Reappraisal of filter effects on P300 voltage and latency

EEG correlates of physical effort and reward processing during reinforcement learning

Effort-based decision making is often modeled using subjective value, a function of reward discounted by effort. We asked whether EEG event-related potential (ERP) correlates of reward processing are also modulated by physical effort. Human participants performed a task in which they were required to accurately produce target levels of muscle activation to receive rewards. Quadriceps muscle activation was recorded with electromyography (EMG) during isometric knee extension. On a given trial, the target muscle activation required either low or high effort. The effort was determined probabilistically according to a binary choice, such that the responses were associated with 20% and 80% probability of high effort. This contingency could only be learned through experience, and it reversed periodically. Binary reinforcement feedback depended on accurately producing the target muscle activity. Participants adaptively avoided effort by switching responses more frequently after choices that resulted in hard effort. Feedback after participants' choices that revealed the resulting effort requirement did not elicit modulation of the feedback-related negativity/reward positivity (FRN/RP). However, the neural response to reinforcement outcome after effort production was increased by preceding physical effort. Source decomposition revealed separable early and late positive deflections contributing to the ERP. The main effect of reward outcome, characteristic of the FRN/RP, loaded onto the earlier component, whereas the reward × effort interaction was observed only in the later positivity, which resembled the P300. Thus, retrospective effort modulates reward processing. This may explain paradoxical behavioral findings whereby rewards requiring more effort to obtain can become more powerful reinforcers.NEW & NOTEWORTHY Choices probabilistically determined the physical effort requirements for a subsequent task, and reward depended on task performance. Feedback revealing whether choices resulted in easy or hard effort did not elicit reinforcement learning signals. However, the neural responses to reinforcement were modulated by preceding effort. Thus, effort itself was not treated as loss or punishment, but it affected the responses to subsequent reinforcement outcomes. This may explain how effort can enhance the motivational effect of reward.

The Detection of the Negative Effects of Interictal Epileptiform Discharges on Cognition: An Event-Related Potential Study

Evidence from a neuropsychological test revealed that interictal epileptiform discharges (IEDs) may have significant impact on cognitive performance. Sometimes, neuropsychological tests may not be sensitive to detection of mild cognitive changes. We applied P300 and mismatch negativity (MMN) to detect mild cognitive changes caused by small amount of IEDs. Sixty-seven adult epilepsy patients and participants were divided into six groups according to different IEDs index. The patients with IED index greater than 7.5% showed longer latency and lower amplitude in the test of P300 and MMN than patients with IED index less than 7.5%, which indicated mild impaired cognitive function. The negative effect of IED index greater than 10% on cognitive has been found by neuropsychological test, whereas the mild negative effect of IED index greater than 7.5% has only been found by P300 and MMN. So, P300 and MMN may be more sensitive than neuropsychological tests to detect mild cognitive impairment caused by IEDs.

The relationship between mismatch response and the acoustic change complex in normal hearing infants

OBJECTIVE

To examine the utility of the mismatch response (MMR) and acoustic change complex (ACC) for assessing speech discrimination in infants.

METHODS

Continuous EEG was recorded during sleep from 48 (24 male, 20 female) normally hearing aged 1.77 to -4.57 months in response to two auditory discrimination tasks. ACC was recorded in response to a three-vowel sequence (/i/-/a/-/i/). MMR was recorded in response to a standard vowel, /a/, (probability 85%), and to a deviant vowel, /i/, (probability of 15%). A priori comparisons included: age, sex, and sleep state. These were conducted separately for each of the three bandpass filter settings were compared (1-18, 1-30, and 1-40 Hz).

RESULTS

A priori tests revealed no differences in MMR or ACC for age, sex, or sleep state for any of the three filter settings. ACC and MMR responses were prominently observed in all 44 sleeping infants (data from four infants were excluded). Significant differences observed for ACC were to the onset and offset of stimuli. However, neither group nor individual differences were observed to changes in speech stimuli in the ACC. MMR revealed two prominent peaks occurring at the stimulus onset and at the stimulus offset. Permutation t-tests revealed significant differences between the standard and deviant stimuli for both the onset and offset MMR peaks (p < 0.01). The 1-18 Hz filter setting revealed significant differences for all participants in the MMR paradigm.

CONCLUSION

Both ACC and MMR responses were observed to auditory stimulation suggesting that infants perceive and process speech information even during sleep. Significant differences between the standard and deviant responses were observed in the MMR, but not ACC paradigm. These findings suggest that the MMR is sensitive to detecting auditory/speech discrimination processing.

SIGNIFICANCE

This paper identified that MMR can be used to identify discrimination in normal hearing infants. This suggests that MMR has potential for use in infants with hearing loss to validate hearing aid fittings.

