor response initiation and execution to the biological bases of extraversion. Specifically, we examined individual differences in the lateralized readiness potential (LRP) for introverts and extraverts under conditions influencing stimulus evaluation time prior to response execution, i.e., stimulus information value and tonal complexity. The salient effects were longer stimulus-locked LRP and shorter response-locked LRP for extraverts than introverts to simple imperative stimuli to respond. The present studies (1) confirm that extraverts initiate movement faster and are less efficient than introverts in the processing of simple stimulus signals to respond and (2) endorse the view differences in sensory-motor processing are important determinants of variation in Extraversion.

Abstract. Negative priming (NP) refers to increased response time (RT) for a probe target that was a distractor in a preceding prime presentation (distractor-target shift, DT), compared to novel targets. The present study used the lateralized readiness potential (LRP) to investigate, in a four-choice identification task, a novel episodic-retrieval explanation of NP introduced by Rothermund, Wentura, and de Houwer (2005) . This theory proposes that retrieval reactivates the prime response which interferes with selection of the correct probe response, thereby producing NP. 20 participants responded to pairs of red and blue digits, contingent on the identity of the digit presented in the target color. Behavioral NP involved RT increase by 16 ms. With shift trials (different hands used for prime and probe responses), in the DT condition LRP onset was delayed relative to control. By contrast, earlier LRP onset was observed for DT relative to control with no-shift trials (same hand used for prime and probe responses). Behavioral NP effects showed similar magnitude for shift and no-shift trials. Results support the Rothermund et al. (2005) theory of prime-response retrieval.

Similar motor regions are activated during voluntarily executed or observed movements. We investigated whether observing movements of one's own hand through a mirror will generate activations in the cortical motor regions of both the moving and nonmoving hands. Using the lateralized readiness potential (LRP), an electrophysiological correlate of premotor activation in the primary motor cortex, we recorded evoked responses to movements while subjects were viewing the performing (right) hand through a mirror placed sagittally, giving the impression that the left hand was performing the task. Reliable LRPs were recorded in relation to the seen hand, indicating motor cortex activity in the contralateral hemisphere of the inactive hand while the opposite hand was performing the movement.

AbstractSmoking/nicotine improves cognitive performance for a variety of tasks. In most cases, reaction time (RT) is generally shorter after smoking/nicotine. While there may be some slight facilitation of stimulus-evaluation processing, most of the RT effects of nicotine appear to take place following the response-selection stage. This study investigated possible effects (in smokers) of smoking/nicotine on response preparation and execution processes using the lateralized readiness potential (LRP). On each trial, a warning stimulus preceded an imperative stimulus by 1.2s. The warning stimulus completely specified the correct response to the imperative stimulus. The study was completed in two morning sessions in which 4 cigarettes were smoked in each session. The nicotine yield of the cigarettes varied between sessions (0.05mg or 1.1mg). Maximum amplitudes of both the stimulus and response-locked LRPs were larger in the 1.1 mg session. For both stimulus- and response-locked LRPs, smoking the 1.1 mg cigarette (but not the 0.05 mg cigarette) shortened onset latency. However, the magnitude of the effect was much larger for the stimulus-locked LRPs, suggesting that response preparation is facilitated by smoking/nicotine to a greater degree than response execution.

Practice effects on dual-task processing are of interest in current research because they may reveal the scope and limits of parallel task processing. Here we used onsets of the lateralized readiness potential (LRP), a time marker for the termination of response selection, to assess processing changes after five consecutive dual-task sessions with three stimulus onset asynchronies (SOAs) and priority on Task 1. Practice reduced reaction times in both tasks and the interference between tasks. As indicated by the LRP, the reduction of dual-task costs can be explained most parsimoniously by a shortening of the temporal demands of central bottleneck stages, without assuming parallel processing. However, the LRP also revealed a hitherto unreported early activation over the parietal scalp after practice in the short SOA condition, possibly indicating the isolation of stimulus–response translation from other central processing stages. In addition, further evidence was obtained from the LRP for a late motoric bottleneck, which is robust against practice.

