MULTI-DIGIT HUMAN PREHENSION

The current dissertation addresses the central nervous system (CNS) strategies to solve kinetic redundancy in multi-digit static prehension under different geometries of hand-held objects and systematically varied mechanical constraints such as translation and rotation of the hand-held object. A series of experiments conducted for this dissertation tested the following hypotheses suggested in the current literatures for multi-digit human static prehension: Hierarchical organization hypothesis, principle of superposition hypothesis, proximity hypothesis, and mechanical advantage hypothesis. (1) Forces and moments produced by fingers during circular object prehension were grouped into two independent subsets: one subset related to grasping stability control and the other associated with rotational equilibrium control. This result supports the principle of superposition hypothesis. Individual fingers acted synergistically to compensate each other's errors. This result confirms the hierarchical organization hypothesis in circular object prehension. (2) During fixed object prehension of a rectangular object, the closer the non-task fingers positioned to the task finger, the greater the forces produced by the non-task fingers. However, during free object prehension, the non-task fingers with longer moment arms produced greater forces. The former and latter results support the proximity hypothesis and the mechanical advantage hypothesis, respectively. (3) The grasping stability control and rotational equilibrium control were decoupled during fixed object prehension as well as free object prehension. This result supports the principle of superposition hypothesis regardless of the mechanical constraints provided for these two prehension types. (4) During torque production, the fingers with longer moment arms produced greater forces when the fingers acted as agonists for the torque production. Therefore, the mechanical advantage hypothesis was supported for agonist fingers. (5) Coupling of thumb normal force and virtual finger normal force was not necessitated when horizontal translation of hand-held object was mechanically fixed. However, the coupling of two normal forces was always observed regardless of given translational constraints, and these two normal forces were independent to other mechanical variables such as tangential forces and moments. This result supports the principle of superposition hypothesis in static prehension under varied combinations of translational constraints

God, Mind, Evolution, and Quantum Reality Based on Process Metaphysics

The genesis of actuality from potentiality, with the apparent role of the observer, is an important and unsolved problem which essentially defines science‟s view of reality in a variety of contexts. Observation then becomes lawful and not emergent. Panentheism is needed to provide a mechanism for order outside of blind efficient causality, in a Universal final causality. Classical physics is over a hundred years out of date, yet scientific models remain mechanistic and deterministic. Deism, a remnant of classical cosmology, is examined and rejected by scientists and philosophers, and certain pre-scientific notions of religion are scorned, putting the matter to rest. Quantum physics, in its basic form, is necessary if there is to be any philosophical or scientific notion of free will and self-determination, as potentiality. Quantum metaphysics is also needed because classical physics is fundamentally limited to localized external relations, lacking the internality and non-locality of relatedness. God, or the equivalent, is necessary to complete the equation. Physicists now tell us that reality is fundamentally mental and is created by observation. Observation is here taken to mean experience, with experience going all the way down to the lowest order of a Universal mentality

Bio-Artificial Synergies for Grasp Posture Control of Supernumerary Robotic Fingers

A new type of wrist-mounted robot, the Supernumerary Robotic (SR) Fingers, is proposed to work closely with the human hand and aid the human in performing a variety of prehensile tasks. For people with diminished functionality of their hands, these robotic fingers could provide the opportunity to live with more independence and work more productively. A natural and implicit coordination between the SR Fingers and the human fingers is required so the robot can be transformed to act as part of the human body. This paper presents a novel control algorithm, termed “Bio-Artificial Synergies”, which enables the SR and human fingers to share the task load together and adapt to diverse task conditions. Through grasp experiments and data analysis, postural synergies were found for a seven-fingered hand comprised of two SR Fingers and five human fingers. The synergy-based control law was then extracted from the experimental data using Partial Least Squares (PLS) regression and tested on the SR Finger prototype as a proof of concept

Editorial: Time & Experience: Twins of the Eternal Now?

In what follows, I suggest that, against most theories of time, there really is an actual present, a now, but that such an eternal moment cannot be found before or after time. It may even be semantically incoherent to say that such an eternal present exists since “it” is changeless and formless (presumably a dynamic chaos without location or duration) yet with creative potential. Such a field of near-infinite potential energy could have had no beginning and will have no end, yet within it stirs the desire to experience that brings forth singularities, like the one that exploded into the Big Bang (experiencing itself through relative and relational spacetime). From the perspective of the eternal now of near-infinite possibilities (if such a sentence can be semantically parsed at all), there is only the timeless creative present, so the Big Bang did not happen some 13 billion years ago. Inasmuch as there is neither time past nor time future nor any time at all at the null point of forever, we must understand the Big Bang (and all other events) as taking place right here and now. In terms of the eternal now, the beginning is happening now and we just appeared (and are always just appearing) to witness it. The rest is all conscious construction; time and experience are so entangled, they need each other to exist

Pre-stimulus influences on auditory perception arising from sensory representations and decision processes

The qualities of perception depend not only on the sensory inputs but also on the brain state before stimulus presentation. Although the collective evidence from neuroimaging studies for a relation between prestimulus state and perception is strong, the interpretation in the context of sensory computations or decision processes has remained difficult. In the auditory system, for example, previous studies have reported a wide range of effects in terms of the perceptually relevant frequency bands and state parameters (phase/power). To dissociate influences of state on earlier sensory representations and higher-level decision processes, we collected behavioral and EEG data in human participants performing two auditory discrimination tasks relying on distinct acoustic features. Using single-trial decoding, we quantified the relation between prestimulus activity, relevant sensory evidence, and choice in different task-relevant EEG components. Within auditory networks, we found that phase had no direct influence on choice, whereas power in task-specific frequency bands affected the encoding of sensory evidence. Within later-activated frontoparietal regions, theta and alpha phase had a direct influence on choice, without involving sensory evidence. These results delineate two consistent mechanisms by which prestimulus activity shapes perception. However, the timescales of the relevant neural activity depend on the specific brain regions engaged by the respective task