Transient reduction of tinnitus intensity is marked by concomitant reductions of delta band power

<p>Abstract</p> <p>Background</p> <p>Tinnitus is an auditory phantom phenomenon characterized by the sensation of sounds without objectively identifiable sound sources. To date, its causes are not well understood. Previous research found altered patterns of spontaneous brain activity in chronic tinnitus sufferers compared to healthy controls, yet it is unknown whether these abnormal oscillatory patterns are causally related to the tinnitus sensation. Partial support for this notion comes from a neurofeedback approach developed by our group, in which significant reductions in tinnitus loudness could be achieved in patients who successfully normalized their patterns of spontaneous brain activity. The current work attempts to complement these studies by scrutinizing how modulations of tinnitus intensity alter ongoing oscillatory activity.</p> <p>Results</p> <p>In the present study the relation between tinnitus sensation and spontaneous brain activity was investigated using residual inhibition (RI) to reduce tinnitus intensity and source-space projected magnetencephalographic (MEG) data to index brain activity. RI is the sustained reduction (criteria: 50% for at least 30 s) in tinnitus loudness after cessation of a tonal tinnitus masker. A pilot study (n = 38) identified 10 patients who showed RI. A significant reduction of power in the delta (1.3–4.0 Hz) frequency band was observed in temporal regions during RI (p ≤ 0.001).</p> <p>Conclusion</p> <p>The current results suggest that changes of tinnitus intensity induced by RI are mediated by alterations in the pathological patterns of spontaneous brain activity, specifically a reduction of delta activity. Delta activity is a characteristic oscillatory activity generated by deafferented/deprived neuronal networks. This implies that RI effects might reflect the transient reestablishment of balance between excitatory and inhibitory neuronal assemblies, via reafferentation, that have been perturbed (in most tinnitus individuals) by hearing damage. As enhancements have been reported in the delta frequency band for tinnitus at rest, this result conforms to our assumption that a normalization of oscillatory properties of cortical networks is a prerequisite for attenuating the tinnitus sensation. For RI to have therapeutic significance however, this normalization would have to be stabilized.</p

Registro de movimientos oculares con el eye tracker Mobile eye XG

93 p.Debido a su importancia en la investigación sobre lo que sucede en el cerebro, el estudio sobre el sistema visual humano se ha especializado cada vez más para indagar sobre la influencia de los movimientos oculares en la percepción durante la observación. Con el fin de acceder a este tipo de procesos se ha diseñado un conjunto de herramientas que permiten hacer un seguimiento a los movimientos oculares, conocidos como eye trackers. Este libro tiene como objetivo aportar elementos para la planeación, el diseño y la ejecución de investigaciones que incluya el uso de eye trackers, en particular del eye tracker Mobile eye XG. Esta es una de las primeras revisiones en español que recopila información sobre los movimientos oculares. Contiene una descripción sobre el eye tracker Mobile eye XG y otros dispositivos; una revisión sobre la visión humana y los movimientos oculares; una reseña acerca de los determinantes cognoscitivos de los movimientos oculares; una aproximación a las condiciones para el diseño, la ejecución y el análisis de datos de las investigaciones con esta herramienta y una revisión sobre sus campos de aplicación.Technological advances in recent decades have made eye trackers, especially glasses, an important tool in the field of cognitive, emotional, and social neurosciences, due to the relationship that exists between visual behavior and neuronal processes. This has facilitated the study of a significant number of psychological processes, including perception, emotions, social cognition, decision making, attention, and literacy, among others. Eye trackers have been applied to research a wide range of human activities, including web page and application design and market studies, the visual behavior of drivers and athletes, human-computer interactions, simulations for military training, and as a support for the clinical diagnosis of personality disorders and neurological conditions. This book aims to provide elements for the planning, design, and execution of research that includes the use of eye trackers, in particular the Mobile Eye-XG eye tracker. This is one of the first reviews in Spanish that collects information on eye movements. The study contains a description of the Mobile Eye-XG eye tracker and other devices; a review of human vision and eye movements; a review of the cognitive determinants of eye movements; an exploration of the conditions that determine the design, execution, and data analysis of research that uses this tool, as well as a review of its fields of application.Introducción Parte 1. Descripción del eye tracker Mobile eye XG Parte 2. Visión humana y movimientos oculares Parte 3. Neurobiología de los movimientos oculares Parte 4. Determinantes cognoscitivos de las fijaciones y de los movimientos oculares Parte 5. Condiciones para el diseño y el registro de estudios con el eye tracker Mobile eye XG Parte 6. Análisis y representación gráfica de los datos Parte 7. Condiciones para el reporte de investigación Parte 8. Aplicaciones del eye tracking Referencias Anexo

Pre- and post-stimulus alpha activity shows differential modulation with spatial attention during the processing of pain.

