Monika Althaus

Influence of respiratory activity on the cardiac response pattern to mental effort

A group of 32 healthy adult volunteers completed three blocks of a reaction time task that varied in the degree of controlled processing load. A rest period preceded each of the task blocks. The task blocks were presented in the order of either increasing or decreasing cognitive load. For each of the six periods, mean values and spectral measures of heart rate and respiration variability were calculated. The spectral measures were obtained for three different frequency bands. Differences between the cardiac measures of the task and preceding rest periods were compared with respect to differences in task load and the order of task presentation. All comparisons were carried out while adjusting for respiratory variability in the corresponding frequency band. The frequency band in which task load-related changes in heart rate variability became manifest appeared to be dependent on the individuals breathing pattern.

Physiological correlates of learning by performance feedback in children : a study of EEG event-related potentials and evoked heart rate

In this study we measured event-related potentials (ERPs) and evoked heart rate (EHR) to investigate performance monitoring in 10-12-year-old children. The children received feedback on their performance while conducting a probabilistic learning task. Error-related ERP components time-locked to the response increased in amplitude when the children had learned the task, whereas the feedback-locked components decreased. Concerning EHR, there was a general reduction in feedback-related heart rate deceleration when the children had learned. Moreover, a prolonged heart rate deceleration was observed at negative feedback onset in comparison to positive feedback, which shifted in timing when the task progressed. Together, the ERP and EHR-measures suggest a shift from external to internal monitoring when the children are learning by performance feedback. The data suggest that error- and feedback-related EHR deceleration is a reflection of the same error monitoring system that is responsible for the emergence of the error-related negativity (ERN).

Face Recognition in Children with a Pervasive Developmental Disorder Not Otherwise Specified

This study investigates the accuracy and speed of face recognition in children with a Pervasive Developmental Disorder Not Otherwise Specified (PDDNOS; DSM-IV, American – Psychiatric Association [APA], 1994). The study includes a clinical group of 26 nonretarded 7- to 10-year-old children with PDDNOS and a control group of 65 normally developing children of the same age. Two computerized reaction time tasks were administered: a face recognition task and a control task designed to measure the recognition of abstract visuospatial patterns. The latter were either easy or difficult to distinguish from a set of alternative patterns. The normally developing children recognized the faces much faster than the hardly distinguishable abstract patterns. The children in the PDDNOS group needed an amount of time to recognize the faces that almost equalled the time they needed to recognize the abstract patterns that were difficult to distinguish. The results suggest that, when processing faces, children with PDDNOS use a strategy that is more attention-demanding and, hence, less automatic or “Gestalt-like” than the one used by the control children. The results are discussed in the light of a theory that explains the development of coherent mental representations.

Cardiac adaptivity to attention-demanding tasks in children with a pervasive developmental disorder not otherwise specified (PDD-NOS)

BACKGROUND Decreases in heart rate variability (HRV) have been repeatedly demonstrated to be an index of effort allocation to attention-demanding tasks. Children with autistic-type problems in social interaction and in adapting to unfamiliar situations (DSM-IV: PDD-NOS) have been shown to have specific attention deficits. These children were hypothesized to exhibit less cardiac adaptivity to attention-demanding tasks. METHODS Two groups of 18 children with PDD-NOS, judged to be hyperactive and nonhyperactive, were compared to 18 healthy children with respect to their performances on a visual attention task and the differences in HRV measured during periods of task performance and periods of rest. RESULTS Compared to the control group, both clinical groups were found to have a stronger capacity limitation in processing high loads of information, and to be less capable of maintaining a stable task performance throughout the whole task. Both clinical groups showed significantly less decreases in HRV during the periods of task performance. The magnitude of rest-task differences in HRV was found to correlate significantly with a behavioral measure of resistance to unexpected changes in daily routines. CONCLUSIONS Children with PDD-NOS are significantly less flexible in their autonomic adaptation to attention-demanding tasks. The findings are interpreted as reflecting a deficiency in the functional organization of those neural pathways that provide cortical control of the visceral efferents.

