Following is a synthetic review on the minimal living cell, defined as an artificial or a semi-artificial cell having the minimal and sufficient number of components to be considered alive. We describe concepts and experiments based on these constructions, and we point out that an operational definition of minimal cell does not define a single species, but rather a broad family of interrelated cell-like structures. The relevance of these researches, considering that the minimal cell should also correspond to the early simple cell in the origin of life and early evolution, is also explained. In addition, we present detailed data in relation to minimal genome, with observations cited by several authors who agree on setting the theoretical full-fledged minimal genome to a figure between 200 and 300 genes. However, further theoretical assumptions may significantly reduce this number (i.e. by eliminating ribosomal proteins and by limiting DNA and RNA polymerases to only a few, less specific molecular species). Generally, the experimental approach to minimal cells consists in utilizing liposomes as cell models and in filling them with genes/enzymes corresponding to minimal cellular functions. To date, a few research groups have successfully induced the expression of single proteins, such as the green fluorescence protein, inside liposomes. Here, different approaches are described and compared. Present constructs are still rather far from the minimal cell, and experimental as well as theoretical difficulties opposing further reduction of complexity are discussed. While most of these minimal cell constructions may represent relatively poor imitations of a modern full-fledged cell, further studies will begin precisely from these constructs. In conclusion, we give a brief outline of the next possible steps on the road map to the minimal cell.
The aim of our study was to use functional magnetic resonance imaging to investigate how spontaneous activity interacts with evoked activity, as well as how the temporal structure of spontaneous activity, that is, long-range temporal correlations, relate to this interaction. Using an extremely sparse event-related design (intertrial intervals: 52-60 s), a novel blood oxygen level-dependent signal correction approach (accounting for spontaneous fluctuations using pseudotrials) and phase analysis, we provided direct evidence for a nonadditive interaction between spontaneous and evoked activity. We demonstrated the discrepancy between the present and previous observations on why a linear superposition between spontaneous and evoked activity can be seen by using co-occurring signals from homologous brain regions. Importantly, we further demonstrated that the nonadditive interaction can be characterized by phase-dependent effects of spontaneous activity, which is closely related to the degree of long-range temporal correlations in spontaneous activity as indexed by both power-law exponent and phase-amplitude coupling. Our findings not only contribute to the understanding of spontaneous brain activity and its scale-free properties, but also bear important implications for our understanding of neural activity in general.
The results show that worry in normal subjects and in subjects with GAD is based on activation of the medial prefrontal and anterior cingulate regions, known to be involved in mentalization and introspective thinking. A dysregulation of the activity of this region and its circuitry may underpin the inability of GAD patients to stop worrying.
ResearchCite this article: Ferri F, Chiarelli AM, Merla A, Gallese V, Costantini M. 2013 The body beyond the body: expectation of a sensory event is enough to induce ownership over a fake hand. Proc R Soc B 280: 20131140. http The body beyond the body: expectation of a sensory event is enough to induce ownership over a fake hand More than 100 papers have been published on the rubber hand illusion since its discovery 14 years ago. The illusion has been proposed as a demonstration that the body is distinguished from other objects by its participation in specific forms of intermodal perceptual correlation. Here, we radically challenge this view by claiming that perceptual correlation is not necessary to produce the experience of this body as mine. Each of 15 participants was seated with his/her right arm resting upon a table just below another smaller table. Thus, the real hand was hidden from the participant's view and a life-sized rubber model of a right hand was placed on the small table in front of the participant. The participant observed the experimenter's hand while approaching-without touching-the rubber hand. Phenomenology of the illusion was measured by means of skin conductance response and questionnaire. Both measures indicated that participants experienced the illusion that the experimenter's hand was about to touch their hidden hand rather than the rubber hand, as if the latter replaced their own hand. This did not occur when the rubber hand was rotated by 1808 or replaced by a piece of wood. This illusion indicates that our brain does not build a sense of self in a merely reactive way, via perceptual correlations; rather it generates predictions on what may or may not belong to itself.
1Synchronous, but not asynchronous, multisensory stimulation has been 2 successfully employed to manipulate the experience of body ownership, as in the 3 case of the rubber hand illusion. Hence, it has been assumed that the rubber 4 hand illusion is bound by the same temporal rules as in multisensory integration. 5However, empirical evidence of a direct link between the temporal limits on the 6 rubber hand illusion and those on multisensory integration is still lacking. Here 7 we provide the first comprehensive evidence that individual susceptibility to the 8 rubber hand illusion depends upon the individual temporal resolution in 9 multisensory perception, as indexed by the temporal binding window. In 10 particular, in two studies we showed that the degree of temporal asynchrony 11 necessary to prevent the induction of the rubber hand illusion depends upon the 12 individuals' sensitivity to perceiving asynchrony during visuo-tactile stimulation. 13That is, the larger the temporal binding window, as inferred from a simultaneity 14 judgment task, the higher the level of asynchrony tolerated in the rubber hand 15 illusion. Our results suggest that current neurocognitive models of body 16 ownership Introduction 23Body representation has been linked to the processing and integration of 24 multisensory signals (for reviews: (Blanke, 2012; Ehrsson, 2012). An 25 outstanding example of the pivotal role played by multisensory mechanisms in 26 body representation is the Rubber Hand Illusion (RHI; (Blanke, 2012; Botvinick 27 & Cohen, 1998; Ehrsson, 2012). This illusion is generated when temporally close 28 visual and tactile events occur on a visible rubber hand and the hidden 29 that the subjective ratings of the illusion and the proprioceptive drift were 67 significantly higher for short delays, up to 300 msec. In the present study we do a 68 step forward by formally associating sensitivity to the rubber hand illusion to 69 temporal sensitivity in multisensory integration. Such a finding would foster new 70 Costantini et al. Page 5 of 32investigations into the temporal unfolding of body ownership, an issue largely 71 neglected so far. 72In order to achieve this, we measured participants' TBWs through the use of a 73 simultaneity judgment task, employing visual and tactile stimuli. Next, in the 74 same participants, and employing the same stimuli, we measured susceptibility 75 to the RHI in the synchronous and asynchronous conditions. Importantly, in the 76 asynchronous condition we individualized the amount of asynchrony (i.e. 77Stimulus Onset Asynchrony, SOA) between the visual and the tactile stimuli, 78 based on the individuals' TBW. This means that the individuals' own TBW was 79 used to establish the asynchrony between the visual stimulus delivered on the 80 rubber hand and the tactile stimulus delivered on the participants' real hand. In 81 more detail, rather than using standard large asynchronies, as used in previous 82 research ( Tsakiris & Haggard, 2005) (usually up to 1000 ms), we selected, at th...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.