The effects of yohimbine and hydrocortisone on selective attention to fearful faces: An fMRI study

INTRODUCTION

Selective attention to salient emotional information can enable an advantage in the face of danger. The present study aims to investigate the influence of the stress neuromodulators, norepinephrine and cortisol, on selective attention processes to fearful faces and its neuronal activation.

METHODS AND MATERIALS

We used a randomized, double-blind, placebo-controlled design. 167 healthy men between 18 and 35 years (mean [SD] age: 25.23 [4.24] years) participated in the study. Participants received either: (A) yohimbine (n= 41), (B) hydrocortisone (n = 41), (C) yohimbine and hydrocortisone (n = 42) or (D) placebo only (n= 43) and participated in a dot-probe task with fearful and neutral faces in an fMRI scanner.

RESULTS

We found an attentional bias toward fearful faces across all groups and related neuronal activation in the left cuneus. We did not find any differences between experimental treatment groups in selective attention and its neuronal activation.

DISCUSSION

Our results provide evidence that fearful faces lead to an attentional bias with related neuronal activation in the left cuneus. We did not replicate formerly reported activation in the amygdala, intraparietal sulcus, dorsal anterior cingulate cortex, and thalamus. Suitability of the dot-probe task for fMRI studies and insignificant treatment effects are discussed.

No changes in triple network engagement following (combined) noradrenergic and glucocorticoid stimulation in healthy men

Successful recovery from stress is integral for adaptive responding to the environment. At a cellular level, this involves (slow genomic) actions of cortisol, which alter or reverse rapid effects of noradrenaline and cortisol associated with acute stress. At the network scale, stress recovery is less well understood but assumed to involve changes within salience-, executive control-, and default mode networks. To date, few studies have investigated this phase and directly tested these assumptions. Here, we present results from a double-blind, placebo-controlled, between-group paradigm (N = 165 healthy males) administering 10 mg oral yohimbine and/or 10 mg oral hydrocortisone two hours prior to resting state scanning. We found no changes in within-network connectivity of the three networks, both after single and combined drug administration. We further report the results of Bayesian parameter inference to provide evidence for the null hypothesis. Our results contrast with previous findings, which may be attributable to systematic differences between paradigms, highlighting the need to isolate paradigm-specific effects from those related to stress.

Neural Correlates of Successful Costly Punishment in the Ultimatum Game on a Trial-by-Trial Basis

Costly punishment describes decisions of an interaction partner to punish an opponent for violating rules of fairness at the expense of personal costs. Here, we extend the interaction process by investigating the impact of a socio-emotional reaction of the opponent in response to the punishment that indicates whether punishment was successful or not. In a modified Ultimatum game, emotional facial expressions of the proposer in response to the decision of the responder served as feedback stimuli. We found that both honored reward following acceptance of an offer (smiling compared to neutral facial expression) and successful punishment (sad compared to neutral facial expression) elicited a reward positivity, indicating that punishment was the intended outcome. By comparing the pattern of results with a probabilistic learning task, we show that the reward positivity on sad facial expressions was specific for the context of costly punishment. Additionally, acceptance rates on a trial-by-trial basis were altered according to P3 amplitudes in response to the emotional facial reaction of the proposer. Our results are in line with the concept of costly punishment as an intentional act following norm-violating behavior. Socio-emotional stimuli have an important influence on the perception and behavior in economic bargaining.

MRI Brain Changes After Marathon Running: Results of the Berlin Beat of Running Study

Several studies report neurological complications such as brain injury induced by ischemia or edema following exhaustive endurance sport. We aimed to detect the frequency of acute brain lesions after a marathon race. In the prospective observational Berlin Beat of Running study, 110 experienced endurance athletes underwent 3-Tesla brain MRI exams 2-3 days prior and within 2 days after a marathon run. MRI results were compared to an age- and sex-matched control group of 68 non-athletes, including the "Age-Related White Matter Changes" (ARWMC) scale to assess white matter lesions (WML) in the brain. 108 athletes (median age 48 years, 24% female, 8% with hypertension; 0% with diabetes) completed the race. No athlete reported neurological deficits, but a single acute ischemic lesion was detected in diffusion-weighted MRI after the race in one athlete. No other acute brain lesions compared to prior MRI were found. An ARWMC score ≥4 was found in 15% of athletes and 12% of non-athletic controls (p=0.7). Chronic ischemic lesions were not found in athletes but in four controls (6%) (p=0.02). In conclusion, acute ischemic brain lesions may be found in endurance runners. Every seventh endurance athlete and every ninth control showed evidence for substantial white matter lesions.

Obesity and the brain: a possible genetic link

Structural brain deficits have been repeatedly linked to body mass index and obesity, which itself is controlled by the effects of a number of independent genetic loci. One of the most consistently replicated of these putative obesity genes is fat mass and obesity-associated protein (FTO). A recent study by investigators from the Alzheimer's Disease Neuroimaging Initiative set out to assess whether polymorphisms in FTO are directly correlated with brain volume in a collection of over 200 healthy older individuals. The authors found a modest but significant reduction in brain volume in the frontal and occipital lobes exerted by the same FTO alleles that also predispose to obesity. Although potentially providing a novel genetic link between obesity and brain structure, the relevance of these findings for normal brain function and disease remains to be determined.

