Striosomes and Matrisomes: Scaffolds for Dynamic Coupling of Volition and Action.

Striosomes form neurochemically specialized compartments of the striatum embedded in a large matrix made up of modules called matrisomes. Striosome-matrix architecture is multiplexed with the canonical direct-indirect organization of the striatum. Striosomal functions remain to be fully clarified, but key information is emerging. First, striosomes powerfully innervate nigral dopamine-containing neurons and can completely shut down their activity, with a following rebound excitation. Second, striosomes receive limbic and cognition-related corticostriatal afferents and are dynamically modulated in relation to value-based actions. Third, striosomes are spatially interspersed among matrisomes and interneurons and are influenced by local and global neuromodulatory and oscillatory activities. Fourth, striosomes tune engagement and the motivation to perform reinforcement learning, to manifest stereotypical behaviors, and to navigate valence conflicts and valence discriminations. We suggest that, at an algorithmic level, striosomes could serve as distributed scaffolds to provide formats of the striatal computations generated through development and refined through learning. We propose that striosomes affect subjective states. By transforming corticothalamic and other inputs to the functional formats of the striatum, they could implement state transitions in nigro-striato-nigral circuits to affect bodily and cognitive actions according to internal motives whose functions are compromised in neuropsychiatric conditions.

Neurons as will and representation.

Memory recollections and voluntary actions are often perceived as spontaneously generated irrespective of external stimuli. Although products of our neurons, they are only rarely accessible in humans at the neuronal level. Here I review insights gleaned from unique neurosurgical opportunities to record and stimulate single-neuron activity in people who can declare their thoughts, memories and wishes. I discuss evidence that the subjective experience of human recollection and that of voluntary action arise from the activity of two internal neuronal generators, the former from medial temporal lobe reactivation and the latter from frontoparietal preactivation. I characterize properties of these generators and their interaction, enabling flexible recruitment of memory-based choices for action as well as recruitment of action-based plans for the representation of conceptual knowledge in memories. Both internal generators operate on surprisingly explicit but different neuronal codes, which appear to arise with distinct single-neuron activity, often observed before participants' reports of conscious awareness. I discuss prediction of behaviour based on these codes, and the potential for their modulation. The prospects of editing human memories and volitions by enhancement, inception or deletion of specific, selected content raise therapeutic possibilities and ethical concerns.

Movement-dependent electrical stimulation for volitional strengthening of cortical connections in behaving monkeys.

Correlated activity of neurons can lead to long-term strengthening or weakening of the connections between them. In addition, the behavioral context, imparted by execution of physical movements or the presence of a reward, can modulate the plasticity induced by Hebbian mechanisms. In the present study, we have combined behavior and induced neuronal correlations to strengthen connections in the motor cortex of adult behaving monkeys. Correlated activity was induced using an electrical-conditioning protocol in which stimuli gated by voluntary movements were used to produce coactivation of neurons at motor-cortical sites involved in those movements. Delivery of movement-dependent stimulation resulted in small increases in the strength of associated cortical connections immediately after conditioning. Remarkably, when paired with further repetition of the movements that gated the conditioning stimuli, there were substantially larger gains in the strength of cortical connections, which occurred in a use-dependent manner, without delivery of additional conditioning stimulation. In the absence of such movements, little change was observed in the strength of motor-cortical connections. Performance of the motor behavior in the absence of conditioning also did not produce any changes in connectivity. Our results show that combining movement-gated stimulation with further natural use of the "conditioned" pathways after stimulation ends can produce use-dependent strengthening of connections in adult primates, highlighting an important role for behavior in cortical plasticity. Our data also provide strong support for combining movement-gated stimulation with use-dependent physical rehabilitation for strengthening connections weakened by a stroke or spinal cord injury.

Aphantasia and involuntary imagery.