Differential effects of 5-HTTLPR and DRD2/ANKK1 polymorphisms on electrocortical measures of error and feedback processing in children

OBJECTIVE Applying a probabilistic learning task we examined the influence of functional polymorphisms of the serotonin transporter gene (5-HTTLPR) and the D2 dopamine receptor gene (DRD2/ANKK1) on error and feedback processing by measuring electrocortical event-related potentials (ERPs) in 10- to 12-year-old children. METHODS Three pairwise group comparisons were conducted on four distinguishable ERP components, two of which were response-related, the other two feedback-related. RESULTS Our ERP data revealed that children carrying the short (S) variant of the 5-HTTLPR gene process their errors more intensively while exhibiting less habituation to negative feedback with task progression compared to children who are homozygous for the 5-HTTLPR long (L) variant. Children possessing the Taq1 A variant of the DRD2 gene showed greater sensitivity to negative feedback and, as opposed to Taq1 A non-carriers, a diminishing sensitivity to positive feedback with task progression. Regarding error processing, children possessing both the S variant of the 5-HTTLPR and the Taq1 A allele of the DRD2 gene showed a picture quite similar to that of the 5-HTTLPR S carriers and regarding feedback processing quite similar to that of the DRD2 Taq1 A carriers. CONCLUSIONS Our findings support the hypotheses that the 5-HTTLPR S allele may predispose to (performance) anxiety, while DRD2 Taq1 A allele may predispose to the reward deficiency syndrome. SIGNIFICANCE The results may further enhance our understanding of known associations between these polymorphisms and psychopathology.

Antiaggressive activity of central oxytocin in male rats

RationaleA substantial body of research suggests that the neuropeptide oxytocin promotes social affiliative behaviors in a wide range of animals including humans. However, its antiaggressive action has not been unequivocally demonstrated in male laboratory rodents.ObjectiveOur primary goal was to examine the putative serenic effect of oxytocin in a feral strain (wild type Groningen, WTG) of rats that generally show a much broader variation and higher levels of intermale aggression than commonly used laboratory strains of rats.MethodsResident animals were intracerebroventricularly (icv) administered with different doses of synthetic oxytocin and oxytocin receptor antagonist, alone and in combination, in order to manipulate brain oxytocin functioning and to assess their behavioral response to an intruder.ResultsOur data clearly demonstrate that acute icv administered oxytocin produces dose-dependent and receptor-selective changes in social behavior, reducing aggression and potentiating social exploration. These antiaggressive effects are stronger in the more offensive rats. On the other hand, administration of an oxytocin receptor antagonist tends to increase (nonsignificantly) aggression only in low–medium aggressive animals.ConclusionsThese results suggest that transiently enhancing brain oxytocin function has potent antiaggressive effects, whereas its attenuation tends to enhance aggressiveness. In addition, a possible inverse relationship between trait aggression and endogenous oxytocinergic signaling is revealed. Overall, this study emphasizes the importance of brain oxytocinergic signaling for regulating intermale offensive aggression. This study supports the suggestion that oxytocin receptor agonists could clinically be useful for curbing heightened aggression seen in a range of neuropsychiatric disorders like antisocial personality disorder, autism, and addiction.

Information Processing Differences and Similarities in Adults with Dyslexia and Adults with Attention Deficit Hyperactivity Disorder during a Continuous Performance Test: A Study of Cortical Potentials.

Twenty male adults with ADHD, 16 dyslexic adults, 15 comorbid adults, and 16 normal controls were compared on performance and underlying brain responses, during a cued Continuous Performance Test (O-X CPT), with the aim of discovering features of information processing differentiating between the groups. The study evaluated both cue- and target-related processes by analysing performance measures (errors, reaction time, and variability of reaction time), and event-related potentials (ERPs). Cue-related ERP components included the Cue-N2, Cue-P3, contingent negative variation (CNV) consisting of the CNV1, related to cue orienting, and the CNV2, related to response preparation. For targets, a distinction was made between response-related (Go), and inhibitory (Nogo) processing. Target-related components included the Go-P3, Nogo-N2, and Nogo-P3. Performance deficits were found only for the ADHD group, who demonstrated a faster decline in response speed with time-on-task and greater overall within-subject variability. No group differences were found for cue-related ERP components. Yet, controlling for group differences in internalising problems, inhibitory control was reduced in all clinical groups compared to controls, as demonstrated by an absence of frontal amplification of P3 in the Nogo condition, relative to the Go condition. For the ADHD group, in contrast to the comorbid and the dyslexic group, this effect remained after controlling for externalising symptoms, indicating that only for the ADHD group deficiencies in inhibitory control were not explained by externalising behaviour.

