Operant conditioning of P300

Interaction of spatial attention and the associated reward value of audiovisual objects

Reward value and selective attention both enhance the representation of sensory stimuli at the earliest stages of processing. It is still debated whether and how reward-driven and attentional mechanisms interact to influence perception. Here we ask whether the interaction between reward value and selective attention depends on the sensory modality through which the reward information is conveyed. Human participants first learned the reward value of uni-modal visual and auditory stimuli during a conditioning phase. Subsequently, they performed a target detection task on bimodal stimuli containing a previously rewarded stimulus in one, both, or neither of the modalities. Additionally, participants were required to focus their attention on one side and only report targets on the attended side. Our results showed a strong modulation of visual and auditory event-related potentials (ERPs) by spatial attention. We found no main effect of reward value but importantly we found an interaction effect as the strength of attentional modulation of the ERPs was significantly affected by the reward value. When reward effects were examined separately with respect to each modality, auditory value-driven modulation of attention was found to dominate the ERP effects whereas visual reward value on its own led to no effect, likely due to its interference with the target processing. These results inspire a two-stage model where first the salience of a high reward stimulus is enhanced on a local priority map specific to each sensory modality, and at a second stage reward value and top-down attentional mechanisms are integrated across sensory modalities to affect perception.

A Neurobiological-Behavioral Approach to Predicting and Influencing Private Events

The primary goals of behavior analysis are the prediction and influence of behavior. These goals are largely achieved through the identification of functional relations between behaviors and the stimulating environment. Behavior-behavior relations are insufficient to meet these goals. Although this environment-behavior approach has been highly successful when applied to public behaviors, extensions to private events have been limited. This article discusses technical and conceptual challenges to the study of private events. We introduce a neurobiological-behavioral approach which seeks to understand private behavior as environmentally controlled in part by private neurobiological stimuli. These stimuli may enter into functional relations with both public and private behaviors. The analysis builds upon several current approaches to private events, delineates private behaviors and private stimulation, and emphasizes the reciprocal interaction between the two. By doing so, this approach can improve treatment and assessment of behavior and advance understanding of concepts such as motivating operations. We then describe the array of stimulus functions that neurobiological stimuli may acquire, including eliciting, discriminative, motivating, reinforcing, and punishing effects, and describe how the overall approach expands the concept of contextual influence. Finally, we describe how advances in behavioral neuroscience that enable the measurement and analysis of private behaviors and stimuli are allowing these once private events to affect the public world. Applications in the area of human-computer interfaces are discussed.

Dignity neuroscience: universal rights are rooted in human brain science

Universal human rights are defined by international agreements, law, foreign policy, and the concept of inherent human dignity. However, rights defined on this basis can be readily subverted by overt and covert disagreements and can be treated as distant geopolitical events rather than bearing on individuals’ everyday lives. A robust case for universal human rights is urgently needed and must meet several disparate requirements: (1) a framework that resolves tautological definitions reached solely by mutual, revocable agreement; (2) a rationale that transcends differences in beliefs, creed, and culture; and (3) a personalization that empowers both individuals and governments to further human rights protections. We propose that human rights in existing agreements comprise five elemental types: (1) agency, autonomy, and self‐determination; (2) freedom from want; (3) freedom from fear; (4) uniqueness; and (5) unconditionality, including protections for vulnerable populations. We further propose these rights and protections are rooted in fundamental properties of the human brain. We provide a robust, empirical foundation for universal rights based on emerging work in human brain science that we term dignity neuroscience. Dignity neuroscience provides an empirical foundation to support and foster human dignity, universal rights, and their active furtherance by individuals, nations, and international law.

On the "Strength" of Behavior

The place of the concept of response strength in a natural science of behavior has been the subject of much debate. This article reconsiders the concept of response strength for reasons linked to the foundations of a natural science of behavior. The notion of response strength is implicit in many radical behaviorists' work. Palmer (2009) makes it explicit by applying the response strength concept to three levels: (1) overt behavior, (2) covert behavior, and (3) latent or potential behavior. We argue that the concept of response strength is superfluous in general, and an explication of the notion of giving causal status to nonobservable events like latent behavior or response strength is harmful to a scientific endeavor. Interpreting EEG recordings as indicators of changes in response strength runs the risk of reducing behavior to underlying mechanisms, regardless of whether such suggestions are accompanied by behavioral observations. Many radical behaviorists understand behavior as a discrete unit, inviting conceptual mistakes reflected in the notion of response strength. A molar view is suggested as an alternative that accounts for the temporally extended nature of behavior and avoids the perils of a response-strength based approach.