Aphantasia is a condition that is often characterized as the impaired ability to create voluntary mental images. Aphantasia is assumed to selectively affect voluntary imagery mainly because even though aphantasics report being unable to visualize something at will, many report having visual dreams. We argue that this common characterization of aphantasia is incorrect. Studies on aphantasia are often not clear about whether they are assessing voluntary or involuntary imagery, but some studies show that several forms of involuntary imagery are also affected in aphantasia (including imagery in dreams). We also raise problems for two attempts to show that involuntary images are preserved in aphantasia. In addition, we report the results of a study about afterimages in aphantasia, which suggest that these tend to be less intense in aphantasics than in controls. Involuntary imagery is often treated as a unitary kind that is either present or absent in aphantasia. We suggest that this approach is mistaken and that we should look at different types of involuntary imagery case by case. Doing so reveals no evidence of preserved involuntary imagery in aphantasia. We suggest that a broader characterization of aphantasia, as a deficit in forming mental imagery, whether voluntary or not, is more appropriate. Characterizing aphantasia as a volitional deficit is likely to lead researchers to give incorrect explanations for aphantasia, and to look for the wrong mechanisms underlying it.

The place of Free Will: the freedom of the prisoner.

Debates about the concept of Free Will date back to ancient times. About 40 years ago, Benjamin Libet designed an experiment showing that the conscious intention to move is preceded by a specific pattern of brain activation. His finding suggested that unconscious processes determine our decisions. Libet-style experiments have continued to dominate the debate about Free Will, pushing some authors to argue that the existence of Free Will is a mere illusion. We believe that this dispute is because we often measure Free Will using arbitrary human decisions rather than deliberate actions. After reviewing the definition of Free Will and the related literature, we conclude that the scientific evidence does not disprove the existence of Free Will. However, our will encounters several constraints and limitations that should be considered when evaluating our deeds' personal responsibility.

A frontoparietal network for volitional control of gaze following.

Gaze following is a major element of non-verbal communication and important for successful social interactions. Human gaze following is a fast and almost reflex-like behaviour, yet it can be volitionally controlled and suppressed to some extent if inappropriate or unnecessary, given the social context. In order to identify the neural basis of the cognitive control of gaze following, we carried out an event-related fMRI experiment, in which human subjects' eye movements were tracked while they were exposed to gaze cues in two distinct contexts: A baseline gaze following condition in which subjects were instructed to use gaze cues to shift their attention to a gazed-at spatial target and a control condition in which the subjects were required to ignore the gaze cue and instead to shift their attention to a distinct spatial target to be selected based on a colour mapping rule, requiring the suppression of gaze following. We could identify a suppression-related blood-oxygen-level-dependent (BOLD) response in a frontoparietal network comprising dorsolateral prefrontal cortex (dlPFC), orbitofrontal cortex (OFC), the anterior insula, precuneus, and posterior parietal cortex (PPC). These findings suggest that overexcitation of frontoparietal circuits in turn suppressing the gaze following patch might be a potential cause of gaze following deficits in clinical populations.

Effects of a Web-Based Behavioral Activation Intervention on Depressive Symptoms, Activation, Motivation, and Volition: Results of a Randomized Controlled Trial.

INTRODUCTION: Behavioral activation (BA) is effective for the treatment of depression. The Health Action Process Approach (HAPA), which is derived from health psychology, can provide a motivational-volitional framework of BA. OBJECTIVE: This study investigated the efficacy of a HAPA-based internet-delivered BA intervention (iBA; called InterAKTIV) in individuals with depression, also assessing HAPA-based motivational and volitional outcomes. METHODS: In a two-arm randomized controlled efficacy trial with a parallel design, 128 participants with a major depressive episode were randomly allocated to the intervention group (IG; TAU + immediate access to iBA) or control group (CG; TAU + access to iBA after follow-up). The primary outcome of clinician-rated depressive symptoms and secondary outcomes were assessed at baseline (T1), 8 weeks (T2), 6-month after randomization (T3). Data were analyzed on an intention-to-treat basis. RESULTS: Linear mixed model analyses revealed a significant group*time interaction effect on clinician-rated depressive symptoms favoring the IG (F2, 156.0 = 7.40; p < 0.001, d = 0.79 at T2, d = 0.25 at T3). The IG was also superior regarding self-rated depressive symptoms, BA, most motivational, and all volitional outcomes. CONCLUSION: This study shows that HAPA-based iBA can significantly improve clinician-rated depressive symptoms, as well as outcomes used in the HAPA model in people with depression. Building on these efficacy results, in the next step, the relationship between BA interventions and activity levels should be investigated, taking into account motivation and volition as potential mediators.

