Infrared oculography-validation of a new method to monitor startle eyeblink amplitudes during fMRI

Amplitude modulation of the eyeblink component of the startle response is a commonly used index for the emotional state of an organism. The use of electromyography (EMG) to determine startle eyeblink amplitudes during functional magnetic resonance imaging (fMRI) is limited as interactions between strong switching magnetic fields, radio pulses and electrodes introduce large artefacts in EMG recordings. We demonstrate a robust linear correlation between time courses and amplitudes of startle eyeblinks recorded by EMG and infrared oculography (IOG), an fMRI compatible technique based on infrared light reflection from the subject's eye. Moreover, our data indicate that IOG, like EMG, recordings of startle eyeblink amplitudes are predicted by verbal ratings of the emotional valence of pictorial foreground stimuli. Thus, IOG provides a valid method to record startle eyeblinks and might be used to monitor affective state during fMRI

AVALIAÇÃO de Usabilidade, Desempenho Ocupacional e Satisfação Com Sistema de Controle de Ambiente Inteligente Por Pessoas Com Deficiência Motora Severa Através de Eletromiografia de Superfície e Oculografia Por Infravermelho

Um ambiente inteligente (AI) é um recurso de Tecnologia Assistiva (TA) que permite que pessoas com deficiência motora, mesmo com pouca mobilidade, possam controlar a iluminação e equipamentos eletrônicos (TV, rádio, ventilador, etc) do ambiente por meio de uma Interface Humano-Máquina (IHM) configurada para ser acionada por sinais biomédicos. No entanto, apesar da reconhecida importância, nem sempre o recurso de TA é considerado útil, atingindo altos índices de abandono, já que é necessária uma avaliação prévia e prescrição feita por profissionais, levando em consideração as reais demandas e necessidades da pessoa com deficiência. Esta Tese de Doutorado objetiva avaliar a eficácia de um sistema de ambiente inteligente controlado através de eletromiografia de superfície e de oculografia por infravermelho, captada por um eye tracker, utilizado por pessoas com deficiências motoras. Seis voluntários participaram da pesquisa, e, inicialmente, foram aplicados formulários de dados sóciodemográficos, Medida de Independência Funcional (MIF) e Medida Canadense de Desempenho Ocupacional (COPM). Os sujeitos foram apresentados aos equipamentos e interface do sistema, sendo treinados para seu uso em ambiente doméstico, utilizando o sistema por uma semana. Após, foram reavaliados com a COPM, além de avaliações de satisfação com o uso do recurso de TA (formulário B-QUEST 2.0), impacto psicossocial (formulário PIADS), usabilidade do sistema (formulário SUS) e entrevista semiestruturada para sugestões ou queixas. O controle da TV foi a demanda comum a todos os participantes. Como resultado desta pesquisa, dos seis voluntários, quatro utilizaram o sistema, apresentando resultados positivos em relação à mudança no desempenho ocupacional, satisfação com o desempenho e com o sistema de ambiente inteligente, alto impacto psicossocial e boa usabilidade do sistema. Avaliou-se que o sistema desenvolvido também proporcionou maior independência dos voluntários para o controle dos equipamentos. Quanto aos voluntários que não usaram o sistema, aspectos como não aceitação da deficiência e a falta de suporte social podem ter influenciado. O sistema de AI mostrou-se eficaz, apresentando melhora de todos os aspectos avaliados nos participantes. Uma solicitação de patente do sistema desenvolvido foi submetida ao INIT-UFES. Estudos futuros devem considerar a ampliação das possibilidades de equipamentos e dispositivos controlados, bem como do tempo de uso

Un nuovo approccio metodologico per l’indagine della modificazione del riflesso di trasalimento (startle) nei primi mesi di vita

