Jan W. Van Strien

Impulsivity is associated with behavioral decision-making deficits

Impaired decision-making is a key-feature of many neuropsychiatric disorders. In the present study, we examined task performance in a healthy population consisting of those whose scores indicated high and low impulsivity on several behavioral decision-making tasks reflecting orbitofrontal functioning. The measures included tasks that assess decision-making with and without a learning component and choice flexibility. The results show that subjects high on impulsivity display an overall deficit in their decision-making performance as compared with subjects low on impulsivity. More specifically, subjects with high impulsivity show weaknesses in learning of reward and punishment associations in order to make appropriate decisions (reversal-learning task and Iowa Gambling Task), and impaired adaptation of choice behavior according to changes in stimulus-reward contingencies (reversal-learning task). Simple, non-learning, components of reward- and punishment-based decision-making (Rogers Decision-Making Task) seem to be relatively unaffected. Above all, the results indicate that impulsivity is associated with a decreased ability to alter choice behavior in response to fluctuations in reward contingency. The findings add further evidence to the notion that trait impulsivity is associated with decision-making, a function of the orbitofrontal cortex.

Error-processing deficits in patients with cocaine dependence

Cocaine abuse and addiction can be characterized by a persisting use of cocaine in the face of adverse consequences. In the present study we focus on one specific element of adverse consequences: the making of errors. The aim of this study was to determine whether cocaine-dependent persons have error-processing deficits as measured using error-related negativity (ERN) and error positivity (Pe). Event-related potentials (ERPs) during an Eriksen flanker task were recorded from cocaine-dependent patients and a control group. Cocaine-addicted patients showed reduced ERN and Pe components as compared to a control group. On the behavioral level, patients showed reduced post-error accuracy improvement. The present findings reveal that cocaine addiction is associated with reduced error processing and impaired behavioral correction of errors after an error is made. These deficits may be associated with a compromised dopamine system. It is argued that these cognitive deficits may contribute to the maintenance of the cocaine addiction.

Opposite hemispheric activations as a result of emotionally threatening and non-threatening words

Twenty right-handed males participated in a tachistoscopic unilateral letter recognition task with three conditions. In the control condition, each trial consisted of three consonants that were flashed horizontally to the left or to the right visual field. In the threat and non-threat conditions, each lateral three-letter presentation was preceded by an emotionally threatening or non-threatening word presented in central fixation. Across conditions, subjects identified more letters correctly in the right visual field than in the left visual field. The concurrent presentation of threatening words resulted in a selective enhancement of left visual-field performances. The concurrent presentation of non-threatening words resulted in a selective right visual-field enhancement. Our conclusion is that threatening stimuli prime the right hemisphere and can alter predicted laterality patterns.

Event-related potential responses to love-related facial stimuli

In event-related potential (ERPs) studies, emotional stimuli usually elicit an enhanced late positive potential (LPP), which is assumed to reflect motivated attention. However, whether a stimulus elicits emotional responses may depend on the individuals state, such as experiencing romantic love. It has been suggested that stimuli that are related to someones beloved will elicit increased attention in that infatuated individual. In this study, participants who were in love viewed faces of their beloved, their friend, and of an unknown, beautiful person. The friend was included to control for familiarity, and the unknown person for perceived beauty. As expected, the LPP was larger in response to the face of the beloved than to the other two emotionally significant faces. Interpreting the LPP as reflecting motivated attention, this implies that romantic love is accompanied by increased attention for the face of ones beloved.

Birth Stress, Autoimmune Diseases, and Handedness

A large nonclinical sample of left-handed and right-handed subjects completed laterality and medical health questionnaires. The group of left-handed subjects showed a raised incidence of birth complications and learning disorders whereas no differences were found for birth order and maternal age. Left-handed and right-handed subjects showed similar incidences of autoimmune diseases, allergies, migraine, and stuttering. These results suggest that an association between early pathology and left-handedness may be found in a subset of the nonclinical left-handed population. The underlying pathological influence seems to manifest itself in pregnancy and birth complications rather than in immune disorders.

Aging and Emotional Memory: The Co-Occurrence of Neurophysiological and Behavioral Positivity Effects

The positivity effect is a trend for adults to increasingly process positive and/or decreasingly process negative information compared with other information with advancing age. The positivity effect has been observed with behavioral measures, such as in attention and memory tests, and with measures of neurophysiological activity, such as in amygdala activation and the late positive potential (LPP). In this study, it was investigated whether these behavioral and neurophysiological positivity effects co-occur. The electroencephalogram of younger (19-26 years) and older (65-82 years) adults was recorded while they encoded unpleasant, neutral, and pleasant pictures for retrieval in free and cued recall tests. Positivity effects occurred in the late LPP amplitude (700-1,000 ms) and in the free recall test, with negativity biases in younger adults and no biases in older adults. The occurrence of a valence bias in the LPP was substantially but nonsignificantly correlated with the occurrence of a similar valence bias in memory in the older adults. In conclusion, neurophysiological and behavioral positivity effects appear to co-occur, a finding that awaits expansion using different neurophysiological and behavioral measures.

