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Investigating the role of oscillations in endogenous and exogenous attentional states : novel methods in neurophenomenology

Abstract : The work presented in this thesis aims to extend our scientific understanding of the subtle relationships between our phenomenological experience of specific states of consciousness, and the corresponding and potentially causal effects on neural activity. In our first experiment, we focused on a phenomenon referred to as spontaneous thought or mind wandering. Our vastly complex inner landscape is an essential aspect of our conscious experience, with research suggesting that people are engaged in some form of inner dialogue unrelated to their surroundings 50% of waking hours. These ongoing trains of thought have been consistently linked to reports of negative affect, even when the specific content is positive. Interestingly, the cornerstones of most meditation and contemplative practices are; a) training the continuous and flexible monitoring of mind wandering and sensory experience, b) the cultivation of sustained attention, and c) enhanced metacognitive awareness. Given that we are generally unaware of mind wandering when it occurs, meditation practitioners may provide more accurate first person phenomenological reports and descriptions of these temporally fluctuating states given their respective training. Thus, we designed a novel paradigm based on experience sampling probe presentations to gain insight into the dynamic measures of mental activity and EEG during meditation. Our findings suggest that meditation expertise is associated with an attenuated frequency of mind wandering, and that meditation training reduces the susceptibility of the mind to wander subsequently leading to longer periods of reported meditative absorption. Increases in theta activity (4-7 Hz) over frontal midline regions of the cortex, and alpha activity (9-12 Hz) primarily focused over the somatosensory cortex, appear to be markers of sustained meditative states when compared to mind wandering. Based on the robustness of the frontal midline theta in advanced meditators, alongside a multitude of findings demonstrating that frontal theta may serve as the backbone for cognitive control via long range information integration in neural networks throughout the brain, we then developed a methodologically novel and exhaustive neurofeedback protocol with the aim of training frontal midline theta (3.5-6.5 Hz at electrode site Fz) by means of instructing our subjects to engage in focused breathing and other techniques similar to meditation. After eight training sessions, we found that subjects who received real neurofeedback were able to significantly modulate and increase theta activity (3-7 Hz) over frontal regions, whereas subject's receiving age and gender matched sham (pseudo) feedback were not. We additionally observed significant modulations in both the alpha (9-11 Hz) and beta bands (13-20 Hz) in subjects who received real neurofeedback training. Together, these findings provide evidence that we can successfully connect neurophysiological features and data to the phenomenological nature of our subjective experience.
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  • HAL Id : tel-01772802, version 1

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Tracy Brandmeyer. Investigating the role of oscillations in endogenous and exogenous attentional states : novel methods in neurophenomenology. Neuroscience. Université Paul Sabatier - Toulouse III, 2017. English. ⟨NNT : 2017TOU30026⟩. ⟨tel-01772802⟩

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