Attention in Athletes of High and Low Experience Engaged in Different Open Skill Sports

In this study were examined differences in attentional style of athletes engaged in two open skill sports requiring high reactivity (karate and volleyball) in groups with high or low experience. 42 healthy men, 24 volleyball players, 12 of High Experience (first division Italian League players whose M age was 28 yr. ( SD = 5) and 12 of Low Experience (prejunior Italian team athletes whose M age was 19 yr. ( SD = 2), and 18 karateka, 9 of High Experience (3rd and 4th dan black belt athletes whose M age was 31 yr., SD = 5) and 9 of Low Experience (1st and 2nd dan black belt karateka whose M age was 32 yr., SD = 5). Tests involved different types of attention: Alert, Go/No-Go, Divided Attention, and Working Memory. For each one, the reaction time (RT), variability, change in RT, and number of errors were analysed. Karateka of High Experience reacted faster than those of Low Experience on the simple RT test, Alert ( M RT: 204 vs 237 msec., p < .01), while on the Divided Attention test, the High Experience subjects performed more poorly and committed more errors ( M errors: 4.89 vs 1.44, p < .003). Young volleyball players of Low Experience reacted faster than colleagues of High Experience on the Alert ( M RT: 187 vs 210 msec., p < .01) and Divided Attention tests ( M RT: 590 vs 688 msec., p < .001) but committed more errors (Divided Attention test, M errors: 6.50 vs 3.08, p < .007). For the Divided Attention and Working Memory tests, correlations were positive among errors, RT, and RT variability but only for volleyball athletes of High Experience, suggesting they showed higher attention and stability in complex reactions than the group with Low Experience. No significant correlations were noted for either group of karateka on complex reactions. Results suggested that the attentional resources were engaged in different ways in the two groups of athletes and, in each group, there were differences between persons of High and Low Experience.

Electrophysiological CNS-processes related to associative learning in humans

The neurophysiology of human associative memory has been studied with electroencephalographic techniques since the 1930s. This research has revealed that different types of electrophysiological processes in the human brain can be modified by conditioning: sensory evoked potentials, sensory induced gamma-band activity, periods of frequency-specific waves (alpha and beta waves, the sensorimotor rhythm and the mu-rhythm) and slow cortical potentials. Conditioning of these processes has been studied in experiments that either use operant conditioning or repeated contingent pairings of conditioned and unconditioned stimuli (classical conditioning). In operant conditioning, the appearance of a specific brain process is paired with an external stimulus (neurofeedback) and the feedback enables subjects to obtain varying degrees of control of the CNS-process. Such acquired self-regulation of brain activity has found practical uses for instance in the amelioration of epileptic seizures, Autism Spectrum Disorders (ASD) and Attention Deficit Hyperactivity Disorder (ADHD). It has also provided communicative means of assistance for tetraplegic patients through the use of brain computer interfaces. Both extra and intracortically recorded signals have been coupled with contingent external feedback. It is the aim for this review to summarize essential results on all types of electromagnetic brain processes that have been modified by classical or operant conditioning. The results are organized according to type of conditioned EEG-process, type of conditioning, and sensory modalities of the conditioning stimuli.

A P300-based brain-computer interface with stimuli on moving objects: four-session single-trial and triple-trial tests with a game-like task design

Brain-computer interfaces (BCIs) are tools for controlling computers and other devices without using muscular activity, employing user-controlled variations in signals recorded from the user's brain. One of the most efficient noninvasive BCIs is based on the P300 wave of the brain's response to stimuli and is therefore referred to as the P300 BCI. Many modifications of this BCI have been proposed to further improve the BCI's characteristics or to better adapt the BCI to various applications. However, in the original P300 BCI and in all of its modifications, the spatial positions of stimuli were fixed relative to each other, which can impose constraints on designing applications controlled by this BCI. We designed and tested a P300 BCI with stimuli presented on objects that were freely moving on a screen at a speed of 5.4°/s. Healthy participants practiced a game-like task with this BCI in either single-trial or triple-trial mode within four sessions. At each step, the participants were required to select one of nine moving objects. The mean online accuracy of BCI-based selection was 81% in the triple-trial mode and 65% in the single-trial mode. A relatively high P300 amplitude was observed in response to targets in most participants. Self-rated interest in the task was high and stable over the four sessions (the medians in the 1st/4th sessions were 79/84% and 76/71% in the groups practicing in the single-trial and triple-trial modes, respectively). We conclude that the movement of stimulus positions relative to each other may not prevent the efficient use of the P300 BCI by people controlling their gaze, e.g., in robotic devices and in video games.