Corticotropin-Releasing Hormone from the Pontine Micturition Center Plays an Inhibitory Role in Micturition.

Lower urinary tract or voiding disorders are prevalent across all ages and affect >40% of adults over 40 years old, leading to decreased quality of life and high health care costs. The pontine micturition center (PMC; i.e., Barrington's nucleus) contains a large population of neurons that localize the stress-related neuropeptide, corticotropin-releasing hormone (CRH) and project to neurons in the spinal cord to regulate micturition. How the PMC and CRH-expressing neurons in the PMC control volitional micturition is of critical importance for human voiding disorders. To investigate the specific role of CRH in the PMC, neurons in the PMC-expressing CRH were optogenetically activated during in vivo cystometry in unanesthetized mice of either sex. Optogenetic activation of CRH-PMC neurons led to increased intermicturition interval and voided volume, similar to the altered voiding phenotype produced by social stress. Female mice showed a significantly more pronounced phenotype change compared with male mice. These effects were eliminated by CRH-receptor 1 antagonist pretreatment. Optogenetic inhibition of CRH-PMC neurons led to an altered voiding phenotype characterized by more frequent voids and smaller voided volumes. Last, in a cyclophosphamide cystitis model of bladder overactivity, optogenetic activation of CRH-PMC neurons returned the voiding pattern to normal. Collectively, our findings demonstrate that CRH from PMC spinal-projecting neurons has an inhibitory function on micturition and is a potential therapeutic target for human disease states, such as voiding postponement, urinary retention, and underactive or overactive bladder.SIGNIFICANCE STATEMENT The pontine micturition center (PMC), which is a major regulator of volitional micturition, is neurochemically heterogeneous, and excitatory neurotransmission derived from PMC neurons is thought to mediate the micturition reflex. In the present study, using optogenetic manipulation of CRH-containing neurons in double-transgenic mice, we demonstrate that CRH, which is prominent in PMC-spinal projections, has an inhibitory function on volitional micturition. Moreover, engaging this inhibitory function of CRH can ameliorate bladder hyperexcitability induced by cyclophosphamide in a model of cystitis. The data underscore CRH as a novel target for the treatment of voiding dysfunctions, which are highly prevalent disease processes in children and adults.

The Role of Action-Effect Contingency on Sensory Attenuation in the Absence of Movement.

Stimuli that have been generated by a person's own willed motor actions generally elicit a suppressed electrophysiological, as well as phenomenological, response compared with identical stimuli that have been externally generated. This well-studied phenomenon, known as sensory attenuation, has mostly been studied by comparing ERPs evoked by self-initiated and externally generated sounds. However, most studies have assumed a uniform action-effect contingency, in which a motor action leads to a resulting sensation 100% of the time. In this study, we investigated the effect of manipulating the probability of action-effect contingencies on the sensory attenuation effect. In Experiment 1, participants watched a moving, marked tickertape while EEG was recorded. In the full-contingency (FC) condition, participants chose whether to press a button by a certain mark on the tickertape. If a button press had not occurred by the mark, a sound would be played a second later 100% of the time. If the button was pressed before the mark, the sound was not played. In the no-contingency (NC) condition, participants observed the same tickertape; in contrast, however, if participants did not press the button by the mark, a sound would occur only 50% of the time (NC-inaction). Furthermore, in the NC condition, if a participant pressed the button before the mark, a sound would also play 50% of the time (NC-action). In Experiment 2, the design was identical, except that a willed action (as opposed to a willed inaction) triggered the sound in the FC condition. The results were consistent across the two experiments: Although there were no differences in N1 amplitude between conditions, the amplitude of the Tb and P2 components were smaller in the FC condition compared with the NC-inaction condition, and the amplitude of the P2 component was also smaller in the FC condition compared with the NC-action condition. The results suggest that the effect of contingency on electrophysiological indices of sensory attenuation may be indexed primarily by the Tb and P2 components, rather than the N1 component which is most commonly studied.

