Tuning and disrupting the brain—modulating the McGurk illusion with electrical stimulation

In the so-called McGurk illusion, when the synchronized presentation of the visual stimulus /ga/ is paired with the auditory stimulus /ba/, people in general hear it as /da/. Multisensory integration processing underlying this illusion seems to occur within the Superior Temporal Sulcus (STS). Herein, we present evidence demonstrating that bilateral cathodal transcranial direct current stimulation (tDCS) of this area can decrease the McGurk illusion-type responses. Additionally, we show that the manipulation of this audio-visual integrated output occurs irrespective of the number of eye-fixations on the mouth of the speaker. Bilateral anodal tDCS of the Parietal Cortex also modulates the illusion, but in the opposite manner, inducing more illusion-type responses. This is the first demonstration of using non-invasive brain stimulation to modulate multisensory speech perception in an illusory context (i.e., both increasing and decreasing illusion-type responses to a verbal audio-visual integration task). These findings provide clear evidence that both the superior temporal and parietal areas contribute to multisensory integration processing related to speech perception. Specifically, STS seems fundamental for the temporal synchronization and integration of auditory and visual inputs. For its part, posterior parietal cortex (PPC) may adjust the arrival of incoming audio and visual information to STS thereby enhancing their interaction in this latter area

Polarity-Dependent Transcranial Direct Current Stimulation Effects on Central Auditory Processing

Given the polarity dependent effects of transcranial direct current stimulation (tDCS) in facilitating or inhibiting neuronal processing, and tDCS effects on pitch perception, we tested the effects of tDCS on temporal aspects of auditory processing. We aimed to change baseline activity of the auditory cortex using tDCS as to modulate temporal aspects of auditory processing in healthy subjects without hearing impairment. Eleven subjects received 2mA bilateral anodal, cathodal and sham tDCS over auditory cortex in a randomized and counterbalanced order. Subjects were evaluated by the Random Gap Detection Test (RGDT), a test measuring temporal processing abilities in the auditory domain, before and during the stimulation. Statistical analysis revealed a significant interaction effect of time vs. tDCS condition for 4000 Hz and for clicks. Post-hoc tests showed significant differences according to stimulation polarity on RGDT performance: anodal improved 22.5% and cathodal decreased 54.5% subjects' performance, as compared to baseline. For clicks, anodal also increased performance in 29.4% when compared to baseline. tDCS presented polarity-dependent effects on the activity of the auditory cortex, which results in a positive or negative impact in a temporal resolution task performance. These results encourage further studies exploring tDCS in central auditory processing disorders

Talking bodies: nonverbal behavior in the assessment of depression severity

BACKGROUND:\ud Evaluations of clinical depression are traditionally based on verbal information. Nonverbal expressive behavior, however, being associated with a person's reflexive responses, may reveal negative emotional or social processes that are not under complete control of the patients. However, investigations of nonverbal behavior in the evaluation of depressed patients are still scarce. This study examines the nonverbal behaviors of a group of Brazilian patients, associating their nonverbal behavior with severity of depression.\ud \ud METHODS:\ud Forty depressed patients were evaluated at baseline (T0) and after a two-week transcranial direct current stimulation treatment (T1), according to rating scales and through a 21-category Ethogram for assessment of the frequency of nonverbal behaviors displayed during an interview.\ud \ud RESULTS:\ud Behaviors that were related to negative feelings and social disinterest decreased with corresponding clinical improvement and were associated with increased severity of symptoms at T0 and greater negative affect and dissatisfaction at T1. Pro-social behaviors were associated with milder symptoms at T0 and increased after treatment. Facial, head and hand expressive movements stood out as important indicators because of their associations with severity of depression.\ud \ud LIMITATIONS:\ud Duration of behaviors was not assessed and there was not a healthy control group with which to compare the findings.\ud \ud CONCLUSIONS:\ud These results support the usefulness of nonverbal behavior as an evaluation technique in the assessment of clinical depression.Brazilian National Counsel of Technological and Scientific Development-CNPq - 142158/2006-2Sao Paulo Research Foundation-FAPESP - 11/51732-6Sao Paulo Research Foundation-FAPESP - 12/50879-

Medial prefrontal cortex stimulation modulates irony processing as indexed by the N400

