Dissociable components of cognitive control: an event-related potential (ERP) study of response inhibition and interference suppression

Background

Cognitive control refers to the ability to selectively attend and respond to task-relevant events while resisting interference from distracting stimuli or prepotent automatic responses. The current study aimed to determine whether interference suppression and response inhibition are separable component processes of cognitive control.

Methodology/Principal Findings

Fourteen young adults completed a hybrid Go/Nogo flanker task and continuous EEG data were recorded concurrently. The incongruous flanker condition (that required interference suppression) elicited a more centrally distributed topography with a later N2 peak than the Nogo condition (that required response inhibition).

Conclusions/Significance

These results provide evidence for the dissociability of interference suppression and response inhibition, indicating that taxonomy of inhibition is warranted with the integration of research evidence from neuroscience.     

Dissociation of category versus item priming in face processing: an event-related potential study

The underlying specificity of visual object categorization and discrimination can be elucidated by studying different types of repetition priming. Here we focused on this issue in face processing. We investigated category priming (i.e. the prime and target stimuli represent different exemplars of the same object category) and item priming (i.e. the prime and target stimuli are exactly the same image), using an immediate repetition paradigm. Twenty-three subjects were asked to respond as fast and accurately as possible to categorize whether the target stimulus was a face or a building image, but to ignore the prime stimulus. We recorded event-related potentials (ERPs) and reaction times (RTs) simultaneously. The RT data showed significant effects of category priming in both face trials and building trials, as well as a significant effect of item priming in face trials. With respect to the ERPs, in face trials, no priming effect was observed at the P100 stage, whereas a category priming effect emerged at the N170 stage, and an item priming effect at the P200 stage. In contrast, in building trials, priming effects occurred already at the P100 stage. Our results indicated that distinct neural mechanisms underlie separable kinds of immediate repetition priming in face processing.     

Aging,caffeine, and information processing: an event-related potential analysis

Structural and energetic processes in information processing were studied in young and elderly subjects. A visually focussed selective search task was used, in which subjects had to select relevant information, followed by controlled memory search processes to locate a target item. Caffeine was used to manipulate the energetic state of the subjects. During task performance event-related potentials (ERPs) and reaction time (RT) were recorded.Subjects were 15 young and 15 elderly healthy, non-smoking, moderate caffeine consumers (250–600 mg/day). Before the experimental sessions they abstained from caffeine for ≥12 h. In the experiment subjects received 250 mg caffeine or placebo dissolved in decaffeinated coffee.RT data seem to indicate that aging effects are at least partly due to a shift in the speed-accuracy trade-off. ERP results provide evidence for decreased levels of energy resources in the elderly. The identification of relevant information and stimulus evaluation processes were delayed in the elderly, suggesting an additional effect of aging on structural processes. Caffeine improved performance and increased the amplitude of the N1, N2b, and P3b, in both young and old subjects. These results suggest that caffeine makes more energy resources available for task performance. The effects of aging on P3b latency were counteracted by caffeine. Other caffeine effects did not differ significantly between young and elderly subjects.     

Visual cognitive dysfunction in depression: an event-related potential study

The P3(00) event-related potentials (ERPs) elicited by visual stimuli in two visual tasks were assessed in depressed patients (12 patients with major depression and 11 patients with bipolar disorder) and compared with those of 20 age-matched normal controls. At remission, the ERPs from 18 of the depressed patients were again recorded. The visual oddball (VO) paradigm presented both target and standard visual stimuli and the simple visual (SV) paradigm presented a target but no standard visual stimulus. Subjects performed the VO task significantly less accurately than the SV task, as reflected by the behavioral measures (reaction-time and task accuracy). Depressed patients of the bipolar group showed longer P3 peak latency for the VO task and no change in P3 amplitude. No significant differences were found in any other ERP component between the groups. During remission, slowing RTs and reduced P3 peak latencies were observed for both major depression and bipolar disorder groups. Thus, the P3 ERP may be an index of the contribution of the slowed central processing to psychomotor retardation in clinically homogenous samples of depressive patients performing an appropriately demanding task.     

