Retrospective revaluation effects following serial compound training and target extinction

Using a conditioned suppression task, two experiments examined retrospective revaluation effects after serial compound training in a release from overshadowing design. In Experiment 1, serial X → A+ training produced suppression to target A, which was enhanced when preceded by feature X, whereas X by itself elicited no suppression. Subsequent A− presentations extinguished responding to A, but had no effect on either responding to X → A or X alone. However, the addition of A− trials did enhance the ability of feature X to elicit suppression to a novel target, B, suggesting retrospective revaluation of X’s properties. Experiment 2 showed that the enhanced transfer effect, observed in Experiment 1, was independent of the training history of the target (B− or Y → B+/B−). Together, these results suggest that feature X did not retrospectively acquire excitatory strength or occasion setting power, but rather a generalized ability to increase responding to any other cue.     

Simultaneous and sequential Feature Negative discriminations: Elemental learning and occasion setting in human Pavlovian conditioning

Using a conditioned suppression task, we investigated simultaneous (XA−/A+) vs. sequential (X → A−/A+) Feature Negative (FN) discrimination learning in humans. We expected the simultaneous discrimination to result in X (or alternatively the XA configuration) becoming an inhibitor acting directly on the US, and the sequential discrimination in X becoming a negative occasion setter acting indirectly on the A-US link. After simultaneous FN training, X+ training completely abolished discriminative XA/A responding (Experiment 1), and X transferred inhibition to new targets B regardless of their training history (B+ or YB−/B+) (Experiment 2), suggesting X became a simple inhibitor. After sequential FN training, X showed the predicted selective transfer to a target B that also had been modulated (Y → B−/B+), not to a simple excitor (B+) (Experiment 4), but turning X into an excitor (X+) likewise disrupted discriminative X → A/A responding (Experiment 3). This suggests that X acquired a combination of modulatory and direct inhibitory properties, and that the joint contribution of both components is necessary for the suppression of the target-induced US activation.     

ERP correlates of language-specific processing of auditory pitch feedback during self-vocalization

The present study investigated whether the neural correlates for auditory feedback control of vocal pitch can be shaped by tone language experience. Event-related potentials (P2/N1) were recorded from adult native speakers of Mandarin and Cantonese who heard their voice auditory feedback shifted in pitch by −50, −100, −200, or −500 cents when they sustained the vowel sound /u/. Cantonese speakers produced larger P2 amplitudes to −200 or −500 cents stimuli than Mandarin speakers, but this language effect failed to reach significance in the case of −50 or −100 cents. Moreover, Mandarin speakers produced shorter N1 latencies over the left hemisphere than the right hemisphere, whereas Cantonese speakers did not. These findings demonstrate that neural processing of auditory pitch feedback in vocal motor control is subject to language-dependent neural plasticity, suggesting that cortical mechanisms of auditory-vocal integration can be shaped by tone language experience.     

Electrophysiological difference between the representations of causal judgment and associative judgment in semantic memory

Causally related concepts like “virus” and “epidemic” and general associatively related concepts like “ring” and “emerald” are represented and accessed separately. The Evoked Response Potential (ERP) procedure was used to examine the representations of causal judgment and associative judgment in semantic memory. Participants were required to remember a task cue (causal or associative) presented at the beginning of each trial, and assess whether the relationship between subsequently presented words matched the initial task cue. The ERP data showed that an N400 effect (250–450 ms) was more negative for unrelated words than for all related words. Furthermore, the N400 effect elicited by causal relations was more positive than for associative relations in causal cue condition, whereas no significant difference was found in the associative cue condition. The centrally distributed late ERP component (650–750 ms) elicited by the causal cue condition was more positive than for the associative cue condition. These results suggested that the processing of causal judgment and associative judgment in semantic memory recruited different degrees of attentional and executive resources.     

