Specific Stimulus Conditions Research Articles

The Morality Game: Is the Evaluation of the Instrumental Utility of Moral Dilemmas Related to Decision Outcomes

This article investigates the relation of the evaluation of the instrumental utility of moral dilemmas to decision outcomes. The results indicate that nuances of dilemma perception assessed in the study (perceived realism of dilemmas, their plausibility, reflection of real behavior and an assessment of the extent to which responses to moral dilemmas can be used to judge moral maturity, empathy, level of intelligence and sense of humor) are not significantly related to objective behavior, as expressed in the number of consequentialist responses. Instruction about the nature of the study, however, may influence the moral choices made. Participants who were informed by instruction that their personality could be judged by their responses to moral dilemmas gave more deontological responses than others. An explanation is proposed that such instruction acts as a factor that provokes the adoption of the role of the apprehensive participant and, as a consequence, socially desirable behavior. This aspect highlights the importance of considering contextual factors in the study of moral behavior. It is suggested that moral dilemmas should not be viewed through the lens of ecological validity but rather as a tool that allows for a high level of experimental control, facilitating a more indepth study of behavior under specific stimulus conditions

Gold capped mesoporous bioactive glass guides bone regeneration via BMSCs recruitment and drug adaptive release

Recruiting endogenous stem cells and achieving controlled drug release are crucial for in situ bone regeneration. However, it remains challenging to design functional platforms that can effectively recruit stem cells and deliver drugs at an appropriate dose and a time-dependent manner under specific stimulus conditions. Herein, mesoporous bioactive glass (MBG), nanoreservoirs of the simvastatin (Sim), was end-capped with E7 peptide-modified gold nanoparticles (Au-NPs). This unique design allowed for effective recruitment of endogenous stem cells and enabled the sustained release of simvastatin. The released simvastatin facilitated the osteogenic differentiation of stem cells, supporting bone-like tissue reconstruction. Meanwhile, under near-infrared light irradiation, MBG@Sim-Au-E7 exhibited adaptive degradation and sustained release of simvastatin and active ions. This capability regulated the osteogenic microenvironment, further facilitating bone regeneration. In addition, the results of in vivo experiments showed that the healing of skull defect was significantly improved by MBG@Sim-Au-E7 after NIR irradiation. These findings highlight the potential of MBG@Sim-Au-E7 as a promising approach for preparing functional bone healing materials.

Underestimation in temporal numerosity judgments computationally explained by population coding model

The ability to judge numerosity is essential to an animal’s survival. Nevertheless, the number of signals presented in a sequence is often underestimated. We attempted to elucidate the mechanism for the underestimation by means of computational modeling based on population coding. In the model, the population of neurons which were selective to the logarithmic number of signals responded to sequential signals and the population activity was integrated by a temporal window. The total number of signals was decoded by a weighted average of the integrated activity. The model predicted well the general trends in the human data while the prediction was not fully sufficient for the novel aging effect wherein underestimation was significantly greater for the elderly than for the young in specific stimulus conditions. Barring the aging effect, we can conclude that humans judge the number of signals in sequence by temporally integrating the neural representations of numerosity.

A window of subliminal perception

Under labels such as unconscious processing and subliminal perception, identification of stimuli falling below the subjective threshold (whether truly unconscious or not) has been found remarkably accurate in some experiments while completely at chance in others. Here, we first identify that an apparent window of subliminal perception arises in humans under specific stimulus conditions using different experimental paradigms and analysis methods. We then show that the standard signal detection theory (SDT) model is unable to account for this window and extend it until it is. We finally compare a range of models on empirical data. The models performing best are notable for their absence of hierarchical levels, indicating that the window could be a base property of any phenomenally conscious system. The models explain previously incompatible findings in the literature, and they allow for estimations of peaks in subthreshold perception across the spectrum of stimulus saliency, which may be used in further studies of subliminal perception.