Auditory selective attention in middle-aged and elderly subjects: an event-related brain potential study

Reaction times (RTs) and event-related brain potentials (ERPs) were recorded in middle-aged (MA) and elderly (ELD) subjects performing an auditory selective attention task. Subjets attended to tone bursts of a specified pitch and ear of delivery and responded to occasional longer duration target tones (75 vs. 25 msec). Infrequent novel stimuli (computer synthesized sounds and digitized environmental noises) were also included in the stimulus sequence.No significant age-related differences were found in the speed or accuracy of target detection. However, in both groups, RTs were delayed (by more than 300 msec) to targets that followed novel sounds. The prolongation was greater following novel sounds in the attended ear, particularly in the ELD group.The effects of selective attention on ERPs to standard tones were isolated as negative difference waves (Nds) by subtracting ERPs to non-attended stimuli from ERPs to the same signals when attended. Nds had similar amplitudes, latencies of onset (60 msec), and distributions in ELD and MA groups. In both groups, Nd waves were more prominent following right ear stimulation, reflecting possible hemispheric asymmetries of generators in posterior temporal regions.The mismatch negativity (MMN) was isolated by subtracting ERPs to standard tones from ERPs to deviant stimuli. MMN amplitudes were reduced in the ELD group. There was also a significant change in MMN distribution with age: the MMN was larger over the right hemisphere for MA subjects but larger over the left for ELD subjects. Elderly subjects showed a trend toward smaller P3 amplitudes and delayed P3 latencies, but group differences did not reach statistical significance. ERPs to novel sounds were characterized by centrally distributed N2 and P3a components. Although the novel P3a was enhanced with attention, no novel Nd waves could be isolated. This suggests that novel sounds fell outside the focus of attention.     

Inter-individual relationships in empathic traits and feedback-related fronto-central brain activity: an event-related potential study

Background

Neuroimaging studies continue to indicate the major role the anterior cingulate cortex (ACC) plays in processing empathic responses. Error-related negativity (ERN), an event-related potential (ERP) thought to arise from the ACC, has been found to correlate with scores for individual empathic personality. This study investigated the relationship between empathic personality traits and the amplitude of feedback-related negativity (FRN), an ERP sourced from the ACC and similar to the ERN, using a task involving feedback of monetary gains or losses.

Methods

Sixteen healthy participants answered an empathy trait questionnaire and performed a gambling task to elicit FRN. Because FRN amplitude is thought to be associated with attention, motivation, emotional state, and anxiety trait, we performed a partial correlation analysis between the empathic trait score and FRN amplitude while controlling for variables.

Results

In partial correlation analysis, FRN amplitude was significantly inversely correlated with scores for personal distress and marginally correlated with scores for empathic concern and with total average score.

Discussion

The study revealed for the first time an association between FRN and emotional empathic traits, after controlling for variables that can affect FRN amplitude. However, we also found a reversed directional correlation contrary to our expectations. This fronto-central brain activity may be associated with empathic properties via dopaminergic neuronal function. Future study using these electric potentials as experimental tools is expected to help elucidate the neurological mechanism of empathy.

     

Auditory development between 7 and 11 years: an event-related potential (ERP) study

Background

There is considerable uncertainty about the time-course of central auditory maturation. On some indices, children appear to have adult-like competence by school age, whereas for other measures development follows a protracted course.

Methodology

We studied auditory development using auditory event-related potentials (ERPs) elicited by tones in 105 children on two occasions two years apart. Just over half of the children were 7 years initially and 9 years at follow-up, whereas the remainder were 9 years initially and 11 years at follow-up. We used conventional analysis of peaks in the auditory ERP, independent component analysis, and time-frequency analysis.

