The minimal self hypothesis

For millennia self has been conjectured to be necessary for consciousness. But scant empirical evidence has been adduced to support this hypothesis. Inconsistent explications of “self” and failure to design apt experiments have impeded progress. Advocates of phenomenological psychiatry, however, have helped explicate “self,” and employed it to explain some psychopathological symptoms. In those studies, “self” is understood in a minimalist sense, sheer “for-me-ness.” Unfortunately, explication of the “minimal self” (MS) has relied on conceptual analysis, and applications to psychopathology have been hermeneutic, allowing for many degrees of interpretive latitude. The result is that MS’s current scientific status is analogous to that of the “atom,” at the time when “atom” was just beginning to undergo transformation from a philosophical to a scientific concept. Fortunately, there is now an opportunity to promote a similar transformation for “MS.” Discovery of the brain’s Default Mode Network (DMN) opened the door to neuroimaging investigations of self. Taking the DMN and other forms of intrinsic activity as a starting point, an empirical foothold can be established, one that spurs experimental research and that enables extension of research into multiple phenomena. New experimental protocols that posit “MS” can help explain phenomena hitherto not thought to be related to self, thereby hastening development of a mature science of self. In particular, targeting phenomena wherein consciousness is lost and recovered, as in some cases of Unresponsive Wakefulness Syndrome (UWS), allow for design of neuroimaging probes that enable detection of MS during non-conscious states. These probes, as well as other experimental protocols applied to NREM Sleep, General Anesthesia (GA), and the waking state, provide some evidence to suggest that not only can self and consciousness dissociate, MS might be a necessary precondition for conscious experience. Finally, these findings have implications for the science of consciousness: it has been suggested that “levels of consciousness” (LoC) is not a legitimate concept for the science of consciousness. But because we have the conceptual and methodological tools with which to refine investigations of MS, we have the means to identify a possible foundation—a bifurcation point—for consciousness, as well as the means by which to measure degrees of distance from that foundation. These neuroimaging investigations of MS position us to better assess whether LoC has a role to play in a mature science of consciousness.     

EEG neurofeedback improves cycling time to exhaustion

ObjectiveThe role of the brain in endurance performance is frequently debated; surprisingly, few investigations have attempted to improve endurance performance by directly targeting brain activity. One promising but untested approach to modifying brain activity is electroencephalogram (EEG) neurofeedback. Consequently, our experiment is the first to examine an EEG neurofeedback intervention for whole-body endurance performance.MethodWe adopted a two-part experiment. The first consisted of a randomized parallel controlled design. Forty participants were allocated to three experimental groups; increase relative left cortical activity (NFL), increase relative right (NFR), and passive control (CON). They performed a depleting cognitive task, followed by either six 2-min blocks of EEG neurofeedback training (NFL or NFR) or time-matched videos of the neurofeedback display (CON). Next, they performed a time-to-exhaustion (TTE) test on a cycle-ergometer. We then tested participants of NFL and NFR groups in an additional experimental visit and administered the opposite neurofeedback training within a fully repeated-measures protocol.ResultsEEG neurofeedback modified brain activity as expected. As hypothesized, the NFL group cycled for over 30% longer than the other groups in the parallel controlled design, NFL: 1382 ± 252 s, NFR: 878 ± 167, CON: 963 ± 117 s. We replicated this result in the repeated-measures design where NFL: 1167 ± 831 s performed 11% longer than NFR: 1049 ± 638 s. There were no differences in pre-exercise fatigue, vigor or self-control; area under the curve group-differences for perceived effort were interpreted within a goal persistence framework.ConclusionThe brief EEG neurofeedback intervention elicited greater relative left frontal cortical activity and enhanced endurance exercise performance.     

Neuroimaging the sleeping brain: Insight on memory functioning in infants and toddlers

Episodic memory, or the ability to remember past events with specific detail, is central to the human experience and is related to learning and adaptive functioning in a variety of domains. In typically developing children, episodic memory emerges during infancy and improves during early childhood and beyond. Developmental processes within the hippocampus are hypothesized to be primarily responsible for both the early emergence and persistence of episodic memory in late infancy and early childhood. However, these hypotheses are based on non-human models. In-vivo investigations in early human development of hippocampal processes have been significantly limited by methodological challenges in acquiring neuroimaging data, particularly task-related functional neuroimaging data, from infants and toddlers. Recent studies in adults have shown neural activity in the brain regions supporting episodic memory during slow-wave sleep using functional magnetic resonance imaging (fMRI), and fMRI has been increasingly utilized in infancy and early childhood to address other research questions. We review initial evidence and present preliminary data showing the promise of this approach for examining hippocampal contribution to how infants and toddlers remember individual events, and their association with information about the context in which the event occurred. Overall, our review, integrated with the presentation of some preliminary data provides insight on leveraging sleep to gain new perspectives on early memory functioning.     

成人注意缺陷多动障碍在内外源冲突时的表现:眼动的证据

在注意定向与维持上,注意缺陷多动障碍(ADHD)个体更容易受到外部刺激的干扰而导致目标任务加工进程受阻,表现出了注意定向反应的缺陷,但导致任务失败的原因是由于对突然出现的外部无关刺激的过度兴奋还是对内源性目标刺激的持续维持能力减弱,尚不清楚。研究采用反向眼跳范式、记忆导向眼跳范式和视觉导向眼跳范式,来探索成人ADHD内外源注意定向反应的情况,以及当二者发生冲突时,成人ADHD失败的可能机制。结果发现,在反向眼跳任务上,成人注意缺陷多动障碍组错误率更高,并且差异性显著。但在记忆导向眼跳任务中,成人注意缺陷多动障碍组与正常组的差异不显著。在视觉导向眼跳任务中,成人注意缺陷多动障碍组的正确眼跳潜伏期比正常组要短,且二者之间的差异显著。这说明,在内外源刺激反应的冲突导致的情境中,成人注意缺陷多动障碍的反应明显落后于正常个体,这种缺陷并非由于其维持内源性注意产生定向反应落后所导致的,而是与其外源注意定向反应过强有关。