Cerebral asymmetry in the control of cardiovascular functioning: evidence from lateral vibrotactile stimulation

Cerebral Autoregulation During Active Standing Test in Juvenile Patients with Instantaneous Orthostatic Hypotension

Instantaneous orthostatic hypotension (INOH) is one of the main types of orthostatic dysregulation in children and adolescents. In patients with INOH arterial pressure drops considerably after active standing and is slow to recover. We investigated changes in cerebral oxygenation in the bilateral prefrontal cortex during an active standing test in juvenile INOH patients to evaluate changes in cerebral oxygen metabolism. We enrolled 82 INOH patients (mean age 13.8 ± 2.2 years, 52 mild and 30 severe patients) at Nihon University Itabashi Hospital from October 2013 to April 2018. We measured cerebral oxygenated hemoglobin, deoxygenated hemoglobin, and total hemoglobin levels in the bilateral prefrontal cortex using near-infrared spectroscopy during an active standing test. In severe INOH patients, cerebral oxygenation of the right prefrontal cortex remained constant when blood pressure dropped; however, de-oxy-Hb significantly increased. These findings confirm that there is asymmetrical autoregulation between the right and left prefrontal cortex.

Hostility and cognitive control: Evidence of increased cardiovascular reactivity as a function of exposure to affective stress using a dichotic listening paradigm

Indices of cognitive control were examined in men with high and low levels of trait hostility as a function of exposure to affective and cognitive stress. A dual concurrent task paradigm was used whereby participants intentionally directed focus to the left or right ear under dichotic listening conditions before and after exposure to angry infant vocalizations. Analysis of the behavioral data supports the prediction of reduced right frontal regulatory control in men with high levels of hostility as indicated by diminished capacity to suppress report of phonemes presented to the language dominant left hemisphere (right ear) in the Focus Left condition. This diminishment in the capacity to suppress report of phonemes presented to the right ear in the Focus Left condition is suggestive of reduced cognitive control. With respect to the neurophysiological data, heart rate increased for only men with high levels of hostility in the Focus Left condition, and this was especially evident in the post-affective stress condition. This increase in right hemisphere arousal provides additional evidence of reduced cognitive control and support for the capacity model of hostility by implicating poor right frontal regulatory control over right posterior cerebral regions under dual task conditions. The results are discussed in terms of integrating the construct of cognitive control into the capacity model as well as providing implications regarding reductions in the capacity to suppress predominant aggressive responses in domestic settings.

Associations between cytokines, endocrine stress response, and gastrointestinal symptoms in autism spectrum disorder

Many children and adolescents with autism spectrum disorder (ASD) have significant gastrointestinal (GI) symptoms, but the etiology is currently unknown. Some individuals with ASD show altered reactivity to stress and altered immune markers relative to typically-developing individuals, particularly stress-responsive cytokines including tumor necrosis factor alpha (TNF-α) and interleukin 6 (IL-6). Acute and chronic stress is associated with the onset and exacerbation of GI symptoms in those without ASD. The present study examined whether GI symptoms in ASD were associated with increases in cortisol, a stress-associated endocrine marker, and TNF-α and IL-6 in response to stress. As hypothesized, a greater amount of lower GI tract symptoms were significantly associated with post-stress cortisol concentration. The relationship between cortisol response to stress and GI functioning was greater for children who had a history of regressive autism. Exploratory analyses revealed significant correlations between cortisol response, intelligence, and inappropriate speech. In contrast, symptoms of the lower GI tract were not associated with levels of TNF-α or IL-6. Significant correlations were found, however, between TNF-α and IL-6 and irritability, socialization, and intelligence. These findings suggest that individuals with ASD and symptoms of the lower GI tract may have an increased response to stress, but this effect is not associated with concomitant changes in TNF-α and IL-6. The relationship between cortisol stress response and lower GI tract symptoms in children with regressive autism, as well as the relationships between cortisol, IL-6, and intelligence in ASD, warrant further investigation.