Decrease in haemoglobin oxygenation during absence seizures in adult humans

Near-infrared spectroscopy (NIRS) is a noninvasive method that allows the assessment of activation-induced cortical oxygenation changes in humans. It has been demonstrated that an increase in oxygenated and a decrease in deoxygenated haemoglobin can be expected over an area activated by functional stimulation. Likewise, an inverse oxygenation pattern has been shown to be associated with cortical deactivation. The aim of the current study was to determine the oxygenation changes that occur during absence seizures. We performed ictal NIRS simultaneously with video-EEG telemetry in three adult patients with typical absence seizures. NIRS probes were placed over the frontal cortex below the F1/F2 leads. During all absence seizures studied, pronounced changes in cerebral Hb-oxygenation were noted and there were no changes in the interval. We observed a reproducible decrease in [oxy-Hb] and an increase in [deoxy-Hb] during absence seizures indicating a reduction of cortical activity. Oxygenation changes started several seconds after the EEG-defined absence onset and outlasted the clinically defined event by 20-30 s.

Decrease in parietal cerebral hemoglobin oxygenation during performance of a verbal fluency task in patients with Alzheimer's disease monitored by means of near-infrared spectroscopy (NIRS)--correlation with simultaneous rCBF-PET measurements

We used near-infrared spectroscopy (NIRS) to study non-invasively changes in cerebral hemoglobin oxygenation in the frontal and parietal cortex during performance of a verbal fluency task in patients with Alzheimer's disease (AD). Whereas healthy elderly subjects (n = 19, age 67 +/- 10 years) showed increases in concentrations of oxygenated hemoglobin [HbO2] (mean (arbitrary units) +/- S.E.M., 1.44 +/- 0.59) and total hemoglobin [HbT] (0.92 +/- 0.81) over the left superior parietal cortex, patients with AD (n = 19, age 71 +/- 10 years) showed significant decreases in [HbO2] (-3.26 +/- 1.30, P < 0.01) as well as [HbT] (-4.45 +/- 1.57, P < 0.01). [HbR] decreased slightly in both groups (-0.62 +/- 0.29 and - 1.18 +/- 0.40, respectively). Using two pairs of NIRS optodes placed on the left superior partietal cortex and on the left prefrontal cortex simultaneous increases in [HbO2] as well as [HbT] in both cortical regions in the healthy elderly subjects (n = 8, age 60 +/- 15) were demonstrated during performance of the task. AD patients (n = 10, age 65 +/- 13 years) showed decreases in [HbO2] and [HbT] in the parietal cortex and, at the same time, increases in [HbO2] and [HbT] in the frontal cortex. Simultaneous NIRS-[HbT] and PET-rCBF measurements showed a significant correlation both when calculated in a 'banana' shaped volume approximated by using cortical thresholds as well as when calculated in a semisphere volume of brain tissue beneath the optodes placed on the head surface (patients with AD, n = 10). The correlation was dependent on the assumed penetration depth of the near-infrared light and was best for all three NIRS variables ([HbO2], [HbR] and [HbT]) when calculated using a semisphere radius of 0.45 cm to 1.35 cm. In conclusion, in Alzheimer's disease a marked reduction of regional cerebral blood flow and cerebral hemoglobin oxygenation may occur during activation of brain function, probably mainly in degenerating brain areas, such as the parietal cortex.

Quality of documentation in medical reports of diabetic patients

In a retrospective analysis of 752 consecutive medical reports of patients with insulin- or non-insulin-dependent diabetes mellitus, we investigated the completeness of documentation of indicators of quality of care. The medical reports are the currently used form of documentation which is sent to the General Practitioner after the patient's discharge from hospital. The indicators of care were data on clinical history, physical examination, laboratory results and secondary complications. The documentation was incomplete; e.g. in 8.0% of insulin-dependent (IDDM) and in 26.4% of non-insulin-dependent diabetics (NIDDM), HbA1c was missing. In 7.6%, the type of diabetes was not stated. The frequency of recorded secondary complications was lower than it has to be expected considering metabolic control and duration of diabetes of the studied group. Documentation was more complete for IDDM patients. The reports of NIDDM patients with incipient or overt diabetic nephropathy revealed less frequent recordings of data on lipid metabolism and blood pressure compared to the group without nephropathy. The documentation of indicators of quality of care in medical reports for general practitioners is incomplete for many diabetic inpatients. Standardized methods of documentation are required urgently.

Near infrared spectroscopy in the diagnosis of Alzheimer's disease

Near infrared spectroscopy (NIRS) is a new technique that permits noninvasive monitoring of cerebral blood and tissue oxygenation. Recently, we and others have shown that NIRS measurements are sensitive enough to follow changes in cerebral hemoglobin oxygenation due to activation of brain function. Based on these findings we have assessed the influence of aging as well as the influence of neurodegeneration on cerebral hemoglobin oxygenation during mental work. The typical NIRS pattern in young healthy subjects while performing calculation tasks measured in the frontal cortex were increases in oxygenated hemoglobin [HbO2] and total hemoglobin [HbT] while reduced hemoglobin [HbR] decreased. Elderly healthy subjects showed a significant lower mean increase in [HbO2] and [HbT] levels. Regression analysis revealed an age-dependent decline in activation-induced local increase of [HbO2] as well as [HbT]. Furthermore, we monitored changes in cerebral hemoglobin oxygenation in the frontal cortex while patients with probable Alzheimer's disease (AD) performed cognitive tasks. Whereas elderly healthy subjects (as well as patients with major depression, age-associated memory impairments or vascular dementia) again showed clear increases in the local concentrations of [HbO2] and [HbT] during brain activation, AD patients showed significant decreases compared to the baseline levels in both variables that were most pronounced in the parietal cortex. To clarify whether the different patterns in cerebral hemoglobin oxygenation during cognitive activation were due to an altered functional brain organization in AD or to alterations in the cerebrovascular response to neuronal activation, we are currently performing simultaneous NIRS and (015-H20-)PET measurements during performance of a cognitive task (Stroop test). Our finding of a regional reduced oxygen supply during activation of brain function may be of relevance to the development and the time course of neurodegeneration.