In this study, we investigated whether the ERP responses observed during a verbal irony comprehension task might represent the cortical manifestation of the Medial Prefrontal Cortex (MPFC) activity. We performed a tDCS-EEG study in which we analyzed the effects of tDCS polarities (anode, cathode, sham) over the MPFC during a verbal irony task. We presented visual short stories portraying everyday situations followed by written statements in either an ironic or literal condition, whose meaning was referred to in the previous context. We manipulated the valence of the stimuli by presenting positive sentences or negative sentences in the ironic and literal conditions. The results revealed that the participants who received the anodal stimulation showed no differences in the N400 amplitude in response to the literal and the ironic condition. This could suggest that anodal stimulation has modulatory effects on N400 responses during irony comprehension. Our results indicated that the MPFC might be critical in accessing ironic information at the initial stage of irony comprehension. Finally, we found that the ironic compliments were more difficult to understand compared to the literal ones, suggesting that irony comprehension is affected by the valence of the information presented

Transcranial Direct Current Stimulation: From Basic Research on Psychological Processes to Rehabilitation Estimulação Transcraniana por Corrente Contínua: Da Pesquisa Básica sobre Processos Psicológicos Básicos à Reabilitação Resumo

Abstract Transcranial direct current stimulation (tDCS) is an "old/new" noninvasive brain modulation technique that has gained increasing popularity and relevance in psychology and neuroscience. The contemporary tDCS procedure is effective and painless. It was shown to modulate motor performance and several sensory and cognitive functions. It can be used to study cortical organization and clarify brain-behavior relationships. Using tDCS for rehabilitation is a promising strategy, and numerous publications suggest that it can be used alone or combined to augment the outcomes of behavioral training and pharmacological interventions. Compared with other brain modulation techniques, it has the advantage of being noninvasive and safe, with easy and effective placebo controls. Its effi cacy, low cost, and ease of use make tDCS a very convenient tool for researchers in developing countries. This review introduces tDCS to a new audience and seeks to inspire future investigations in the fi eld. We highlight work that illustrates the main concepts and applications of tDCS as a basic research and rehabilitation tool. Keywords: Transcranial Direct Current Stimulation, basic research, rehabilitation. Estimulação Transcraniana por Corrente Contínua: Da Pesquisa Básica sobre Processos Psicológicos Básicos à Reabilitação Resumo Estimulação Transcraniana por Corrente Contínua (ETCC) é uma técnica de estimulação cerebral não-invasiva com crescente popularidade na pesquisa em psicologia e neurociências. A aplicação da ETCC é indolor, efi caz e pode afetar o desempenho motor, sensorial e cognitivo. ETCC pode ser usada para estudar a organização cortical e relações entre cérebro e comportamento. Seu uso clínico também é relevante e vários estudos sugerem que pode ser aplicada só ou como complemento a intervenções com

Mapping Spectral Traces Symposium Guide 2010

Mapping Spectral Traces is an international and interdisciplinary Virginia Tech Humanities Symposium that considers how difficult pasts can be researched, documented, represented, and animated in responsible and ethical ways. Held at historic, educational, and artistic venues in Blacksburg, Christiansburg, and Roanoke, the series calls on Virginia Tech faculty and students, local community members and leaders, and invited international artists and scholars to engage with a larger public to consider and develop socially engaged and creative research practices that might enable us to become witnesses of the geographies of loss that continue to structure local and global worlds. The range of events and venues, and forms of collaboration and conversation is intended to allow participants to explore multi-sensual aesthetic forms, alternative narratives, and activist topographies that delve into terrains not usually observable on Cartesian maps. International and local artists, scholars, and practitioners will consider the following questions through exhibitions, workshops, excursions, lectures, and forums

Falsa memória e autismo: qual é a extensão dos déficits semânticos?

En las últimas décadas el interés por la investigación de la falsa memoria se ha ampliado. Sin embargo, se observan pocos estudios que investigan los componentes electrofisiológicos subyacentes implicados en el reconocimiento verdadero y el falso, especialmente con respecto a los pacientes con autismo. Este artículo tiene como ob-jetivo presentar los estudios de investigación de la falsa memoria y procesamiento se-mántico en las personas con desarrollo típico a través del uso de la electroencefalogra-fía, además de presentar la literatura restringida sobre el tema en los pacientes con autismo. Existe un debate acerca de los déficits semánticos en el autismo, pero hay pocos estudios en esta área y con resultados contradictorios. Por último, se presentan nuevas direcciones para el desarrollo y mejora de nuevos estudios