The Effect of Early Infection on the Rate of Volitional Voiding after Spinal Cord Injury: A Potential Modifiable Risk Factor for Bladder Outcomes.

PURPOSE: Recently, it has been observed that early infections after spinal cord injury (SCI) are associated with decreased long-term motor and sensory recovery. We investigate the effects of early infection after SCI on long-term bladder function. MATERIALS AND METHODS: We assessed data for the years 1995 to 2006 using the National Spinal Cord Injury Database. Postoperative wound infections and pneumonia were used to classify infections during the acute inpatient and rehabilitation periods. The effect of early infections on volitional voiding status at 1-year followup was assessed. Age, gender and neurological status at rehabilitation discharge (level of injury, American Spinal Injury Association Impairment Scale [AIS] and bilateral lower extremity motor scores) were included in multivariate logistic regression modeling to control for confounding. RESULTS: Of the 3,561 persons studied, 1,233 (34.6%) had an early infection. Those with an infection during early recovery were less likely to void than their noninfected counterparts if in the AIS A (0.3% vs 1.9%, p=0.010), AIS B (3.8% vs 10.5%, p=0.018) and AIS C (29.1% vs 37.3%, p=0.071) classification, while those with less complete injuries (AIS D) did not appear to be affected (62.6% vs 65.4%, p=0.456). Similar findings were found when stratifying by lower extremity motor scores and persisted on multivariate analysis, where early infection decreased the odds of volitional voiding at 1-year followup (OR=0.79, p=0.042). CONCLUSIONS: Infections during the early recovery period may modify volitional voiding at 1-year followup by 20% or more. Future investigations to confirm our findings and potentially evaluate mitigation strategies are warranted.

Volitional control of vocalizations in corvid songbirds.

Songbirds are renowned for their acoustically elaborate songs. However, it is unclear whether songbirds can cognitively control their vocal output. Here, we show that crows, songbirds of the corvid family, can be trained to exert control over their vocalizations. In a detection task, three male carrion crows rapidly learned to emit vocalizations in response to a visual cue with no inherent meaning (go trials) and to withhold vocalizations in response to another cue (catch trials). Two of these crows were then trained on a go/nogo task, with the cue colors reversed, in addition to being rewarded for withholding vocalizations to yet another cue (nogo trials). Vocalizations in response to the detection of the go cue were temporally precise and highly reliable in all three crows. Crows also quickly learned to withhold vocal output in nogo trials, showing that vocalizations were not produced by an anticipation of a food reward in correct trials. The results demonstrate that corvids can volitionally control the release and onset of their vocalizations, suggesting that songbird vocalizations are under cognitive control and can be decoupled from affective states.

Mistakes strengthen the temporal binding effect in the context of goal-directed actions.

Temporal binding is an illusion in which the temporal interval between two events appears compressed. In the context of intentional actions, this effect is observed as a compression of the perceived interval between these actions and their causal outcomes. This 'intentional binding effect' has been used to investigate the Sense of Agency, which is the experience of intentionally causing an outcome through volitional action. Intentional binding is reduced for negative outcomes such as error feedback, but the role of mistakes (e.g., errors of commission) for binding and agency has not been extensively studied. In our study, participants played a virtual game in which they attempted to 'splat' (hit) visual stimuli that looked like coloured bugs, using mouse clicks. On some trials, stimulus colours changed unpredictably immediately before actions were made, sometimes inducing mistakes. Actions were thus clearly identifiable as mistakes at the time of their onset before any outcome feedback had been provided. Participants reported shorter action-outcome intervals when stimuli changed, but only when this change caused a mistake according to the game's rules. This suggests that intentional binding is strengthened by errors of commission. We discuss how this effect may be accounted for by agency itself and via more general processes such as changes in arousal.

Expectation of volitional arm movement has prolonged effects on the grip force exerted on a pinched object.

