Stimulus-preceding negativity in ADHD

Children with ADHD often show disrupted response preparation as indicated by attenuated stimulus-preceding negativity (SPN). This study examined response preparation in a relatively short cue-stimulus interval. No differences in SPN occurred between children with ADHD and their normal peers. A strong positive relationship was found between SPN and mean reaction time in both groups. Children with ADHD are able to mentally prepare themselves for upcoming events in short cue-stimulus intervals. © 2013 Springer-Verlag Wien

Event-related brain potential correlates of human auditory sensory memory-trace formation

The event-related potential (ERP) component mismatch negativity (MMN) is a neural marker of human echoic memory. MMN is elicited by deviant sounds embedded in a stream of frequent standards, reflecting the deviation from an inferred memory trace of the standard stimulus. The strength of this memory trace is thought to be proportional to the number of repetitions of the standard tone, visible as the progressive enhancement of MMN with number of repetitions (MMN memory-trace effect). However, no direct ERP correlates of the formation of echoic memory traces are currently known. This study set out to investigate changes in ERPs to different numbers of repetitions of standards, delivered in a roving-stimulus paradigm in which the frequency of the standard stimulus changed randomly between stimulus trains. Normal healthy volunteers (n = 40) were engaged in two experimental conditions: during passive listening and while actively discriminating changes in tone frequency. As predicted, MMN increased with increasing number of standards. However, this MMN memory-trace effect was caused mainly by enhancement with stimulus repetition of a slow positive wave from 50 to 250 ms poststimulus in the standard ERP, which is termed here "repetition positivity" (RP). This RP was recorded from frontocentral electrodes when participants were passively listening to or actively discriminating changes in tone frequency. RP may represent a human ERP correlate of rapid and stimulus-specific adaptation, a candidate neuronal mechanism underlying sensory memory formation in the auditory cortex

Gamma and beta frequency oscillations in response to novel auditory stimuli: A comparison of human electroencephalogram (EEG) data with in vitro models

Investigations using hippocampal slices maintained in vitro have demonstrated that bursts of oscillatory field potentials in the gamma frequency range (30-80 Hz) are followed by a slower oscillation in the beta 1 range (12-20 Hz). In this study, we demonstrate that a comparable gamma-to-beta transition is seen in the human electroencephalogram (EEG) in response to novel auditory stimuli. Correlations between gamma and beta 1 activity revealed a high degree of interdependence of synchronized oscillations in these bands in the human EEG. Evoked (stimulus-locked) gamma oscillations preceded beta 1 oscillations in response to novel stimuli, suggesting that this may be analogous to the gamma-to-beta shift observed in vitro. Beta 1 oscillations were the earliest discriminatory responses to show enhancement to novel stimuli, preceding changes in the broad-band event-related potential (mismatch negativity). Later peaks of induced beta activity over the parietal cortex were always accompanied by an underlying gamma frequency oscillation as seen in vitro. A further analogy between in vitro and human recordings was that both gamma and beta oscillations habituated markedly after the initial novel stimulus presentation

Temporal regularity effects on pre-attentive and attentive processing of deviance

Temporal regularity allows predicting the temporal locus of future information thereby potentially facilitating cognitive processing. We applied event-related brain potentials (ERPs) to investigate how temporal regularity impacts pre-attentive and attentive processing of deviance in the auditory modality. Participants listened to sequences of sinusoidal tones differing exclusively in pitch. The inter-stimulus interval (ISI) in these sequences was manipulated to convey either isochronous or random temporal structure. In the pre-attentive session, deviance processing was unaffected by the regularity manipulation as evidenced in three event-related-potentials (ERPs): mismatch negativity (MMN), P3a, and reorienting negativity (RON). In the attentive session, the P3b was smaller for deviant tones embedded in irregular temporal structure, while the N2b component remained unaffected. These findings confirm that temporal regularity can reinforce cognitive mechanisms associated with the attentive processing of deviance. Furthermore, they provide evidence for the dynamic allocation of attention in time and dissociable pre-attentive and attention-dependent temporal processing mechanisms

