Geert J. M. van Boxtel

The N2 in go/no-go tasks reflects conflict monitoring not response inhibition

The functional significance of the N2 in go/no-go tasks was investigated by comparing electrophysiological data obtained from two tasks: a go/no-go task involving both response inhibition as well as response conflict monitoring, and a go/GO task associated with conflict monitoring only. No response was required to no-go stimuli, and a response with maximal force to GO stimuli. The relative frequency of the go stimuli (80% vs. 50%) was varied. The N2 peaked on both no-go and GO trials, with larger amplitudes for both signals when presented in a context of frequent (80%) go signals. These results support the idea that the N2 reflects conflict monitoring not response inhibition.

Stimulation of the Subthalamic Region Facilitates the Selection and Inhibition of Motor Responses in Parkinson's Disease

The aim of the present study was to specify the involvement of the basal ganglia in motor response selection and response inhibition. Two samples were studied. The first sample consisted of patients diagnosed with Parkinsons disease (PD) who received deep-brain stimulation (DBS) of the subthalamic nucleus (STN). The second sample consisted of patients who received DBS for the treatment of PD or essential tremor (ET) in the ventral intermediate nucleus of the thalamus (Vim). Stop-signal task and go/no-go task performances were studied in both groups. Both groups performed these tasks with (on stimulation) and without (off stimulation) DBS to address the question of whether stimulation is effective in improving choice reaction time (RT) and stop-signal RT. The results show that DBS of the STN was associated with significantly enhanced inhibitory control, as indicated by shorter stop-signal RTs. An additional finding is that DBS of the STN led to significantly shorter choice RT. The effects of DBS on responding and response inhibition were functionally independent. Although DBS of the Vim did not systematically affect task performance in patients with ET, a subgroup of Vim-stimulated PD patients showed enhanced stop-signal RTs in on stimulation versus off stimulation. This result suggests that the change in performance to stop signals may not be directly related to STN function, but rather results from a change in PD function due to DBS in general. The findings are discussed in terms of current functional and neurobiological models that relate basal ganglia function to the selection and inhibition of motor responses.

Cortical Measures of Anticipation

Abstract Anticipation increases the efficiency of cognitive processes by partial advance activation of the neural substrate involved in those processes. In the case of perceptual anticipation, a slow cortical potential named Stimulus-Preceding Negativity (SPN) has been identified. The SPN has been observed preceding four types of stimuli: (1) stimuli providing knowledge-of-results (KR) about past performance, (2) stimuli conveying an instruction about a future task, (3) probe stimuli against which the outcome of a previous task has to be matched, and (4) affective stimuli. The morphology and scalp distribution of the SPN is different in each of these cases, suggesting the presence of separable components. This article reviews more than 15 years of SPN research. Possible neurophysiological generators are considered, as well as models that may describe the generation of the SPN. Suggestions for future research into anticipatory processes and the associated psychophysiological measures are made.

Intact navigation skills after bilateral loss of striate cortex

A patient with bilateral damage to primary visual (striated) cortex has provided the opportunity to assess just what visual capacities are possible in the absence of geniculo-striate pathways. Patient TN suffered two strokes in succession, lesioning each visual cortex in turn and causing clinical blindness over his whole visual field. Functional and anatomical brain imaging assessments showed that TN completely lacks any functional visual cortex. We report here that, among other retained abilities, he can successfully navigate down the extent of a long corridor in which various barriers were placed. A video recording shows him skillfully avoiding and turning around the blockages. This demonstrates that extra-striate pathways in humans can sustain sophisticated visuo-spatial skills in the absence of perceptual awareness, akin to what has been previously reported in monkeys. It remains to be determined which of the several extra-striate pathways account for TNs intact navigation skills.

Mindfulness-based stress reduction and physiological activity during acute stress: a randomized controlled trial

OBJECTIVE The aim was to examine the effects of a Mindfulness-Based Stress Reduction (MBSR) intervention on cardiovascular and cortisol activity during acute stress. METHOD Eighty-eight healthy community-dwelling individuals reporting elevated stress levels were randomly assigned to the MBSR protocol or a waitlist control group. Before and after the intervention period they participated in a laboratory stress protocol consisting of mental arithmetic and speech tasks. Laboratory measurements included continuous cardiovascular parameters (heart period, heart rate variability, and systolic and diastolic blood pressure [SBP and DBP]), and salivary cortisol. RESULTS Compared to the control group and controlling for age, sex, body mass index, and beta-blockers, the MBSR group showed larger pre- to postintervention decreases in overall SBP (F(1, 58) = 4.99, p = .029, partial η² = .08) and DBP (F(1, 58) = 11.09, p = .002, partial η² = .16). In addition, the MBSR group exhibited smaller SBP and DBP stress-related changes from pre- to postintervention (F(2, 116) = 4.89, p = .012, partial η² = .08; F(2, 116) = 6.07, p = .007, partial η² = .10, respectively). No effects were obtained on other physiological measures. CONCLUSION MBSR may help reducing blood pressure levels and blood pressure reactivity to stress.

Waiting to perceive: Reward or punishment?