Sex differences in neurophysiological responses are modulated by attentional aspects of impulse control

The amplitudes of the N2 and P3 components of event-related potentials (ERPs) may be influenced by personality traits such as impulsivity, and male/female differences may also have an effect. However, few studies have assessed the interaction between personality traits and the sex of the subject in these components. Therefore, in this study we evaluated sex differences in the amplitudes of the N2 and P3 ERP components during a continuous performance task, and their relation to impulse control. Twenty-seven healthy participants were asked to perform an AX-type continuous performance task, also known as a Go/Nogo task, during electroencephalographic recording. Participants then completed the Barratt impulsiveness scale (version 11; BIS-11), and the effortful control (EC) scale to self-report personality measures related to impulse control. We found that in the Nogo condition, males showed significantly larger N2 amplitudes than females in the frontal area. Interestingly, Nogo-N2 amplitudes were positively correlated with BIS-attentional subscale scores, but were negatively correlated with EC-attentional subscale scores, and both correlations were observed only in males. These results suggest that attentional aspects of impulse control modulate Nogo-N2 amplitude only in males. This modulatory effect may be related to a sex-specific inhibitory control mechanism acting during early stimulus evaluation.

On the development of auditory distraction: A review

The present review focuses on the development of involuntary attention mechanisms in the context of the occurrence of unexpected events during childhood. We introduce a prevailing three-stage model of auditory involuntary attention describing the processes leading to, accompanying, and following the distraction of attention by prediction violations: (a) the automatic detection of prediction violations (associated with the event-related potential [ERP] component mismatch negativity [MMN]), (b) the involuntary orienting of attention processes towards the prediction violating sound (associated with the ERP component P3a), and (c) the reorienting back to task-relevant information (associated with the ERP components reorienting negativity [RON] or late discriminative negativity [LDN]). Within this framework we give an overview of studies investigating MMN, P3a, RON/LDN, and behavioral distraction effects in children. We discuss the development of the underlying involuntary attention mechanisms and highlight the relevance of and future perspectives for this important field of research.

Separating acoustic deviance from novelty during the first year of life: a review of event-related potential evidence

Orienting to salient events in the environment is a first step in the development of attention in young infants. Electrophysiological studies have indicated that in newborns and young infants, sounds with widely distributed spectral energy, such as noise and various environmental sounds, as well as sounds widely deviating from their context elicit an event-related potential (ERP) similar to the adult P3a response. We discuss how the maturation of event-related potentials parallels the process of the development of passive auditory attention during the first year of life. Behavioral studies have indicated that the neonatal orientation to high-energy stimuli gradually changes to attending to genuine novelty and other significant events by approximately 9 months of age. In accordance with these changes, in newborns, the ERP response to large acoustic deviance is dramatically larger than that to small and moderate deviations. This ERP difference, however, rapidly decreases within first months of life and the differentiation of the ERP response to genuine novelty from that to spectrally rich but repeatedly presented sounds commences during the same period. The relative decrease of the response amplitudes elicited by high-energy stimuli may reflect development of an inhibitory brain network suppressing the processing of uninformative stimuli. Based on data obtained from healthy full-term and pre-term infants as well as from infants at risk for various developmental problems, we suggest that the electrophysiological indices of the processing of acoustic and contextual deviance may be indicative of the functioning of auditory attention, a crucial prerequisite of learning and language development.

Neuropsychological correlates of the P300 in patients with Alzheimer's disease

OBJECTIVES

The P300 is a useful psychophysiological index that reflects cognitive functions; however, the relationship between P300 indices and neuropsychological tests in Alzheimer's disease (AD) patients is unclear.

METHODS

Thirty-one AD patients and 31 elderly normal control (NC) subjects were recruited. Age and education level were matched between the two groups. The relationship between the P300 and the Korean version of the Consortium to Establish a Registry for Alzheimer's disease (CERAD-K) assessment packet (including 11 neuropsychological tests) was examined in AD patients.

RESULTS

Compared to the NC subjects, the AD patients exhibited significantly decreased P300 amplitudes; however, there was no significant difference between the two groups in terms of P300 latency. After a permutation-based correction for multiple tests, P300 amplitudes at the Cz and Pz electrodes were significantly correlated with performance on the word list recognition, constructional praxis, and word fluency neuropsychological tests in the AD patients. Additionally, P300 latencies at the Pz and C6 electrodes were also significantly correlated with performance on the Mini-Mental State Examination, CERAD-K version (MMSE-K), and Trail Making Test part A (TMT-A) neuropsychological tests in the AD patients.

CONCLUSIONS

The results suggest that the P300 is responsive to the deterioration of language, memory, and executive functions observed in AD patients. Although there was no significant difference between the AD patients and NC subjects in the P300 latency, P300 latency has been shown to reflect impaired global cognition and attention deficits associated with AD. Our results suggest that P300 indices could be used as biological markers that indicate impaired neuropsychological functions in AD patients.

Cortical activity and children's rituals, habits and other repetitive behavior: a visual P300 study

This study examines the link between children's repetitive, ritualistic, behavior and cortical brain activity. Twelve typically developing children between the ages of 6 and 12 years were administered two visual P300, oddball tasks with a 32-electrode electroencephalogram (EEG) system. One of the oddball tasks was specifically designed to reflect sensitivity to asymmetry, a phenomenon common in children and in a variety of disorders involving compulsive behavior. Parents completed the Childhood Routines Inventory. Children's repetitive, compulsive-like behaviors were strongly associated with faster processing of an asymmetrical target stimulus, even when accounting for their P300 latencies on a control task. The research punctuates the continuity between observed brain-behavior links in clinical disorders such as OCD and autism spectrum disorders, and normative variants of repetitive behavior.