Humans closely coordinate the grip force exerted on a hand-held object with changes in the load arising from the object's dynamics. Recent work suggests the grip force is responsive to the predictability of the load forces as well. The well-known grip-force-load-force coupling is intermittent when the load arising from volitional movements fluctuates predictably, whereas grip force increases when loads are unpredictable. Here, we studied the influence of expected but uncertain volitional movements on the digit forces during a static grasp. Young, healthy participants used a pinch grasp to hold an instrumented object and track visual targets by moving the object. We quantified the mean grip force, the temporal decline in grip force (slacking), and the coupling between the pressing digit forces that yield the grip force during static prehension with no expectation of movement, and during the static phase of a choice reaction time task, when the participant expected to move the object after a variable duration. Simply expecting to move the object led to sustained (for at least 5 s) higher magnitude and lower slacking in the grip force, and weaker coupling between the pressing digit forces. These effects were modulated by the direction of the expected movement and the object's mass. The changes helped to maintain the safety margin for the current grasp and likely facilitated the transition from static to dynamic object manipulation. Influence of expected actions on the current grasp may have implications for manual dexterity and its well-known loss with age.

Volitional control of individual neurons in the human brain.

Brain-machine interfaces allow neuroscientists to causally link specific neural activity patterns to a particular behaviour. Thus, in addition to their current clinical applications, brain-machine interfaces can also be used as a tool to investigate neural mechanisms of learning and plasticity in the brain. Decades of research using such brain-machine interfaces have shown that animals (non-human primates and rodents) can be operantly conditioned to self-regulate neural activity in various motor-related structures of the brain. Here, we ask whether the human brain, a complex interconnected structure of over 80 billion neurons, can learn to control itself at the most elemental scale-a single neuron. We used the unique opportunity to record single units in 11 individuals with epilepsy to explore whether the firing rate of a single (direct) neuron in limbic and other memory-related brain structures can be brought under volitional control. To do this, we developed a visual neurofeedback task in which participants were trained to move a block on a screen by modulating the activity of an arbitrarily selected neuron from their brain. Remarkably, participants were able to volitionally modulate the firing rate of the direct neuron in these previously uninvestigated structures. We found that a subset of participants (learners), were able to improve their performance within a single training session. Successful learning was characterized by (i) highly specific modulation of the direct neuron (demonstrated by significantly increased firing rates and burst frequency); (ii) a simultaneous decorrelation of the activity of the direct neuron from the neighbouring neurons; and (iii) robust phase-locking of the direct neuron to local alpha/beta-frequency oscillations, which may provide some insights in to the potential neural mechanisms that facilitate this type of learning. Volitional control of neuronal activity in mnemonic structures may provide new ways of probing the function and plasticity of human memory without exogenous stimulation. Furthermore, self-regulation of neural activity in these brain regions may provide an avenue for the development of novel neuroprosthetics for the treatment of neurological conditions that are commonly associated with pathological activity in these brain structures, such as medically refractory epilepsy.

Predictors of volitional motor recovery with epidural stimulation in individuals with chronic spinal cord injury.

Spinal cord epidural stimulation (scES) has enabled volitional lower extremity movements in individuals with chronic and clinically motor complete spinal cord injury and no clinically detectable brain influence. The aim of this study was to understand whether the individuals' neuroanatomical characteristics or positioning of the scES electrode were important factors influencing the extent of initial recovery of lower limb voluntary movements in those with clinically motor complete paralysis. We hypothesized that there would be significant correlations between the number of joints moved during attempts with scES prior to any training interventions and the amount of cervical cord atrophy above the injury, length of post-traumatic myelomalacia and the amount of volume coverage of lumbosacral enlargement by the stimulation electrode array. The clinical and imaging records of 20 individuals with chronic and clinically motor complete spinal cord injury who underwent scES implantation were reviewed and analysed using MRI and X-ray integration, image segmentation and spinal cord volumetric reconstruction techniques. All individuals that participated in the scES study (n = 20) achieved, to some extent, lower extremity voluntary movements post scES implant and prior to any locomotor, voluntary movement or cardiovascular training. The correlation results showed that neither the cross-section area of spinal cord at C3 (n = 19, r = 0.33, P = 0.16) nor the length of severe myelomalacia (n = 18, r = -0.02, P = 0.93) correlated significantly with volitional lower limb movement ability. However, there was a significant, moderate correlation (n = 20, r = 0.59, P = 0.006) between the estimated percentage of the lumbosacral enlargement coverage by the paddle electrode as well as the position of the paddle relative to the maximal lumbosacral enlargement and the conus tip (n = 20, r = 0.50, P = 0.026) with the number of joints moved volitionally. These results suggest that greater coverage of the lumbosacral enlargement by scES may improve motor recovery prior to any training, possibly because of direct modulatory effects on the spinal networks that control lower extremity movements indicating the significant role of motor control at the level of the spinal cord.