Principal Findings

We demonstrated maturational changes in the auditory ERP between 7 and 11 years, both using conventional peak measurements, and time-frequency analysis. The developmental trajectory was different for temporal vs. fronto-central electrode sites. Temporal electrode sites showed strong lateralisation of responses and no increase of low-frequency phase-resetting with age, whereas responses recorded from fronto-central electrode sites were not lateralised and showed progressive change with age. Fronto-central vs. temporal electrode sites also mapped onto independent components with differently oriented dipole sources in auditory cortex. A global measure of waveform shape proved to be the most effective method for distinguishing age bands.

Conclusions/Significance

The results supported the idea that different cortical regions mature at different rates. The ICC measure is proposed as the best measure of ‘auditory ERP age’.     

Effects of attention and emotion on face processing in the human brain: an event-related fMRI study.

We used event-related fMRI to assess whether brain responses to fearful versus neutral faces are modulated by spatial attention. Subjects performed a demanding matching task for pairs of stimuli at prespecified locations, in the presence of task-irrelevant stimuli at other locations. Faces or houses unpredictably appeared at the relevant or irrelevant locations, while the faces had either fearful or neutral expressions. Activation of fusiform gyri by faces was strongly affected by attentional condition, but the left amygdala response to fearful faces was not. Right fusiform activity was greater for fearful than neutral faces, independently of the attention effect on this region. These results reveal differential influences on face processing from attention and emotion, with the amygdala response to threat-related expressions unaffected by a manipulation of attention that strongly modulates the fusiform response to faces.     

Cortical processing of human gut sensation: an evoked potential study

The rectum has a unique physiological role as a sensory organ and differs in its afferent innervation from other gut organs that do not normally mediate conscious sensation. We compared the central processing of human esophageal, duodenal, and rectal sensation using cortical evoked potentials (CEP) in 10 healthy volunteers (age range 21-34 yr). Esophageal and duodenal CEP had similar morphology in all subjects, whereas rectal CEP had two different but reproducible morphologies. The rectal CEP latency to the first component P1 (69 ms) was shorter than both duodenal (123 ms; P = 0.008) and esophageal CEP latencies (106 ms; P = 0.004). The duodenal CEP amplitude of the P1-N1 component (5.0 microV) was smaller than that of the corresponding esophageal component (5.7 microV; P = 0.04) but similar to that of the corresponding rectal component (6.5 microV; P = 0.25). This suggests that rectal sensation is either mediated by faster-conducting afferent pathways or that there is a difference in the orientation or volume of cortical neurons representing the different gut organs. In conclusion, the physiological and anatomic differences between gut organs are reflected in differences in the characteristics of their afferent pathways and cortical processing.     

Sonic hedgehog, BOC, and synaptic development: new players for an old game

In this issue of Neuron, Harwell et?al. (2012) identify a new role for the secreted molecule Shh and its receptor Boc in synapse formation. These results add an unexpected new player to the expanding list of extracellular cues regulating the spatial specificity of synapse formation.     

Effect of empathy trait on attention to faces: an event-related potential (ERP) study

Background

Empathy is deeply linked with the ability to adapt to human social environments. The present study investigated the relationship between the empathy trait and attention elicited by discriminating facial expressions.

Methods

Event-related potentials were measured while 32 participants (17 men and 15 women) discriminated facial expressions (happy or angry) and colors of flowers (yellow or purple) under an oddball paradigm. The empathy trait of participants was measured using the Interpersonal Reactivity Index (Davis, 1980).

Results

The empathy trait correlated positively with both the early portion (300 to 600 ms after stimulus onset) and late portion (600 to 800 ms after stimulus onset) of late positive potential (LPP) amplitude elicited by faces, but not with LPP elicited by flowers.

Conclusions

This result suggests that, compared to people with low empathy, people with high empathy pay more attention when discriminating facial expressions. The present study suggests that differences exist in methods of adapting to social environments between people with high and low empathy.     