Cerebral organization of verbal and motor functions in left-handed and right-handed adults: effects of concurrent verbal tasks on unimanual tapping performance.

Two experiments were conducted to study the interference effects of different concurrent verbal tasks on unimanual single-finger tapping and unimanual sequential finger tapping. Experiment 1 involved 24 right-handed university students. In the dual-task conditions, right-handers showed a greater right-hand than left-hand performance reduction for single-finger tapping, and an equal right-hand and left-hand reduction for sequential tapping. Experiment 2 involved 60 left-handed university students, divided into four groups according to familial sinistrality and writing hand posture. In the dual-task conditions, left-handers showed a greater left-hand than right-hand performance reduction for single-finger tapping, and an equal left-hand and right-hand reduction for sequential finger tapping. A dichotic listening task revealed a left hemispheric dominance for auditory linguistic functioning in most of the left-handers. Familial sinistrality and hand posture, on the whole, did not influence tapping performances. However, these factors influenced the ear asymmetries on the dichotic listening task. It is speculated that, with single-finger tapping, interference only takes place beyond the point of language motor programming, that is to say, at the motor areas and the supplementary motor areas of the cortex.

Sex differences in the latency of the late event-related potential mental rotation effect.

Sex differences in event-related potentials were examined in 23 women and 24 men during a mental rotation task. We found an early (130–400 ms) and a late (400–700 ms) ERP mental rotation effect. The late rotation effect, which is thought to indicate the onset of the cognitive process of mental rotation, emerged about 100 ms earlier in men than in women. Moreover, men showed about 100 ms shorter response latencies to the task than women. These findings suggest that the faster response in men can be explained as a result of actual mental rotation taking place earlier. Furthermore, we found increased involvement of the right hemisphere specifically in men, probably pointing at a holistic strategy in men during mental rotation.

Age differences in the emotional modulation of ERP old/new effects

The emotional salience of stimuli influences ERP old/new effects, but despite proven age differences in emotional processing, the influence of emotion on old/new effects has previously been investigated in younger adults only. Therefore, we set out to examine age differences in the emotional modulation of old/new effects. To this end, the electroencephalogram of younger (17-27 years) and older (63-77 years) adults was recorded while they completed a continuous recognition test with unpleasant, neutral and pleasant pictures. Because recollection is typically enhanced by emotion, the parietal old/new effect was expected to be larger for emotional than neutral stimuli in the younger adults. Because recollection suffers from age-related decline, emotion enhancement of the parietal old/new effect was not expected in the older adults. The results showed that, in both age groups, recognition accuracy was not affected by emotion and that the response bias was more liberal for unpleasant pictures. The younger adults displayed an early, a parietal and a late frontal old/new effect, whereas the older adults showed an early, no parietal and an inverse left-lateralized late frontal old/new effect. Further, the emotional modulation of the old/new effects differed with age. Importantly, emotion enhanced the parietal and late frontal old/new effects in younger adults, and the early old/new effect in older adults. This suggests that whereas recollection and post-retrieval processes are augmented in emotional recognition memory in younger adults, familiarity is enhanced by emotional salience in older adults.

Cocaine craving is associated with electrophysiological brain responses to cocaine-related stimuli.

Several studies show that substance dependence disorders are characterized by an enhanced processing of substance‐related stimuli. The present study was designed to examine the association between craving levels and selective processing of drug cues in cocaine‐dependent patients using event‐related brain potentials (ERPs). In abstinent cocaine‐dependent patients and a healthy control group, we studied the late positive potential (LPP) amplitudes elicited by neutral and cocaine‐related stimuli. The results show that cocaine‐dependent patients have an enhanced electrophysiological response in the late LPP time window to cocaine‐related stimuli as compared to controls, suggesting an enhanced processing of these stimuli. Most importantly, a robust association was observed between cocaine craving and LPP amplitude. High craving levels were associated with larger LPP amplitudes at central electrode sites in the right hemisphere. These findings are in line with theories linking motivational aspects and appetitive stimulus processing. Furthermore, it is demonstrated that ERPs are a useful index to assess motivational properties of stimuli in cocaine‐dependent patients. These findings suggest that electrophysiological measures may have clinical relevance in substance use disorders.