Neuroscientific measures of covert behavior

In radical behaviorism, the difference between overt and covert responses does not depend on properties of the behavior but on the sensitivity of the measurement tools employed by the experimenter. Current neuroscientific research utilizes technologies that allow measurement of variables that are undetected by the tools typically used by behavior analysts. Data from a specific neuroscientific technique, event-related potential (ERP), suggest that emission of otherwise covert responses can be indexed and that such covert responses are sensitive to stimulus control and selection by consequences. The P3 ERP effect is proposed as indicative of emission. Moreover, ERP results in semantic priming experiments suggest that operants are sensitive to changes in stimulus control even when they are not emitted (latent responses). Changes in response strength of latent responses as a function of stimulus control can in fact be measured by reaction time data and an ERP dependent variable called the N400 effect. If the interpretations provided in this paper are accurate, an index of covertly emitted operants (P3 effect) constitutes experimental evidence suggesting the validity of a Skinnerian radical behaviorist perspective on behavior. Moreover, in a Skinnerian paradigm, measured fluctuations in the response strength of latent operants as a function of environmental changes (N400 effect) would validate Palmer's (2009) concept of the repertoire.

Effects of SOA and flash pattern manipulations on ERPs, performance, and preference: Implications for a BCI system

P3 brain-computer interfaces (BCIs) are synchronous communication systems that allow users to communicate interest in a target event by choosing to attend to it while ignoring other events. In such a system, a cogneme refers to the user's response to: "/attend to the event/" or "/ignore the event/". The present study examined subjects' ability to generate more cognemes per minute (by varying stimulus onset asynchrony or SOA), or requiring fewer cognemes to convey a message (by varying the pattern of stimulus presentation). Both of these have implications for improved information throughput in a P3 BCI. SOAs of 125, 250, and 500 ms were used. Additionally, the conventional "single flash" approach was compared to a new "multiple flash" condition in which half of the stimuli in an 8 x 8 grid were flashed simultaneously. In both conditions, P3-like component amplitudes decreased with faster SOAs at low target probabilities, but the trend did not hold for higher probabilities. The multiple flash condition produced more robust ERPs at the faster speeds. The results also indicate that attend/ignore differences were more apparent following multiple flashes for low target probabilities, but less apparent for high target probabilities. Although information throughput alone does not support the superiority of one approach over the other, only six cognemes are needed in the multiple flash conditions to identify a character, compared to sixteen cognemes in the single flash condition. This suggests that the former approach could operate more rapidly. Thus, the present results suggest that the multiple flash approach may be a more efficient and faster basis for a P3 BCI system.

Brain-computer interfaces for communication and control

For many years people have speculated that electroencephalographic activity or other electrophysiological measures of brain function might provide a new non-muscular channel for sending messages and commands to the external world - a brain-computer interface (BCI). Over the past 15 years, productive BCI research programs have arisen. Encouraged by new understanding of brain function, by the advent of powerful low-cost computer equipment, and by growing recognition of the needs and potentials of people with disabilities, these programs concentrate on developing new augmentative communication and control technology for those with severe neuromuscular disorders, such as amyotrophic lateral sclerosis, brainstem stroke, and spinal cord injury. The immediate goal is to provide these users, who may be completely paralyzed, or 'locked in', with basic communication capabilities so that they can express their wishes to caregivers or even operate word processing programs or neuroprostheses. Present-day BCIs determine the intent of the user from a variety of different electrophysiological signals. These signals include slow cortical potentials, P300 potentials, and mu or beta rhythms recorded from the scalp, and cortical neuronal activity recorded by implanted electrodes. They are translated in real-time into commands that operate a computer display or other device. Successful operation requires that the user encode commands in these signals and that the BCI derive the commands from the signals. Thus, the user and the BCI system need to adapt to each other both initially and continually so as to ensure stable performance. Current BCIs have maximum information transfer rates up to 10-25bits/min. This limited capacity can be valuable for people whose severe disabilities prevent them from using conventional augmentative communication methods. At the same time, many possible applications of BCI technology, such as neuroprosthesis control, may require higher information transfer rates. Future progress will depend on: recognition that BCI research and development is an interdisciplinary problem, involving neurobiology, psychology, engineering, mathematics, and computer science; identification of those signals, whether evoked potentials, spontaneous rhythms, or neuronal firing rates, that users are best able to control independent of activity in conventional motor output pathways; development of training methods for helping users to gain and maintain that control; delineation of the best algorithms for translating these signals into device commands; attention to the identification and elimination of artifacts such as electromyographic and electro-oculographic activity; adoption of precise and objective procedures for evaluating BCI performance; recognition of the need for long-term as well as short-term assessment of BCI performance; identification of appropriate BCI applications and appropriate matching of applications and users; and attention to factors that affect user acceptance of augmentative technology, including ease of use, cosmesis, and provision of those communication and control capacities that are most important to the user. Development of BCI technology will also benefit from greater emphasis on peer-reviewed research publications and avoidance of the hyperbolic and often misleading media attention that tends to generate unrealistic expectations in the public and skepticism in other researchers. With adequate recognition and effective engagement of all these issues, BCI systems could eventually provide an important new communication and control option for those with motor disabilities and might also give those without disabilities a supplementary control channel or a control channel useful in special circumstances.