Psychophysiological Associations with Gastrointestinal Symptomatology in Autism Spectrum Disorder

Autism spectrum disorder (ASD) is often accompanied by gastrointestinal disturbances, which also may impact behavior. Alterations in autonomic nervous system functioning are also frequently observed in ASD. The relationship between these findings in ASD is not known. We examined the relationship between gastrointestinal symptomatology, examining upper and lower gastrointestinal tract symptomatology separately, and autonomic nervous system functioning, as assessed by heart rate variability and skin conductance level, in a sample of 120 individuals with ASD. Relationships with co-occurring medical and psychiatric symptoms were also examined. While the number of participants with significant upper gastrointestinal tract problems was small in this sample, 42.5% of participants met criteria for functional constipation, a disorder of the lower gastrointestinal tract. Heart rate variability, a measure of parasympathetic modulation of cardiac activity, was found to be positively associated with lower gastrointestinal tract symptomatology at baseline. This relationship was particularly strong for participants with co-occurring diagnoses of anxiety disorder and for those with a history of regressive ASD or loss of previously acquired skills. These findings suggest that autonomic function and gastrointestinal problems are intertwined in children with ASD; although it is not possible to assess causality in this data set. Future work should examine the impact of treatment of gastrointestinal problems on autonomic function and anxiety, as well as the impact of anxiety treatment on gastrointestinal problems. Clinicians should be aware that gastrointestinal problems, anxiety, and autonomic dysfunction may cluster in children with ASD and should be addressed in a multidisciplinary treatment plan. Autism Res 2017, 10: 276-288. © 2016 International Society for Autism Research, Wiley Periodicals, Inc.

Physiological and behavioural indices of hostility: an extension of the capacity model to include exposure to affective stress and right lateralized motor stress

Right hemisphere functional cerebral systems have reliably been associated with sympathetic nervous system arousal and the perception of negative affective events. The goal of the current research was to provide additional support for the capacity model of hostility by examining changes attributable to functional cerebral systems within the right hemisphere using a dual concurrent task paradigm. To incorporate exposure to negative affective and right-lateralized motor stress using this approach, high and low hostile individuals completed a series of grip-strength tasks before and after hearing a recording of angry infant vocalizations. Results supported the capacity model in that high hostile individuals were unable to maintain regulatory control over right hemisphere activation as indicated through increased motor perseveration in the pre- and post-affective stress conditions, heightened systolic blood pressure (SBP) upon exposure to negative emotional sounds, and increased heart rate (HR) following stress. Conversely, low hostile individuals showed improved regulatory control over these regions as evidenced by reduced motor perseveration in the pre- and post-affective stress conditions, maintenance of SBP and reductions in HR following stress. The current data support the capacity model and extend its scope to include exposure to affective and right-lateralized motor stress.

The neural basis of optimism and pessimism

Our survival and wellness require a balance between optimism and pessimism. Undue pessimism makes life miserable; however, excessive optimism can lead to dangerously risky behaviors. A review and synthesis of the literature on the neurophysiology subserving these two worldviews suggests that optimism and pessimism are differentially associated with the two cerebral hemispheres. High self-esteem, a cheerful attitude that tends to look at the positive aspects of a given situation, as well as an optimistic belief in a bright future are associated with physiological activity in the left-hemisphere (LH). In contrast, a gloomy viewpoint, an inclination to focus on the negative part and exaggerate its significance, low self-esteem as well as a pessimistic view on what the future holds are interlinked with neurophysiological processes in the right-hemisphere (RH). This hemispheric asymmetry in mediating optimistic and pessimistic outlooks is rooted in several biological and functional differences between the two hemispheres. The RH mediation of a watchful and inhibitive mode weaves a sense of insecurity that generates and supports pessimistic thought patterns. Conversely, the LH mediation of an active mode and the positive feedback it receives through its motor dexterity breed a sense of confidence in one's ability to manage life's challenges, and optimism about the future.