Psychopathy and Event-Related Brain Potentials (ERPs) associated with attention to speech stimuli

Event-related brain potentials (ERPs) were used to determine whether low left-hemisphere arousal or unusual cortical responses to speech stimuli might be associated with anomalies in language function that reportedly occur when psychopaths perform lateralized information-processing tasks. ERPs to phonemic stimuli were recorded while 11 psychopathic (P) and 13 nonpsychopathic (NP) male prison inmates performed a Single-Task and a Dual-Task. In the Single-Task, a speech discrimination ‘oddball’ paradigm, the subject was required to respond whenever a target stimulus (the less frequent of two phonemes) occured. In the Dual-Task, he had to respond to target stimuli while simultaneously performing a perceptual-motor (distractor) task. There were no group differences in ERP measures of central arousal (N100) during performance of the Single- and Dual-Tasks. For both groups, the P300 component of the ERP to the target stimulus was smaller and had longer latency during the Dual-Task than during the Single-Task, indicating that in the Dual-Task phonemic discrimination and the perceptual-motor task completed for similar perceptual resources. Overlapping Group P's P300 responses to the target stimulus during the Dual-Task was a vertex and asymmetric (left-hemisphere) positive slow wave (SW), suggesting unusual speech processing in psychopaths under conditions of distraction, perhaps related to reduced sensitivity to the sequential probabilities associated with events presented in an auditory channel. The results were consistent with the hypothesis that psychopaths have limited left-hemisphere resources for processing linguistic stimuli.     

Neurophysiological marker of inhibition distinguishes language groups on a non-linguistic executive function test

Successful interaction with the environment depends on flexible behaviors which require shifting attention, inhibiting primed responses, ignoring distracting information, and withholding motor responses. These abilities, termed executive function (EF), are believed to be mediated by inhibitory processes in the frontal lobes. Superior performance on EF tests (i.e., faster reaction times (RT), and fewer errors) has been shown in bilinguals compared to monolingual speakers. However, findings are inconsistent, and no study has directly linked this bilingual advantage to frontal lobe inhibitory processes. To clarify this uncertainty, we concomitantly tested neural inhibitory processes and behavioral responses on an EF test in bilinguals and monolinguals. Specifically, we compared English monolinguals (N = 15) to Spanish/English bilinguals (N = 13) on event-related brain potentials (ERP) during a non-linguistic, auditory Go/NoGo task, a task linked to non-motor, cognitive inhibition in monolinguals. Participants responded with a button press on trials in which target tone-pairs (Go trials) were presented and withheld their responses on non-target trials (NoGo trials). Results revealed significantly greater inhibition (i.e., greater mean N2 amplitude) in bilinguals compared to monolinguals during NoGo trials even though both groups performed the task equally well (i.e., withheld a motor response). On Go trials where participants pressed a response button, neither ERPs nor RT distinguished the groups. Additionally, scores on a second language proficiency test (i.e., English in our bilingual group) were positively correlated with N2 amplitude. These findings are the first to directly link this bilingual advantage to a neural correlate of inhibition and to reveal that inhibition in bilinguals is moderated by second language proficiency. Results are discussed in the context of plasticity, and we propose that evaluating bilinguals at varying levels of second-language proficiency may serve as a model of human neuroplasticity.     

Cue type affects preparatory influences on task inhibition

The present study investigates the influence of preparation on inhibitory effects in cued task switching. In three experiments, we assessed n − 2 repetition costs as marker of inhibition of the just executed and now irrelevant task by comparing performance in task sequences such as ABA (i.e., n − 2 repetitions, with A, B and C standing for different tasks) to task sequences such as CBA (i.e., n − 2 switches). Specifically, we varied the cue–target interval (CTI) to examine cue-based preparation effects. In addition, we manipulated cue type (i.e., abstract, verbal, and direct cues) across the three experiments. We obtained significant reductions of n − 2 repetition costs with prolonged CTI when using abstract cues (i.e., coloured frames) and task names (i.e., digit), but not when using the task-specific stimulus–response mapping as cue for the upcoming task. These data suggest that cue-based preparation is not a uniform process but depends on the information provided by the cue.     

Distributed attentional deficits in chronic methamphetamine abusers: evidence from the Attentional Network Task (ANT)

Objective

The goal of the present study was to examine distributed attentional functions in long-term but currently abstinent methamphetamine (MA) abusers using a task that measures attentional alertness, orienting, and conflict resolution.

Methods

Thirty currently abstinent MA abusers (1 month-5 years) and 22 healthy non-substance using adults were administered a multimodal version of the Attentional Network Task (ANT-I). In this task subjects identified the direction of a centrally presented arrow using a key press. Analyses examined the interaction between alerting tones, location cueing and congruency between the target arrows and flanking distractor stimuli.