Acute and repeated intranasal oxytocin administration exerts anti-aggressive and pro-affiliative effects in male rats

Socio-emotional deficits and impulsive/aggressive outbursts are prevalent symptoms of many neuropsychiatric disorders, and intranasal administration of oxytocin (OXT) is emerging as a putative novel therapeutic approach to curb these problems. Recently, we demonstrated potent anti-aggressive and pro-social effects of intracerebroventricular (icv) OXT administration in male rats. The present study tested whether similar behavioral effects are induced when OXT is delivered intranasally. Heart-rate and blood-pressure responses were telemetrically monitored to investigate whether peripheral physiological effects were provoked after intranasal OXT administration. Intranasal OXT administration in resident animals reduced offensive aggression and increased social exploration toward an unfamiliar male intruder. Using a partner-preference test, intranasal OXT also strengthened the bonding between the male resident and its female partner. No changes in cardiovascular (re)activity were found, indicating an absence of direct peripheral physiological effects after intranasal OXT treatment. In conclusion, although the precise route and mechanisms of nose-to-brain transport/communication remain to be elucidated, our data demonstrated intranasal OXT to be an effective application method for suppressing intermale aggression and enhancing social affiliation.

Oxytocin microinjected into the central amygdaloid nuclei exerts anti-aggressive effects in male rats

We recently demonstrated that acute and chronic intracerebroventricular enhancement of brain OXT levels induces potent anti-aggressive and pro-social explorative effects during social challenges. However, the exact anatomical location in the brain where OXT exerts its action is still elusive. In the present study, we targeted two critical brain areas, i.e. the central amygdala (CeA) and the dorsal raphe (DR), both containing high levels of OXT receptors (OXTRs) and constituting important nodes of the neural circuitry related to aggression. Behavioral effects of local micro-infusion of OXT and OXTR antagonist, L368.899, (alone and combined) were evaluated in resident male rats during confrontations with an unfamiliar male intruder. Our results show that OXT microinjected into the CeA markedly reduced residents offensive behavior and facilitated social exploration, without affecting other non-aggressive behaviors. The receptor specificity of the behavioral effects was verified when a micro-infusion of a selective OXTR antagonist nullified the changes. Pharmacological blockade of CeA OXTRs per se was without clear behavioral effects suggesting that endogenous OXT within the CeA does not play a major inhibitory role on offensiveness. Anatomical specificity was also supported by the absence of relevant behavioral effects when OXT was microinjected into more medial sub-regions of the amygdala. Likewise, within the DR neither OXT nor OXTR exerted significant effects on offensive aggression, while microinjection of the 5-HT1A autoreceptor agonist in this region significantly suppressed aggression. In conclusion, our results point at the CeA as an important brain site of action for the anti-aggressive and pro-social explorative effects induced by exogenous enhancement of brain OXT levels.

Local oxytocin expression and oxytocin receptor binding in the male rat brain is associated with aggressiveness

We recently demonstrated in male wild-type Groningen rats that enhancing brain oxytocin (OXT) levels acutely produces marked pro-social explorative and anti-aggressive effects. Moreover, these pharmacologically-induced changes are moderated by the individuals aggressive phenotype, suggesting an inverse relationship between aggressiveness and tonic endogenous OXT signaling properties. Aim of the present study was to verify the hypothesis that variations in OXT expression and/or OXT receptor (OXTR) binding in selected brain regions are associated with different levels or forms of aggression. To this end, male resident wild-type Groningen rats that repeatedly contested and dominated intruder conspecifics were categorized as being low aggressive, highly aggressive or excessively aggressive. Their brains were subsequently collected and quantified for OXT mRNA expression and OXTR binding levels. Our results showed that OXT mRNA expression in the hypothalamic paraventricular nucleus (PVN), but not in the supraoptic nucleus (SON), negatively correlates with the level of offensiveness. In particular, the excessively aggressive group showed a significantly lower OXT mRNA expression in the PVN as compared to both low and highly aggressive groups. Further, the excessively aggressive animals showed the highest OXTR binding in the central amygdala (CeA) and bed nucleus of the stria terminalis (BNST). These findings demonstrate that male rats with excessively high levels and abnormal forms of aggressive behavior have diminished OXT transcription and enhanced OXTR binding capacities in specific nodes of the social behavioral brain circuitry.