Neurobiological accounts of the dopaminergic reward system and psychophysiological explanations of the error-related negativity (ERN) both emphasize the comparison of expected versus actual outcome for voluntary actions. The stimulus-preceding negativity (SPN) constitutes a valuable index of that expectation, in that it has high temporal resolution and its anatomical, cognitive and affective correlates have been reasonably well characterized. This review links established findings regarding the SPN to current research on the dorsal and ventral attention systems, somatic marker hypothesis, ERN, the reward system and relevant neurological and psychiatric findings. Special emphasis is given to the pre-feedback SPN and its origin within anterior insular cortex.

A novel self-guided approach to alpha activity training

Fifty healthy participants took part in a double-blind placebo-controlled study in which they were either given auditory alpha activity (8-12Hz) training (N=18), random beta training (N=12), or no training at all (N=20). A novel wireless electrode system was used for training without instructions, involving water-based electrodes mounted in an audio headset. Training was applied approximately at central electrodes. Post-training measurement using a conventional full-cap EEG system revealed a 10% increase in alpha activity at posterior sites compared to pre-training levels, when using the conventional index of alpha activity and a non-linear regression fit intended to model individual alpha frequency. This statistically significant increase was present only in the group that received the alpha training, and remained evident at a 3 month follow-up session, especially under eyes open conditions where an additional 10% increase was found. In an exit interview, approximately twice as many participants in the alpha training group (53%) mentioned that the training was relaxing, compared to those in either the beta (20%) or no training (21%) control groups. Behavioural measures of stress and relaxation were indicative of effects of alpha activity training but failed to reach statistical significance. These results are discussed in terms of a lack of statistical power. Overall, results suggest that self-guided alpha activity training using this novel system is feasible and represents a step forward in the ease of instrumental conditioning of brain rhythms.

Mediofrontal Negativities to Averted Gains and Losses in the Slot-Machine Task

Abstract: In a previous study we addressed the question whether a feedback-related negativity (FRN) can be elicited by outcomes that are not contingent on any preceding choice or action (Donkers, Nieuwenhuis, & Van Boxtel, 2005). Participants took part in a simple slot-machine task in which they experienced monetary gains and losses in the absence of responses. In addition, they performed a time estimation task often used to study the FRN, and a flanker task known to elicit the error-related negativity (Ne/ERN). Outcomes in the slot-machine task elicited a mediofrontal negativity whose amplitude correlated with the amplitude of the FRN associated with negative feedback in the time estimation task. However, the mediofrontal negativity was observed both for (unfavorable) outcomes that averted a gain and for (favorable) outcomes that averted a loss of money, a finding that is inconsistent with previous FRN research. In the present study we examined the similarity between the mediofrontal negativity observed ...

The Body Action Coding System I: Muscle activations during the perception and expression of emotion

Body postures provide clear signals about emotional expressions, but so far it is not clear what muscle patterns are associated with specific emotions. This study lays the groundwork for a Body Action Coding System by investigating what combinations of muscles are used for emotional bodily expressions and assessing whether these muscles also automatically respond to the perception of emotional behavior. Surface electromyography of muscles in the arms (biceps and triceps) and shoulders (upper trapezius and deltoids) were measured during both active expression and passive viewing of fearful and angry bodily expressions. The biceps, deltoids, and triceps are recruited strongly for the expression of anger and fear expression predominantly depends on the biceps and the deltoids. During passive viewing, all muscles automatically activate during the passive viewing of anger. During fear perception, a clear activation can be seen in the trapezius, deltoid, and triceps muscles, whereas the biceps shows inhibition. In conclusion, this study provides more insight into the perception and expression of emotions in the body.Body postures provide clear signals about emotional expressions, but so far it is not clear what muscle patterns are associated with specific emotions. This study lays the groundwork for a Body Action Coding System by investigating what combinations of muscles are used for emotional bodily expressions and assessing whether these muscles also automatically respond to the perception of emotional behavior. Surface electromyography of muscles in the arms (biceps and triceps) and shoulders (upper trapezius and deltoids) were measured during both active expression and passive viewing of fearful and angry bodily expressions. The biceps, deltoids, and triceps are recruited strongly for the expression of anger and fear expression predominantly depends on the biceps and the deltoids. During passive viewing, all muscles automatically activate during the passive viewing of anger. During fear perception, a clear activation can be seen in the trapezius, deltoid, and triceps muscles, whereas the biceps shows inhibition. In conclusion, this study provides more insight into the perception and expression of emotions in the body.

Lifespan Changes in Global and Selective Stopping and Performance Adjustments

This study examined stopping and performance adjustments in four age groups (M ages: 8, 12, 21, and 76 years). All participants performed on three tasks, a standard two-choice task and the same task in which stop-signal trials were inserted requiring either the suppression of the response activated by the choice stimulus (global stop task) or the suppression of the response when one stop signal was presented but not when the other stop signal occurred (selective stop task). The results showed that global stopping was faster than selective stopping in all age groups. Global stopping matured more rapidly than selective stopping. The developmental gain in stopping was considerably more pronounced compared to the loss observed during senescence. All age groups slowed the response on trials without a stop signal in the stop task compared to trials in the choice task, the elderly in particular. In addition, all age groups slowed on trials following stop-signal trials, except the elderly who did not slow following successful inhibits. By contrast, the slowing following failed inhibits was disproportionally larger in the elderly compared to young adults. Finally, sequential effects did not alter the pattern of performance adjustments. The results were interpreted in terms of developmental change in the balance between proactive and reactive control.