Decent work among women workers: An intersectional approach.

The present study sought to apply an intersectional lens in predicting decent work (i.e., work that meets minimum standards for supporting worker dignity and livelihood). With a racially diverse sample of 302 women workers, we tested a moderated mediation model predicting decent work from economic constraints, experiences of sexism, experiences of racism, and the interaction of racism and sexism. Following psychology of working theory (PWT), we positioned work volition and career adaptability as mediators. Main effects were consistent with previous PWT theory and research, indicating that experiences of sexism and racism were important direct and indirect predictors of decent work. Interaction effects indicated that the interaction of sexism and racism predicted work volition and that the indirect effect of sexism on decent work was stronger at higher levels of racism. Results have implications for policymakers and practitioners seeking to support women across racial backgrounds in securing decent work. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Anatomical bases of fast parietal grasp control in humans: A diffusion-MRI tractography study.

The dorso-posterior parietal cortex (DPPC) is a major node of the grasp/manipulation control network. It is assumed to act as an optimal forward estimator that continuously integrates efferent outflows and afferent inflows to modulate the ongoing motor command. In agreement with this view, a recent per-operative study, in humans, identified functional sites within DPPC that: (i) instantly disrupt hand movements when electrically stimulated; (ii) receive short-latency somatosensory afferences from intrinsic hand muscles. Based on these results, it was speculated that DPPC is part of a rapid grasp control loop that receives direct inputs from the hand-territory of the primary somatosensory cortex (S1) and sends direct projections to the hand-territory of the primary motor cortex (M1). However, evidence supporting this hypothesis is weak and partial. To date, projections from DPPC to M1 grasp zone have been identified in monkeys and have been postulated to exist in humans based on clinical and transcranial magnetic studies. This work uses diffusion-MRI tractography in two samples of right- (n = 50) and left-handed (n = 25) subjects randomly selected from the Human Connectome Project. It aims to determine whether direct connections exist between DPPC and the hand control sectors of the primary sensorimotor regions. The parietal region of interest, related to hand control (hereafter designated DPPChand), was defined permissively as the 95% confidence area of the parietal sites that were found to disrupt hand movements in the previously evoked per-operative study. In both hemispheres, irrespective of handedness, we found dense ipsilateral connections between a restricted part of DPPChand and focal sectors within the pre and postcentral gyrus. These sectors, corresponding to the hand territories of M1 and S1, targeted the same parietal zone (spatial overlap > 92%). As a sensitivity control, we searched for potential connections between the angular gyrus (AG) and the pre and postcentral regions. No robust pathways were found. Streamline densities identified using AG as the starting seed represented less than 5 % of the streamline densities identified from DPPChand. Together, these results support the existence of a direct sensory-parietal-motor loop suited for fast manual control and more generally, for any task requiring rapid integration of distal sensorimotor signals.

Exercising muscle mass influences neuromuscular, cardiorespiratory, and perceptual responses during and following ramp-incremental cycling to task failure.

