Adapting non-invasive human recordings along multiple task-axes shows unfolding of spontaneous and over-trained choice

Choices rely on a transformation of sensory inputs into motor responses. Using invasive single neuron recordings, the evolution of a choice process has been tracked by projecting population neural responses into state spaces. Here we develop an approach that allows us to recover similar trajectories on a millisecond timescale in non-invasive human recordings. We selectively suppress activity related to three task-axes, relevant and irrelevant sensory inputs and response direction in magnetoencephalography data acquired during context-dependent choices. Recordings from premotor cortex show a progression from processing sensory input to processing the response. In contrast to previous macaque recordings, information related to choice-irrelevant features is represented more weakly than choice-relevant sensory information. To test whether this mechanistic difference between species is caused by extensive overtraining common in non-human primate studies, we trained humans on >20,000 trials of the task. Choice-irrelevant features were still weaker than relevant features in premotor cortex after overtraining.

Cellulose-Multiwall Carbon Nanotube Fiber Actuator Behavior in Aqueous and Organic Electrolyte

As both consumers and producers are shifting from fossil-derived materials to other, more sustainable approaches, there is a growing interest in bio-origin and biodegradable polymers. In search of bio-degradable electro-mechanically active materials, cellulose-multi wall carbon nanotube (Cell-CNT) composites are a focus for the development of actuators and sensors. In the current study, our aim was to fabricate Cell-CNT composite fibers and study their electro-mechanical response as linear actuators in aqueous and propylene carbonate-based electrolyte solutions. While the response was (expectedly) strongly solvent dependent, the different solvents also revealed unexpected phenomena. Cell-CNT fibers in propylene carbonate revealed a strong back-relaxation process at low frequencies, and also a frequency dependent response direction change (change of actuation direction). Cell-CNT fibers operated in aqueous electrolyte showed response typical to electrochemical capacitors including expansion at discharging with controllable actuation dependence on charge density. While the response was similarly stable in both electrolyte solution systems, the aqueous electrolytes were clearly favorable for Cell-CNT with 3.4 times higher conductivities, 4.3 times higher charge densities and 11 times higher strain.

Projections of non-invasive human recordings into state space show unfolding of spontaneous and over-trained choice

Choices rely on a transformation of sensory inputs into motor responses. Using invasive single neuron recordings, the evolution of a choice process has been tracked by projecting population neural responses into state spaces. Here we develop an approach that allows us to recover state space trajectories on a millisecond timescale in non-invasive human recordings. We selectively suppress activity related to relevant and irrelevant sensory inputs and response direction in magnetoencephalography data acquired during context-dependent choices. Recordings from premotor cortex show a smooth progression from sensory input encoding to response encoding. In contrast to previous macaque recordings, information related to choice-irrelevant features is represented more weakly than choice-relevant sensory information. To test whether this mechanistic difference between species is caused by extensive overtraining common in non-human primate studies, we trained humans on >20,000 trials of the task. Choice-irrelevant features were still weaker than relevant features in premotor cortex after overtraining.

The Effects of Controlled Tempo Manipulations on Cardiovascular Autonomic Function

Music has been associated with alterations in autonomic function. Tempo, the speed of music, is one of many musical parameters that may drive autonomic modulation. However, direct measures of sympathetic nervous system activity and control groups and/or control stimuli do not feature in prior work. This article therefore reports an investigation into the autonomic effects of increases and decreases in tempo. Fifty-eight healthy participants (age range: 22–80 years) were randomly allocated to either an experimental ( n = 29, tune) or control (rhythm of the same tune) group. All participants underwent five conditions: baseline, stable tempo (tune/rhythm repeatedly played at 120 bpm), tempo increase (tune/rhythm played at 60 bpm, 90 bpm, 120 bpm, 150 bpm, 180 bpm), tempo decrease (tune/rhythm played at 180 bpm, 150 bpm, 120 bpm, 90 bpm, 60 bpm) and recovery. Heart rate, blood pressure, respiration, and muscle sympathetic nerve activity were continuously recorded. The 60 bpm in the tempo decrease stimulus was associated with increases in measures of parasympathetic activity. The 180 bpm in the tempo increase stimulus was also associated with shifts towards parasympathetic predominance. Responses to the stimuli were predicted by baseline %LF. It is concluded that the individual tempi impacted upon autonomic function, despite the entire stimulus having little effect. The 60 bpm in an increasingly slower stimulus was associated with greater vagal modulations of heart rate than faster tempi. For the first time, this study shows that response direction and magnitude to tempo manipulations were predicted by resting values, suggesting that music responders may be autonomically distinct from non-responders.