TCR zeta-chain downregulation: curtailing an excessive inflammatory immune response

The T-cell receptor (TCR) functions in both antigen recognition and signal transduction, which are crucial initial steps of antigen-specific immune responses. TCR integrity is vital for the induction of optimal and efficient immune responses, including the routine elimination of invading pathogens and the elimination of modified cells and molecules. Of the TCR subunits, the zeta-chain has a key role in receptor assembly, expression and signalling. Downregulation of TCR zeta-chain expression and impairment of T-cell function have been shown for T cells isolated from hosts with various chronic pathologies, including cancer, and autoimmune and infectious diseases. This review summarizes studies of the various pathologies that show this phenomenon and provides new insights into the mechanism responsible for downregulation of zeta-chain expression, its relevance and its clinical implications.     

Neuroelectric evidence for cognitive association formation: an event-related potential investigation

Although many types of learning require associations to be formed, little is known about the brain mechanisms engaged in association formation. In the present study, we measured event-related potentials (ERPs) while participants studied pairs of semantically related words, with each word of a pair presented sequentially. To narrow in on the associative component of the signal, the ERP difference between the first and second words of a pair (Word2-Word1) was derived separately for subsequently recalled and subsequently not-recalled pairs. When the resulting difference waveforms were contrasted, a parietal positivity was observed for subsequently recalled pairs around 460 ms after the word presentation onset, followed by a positive slow wave that lasted until around 845 ms. Together these results suggest that associations formed between semantically related words are correlated with a specific neural signature that is reflected in scalp recordings over the parietal region.     

Effects of cue information on response production and inhibition measured by event-related potentials

The aim of this study was to investigate how information carried by a cue stimulus modulate event-related potentials (ERPs) to a subsequent target stimulus which either calls for an overt response (Go stimulus) or no response (Nogo stimulus). One of the cues predicted the likely appearance of the Go stimulus (Go cue) whereas the other cue predicted the likely appearance of the Nogo stimulus (Nogo cue). Our results showed that unpredicted Nogo stimuli elicited enlarged N200 component. This finding supports the notion that Nogo N200 reflects response inhibition processes, i.e., the amplitude of the N200 is a function of the difficulty of response inhibition. In other words, increased N200 to Nogo stimuli following Go cues might be related to increased efforts in activating the response inhibition system thereby interrupting preparations to respond.     

Deoxyribozymes: new players in the ancient game of biocatalysis.

The repetitive and extraordinarily stable polynucleotide chains of DNA serve as an ideal storage system for genetic information. Although it is best known for its helical structure and relatively inert character, in vitro selection can be used to compel DNA to perform a surprising variety of chemical reactions. These artificial DNA enzymes or 'deoxyribozymes' generate large chemical rate enhancements and demonstrate precise substrate recognition, much like their protein and RNA counterparts. Recent studies with these prototypic deoxyribozymes indicate that DNA has a substantial untapped potential for intricate structure formation that could be exploited in novel chemical and biological catalysis.     

Three-dimensional tomography of event-related potentials during response inhibition: evidence for phasic frontal lobe activation

Objectives: Spatial analysis of the evoked brain electrical fields during a cued revealed an extremely robust anteriorization of the positivity of a P300 microstate in the NoGo compared to the Go condition (NoGo-anteriorization in a prevailing study). To allow a neuroanatomical interpretation the NoGo-anteriorization was investigated with a new three-dimensional source tomography method (LORETA) was applied.Methods: The test contains subsets of stimuli requiring the execution (Go) or the inhibition (NoGo) of a cued motor response which can be considered as mutual control conditions for the study of inhibitory brain functions. 21-channel ERPs were obtained from 10 healthy subjects during a cued CPT, And analyzed with LORETA.Results: Topographic analyses revealed significantly different scalp distributions between the Go and the NoGo conditions in both P100 and P300 microstates, indicating that already at an early stage different neural assemblies are activated. LORETA disclosed a significant hyperactivity located in the right frontal lobe during the NoGo condition in the P300 microstate.Conclusions: The results indicate that right frontal sources are responsible for the NoGo-anteriorization of the scalp P300 which is consistent with animal and human lesion studies of inhibitory brain functions. Furthermore, it demonstrates that frontal activation is confined to a brief microstate and time-locked to phasic inhibitory motor control. This adds important functional and chronometric specificity to findings of frontal activation obtained with PET and Near-Infrared-Spectroscopy studies during the cued CPT, and suggests that these metabolic results are not due to general task demands.     

