Vision loss after optic neuropathy is considered irreversible. Here, repetitive transorbital alternating current stimulation (rtACS) was applied in partially blind patients with the goal of ...activating their residual vision.
We conducted a multicenter, prospective, randomized, double-blind, sham-controlled trial in an ambulatory setting with daily application of rtACS (n = 45) or sham-stimulation (n = 37) for 50 min for a duration of 10 week days. A volunteer sample of patients with optic nerve damage (mean age 59.1 yrs) was recruited. The primary outcome measure for efficacy was super-threshold visual fields with 48 hrs after the last treatment day and at 2-months follow-up. Secondary outcome measures were near-threshold visual fields, reaction time, visual acuity, and resting-state EEGs to assess changes in brain physiology.
The rtACS-treated group had a mean improvement in visual field of 24.0% which was significantly greater than after sham-stimulation (2.5%). This improvement persisted for at least 2 months in terms of both within- and between-group comparisons. Secondary analyses revealed improvements of near-threshold visual fields in the central 5° and increased thresholds in static perimetry after rtACS and improved reaction times, but visual acuity did not change compared to shams. Visual field improvement induced by rtACS was associated with EEG power-spectra and coherence alterations in visual cortical networks which are interpreted as signs of neuromodulation. Current flow simulation indicates current in the frontal cortex, eye, and optic nerve and in the subcortical but not in the cortical regions.
rtACS treatment is a safe and effective means to partially restore vision after optic nerve damage probably by modulating brain plasticity. This class 1 evidence suggests that visual fields can be improved in a clinically meaningful way.
ClinicalTrials.gov NCT01280877.
Covertly directing visual attention toward a spatial location in the absence of visual stimulation enhances future visual processing at the attended position. The neuronal correlates of these ...attention shifts involve modulation of neuronal "baseline" activity in early visual areas, presumably through top-down control from higher-order attentional systems. We used electroencephalography to study the largely unknown relationship between these neuronal modulations and behavioral outcome in an attention orienting paradigm. Covert visuospatial attention shifts to either a left or right peripheral position in the absence of visual stimulation resulted in differential modulations of oscillatory alpha-band (8-14 Hz) activity over left versus right posterior sites. These changes were driven by varying degrees of alpha-decreases being maximal contralateral to the attended position. When expressed as a lateralization index, these alpha-changes differed significantly between attention conditions, with negative values (alpha_right < alpha_left) indexing leftward and more positive values (alpha_left < or = alpha_right) indexing rightward attention. Moreover, this index appeared deterministic for processing of forthcoming visual targets. Collapsed over trials, there was an advantage for left target processing in accordance with an overall negative bias in alpha-index values. Across trials, left targets were detected most rapidly when preceded by negative index values. Detection of right targets was fastest in trials with most positive values. Our data indicate that collateral modulations of posterior alpha-activity, the momentary bias of visuospatial attention, and imminent visual processing are linked. They suggest that the momentary direction of attention, predicting spatial biases in imminent visual processing, can be estimated from a lateralization index of posterior alpha-activity.
Research has suggested that computer-mediated communication (CMC) can be effective in facilitating positive psychosocial outcomes when such interactions increase one's perceived social support. These ...findings bear valuable implications for sexual minority men (SMM), who can experience a lack of social support due to their stigmatized identities, and thus may turn to social networking sites (SNS) for identity-related support. This research quantitatively examined whether perceived identity-related social support received on SNS was associated with positive psychosocial outcomes in SMM. Participants (N = 205) completed an online survey measuring interactions with similar others (i.e., people who identity as sexual and/or gender minorities) on SNS and face-to-face (FTF), perceived identity-related support from SNS and FTF sources, perceptions of mattering (i.e., feelings that one is important to others), and psychological well-being. Results revealed that identity-related SNS support from similar others was associated with higher psychological well-being above and beyond FTF support. Similarly, SNS support from similar others was associated with higher perceptions of mattering when FTF support from friends was relatively low. These associations were specific to support received from similar others and not from non-similar others (i.e., cisgender heterosexual interaction partners). Results suggest that SNS support from similar others is related to positive psychosocial outcomes for SMM, even when FTF support is lacking.
•Sexual minority men use the internet to connect with supportive similar others.•Interactions with similar others are more frequent online than in-person.•Online support is associated with well-being over and above offline support.•Online support is associated with mattering when offline support is low.•Positive associations only found for online support from similar others.