Results

All participants were faster when an auditory tone preceded the trial onset (p < 0.001), on trials in which a valid cue preceded the location of the target arrow (p < 0.001), and on congruent trials (i.e., when all display arrows faced in the same direction) (p < 0.001). Of primary interest was the finding that MA abusers were more influenced by the conflict between the peripheral arrows and the central target arrow (p = 0.009). There were also correlations between length of drug sobriety and executive function as well as between drug-induced psychiatric symptoms and alertness.

Conclusions

These results suggest that chronic MA abusers display cognitive deficits that may reflect a specific vulnerability to distraction on a task of executive function. These findings are consistent with other studies that have reported deficits in anterior attentional systems and top-down cognitive control.     

The effect of gender on the N1-P2 auditory complex while listening and speaking with altered auditory feedback

The effect of gender on the N1-P2 auditory complex was examined while listening and speaking with altered auditory feedback. Fifteen normal hearing adult males and 15 females participated. N1-P2 components were evoked while listening to self-produced nonaltered and frequency shifted /a/ tokens and during production of /a/ tokens during nonaltered auditory feedback (NAF), frequency altered feedback (FAF), and delayed auditory feedback (DAF; 50 and 200 ms). During speech production, females exhibited earlier N1 latencies during 50 ms DAF and earlier P2 latencies during 50 ms DAF and FAF. There were no significant differences in N1-P2 amplitudes across all conditions. Comparing listening to active speaking, N1 and P2 latencies were earlier among females, with speaking, and under NAF. N1-P2 amplitudes were significantly reduced during speech production. These findings are consistent with the notions that speech production suppresses auditory cortex responsiveness and males and females process altered auditory feedback differently while speaking.     

Effective connectivity hierarchically links temporoparietal and frontal areas of the auditory dorsal stream with the motor cortex lip area during speech perception

A left-hemispheric cortico-cortical network involving areas of the temporoparietal junction (Tpj) and the posterior inferior frontal gyrus (pIFG) is thought to support sensorimotor integration of speech perception into articulatory motor activation, but how this network links with the lip area of the primary motor cortex (M1) during speech perception is unclear. Using paired-coil focal transcranial magnetic stimulation (TMS) in healthy subjects, we demonstrate that Tpj → M1 and pIFG → M1 effective connectivity increased when listening to speech compared to white noise. A virtual lesion induced by continuous theta-burst TMS (cTBS) of the pIFG abolished the task-dependent increase in pIFG → M1 but not Tpj → M1 effective connectivity during speech perception, whereas cTBS of Tpj abolished the task-dependent increase of both effective connectivities. We conclude that speech perception enhances effective connectivity between areas of the auditory dorsal stream and M1. Tpj is situated at a hierarchically high level, integrating speech perception into motor activation through the pIFG.     

视觉空间指令条件下SOAs变化对数字-空间联结编码的影响:来自ERP的证据

采用数字奇偶判断任务,以数字1-9(5除外)及汉字标签(左、右)作为实验材料,在视觉空间任务指令下探讨系统改变SOAs对数字-空间联结编码方式的影响。行为结果发现,SNARC效应以视觉空间编码方式为主,SOA为0ms并未出现SNARC效应; ERP结果发现,物理一致性在早期成分N1上的主效应显著。表明任务指导语影响SNARC效应的编码方式,其本质受词语信息标签加工程度的影响,且对SNARC效应的编码出现早期感觉阶段,SOAs与目标数字的特性影响SNARC效应的产生。     

Associative learning of discrimination with masked stimuli

Great controversy exists on whether associative learning occurs without awareness. In Experiment 1, 31 participants received discrimination training by repeated presentations of two stimulus sequences (S1_A → S2_A, and S1_B → S2_B), S1 being a masked stimulus. S2 were imperative stimuli for a reaction time (RT) task. After the acquisition phase, all participants were tested with 20 presentations of congruent (S1_A → S2_A and S1_B → S2_B) and incongruent (S1_A → S2_B and S1_B → S2_A) stimulus sequences. The RT in the testing phase was faster in congruent than in incongruent stimulus sequences. These results are considered strong evidence of associative learning without awareness of the contingency between the stimuli. A second experiment was designed with SOA varied between three groups (23, 58, and 117 ms). The results showed that the participants responded more quickly to congruent stimulus sequences and that the SOA did not affect RT. The SOA did not modify the effect of congruence either, although the interaction was near significance.     