Extensive work using magneto- and electroencephalography (M/EEG) suggests that cortical alpha activity represents a top-down controlled gating mechanism employed by processes like attention across different modalities. However, it is not yet clear to what extent this presumed gating function of alpha activity also applies to the processing of pain. In the current study, a spatial attention paradigm was employed requiring subjects to attend to painful laser stimuli on one hand while ignoring stimuli on the other hand. Simultaneously, brain activity was recorded with MEG. In order to disentangle pre- and post-stimulus effects of attention, alpha activity was analyzed during time windows in anticipation of and in response to painful laser stimulation. Painful laser stimuli led to a suppression of alpha activity over both ipsi- and contralateral primary somatosensory areas irrespective if they were attended or ignored. Spatial attention was associated with a lateralization of anticipatory pre-stimulus alpha activity. Alpha activity was lower over primary somatosensory areas when the contralateral hand was attended compared to when the ipsilateral hand was attended, in line with the notion that oscillatory alpha activity regulates the flow of incoming information by engaging and/or disengaging early sensory areas. On the contrary, post-stimulus alpha activity, for stimuli on either hand, was consistently decreased with attention over contralateral areas. Most likely, this finding reflects an increased cortical activation and enhanced alerting if a painful stimulus is attended. The present results show that spatial attention results in a modulation of both pre- and post-stimulus alpha activity associated with pain. This flexible regulation of alpha activity matches findings from other modalities. We conclude that the assumed functional role of alpha activity as a top-down controlled gating mechanism includes pain processing and most likely represents a unified mechanism used throughout the brain

Reversing pathologically increased EEG power by acoustic coordinated reset neuromodulation.

Acoustic Coordinated Reset (CR) neuromodulation is a patterned stimulation with tones adjusted to the patient's dominant tinnitus frequency, which aims at desynchronizing pathological neuronal synchronization. In a recent proof-of-concept study, CR therapy, delivered 4-6 h/day more than 12 weeks, induced a significant clinical improvement along with a significant long-lasting decrease of pathological oscillatory power in the low frequency as well as γ band and an increase of the α power in a network of tinnitus-related brain areas. As yet, it remains unclear whether CR shifts the brain activity toward physiological levels or whether it induces clinically beneficial, but nonetheless abnormal electroencephalographic (EEG) patterns, for example excessively decreased δ and/or γ. Here, we compared the patients' spontaneous EEG data at baseline as well as after 12 weeks of CR therapy with the spontaneous EEG of healthy controls by means of Brain Electrical Source Analysis source montage and standardized low-resolution brain electromagnetic tomography techniques. The relationship between changes in EEG power and clinical scores was investigated using a partial least squares approach. In this way, we show that acoustic CR neuromodulation leads to a normalization of the oscillatory power in the tinnitus-related network of brain areas, most prominently in temporal regions. A positive association was found between the changes in tinnitus severity and the normalization of δ and γ power in the temporal, parietal, and cingulate cortical regions. Our findings demonstrate a widespread CR-induced normalization of EEG power, significantly associated with a reduction of tinnitus severity

Acute Effects of Alcohol on Stimulus-Induced Gamma Oscillations in Human Primary Visual and Motor Cortices

Alcohol is a rich drug affecting both the γ-amino butyric acid (GABA) and glutamatergic neurotransmitter systems. Recent findings from both modeling and pharmacological manipulation have indicated a link between GABAergic activity and oscillations measured in the gamma frequency range (30–80 Hz), but there are no previous reports of alcohol’s modulation of gamma-band activity measured by magnetoencephalography (MEG) or electroencephalography (EEG). In this single-blind, placebo-controlled crossover study, 16 participants completed two study days, on one day of which they consumed a dose of 0.8 g/kg alcohol, and on the other day a placebo. MEG recordings of brain activity were taken before and after beverage consumption, using visual grating and finger abduction paradigms known to induce gamma-band activity in the visual and motor cortices respectively. Time–frequency analyses of beamformer source reconstructions in the visual cortex showed that alcohol increased peak gamma amplitude and decreased peak frequency. For the motor task, alcohol increased gamma amplitude in the motor cortex. These data support the notion that gamma oscillations are dependent, in part, on the balance between excitation and inhibition. Disruption of this balance by alcohol, by increasing GABAergic inhibition at GABAA receptors and decreasing glutamatergic excitation at N-methyl-D-aspartic acid receptors, alters both the amplitude and frequency of gamma oscillations. The findings provide further insight into the neuropharmacological action of alcohol