Reactivity and event-related potentials in attentional tests: effect of training

To study the effects of training on reactivity and event-related potentials a complex attentional shifting test involving reaction time was administered (Test 1) to 24 healthy, young students. After five days, 12 subjects were tested with the same procedure (Test 2) without training (Untrained Subjects) while 12 repeated the test at the fifth day after four days of training (Trained Subjects). During Tests 1 and 2, event-related potentials were recorded by electroencephalogram. The task consisted of each subject responding to a stimulus of a letter appearing in the centre of a geometric figure on the screen of a computer monitor. In the prestimulus period black points were drawn and crowded randomly into a zone of the screen. The geometric figure and the letter were shown in the centre of the crowding. There were two letters and four geometric figures randomly combined in different ways. The subject had to press different keys of the computer keyboard when specific combinations appeared. The averaged event-related potentials were characterized by a negative wave with a close relationship to selective attention before the onset of the stimulus of a geometric figure followed by letters. After the stimulus onset, a P3 complex was recorded. Trained subjects were no different from untrained subjects in Test 1, while in Test 2 they had a shorter reaction time, an earlier peak of the selective attention related wave and P3, and a higher amplitude for the P3 complex. These measures and the correlations between them can be considered an index of the training effect. Thus, these tests could be used for evaluation of the attentional style and its modification with training.

The effect of accomplishment and failure on P300 potentials evoked by neutral stimuli

The effects of emotional states of 'being successful' vs. 'being unsuccessful' were studied by measuring the P300 component of event-related potentials (ERPs). Nine subjects were instructed to reduce their P300 amplitude using feedback. Feedback was random but the relative probability of different signals created the situations of 'being successful' or 'being unsuccessful'. The probability of 'small' feedback was 0.7 in 'successful' and 0.15 in 'unsuccessful' trials. ERPs recorded without the feedback were used as a reference. Potentials, evoked by light stimuli in a standard 'odd-ball' procedure, were recorded from Fz, Cz and Pz scalp sites. The amplitudes of P300 components were reduced in 'unsuccessful' trials whereas in 'successful' trials they did not differ significantly from responses recorded without the feedback. There were no significant differences in peak latencies. These findings indicate that tonic emotional states affect the processing of neutral stimuli and that late components of ERPs can be useful indices in the analysis of these alterations. The results also indicate that the effects of positive and negative emotional states are not always reciprocal. Manipulated feedback is suggested as an useful model in the studies of emotions. Data can also facilitate the interpretation of the real feedback effects.

The demonstration of long latency potentials in the CA1 region of the rat hippocampal slice

Shaffer collateral evoked extracellular DC potentials with latencies greater than 100 ms are demonstrated in the CA1 region of the rat hippocampal slice preparation. The most prominent potential following the population spike is a positive potential peaking between 150 and 400 ms after the stimulus. The amplitude of the potential is approximately two orders of magnitude smaller than the population spike. This potential shares several characteristics with the P300 from electroencephalogram studies of evoked potentials. Thus, it was dubbed the in vitro P3. One of the most distinguishing characteristics of the in vitro P3 is a negative potential that immediately follows it. The negative potential is smaller in amplitude than the in vitro P3, but lasts for several seconds. A similar potential also follows the P300 in electroencephalogram studies. These data suggest that the in vitro P3 is an in vitro version of the long latency evoked potential known as the P300 in electroencephalogram studies.