The startle reflex is an innate defensive reaction (Lang, 1995; Yeomans, Li, Scott, & Frankland, 2002), delegate to the instantaneous reaction following an unexpected and intense stimulus. The startle widely satisfies the requirements essential to be used as a research tool, since it is modified by the experience, it is easily and universally elicitable (Landis & Hunt, 1939), and its physical and temporal characteristics are well known and highly controllable (Costa & Ricci Bitti, 1998; Davis, Hitchcock, & Rosen, 1987). Yet, despite the importance of the study of this reflex in various research fields (from the study of motivational, emotional and attentive phenomena, to the investigation of neurological, neurophysiological and neuropsychological diseases; Balaban, 1996; Lang, 1995; Richards, 1998; Prechtl & Beintema, 1964), the startle modification is still relatively unexplored in early infancy. This lack in developmental psychological research is mainly due to two problems: the difficulty to identify and develop new methodologies suitable to explore the startle modification in early infancy; the intrusiveness and invasiveness of the commonly used measurement methodology, that is the eyeblink electromyography. Two experimental studies are presented in this dissertation. They were designed to explore the startle modification by using a new non-invasive methodology (AIMMSS) and a new experimental paradigm based on the use of infants facial expressions. In particular, the main indexes of positive (smile) and negative (distress) facial expressions were analysed using the most known anatomically based systems to coding the infants’ facial behaviour (Baby FACS, Oster, in press; AFFEX, Izard, Dougherty, & Hembree, 1983; MAX, Izard, 1979). The first study (N = 12) was aimed at analysing the affective modulation of the startle response elicited during the 5-month-old infants’ spontaneous exhibition of positive facial expressions (smile) and negative facial expressions (distress). The data obtained induce to hypothesize that the facial expressions act like a sort of motivational priming able to diversify, depending on their negative (distress) or positive (smile) nature, the intensity of the startle response elicited immediately after their exhibition. The second study (N = 26) was designed to analyse the modulatory influences exerted on the startle response by both the attentive state and the emotional state displayed by 3- and 5-month-old infants. The main result highlights that a synergy between the attentive and emotional systems cause the phenomenon of the affective modulation of the startle response

The neural basis of the sense of fatigue

Evidence suggests that the genesis and regulation of the sense of exertional fatigue is rooted within the same neural networks responsible for processing affective responses. One key mechanism proposed to be involved in the sense of exertional fatigue is the interaction between the cognitive inhibitory processes of the dorsolateral prefrontal cortex (DLPFC) and the interoceptive inputs to the amygdala. The primary purpose of this dissertation is to examine the development and progression of exertional fatigue during exercise by examining the interactions between the level of bodily perturbations evoked by the exercise, the activity of the DLPFC (Tissue Oxygenation Index [TOI] percentage), the amygdala (indexed by the acoustic startle eyeblink response [ASER] amplitude), and affective responses (Empirical Valence Scale [EVS] score). The secondary purpose is to modulate the interaction between the DLPFC TOI, the EVS scores, and the ASER amplitudes using transcranial direct current stimulation (tDCS), to explore its potential as a treatment for attenuating the sense of fatigue during physical exertion. Individual differences were also examined. Thirty healthy university students—12 women and 18 men—exercised on a cycle ergometer for up to 20 minutes or until volitional termination at (1) heavy-intensity exercise while receiving sham tDCS on the right and left DLPFC (H-Sham), (2) heavy-intensity exercise while receiving active tDCS (H-Active), (3) severe-intensity exercise while receiving sham tDCS (S-Sham), and (4) severe-intensity exercise while receiving active tDCS (S-Active). The rate of decline in EVS scores was significantly greater during severe-intensity exercise compared to heavy-intensity exercise. The decline in the right and left DLPFC TOI percentages was significantly greater during severe-intensity exercise compared to heavy-intensity exercise, and this decline was larger in the right DLPFC compared to the left DLPFC. During both exercise intensities, the strength of the correlations between EVS scores and the right and left DLPFC TOI percentages increased as the interoceptive cues intensified. tDCS significantly increased DLPFC TOI percentages and the pattern of the ASER amplitudes. In conjunction with the decline in EVS scores, the drop in TOI was most prominent during severe-intensity exercise when, on average, the right DLPFC TOI dropped below baseline and, therefore, the DLPFC entered a hypometabolic state. Individuals with a higher level of tolerance demonstrated a greater activation of the right DLPFC during the heavy-intensity exercise compared to individuals with lower tolerance. The findings of this dissertation suggest that affective responses during exercise were a function of both the severity of homeostatic perturbations and the level of inhibitory control exerted by the right DLPFC. These results support the model for hemispheric specialization of the right PFC in the cognitive inhibition of displeasure. The regulation of the sense of exertional fatigue is, therefore, likely controlled by the right DLPFC. Exertional fatigue emerged at a defined threshold. Accordingly, the physiological response pattern entered a non-steady-state, accompanied by feelings of greater displeasure (or less pleasure) and high perceived activation. Proximal to the point of termination, the hypometabolic state of the DLPFC and the decline in affective responses were not reversed with active tDCS. As such, near one’s physiological limits, if the deactivation of the DLPFC and the corresponding displeasure serve to protect the body from reaching dangerous levels of perturbation, then this mechanism appears to be immutable. Future work should evaluate the potential of therapies that target the modulation of DLPFC inhibitory control (top–down) or interoceptive sensitivity (bottom–up) networks in relation to types of fatigue (e.g., clinical)