Neuromuscular (NM), cardiorespiratory, and perceptual responses to maximal-graded exercise using different amounts of active muscle mass remain unclear. We hypothesized that during dynamic exercise, peripheral NM fatigue (declined twitch force) and muscle pain would be greater using smaller muscle mass, whereas central fatigue (declined voluntary activation) and ventilatory variables would be greater using larger muscle mass. Twelve males (29.8 ± 4.7 years) performed two ramp-incremental cycling tests until task failure: 1) single-leg (SL) with 10 W·min-1 ramp and 2) double-leg (DL) with 20 W·min-1 ramp. NM fatigue was assessed at baseline, task failure (post), and after 1, 4, and 8 min of recovery. Cardiorespiratory and perceptual variables [i.e., ratings of perceived exertion (RPE), pain, and dyspnea] were measured throughout cycling. Exercise duration was similar between sessions (SL: 857.7 ± 263.6 s; DL: 855.0 ± 218.8 s; P = 0.923), and higher absolute peak power output was attained in DL (SL: 163.2 ± 43.8 W; DL: 307.0 ± 72.0 W; P < 0.001). Although central fatigue did not differ between conditions (SL: -6.6 ± 6.5%; DL: -3.5 ± 4.8%; P = 0.091), maximal voluntary contraction (SL: -41.6 ± 10.9%; DL: -33.7 ± 8.5%; P = 0.032) and single twitch forces (SL: -59.4 ± 18.8%; DL: -46.2 ± 16.2%; P = 0.003) declined more following SL. DL elicited higher peak oxygen uptake (SL: 42.1 ± 10.0 mL·kg-1·min-1; DL: 50.3 ± 9.3 mL·kg-1·min-1; P < 0.001), ventilation (SL: 137.1 ± 38.1 L·min-1; DL: 171.5 ± 33.2 L·min-1; P < 0.001), and heart rate (SL: 167 ± 21 bpm; DL: 187 ± 8 bpm; P = 0.005). Dyspnea (P = 0.025) was higher in DL; however, RPE (P = 0.005) and pain (P < 0.001) were higher in SL. These results suggest that interplay between NM, cardiorespiratory, and perceptual determinants of exercise performance during ramp-incremental cycling to task failure is muscle mass dependent.

Eligible blood donors' decisions about donating stool for fecal microbiota transplantation: Does ambivalence play a role?

Blood collection agencies (BCAs) are expanding core business by inviting blood donors to donate stool for fecal microbiota transplantation (FMT). However, whether blood donors also want to donate stool is unclear since, despite its benefits, stool donation is viewed by many as unpleasant. This study examined the prevalence, contributors to, and role of these mixed feelings (ambivalence) in stool donation intentions. STUDY DESIGN AND METHODS: This cross-sectional study surveyed Australian residents aged 18 years or more who believed themselves eligible to donate blood and met broad criteria for prescreening as a stool donor (eg, healthy, not taking medication). Survey questions assessed attitude, norms, self-efficacy, motives, disgust, ambivalence, and intentions to donate stool. RESULTS: A total of 382 eligible blood donors aged not more than 50 years (mean, 28.71 years; 48% female, 62% "healthy" body mass index) participated. Six percent indicated no ambivalence about donating stool. In regression, significant determinants of ambivalence were less awareness of FMT, lower self-efficacy, motivated by ensuring that stool is available for loved ones, and more disgust about stool donation. Higher ambivalence contributed to decreased donation intention. Self-efficacy and disgust differentiated participants with moderate ambivalence, a group likely responsive to intervention, from those with low or high ambivalence. CONCLUSION: Ambivalence about donating stool was common among eligible blood donors. BCAs should raise awareness about stool donation and FMT before requesting donation. BCAs may increase cost savings and donor retention by giving clear guidance about donation requirements and implementing processes that build confidence. Early screening of potential donors for ambivalence and disgust will enable BCAs to provide decision support.

Volition in prospective Memory: Evidence against differences between free and fixed target events.

Volition is the extent to which actions are generated as a result of internal states in contrast to responses to external conditions or dictated by external events. Delayed intentions about future action are stored in prospective memory until the intended action has to be formed at a later point in time. It is unknown how voluntary choice affects prospective memory. We compared the difference between freely chosen and fixed targets on the reaction times and task performance in the ongoing task and for the target stimuli in a prospective memory task. The task performance and the reaction time was modelled using a Bayesian hierarchical drift-diffusion model. The analysis showed no differences between self-chosen and fixed prospective memory cues on task responses. The result suggests that volition in choosing the cue to act upon or given a fixed cue does not make a difference for prospective memory task performance.