Early EEG correlates of word frequency and contextual predictability in reading

Previous research into written language comprehension has been equivocal as to whether word frequency and contextual predictability effects share an early time course of processing. Target word frequency (low, high) and its predictability from prior context (low, high) were manipulated across two-sentence passages. Context sentences were presented in full, followed by word-by-word presentation (300 ms SOA) of target sentences. ERPs were analysed across left-to-right and anterior-to-posterior regions of interest within intervals from 50 to 550 ms post-stimulus. The onset of significant predictability effects (50–80 ms) preceded that of frequency (P1, 80–120 ms), while both main effects were generally sustained through the N400 (350–550 ms). Critically, the frequency-predictability interaction became significant in the P1 and was sustained through the N400, although the specific configuration of effects differed across components. The pattern of findings supports an early, chronometric locus of contextual predictability in recognising words during reading

Predictive information and error processing : the role of medial-frontal cortex during motor control

We have recently provided evidence that an error-related negativity (ERN), an ERP component generated within medial-frontal cortex, is elicited by errors made during the performance of a continuous tracking task (O.E. Krigolson & C.B. Holroyd, 2006). In the present study we conducted two experiments to investigate the ability of the medial-frontal error system to evaluate predictive error information. In two experiments participants used a joystick to perform a computer-based continuous tracking task in which some tracking errors were inevitable. In both experiments, half of these errors were preceded by a predictive cue. The results of both experiments indicated that an ERN-like waveform was elicited by tracking errors. Furthermore, in both experiments the predicted error waveforms had an earlier peak latency than the unpredicted error waveforms. These results demonstrate that the medial-frontal error system can evaluate predictive error information

Attention, predictive learning, and the inverse base-rate effect: Evidence from event-related potentials

We report the first electrophysiological investigation of the inverse base-rate effect (IBRE), a robust non-rational bias in predictive learning. In the IBRE, participants learn that one pair of symptoms (AB) predicts a frequently occurring disease, whilst an overlapping pair of symptoms (AC) predicts a rarely occurring disease. Participants subsequently infer that BC predicts the rare disease, a non-rational decision made in opposition to the underlying base rates of the two diseases. Error-driven attention theories of learning state that the IBRE occurs because C attracts more attention than B. On the basis of this account we predicted and observed the occurrence of brain potentials associated with visual attention: a posterior Selection Negativity, and a concurrent anterior Selection Positivity, for C vs. B in a post-training test phase. Error-driven attention theories further predict no Selection Negativity, Selection Positivity or IBRE, for control symptoms matched on frequency to B and C, but for which there was no shared symptom (A) during training. These predictions were also confirmed, and this confirmation discounts alternative explanations of the IBRE based on the relative novelty of B and C. Further, we observed higher response accuracy for B alone than for C alone; this dissociation of response accuracy (B>C) from attentional allocation (C>B) discounts the possibility that the observed attentional difference was caused by the difference in response accuracy

The feedback correct-related positivity : sensitivity of the event-related brain potential to unexpected positive feedback

The N200 and the feedback error-related negativity (fERN) are two components of the event-related brain potential (ERP) that share similar scalp distributions, time courses, morphologies, and functional dependencies, which raises the question as to whether they are actually the same phenomenon. To investigate this issue, we recorded the ERP from participants engaged in two tasks that independently elicited the N200 and fERN. Our results indicate that they are, in fact, the same ERP component and further suggest that positive feedback elicits a positive-going deflection in the time range of the fERN. Taken together, these results indicate that negative feedback elicits a common N200 and that modulation of fERN amplitude results from the superposition on correct trials of a positive-going deflection that we term the feedback correct-related positivity

Error-related scalp potentials elicited by hand and foot movements : evidence for an output-independent error-processing system in humans

The error-related negativity (ERN) is a fronto-centrally distributed component of the event-related brain potential (ERP) that occurs when human subjects make errors in a variety of experimental tasks. In the present study, we recorded ERPs from 128 scalp electrodes while subjects performed a choice reaction time task using either their hands or feet. We applied the brain electric source analysis technique to compare ERNs elicited by hand and foot errors. The scalp distributions of these error potentials suggest that they share the same neural generator and, therefore, that the ERN process is output-independent. Together with other findings, the results are consistent with the hypothesis that the ERN is generated within the anterior cingulate cortex and is elicited by the activation of a generic error-processing system. (C) 1998 Elsevier Science Ireland Ltd