Speed of lower-level auditory and visual processing as a basic factor in dyslexia: electrophysiological evidence

This study investigated speed of processing (SOP) among college-level adult dyslexic and normal readers in nonlinguistic and sublexical linguistic auditory and visual oddball tasks, and a nonlinguistic cross-modal choice reaction task. Behavioral and electrophysiological (ERP) measures were obtained. The results revealed that between both groups, reaction times (RT) were longer and the latencies of P2 and P3 components occurred later in the visual as compared to auditory oddball tasks. RT and ERP latencies were longest in the cross-modal task. RT and ERP latencies were delayed among dyslexic as compared to normal readers across tasks. On the oddball tasks, group differences in brain activity were observed only when responding to low-probability targets. These differences were largest for the P3 component, and most pronounced in the case of phonemes. The gap between ERP latencies in the visual versus the auditory modalities for each component was larger among dyslexic as compared to normal readers, and was particularly evident at the linguistic level. A hypothesis is proposed that suggests an amodal, basic SOP deficit among dyslexic readers. The slower cross-modal SOP is attributed to slower information processing in general and to disproportionate "asynchrony" between SOP in the visual versus the auditory system. It is suggested that excessive asynchrony in the SOP of the two systems may be one of the underlying causes of dyslexics' impaired reading skills.     

Associations in human instrumental conditioning

Four experiments were conducted to study the contents of human instrumental conditioning. Experiment 1 found positive transfer between a discriminative stimulus (S^D) and an instrumental response (R) that shared the outcome (O) with the response that was originally trained with the S^D, showing the formation of an S^D → O association. Experiment 2 found that post-acquisition devaluation of an outcome selectively reduced the response trained with that outcome, showing the formation of a R → O association. In Experiment 3, changing the outcome did not prevent participants from giving the response learned with each S^D, even though none of the responses was appropriate for the new outcome, showing evidence of the formation of S^D → R associations in instrumental learning. The three binary associations were shown within the same basic experimental situation. Finally, Experiment 4 found evidence of the formation of the higher order association S^D(R → O) in human instrumental conditioning.     

The Relation of ERP Components to Complex Memory Processing

The relation between various ERP components generated during encoding of a word and its subsequent recall were investigated using a “rote” serial-order and an “elaborative” category memory task. Words (flashed separately) were time-locked to EEG recordings from 21 cortical sites. ERP components from the five subjects having the highest recall scores were compared to the five lowest scoring subjects. Results based on the P200 peak amplitude data as well as the N400 and late positive component peak amplitude and latency data suggest that anterior and posterior distributional differences are elicited during encoding of words for rote and elaborative memory tasks. Furthermore, strong individual differences in these patterns were found as a function of task. A tentative argument was made that the obtained anterior and posterior differences may index different word feature selection and encoding processes, which are differentially utilized by high and low recallers.     

The N400 effect in children: relationships with comprehension, vocabulary and decoding

Using event-related potentials (ERPs), we investigated the N400 (an ERP component that occurs in response to meaningful stimuli) in children aged 8-10 years old and examined relationships between the N400 and individual differences in listening comprehension, word recognition and non-word decoding. Moreover, we tested the claim that the N400 effect provides a valuable indicator of behavioural vocabulary knowledge. Eighteen children were presented with picture-word pairs that were either ‘congruent’ (the picture depicted the spoken word) or ‘incongruent’ (they were unrelated). Three peaks were observed in the ERP waveform triggered to the onset of the picture-word stimuli: an N100 in fronto-central channels, an N200 in central-parietal channels and an N400 in frontal, central and parietal channels. In contrast to the N100 peak, the N200 and N400 peaks were sensitive to semantic incongruency with greater peak amplitudes for incongruent than congruent conditions. The incongruency effects for each peak correlated positively with listening comprehension but when the peak amplitudes were averaged across congruent/incongruent conditions they correlated positively with non-word decoding. These findings provide neurophysiological support for the position that sensitivity to semantic context (reflected in the N400 effect) is crucial for comprehension whereas phonological decoding skill relates to more general processing differences reflected in the ERP waveform. There were no correlations between ERP and behavioural measures of expressive or receptive vocabulary knowledge for the same items, suggesting that the N400 effect may not be a reliable estimate of vocabulary knowledge in children aged 8-10 years.     