The influence of number magnitude on continuous swiping movements

There is accumulating evidence that numerical information influences the way in which we perform bodily movements. Specifically, the idea that our cognitive representations of numbers and space interact is supported by systematic associations of space with both number magnitude (SNARC effect) and number parity (MARC effect). However, whether this influence is bound to the left or right side of space or to the hand with which we perform the movement remains debated. One novel and interesting way to disentangle these factors is to use movement responses in which hand and movement direction can be dissociated. In the present study, participants moved a central object to the left or right side on a touchscreen with their index fingers as response to a parity judgment and magnitude classification task. We observed significant SNARC effects in both tasks. Number magnitude and response direction interacted, but magnitude and response hand did not. This indicated that the SNARC effect can be independent of the responding hand. Importantly, however, a MARC effect was observed not only in an interaction between response direction and parity, but also in an interaction between response hand and parity, suggesting that response hand plays a role in the interaction between physical space and parity. Additionally, number magnitude influenced the amplitude of participants’ response movements, with larger numbers eliciting longer movements. These results indicate that space, magnitude and parity interact on different levels that can be unraveled in a paradigm utilizing continuous movements such as swiping.

Constructing meaning for up and down situated sentences: Is a sentence more than the sum of its words?

abstractThe present study was concerned with the question whether comprehension is based on mental simulation processes beyond the word level. In Experiment 1, participants were presented with coherent sentence pairs, consisting of a context sentence and a target sentence. Target sentences ended with a word referring to an entity with a typical location in the upper vertical space (e.g., bird in There she sees a bird). Context sentences either supported the target entity’s typical location or not (Anna looks to the sky vs. Anna looks to the ground, respectively). Participants responded to the final word of the sentence pair by pressing an up- or a down-key. The results showed a main effect of response direction (faster up compared to down responses) as well as an interaction between context location and response direction. In Experiment 2, participants were presented with incoherent sentence pairs with the same context sentences and different target sentences (whereby the target word was kept identical), but in an incoherent manner (target sentence: On the poster one sees a bird). Here, the results showed a main effect of response direction but no interaction. The same result was obtained in Experiment 3, in which participants were presented with word pairs consisting of an up- or down-context word (e.g., sky vs. ground) and an up-target word (e.g., bird). Overall, the results provide evidence for the view that comprehension involves simulation processes at the word level as well as simulation processes at the sentence or discourse level.

Difference in perceptual and oculomotor responses revealed by apparent motion stimuli presented with an interstimulus interval

To understand the mechanisms underlying visual motion analyses for perceptual and oculomotor responses and their similarities/differences, we analyzed eye movement responses to two-frame animations of dual-grating 3 f5 f stimuli while subjects performed direction discrimination tasks. The 3 f5 f stimulus was composed of two sinusoids with a spatial frequency ratio of 3:5 (3 f and 5 f), creating a pattern with fundamental frequency f. When this stimulus was shifted by 1/4 of the wavelength, the two components shifted 1/4 of their wavelengths and had opposite directions: the 5 f forward and the 3 f backward. By presenting the 3 f5 f stimulus with various interstimulus intervals (ISIs), two visual-motion-analysis mechanisms, low-level energy-based and high-level feature-based, could be effectively distinguished. This is because response direction depends on the relative contrast between the components when the energy-based mechanism operates, but not when the feature-based mechanism works. We found that when the 3 f5 f stimuli were presented with shorter ISIs (<100 ms), and 3 f component had higher contrast, both perceptual and ocular responses were in the direction of the pattern shift, whereas the responses were reversed when the 5 f had higher contrast, suggesting operation of the energy-based mechanism. On the other hand, the ocular responses were almost negligible with longer ISIs (>100 ms), whereas perceived directions were biased toward the direction of pattern shift. These results suggest that the energy-based mechanism is dominant in oculomotor responses throughout ISIs; however, there is a transition from energy-based to feature-tracking mechanisms when we perceive visual motion.

Experimental Analysis of Surface Geometry, External Damping and Waves on Semisubmersible Vortex Induced Motions

Semisubmersible Vortex Induced Motions have been studied extensively at model scales, and observed under field conditions. VIM response is of particular concern in evaluations of Steel Catenary Riser (SCR) fatigue damage. Historically, most of this experimental work was done with bare models, without much effort to represent actual hull surface characteristics. In this paper, the effect of these appurtenances, tow direction and wave action is investigated. There is also an examination of vortex induced yaw response. VIM response is assessed using motion trajectories, dominant response direction, and amplitudes and periods of response. Variations in these quantities are also investigated.