Die Studie hat zum Ziel, im Rahmen des Äußerungsproduktionsmodells die Annahme thinking for speaking (Slobin, 1996) experimentell zu überprüfen. Ansatzpunkt ist der Unterschied in der Stellung der Markierung einer Entscheidungsfrage zwischen drei Sprachen. Während der Fragemodus im Deutschen/Polnischen vor dem Frageinhalt markiert wird, geschieht die Modusmarkierung im Chinesischen nach dem Inhalt. Um die entsprechende Satzstruktur aufzubauen, sollte der Fragemodus beim syntaktischen Kodierungsprozess (speaking) im Deutschen/Polnischen vor, im Chinesischen nach dem Inhalt verarbeitet werden. Unter Zugrundelegung der inkrementellen Äußerungsproduktion gehen wir davon aus, dass die Verarbeitungsreihenfolge beim vorangehenden Konzeptualisierungsprozess (thinking) mit der syntaktischen Kodierungsabfolge übereinstimmt: Der Fragemodus wird im Deutschen/ Polnischen vor, im Chinesischen hingegen nach dem Inhalt konzeptualisiert. Um den zeitlichen Ablauf der zwei Konzeptualisierungsprozess zu ermitteln, bedienten wir uns des lateralisierten Bereitschaftspotenzials (lateralized readiness potential, LRP) im binären Wahlreaktions-Go/Nogo-Paradigma. Im Versuch reagierten deutsche, chinesische und polnische Muttersprachler auf dargebotene Bilder mit Tastendrücken und Sprechen. Zu beobachten war das Auftreten eines LRP bei Nogo, das signalisierte, in welcher Reihenfolge sich die Handwahl und die Nogo-Entscheidung realisierten Ein Nogo-LRP trat bei allen drei Sprechergruppen auf. Zudem wurde festgestellt, dass die Nogo-Entscheidung, die erwartungsgemäß mit der sprachlichen Verarbeitung des Fragemodus verbunden wurde, bei den drei Sprechergruppen ungefähr zeitgleich getroffen wurde. Die Befunde legen nahe, dass der Fragemodus in den drei Sprachen zeitlich nicht unterschiedlich, sondern einheitlich geplant wurde. Die Schlussfolgerung wird im Rahmen von thinking for speaking sowie dem Äußerungsproduktionsmodell diskutiert.
Languages differ in the marking of the sentence mood of a polar interrogative (yes/no question). For instance, the interrogative mood is marked at the beginning of the surface structure in Polish, whereas the marker appears at the end in Chinese. In order to generate the corresponding sentence frame, the syntactic specification of the interrogative mood is early in Polish and late in Chinese. In this respect, German belongs to an interesting intermediate class. The yes/no-question is expressed by a shift of the finite verb from its final position in the underlying structure into the utterance initial position, a move affecting, hence, both the sentence final and the sentence initial constituents. The present study aimed to investigate whether during generation of the semantic structure of a polar interrogative, i.e. the processing preceding the grammatical formulation, the interrogative mood is encoded according to its position in the syntactic structure at distinctive time points in Chinese, German, and Polish. In a two-choice go/nogo experimental design, native speakers of the three languages responded to pictures by pressing buttons and producing utterances in their native language while their brain potentials were recorded. The emergence and latency of lateralized readiness potentials (LRP) in nogo conditions, in which speakers asked a yes/no question, should indicate the time point of processing the interrogative mood. The results revealed that Chinese, German, and Polish native speakers did not differ from each other in the electrophysiological indicator. The findings suggest that the semantic encoding of the interrogative mood is temporally consistent across languages despite its disparate syntactic specification. The consistent encoding may be ascribed to economic processing of interrogative moods at various sentential positions of the syntactic structures in languages or, more generally, to the overarching status of sentence mood in the semantic structure.

Emotiv EPOC is a low-cost consumer headset capable of acquiring a raw EEG signal. The thesis evaluates its usage for an acquisition of research event-related potentials. A controlled laboratory experiment was performed with an objective of isolating the Bereitschaftspotential (Readiness Potential) and other movement-related potentials and comparing the results with the results of the previous research. The possibility of measuring the potential with Emotiv EPOC was not confirmed, most probably due to procedural issues during the experiment, however, further analysis of the data suggests its presence. Other outcomes of the research include qualitative findings about the headset, mainly its hardware construction, and testing feedback of EEGLab, an open source toolbox for EEG processing and visualization.