Task-dependent modulation of word processing mechanisms during modified visual search tasks

During visual search for words, the impact of the visual and semantic features of words varies as a function of the search task. This event-related potential (ERP) study focused on the way these features of words are used to detect similarities between the distractor words that are glanced at and the target word, as well as to then reject the distractor words. The participants had to search for a target word that was either given literally or defined by a semantic clue among words presented sequentially. The distractor words included words that resembled the target and words that were semantically related to the target. The P2a component was the first component to be modulated by the visual and/or semantic similarity of distractors to the target word, and these modulations varied according to the task. The same held true for the later N300 and N400 components, which confirms that, depending on the task, distinct processing pathways were sensitized through attentional modulation. Hence, the process that matches what is perceived with the target acts during the first 200?ms after word presentation, and both early detection and late rejection processes of words depend on the search task and on the representation of the target stored in memory.     

When sounds look right and images sound correct: Cross-modal coherence enhances claims of pattern presence

How do people decide whether a stimulus contains a pattern? One possibility is that they rely on a global, non-specific signal of coherence. Interestingly, this signal might reflect a combination of different stimulus sources. Consequently, the coherence of one stimulus might influence decisions about coherence of a second, unrelated stimulus. We explored this possibility in three experiments in which participants judged the presence of a pattern in targets from one sensory modality, while being exposed in the background to incidental coherent and incoherent stimuli in a different modality (visual → auditory, auditory → visual). Across all three experiments, using a variety of judgments, coherence of incidental background cross-modal patterns enhanced claims of pattern presence. These findings advance our understanding of how people judge order in the structured as well as in the unstructured world.     

Assessing crossmodal matching of abstract auditory and visual stimuli in posterior superior temporal sulcus with MEG

Associating crossmodal auditory and visual stimuli is an important component of perception, with the posterior superior temporal sulcus (pSTS) hypothesized to support this. However, recent evidence has argued that the pSTS serves to associate two stimuli irrespective of modality. To examine the contribution of pSTS to crossmodal recognition, participants (N = 13) learned 12 abstract, non-linguistic pairs of stimuli over 3 weeks. These paired associates comprised four types: auditory–visual (AV), auditory–auditory (AA), visual–auditory (VA), and visual–visual (VV). At week four, participants were scanned using magnetoencephalography (MEG) while performing a correct/incorrect judgment on pairs of items. Using an implementation of synthetic aperture magnetometry that computes real statistics across trials (SAMspm), we directly contrasted crossmodal (AV and VA) with unimodal (AA and VV) pairs from stimulus-onset to 2 s in theta (4–8 Hz), alpha (9–15 Hz), beta (16–30 Hz), and gamma (31–50 Hz) frequencies. We found pSTS showed greater desynchronization in the beta frequency for crossmodal compared with unimodal trials, suggesting greater activity during the crossmodal pairs, which was not influenced by congruency of the paired stimuli. Using a sliding window SAM analysis, we found the timing of this difference began in a window from 250 to 750 ms after stimulus-onset. Further, when we directly contrasted all sub-types of paired associates from stimulus-onset to 2 s, we found that pSTS seemed to respond to dynamic, auditory stimuli, rather than crossmodal stimuli per se. These findings support an early role for pSTS in the processing of dynamic, auditory stimuli, and do not support claims that pSTS is responsible for associating two stimuli irrespective of their modality.     

Effects of visual attentional load on low-level auditory scene analysis

The sharing of processing resources between the senses was investigated by examining the effects of visual task load on auditory event-related brain potentials (ERPs). In Experiment 1, participants completed both a zero-back and a one-back visual task while a tone pattern or a harmonic series was presented. N1 and P2 waves were modulated by visual task difficulty, but neither mismatch negativity (MMN) elicited by deviant stimuli from the tone pattern nor object-related negativity (ORN) elicited by mistuning from the harmonic series was affected. In Experiment 2, participants responded to identity (what) or location (where) in vision, while ignoring sounds alternating in either pitch (what) or location (where). Auditory ERP modulations were consistent with task difficulty, rather than with task specificity. In Experiment 3, we investigated auditory ERP generation under conditions of no visual task. The results are discussed with respect to a distinction between process-general (N1 and P2) and processspecific (MMN and ORN) auditory ERPs.