Vasopressin and cognitive processes: Two event-related potential studies

Two experiments studied the influence of arginine-vasopressin (AVP) on cognitive processes by means of an electrophysiological measure, the late positive complex (LPC) of the event-related potential. The LPC varies systematically with cognitive processes. The classical oddball paradigm and an incidental memory task (structural encoding of emotional adjectives) were used. The two studies differed only in the dose of AVP (study 1: three time nasal application of 10 IU AVP; study 2: 20 IU). In study 1, AVP intake enhanced memory performance. The LPC elicited by oddball stimuli was not influenced by AVP, neither when compared before and after intake nor when compared to placebo treatment. However, specific influences of AVP on the LPC elicited during the structural encoding task were observed. In both studies, AVP intake resulted in a marked change of the scalp distribution of the P3 component, which is a prominent part of the LPC. Furthermore, subjects treated with the lower dose of AVP showed a more positive P3 component on emotional (negative and positive) adjectives, when compared to neutral ones. The results suggest that vasopressin influences the central nervous processing of the emotional content of stimuli.     

Emotional expectations influence neural sensitivity to fearful faces in humans: An event-related potential study

The present study tested whether neural sensitivity to salient emotional facial expressions was influenced by emotional expectations induced by a cue that validly predicted the expression of a subsequently presented target face. Event-related potentials (ERPs) elicited by fearful and neutral faces were recorded while participants performed a gender discrimination task under cued (‘expected’) and uncued (‘unexpected’) conditions. The behavioral results revealed that accuracy was lower for fearful compared with neutral faces in the unexpected condition, while accuracy was similar for fearful and neutral faces in the expected condition. ERP data revealed increased amplitudes in the P2 component and 200–250 ms interval for unexpected fearful versus neutral faces. By contrast, ERP responses were similar for fearful and neutral faces in the expected condition. These findings indicate that human neural sensitivity to fearful faces is modulated by emotional expectations. Although the neural system is sensitive to unpredictable emotionally salient stimuli, sensitivity to salient stimuli is reduced when these stimuli are predictable.     

Myc,Cdk2 and cellular senescence: Old players,new game

The aberrant activation of oncogenic pathways promotes tumor progression, but concomitantly elicits compensatory tumor-suppressive responses, such as apoptosis or senescence. For example, Ras induces senescence, while Myc generally triggers apoptosis. Myc is in fact viewed as an anti-senescence oncogene, as it is a potent inducer of cell proliferation and immortalization, bypasses growth-inhibitory signals, and cooperates with Ras in cellular transformation. Recent reports prompt re-evaluation of Myc-induced senescence, and of its role in tumor progression and therapy. We have shown that the cyclin-dependent kinase Cdk2, although redundant for cell cycle progression, has a unique role in suppressing a Myc-induced senescence program: Myc activation elicited expression of p16^INK4a and p21^Cip1, and caused senescence in cell lacking Cdk2, but not in Cdk2-proficient cells. Additional cellular activities have been identified that suppress Myc-induced senescence, including the Wrn helicase, Telomerase and Miz1. These senescence-suppressing activities were critical for tumor progression, as deficiency in Cdk2, telomerase or Miz1 reduced the onset of Myc-induced lymphoma in transgenic mice. Other gene products like p53, SUV39H1 or TGFß promoted senescence, which together with apoptosis contributed to tumor suppression. Paradoxically, Myc directly counteracted the very same senescence program that it potentially elicits, since it positively regulated Wrn, Telomerase and Cdk2 activity, and Cdk2 inhibition re-activated the latent senescence program in Myc expressing cells. Hence, while these molecules are instrumental to the oncogenic action of Myc, they may simultaneously constitute its Achille's heel for therapeutic development.