In this article, we examine phantom limb syndrome to gain insights into how the brain functions as the mind and how consciousness arises. We further explore our previously proposed consciousness model in which consciousness and body schema arise when information from throughout the body is processed by corticothalamic feedback loops and integrated by the thalamus. The parietal lobe spatially maps visual and non-visual information and the thalamus integrates and recreates this processed sensory information within a three-dimensional space termed the ‘‘3D (...) default space.’’ We propose that phantom limb syndrome and phantom limb pain arise when the afferent signaling from the amputated limb is lost but the neural circuits remain intact. In addition, integration of conflicting sensory information within the default 3D space and the loss of inhibitory afferent feedback to efferent motor activity from the amputated limb may underlie phantom limb pain. (shrink)

Our experiences with the external world are possible mainly through vision, hearing, taste, touch, and smell providing us a sense of reality. How the brain is able to seamlessly integrate stimuli from our external and internal world into our sense of reality has yet to be adequately explained in the literature. We have previously proposed a three-dimensional unified model of consciousness that partly explains the dynamic mechanism. Here we further expand our model and include illustrations to provide a better conception (...) of the ill-defined space within the self, providing insight into a unified mind-body concept. In this article, we propose that our senses “super-impose” on an existing dynamic space within us after a slight, imperceptible delay. The existing space includes the entire intrapersonal space and can also be called the “the body’s internal 3D default space”. We provide examples from meditation experiences to help explain how the sense of ‘self’ can be experienced through meditation practice associated with underlying physiological processes that take place through cardio-respiratory synchronization and coherence that is developed among areas of the brain. Meditation practice can help keep the body in a parasympathetic dominant state during meditation, allowing an experience of inner ‘self’. Understanding this physical and functional space could help unlock the mysteries of the function of memory and cognition, allowing clinicians to better recognize and treat disorders of the mind by recommending proven techniques to reduce stress as an adjunct to medication treatment. (shrink)

Current research on the various forms of autoscopic phenomena addresses the clinical and neurological correlates of out-of-body experiences, autoscopic hallucinations,and heautoscopy. Yet most of this research is based on functional magnetic resonance imaging results and focuses predominantly on abnormal cortical activity. Previously we proposed that visual consciousness resulted from the dynamic retinogeniculo-cortical oscillations, such that the photoreceptors dynamically integrated with visual and other vision-associated cortices, and was theorized to be mapped out by photoreceptor discs and rich retinal networks which synchronized (...) with the retinotopic mapping and the associated cortex. The feedback from neural input that is received from the thalamus and cortex via retinogeniculo-cortical oscillations and sent to the retina is multifold higher than feed-forward input to the cortex. This can effectively translate into out-of-body experiences projected onto the screen formed by the retina as it is perceived via feedback and feed-forward oscillations from the reticular thalamic nucleus, or “internal searchlight”. This article explores the role of the reticular thalamic nucleus and the retinogeniculo-cortical oscillations as pivotal internal components in vision and various autoscopic phenomena. (shrink)

Located within the ascending reticular activating system are nuclei which release neurotransmitters such as acetylcholine, serotonin, dopamine, and norepinephrine. These nuclei have widespread projections that extend into the limbic system and throughout cortex. Activation of these neurotransmitters during awake states leads to arousal, while inhibition leads to the loss of consciousness experienced during slow-wave sleep. Previously, we proposed a mechanism in which cardiorespiratory synchronization may underlie the widespread hyperpolarization that occurs throughout the brain during slow-wave sleep. We further propose that (...) a similar homeostatic mechanism may be involved in sleep-wake transitions and maintaining various arousal states including rapid eye movement sleep, waking, and anxiety. Widespread depolarization associated with more rapid, shallow breathing and desynchronized cardiorespiratory oscillatory activity may underlie waking, anxiety, and rapid eye movement sleep states. The exact voltage values of these widespread membrane potential changes remain unknown and possibly highly variable between different neural areas and cell types. Here, we place these consciousness states on a spectrum of approximated widespread membrane potential values with anxiety states being the most depolarized, followed by waking states, and rapid eye movement sleep. We propose that although these widespread membrane potential changes are minor, they may underlie transitions between and maintenance of varying levels of arousal. Further research on these mechanisms could provide insights into how the brain functions. This homeodynamic arousal mechanism involves the established feed-forward and feedback signaling between the ascending reticular activating system and the hypothalamus, as well as the modulation by cardiorespiratory oscillatory feedback from the body. Understanding the basic mechanisms responsible for the states of sleep, waking, and anxiety could lead to better treatment options in health and disease. (shrink)