Cognitive control can be reactive or proactive in nature. Reactive control mechanisms, which support the resolution of interference, start after its onset. Conversely, proactive control involves the ...anticipation and prevention of interference prior to its occurrence. The interrelation of both types of cognitive control is currently under debate: Are they mediated by different neuronal networks? Or are there neuronal structures that have the potential to act in a proactive as well as in a reactive manner? This review illustrates the way in which integrating knowledge gathered from behavioral studies, functional imaging, and human electroencephalography proves useful in answering these questions. We focus on studies that investigate interference resolution at the level of working memory representations. In summary, different mechanisms are instrumental in supporting reactive and proactive control. Distinct neuronal networks are involved, though some brain regions, especially pre-SMA, possess functions that are relevant to both control modes. Therefore, activation of these brain areas could be observed in reactive, as well as proactive control, but at different times during information processing.
There is an ongoing need for clear explanation of the diagnostic entity called "irreversible loss of brain function" (ILBF), as the absolute reliability of this diagnosis and its significance ...continue to be widely misunderstood. The determination of death as an objective medical-scientific matter is often not clearly distinguished from various other aspects of death, such as its metaphysical and cultural aspects and the ways in which the living deal with the dead.
This review is based on articles retrieved by a selective literature search in the PubMed database and on guidelines and standardized diagnostic protocols from Germany and abroad.
ILBF can be caused by brain ischemia or anoxia or by any other type of brain disease or injury leading to an elevation of the intracranial pressure above the blood pressure and thereby to an arrest of the cerebral circulation. All situations in which brain function is merely reduced but not abolished, or only temporarily but not permanently abolished, can be clearly differentiated from ILBF through the use of standard diagnostic procedures as recommended in the relevant guidelines. Biological features that are common to all human beings underlie the medical criteria for the determination of death. The most important elements of the determination of death are irreversibility of the loss of brain function, loss of integration of bodily functions into a single living being, and loss of ability for any self-reflection or any independent interaction with the environment.
ILBF is a reliable sign that a human being is dead. There has never been even one known case of incorrect determination of ILBF after proper application of the standardized diagnostic procedures that are set down in the guideline according to §16 of the German Transplantation Law.
We used eye tracking to quantify the extent to which combinations of salient contrasts (orientation, luminance, and movement) influence a central salience map that guides eye movements. We found that ...luminance combined additively with orientation and movement, suggesting that the salience system processes luminance somewhat independently of the two other features. On the other hand, orientation and movement together influenced salience underadditively, suggesting that these two features are processed nonindependently. This pattern of results suggests that the visual system does not sum sources of salience linearly, but treats some sources of salience as redundant.
Little is known about how the human brain processes multiple relevant information streams competing for behavior. The present study aimed at specifying the interaction of the lateral prefrontal ...cortex (lPFC) with task-relevant sensory brain regions during concurrent stimulus processing of two relevant stimuli (S1, S2) in a classical dual-task situation. In detail, we tested whether S1 processing is independent of the task relevance of S2 as has been hypothesised in cognitive theories on dual-task processing. Using functional Magnetic Resonance Imaging, we tested two neural mechanisms that might reflect effects of S2 relevance on S1 processing at different temporal overlaps. The results indicate that: (1) activity amplitudes in S1-relevant regions in the inferior temporal cortex were similarly affected by the temporal overlap between the two stimuli when S2 was relevant or irrelevant and (2) only when S2 was relevant in the dual task, significant increases in the functional coupling between S1-relevant regions and dual-task-related regions in the posterior lPFC were present at high temporal overlap. No similar effects were found for S2-relevant regions. These findings suggest that concurrent stimulus processing in dual tasks is realised by transient changes in functional coupling for stimuli with relatively higher priority (S1).
•Effects of tDCS on performance monitoring examined in OCD and healthy individuals.•A preregistered, randomized, sham-controlled tDCS–EEG study was conducted.•Cathodal tDCS over the pre-SMA reduced ...the error-related negativity (ERN).•Correct-response negativity was enhanced, error positivity reduced by cathodal tDCS.•The findings substantiate the role of the ERN as a target for new interventions.