Il “blink” o “batter d’occhi” è un movimento di rapida chiusura e riapertura delle palpebre. Il “blink” può essere un movimento spontaneo, riflesso o volontario. “Blink” con identiche caratteristiche cinematiche possono avere differenti origini e significati. Per esempio, un blink può essere spontaneo quando ha la funzione fisiologica di creare un film lacrimale evitando la seccazione della cornea, può essere riflesso in riposta a stimoli esterni ed infine può essere volontario per comunicare un messaggio attraverso un canale comunicativo preservato, per esempio quando un paziente locked in cerca di comunicare gioia, accordo o disaccordo, frustrazione attraverso gli occhi (Laureys et al., 2005). Lo scopo principale di questo studio è stato quello di trovare una misura oggettiva relativa alla distinzione tra un blink spontaneo e uno volontario: il “potenziale di preparazione” (Readiness Potential). Il presente studio è quindi rilevante per due ragioni: 1. Nei soggetti sani, i blink spontanei appaiono con una frequenza di circa 1 ogni 5 secondi. Allo stesso tempo, i soggetti sani possono “controllare” il movimento spontaneo e riprodurlo in maniera intenzionale se opportunamente istruiti. In questo modo, il “blink” o “ammiccamento oculare” offre un contrasto ideale tra atto conscio e inconscio, a parità di cinematica. In questa prospettiva, l’analisi dell’attività cerebrale che precede un atto spontaneo o automatico messa a confronto con l’attività che precedere un “blink” volontario può offrire uno sguardo unico sui correlati neurali di un atto cosciente. 2. Nei pazienti con gravi cerebrolesioni, il “blink” è spesso l’unico atto motorio che può essere individuato. È infatti impossibile per molti pazienti effettuare movimenti più complessi. Per questo motivo, attraverso un condizionamento operante in cui ad uno specifico comportamento viene associato un rinforzo positivo, il nostro scopo è quello di indirizzare i pazienti ad associare un determinato tipo di “blink”, opportunamente selezionato, con un rinforzo positivo rappresentato da voci familiari/amiche che si suppone possano avere una valenza emotiva positiva per il paziente. Nella prima parte della tesi verranno introdotte le premesse teorico/sperimentali alla base dello studio e verranno presentati i materiali e metodi e i risultati relativi alla popolazione di controllo (soggetti sani). Nella seconda parte, verrà introdotto il “disturbo di coscienza” dal punto di vista clinico, il nuovo protocollo sperimentale applicato ai pazienti con disturbo di coscienza e i risultati preliminari. In conclusione, verranno valutate le potenzialità dello studio da un punto di vista teorico, da un punto di vista clinico/riabilitativo ed infine da un punto di vista etico.
Blinking is a rapid closing and opening of the eyelid. Eye blinks with identical kinematical features can have different origins and meanings. For example, one can blink automatically, due to a simple reflex arc – such as when moistening the cornea – or one can blink voluntarily to communicate a fundamental message – such as when a locked-in patient communicates that he/she is happy or frustrated (Laureys, et al., 2005) The main aim of the present project is to find a brain-based objective way to know whether a given blink is a meaningless automatic neural event or the endpoint of a complex conscious process. The proposal builds up on the empirical work by Kornhuber & Deecke and Benjamin Libet, who showed that the awareness of intention to move is preceded by a recordable cerebral activity called “Readiness Potential”. The present proposal is relevant for two reasons: 1. In healthy subjects, automatic blinking occurs spontaneously every 5 seconds, or so. At the same time, healthy subjects can be instructed to blink voluntarily in a controlled fashion. In this way, blinking offers the ideal contrast between unconscious and conscious acts – the physical, kinematic aspects of the movement being equal. In this perspective, analyzing brain activity prior to automatic and voluntary blinks may offer a unique insight on the neural correlates of a conscious act. 2. In patients with severe brain injuries blinking is often the only motor act that can be reliably detected. By employing operant conditioning, we aim at training patients on the association between a specific eyelid closure and a positive reinforcement. Specifically, Readiness Potential like activity will be computed on the cortical activity preceding eye blinking as a measure of “volition,” first in healthy controls and then in vegetative and minimally conscious state patients undergoing operant conditioning. In healthy controls, we will contrast spontaneous blinks against voluntary blinks. The results of this experiment are meant to explore the dynamic range of the changes in brain activity that underlies voluntary vs. spontaneous blinks in controlled conditions. In patients, detecting a progressive increase in the strength or complexity of brain activity (up to the levels obtained in healthy subjects during voluntary blinks) during the course of the conditioning sessions will indicate that their blinking might reflect a voluntary act. Ultimately, this project, if successful, will link operant conditioning to the long-standing topic of the neural substrates of a wilful decision to act, bearing important scientific/ethical implications. The novelty of this project rests on: a. Exploring, empirically, the relationships between brain activity and the will. The underlying hypothesis guiding this project is that a wilful act should be reflected, to some measurable degree, in high levels of anticipatory brain dynamics. b. Taking Libet’s work one-step forward, by using slow cortical potentials such as the “Readiness Potential” as a neural marker of volition. c. Using the “Readiness Potential” to distinguish between spontaneous and voluntary blinks. d. Answering the critical question of whether the blinks produced by vegetative patients after a conditioning protocol are voluntary or not.

A wide literature of predominantly behavioural experiments that use Stimulus Response Compatibility (SRC) have suggested that visual action information such as object affordance yields rapid and concurrent activation of visual and motor brain areas, but has rarely provided direct evidence for this proposition. This thesis examines some of the key claims from the affordance literature by applying electrophysiological measures to well established SRC procedures to determine the verities of the behavioural claims of rapid and automatic visuomotor activation evoked by viewing affording objects. The temporal sensitivity offered by the Lateralised Readiness Potential and by visual evoked potentials P1 and N1 made ideal candidates to assess the behavioural claims of rapid visuomotor activation by seen objects by examining the timecourse of neural activation elicited by viewing affording objects under various conditions. The experimental work in this thesis broadly confirms the claims of the behavioural literature however it also found a series of novel results that are not predicted by the behavioural literature due to limitations in reaction time measures. For example, while different classes of affordance have been shown to exert the same behavioural facilitation, electrophysiological measures reveal very different patterns of cortical activation for grip-type and lateralised affordances. These novel findings question the applicability of the label ‘visuomotor’ to grip-type affordance processing and suggest considerable revision to models of affordance. This thesis also offers a series of novel and surprising insights into the ability to dissociate afforded motor activity from behavioural output, into the relationship between affordance and early visual evoked potentials, and into affordance in the absence of the intention to act. Overall, this thesis provides detailed suggestions for considerable changes to current models of the neural activity underpinning object affordance.