Overactive performance monitoring, as reflected by enhanced neural responses to errors (the error-related negativity, ERN), is considered a biomarker for obsessive-compulsive disorder (OCD) and may be a promising target for novel treatment approaches. Prior research suggests that non-invasive brain stimulation with transcranial direct current stimulation (tDCS) may reduce the ERN in healthy individuals, yet no study has investigated its efficacy in attenuating the ERN in OCD. In this preregistered, randomized, sham-controlled, crossover study, we investigated effects of tDCS on performance monitoring in patients with OCD (n = 28) and healthy individuals (n = 28). Cathodal and sham tDCS was applied over the presupplementary motor area (pre-SMA) in two sessions, each followed by electroencephalogram recording during a flanker task. Cathodal tDCS reduced the ERN amplitude compared to sham tDCS, albeit this effect was only marginally significant (p = .052; mean difference: 0.86 μV). Additionally, cathodal tDCS reduced the correct-response negativity and increased the error positivity. These neural modulations were not accompanied by behavioral changes. Moreover, we found no evidence that the tDCS effect was more pronounced in the patient group. In summary, our findings indicate that tDCS over the pre-SMA modulates neural correlates of performance monitoring across groups. Therefore, this study represents a valuable starting point for future research to determine whether repeated tDCS application induces a more pronounced ERN attenuation and normalizes aberrant performance monitoring in the long term, thereby potentially alleviating obsessive-compulsive symptoms and providing a psychophysiological intervention strategy for individuals who do not benefit sufficiently from existing interventions.
The determination of the irreversible cessation of brain function (ICBF) is conducted in Germany according to the guideline of the German Medical Association, which is currently its fourth update ...issued in July 2015. This article provides an assessment of the current situation including an international comparison. International case reports with allegedly incorrect ICBF diagnosis are reviewed from the point of view of the German guideline. These case reports underpin the validity of the German guideline, especially its following provisions: (1) in patients with known or suspected adaptation to chronic hypercapnia, apnea cannot be diagnosed as usual; therefore in such a case the proof of cerebral circulatory arrest is mandatory; (2) if perfusion scintigraphy is used for proof of cerebral circulatory arrest, only validated lipophilic radiopharmaceuticals are allowed. This is compatible with new research data which indicate that cellular function can be reactivated for several hours after circulatory arrest but not the brain function. The recently updated recommendations of the German Society for Clinical Neurophysiology and Functional Imaging (DGKN) for ancillary testing include editorial adaptations (e.g., the more precise specification of the electrode positions for electroencephalography), standards of display screen with digital electroencephalography and age-related minimum values of mean arterial pressure for Doppler and duplex sonography in children. The novel requirements regarding the institutional organization of ICBF diagnostics in Germany issued in the "Second law on the amendment of transplantation law-improvement of the cooperation and the framework for organ donation" that became effective recently are presented and discussed critically in this review.
Intimate partner violence (IPV) is prevalent among young gay and bisexual men (YGBM) and is associated with physical and mental health problems, as well as deleterious psychosocial conditions. Most ...previous studies of IPV among YGBM have been quantitative in nature and have not examined the numerous subtypes of IPV, the chronicity of IPV experiences, and how is IPV manifested in the context of these same-sex relationships. Thus, a qualitative approach may be useful in exploring these multidimensional and understudied experiences. The present qualitative study sought to (a) explore dimensions of IPV victimization, perpetration, and bidirectional IPV among a sample of (n = 26) YGBM living in New York City and (b) explore the chronicity of IPV experiences among these YGBM. Participants were recruited from an ongoing cohort study of YGBM. Participants completed semistructured interviews that included questions about IPV victimization, perpetration, and bidirectional IPV. A modified version of the consensual qualitative research method was used to analyze the data. The YGBM in this study reported numerous forms of physical, psychological, sexual, and financial IPV victimization and perpetration. Bidirectional experiences of IPV were common. The various subtypes of IPV victimization and perpetration are explored in detail in this manuscript. In addition, many participants reported multiple experiences of abuse within the same relationship, and some participants experienced a pattern of abusive relationships over time. This study corroborates findings from quantitative studies, which indicate that IPV is a prevalent and significant health problem among YGBM, and one that warrants additional attention from researchers, practitioners, and policy-makers. Furthermore, this study adds rich qualitative data to the existing literature—data that can be used to help develop and refine future measures of IPV that are tailored for use with YGBM.
PDF