Preservation of Eye Movements in Parkinson's Disease Is Stimulus- and Task-Specific.

Parkinson's disease (PD) is a neurodegenerative disease that includes motor impairments, such as tremor, bradykinesia, and postural instability. Although eye movement deficits are commonly found in saccade and pursuit tasks, preservation of oculomotor function has also been reported. Here we investigate specific task and stimulus conditions under which oculomotor function in PD is preserved. Sixteen PD patients and 18 healthy, age-matched controls completed a battery of movement tasks that included stationary or moving targets eliciting reactive or deliberate eye movements: pro-saccades, anti-saccades, visually guided pursuit, and rapid go/no-go manual interception. Compared with controls, patients demonstrated systematic impairments in tasks with stationary targets: pro-saccades were hypometric and anti-saccades were incorrectly initiated toward the cued target in ∼35% of trials compared with 14% errors in controls. In patients, task errors were linked to short latency saccades, indicating abnormalities in inhibitory control. However, patients' eye movements in response to dynamic targets were relatively preserved. PD patients were able to track and predict a disappearing moving target and make quick go/no-go decisions as accurately as controls. Patients' interceptive hand movements were slower on average but initiated earlier, indicating adaptive processes to compensate for motor slowing. We conclude that PD patients demonstrate stimulus and task dependency of oculomotor impairments, and we propose that preservation of eye and hand movement function in PD is linked to a separate functional pathway through the superior colliculus-brainstem loop that bypasses the fronto-basal ganglia network. Our results demonstrate that studying oculomotor and hand movement function in PD can support disease diagnosis and further our understanding of disease progression and dynamics.SIGNIFICANCE STATEMENT Eye movements are a promising clinical tool to aid in the diagnosis of movement disorders and to monitor disease progression. Although Parkinson's disease (PD) patients show some oculomotor abnormalities, it is not clear whether previously described eye movement impairments are task-specific. We assessed eye movements in PD under different visual (stationary vs moving targets) and movement (reactive vs deliberate) conditions. We demonstrate that PD patients are able to accurately track moving objects but make inaccurate eye movements toward stationary targets. The preservation of eye movements toward dynamic stimuli might enable patients to accurately act on the predicted motion path of the moving target. These results can inform the development of tools for the rehabilitation or maintenance of functional performance.

A role for representations in inflexible behavior

Representationalists have routinely expressed skepticism about the idea that inflexible responses to stimuli (e.g. reflexive responses like the pupillary light reflex) are to be explained in representational terms. Representations are supposed to be more than just causal mediators in the chain of events stretching from stimulus to response, and it is difficult to see how the sensory states driving reflexes are doing more than playing the role of causal intermediaries. One popular strategy for distinguishing representations from mere causal mediators is to require that representations are decoupled from specific stimulus conditions. I believe this requirement on representation is mistaken and at odds with explanatory practices in sensory ecology. Even when sensory states have the job of coordinating a specific output with a specific input, we can still find them doing the work of representations, carrying information needed for organisms to respond successfully to environmental conditions. We can uncover information at work by intervening specifically on the information conveyed by sensory states, leaving their causal role undisturbed.

Developmental trends in infant temporal processing speed

Processing speed, which can be measured behaviorally in various sensory domains, has been shown to be a strong marker of central nervous system health and functioning in adults. Visual temporal processing speed (measured via critical flicker fusion [CFF] thresholds) represents the maximum speed at which the visual system can detect changes. Previous studies of infant CFF development have been limited and inconsistent. The present study sought to characterize the development of CFF thresholds in the first year of life using a larger sample than previous studies and a repeated measures design (in Experiment 2) to control for individual differences. Experiment 1 (n=44 infants and n=24 adults) used a cross-sectional design aimed at examining age-related changes that exist in CFF thresholds across infants during the first year of life. Adult data were collected to give context to infant CFF thresholds obtained under our specific stimulus conditions. Experiment 2 (N=28) used a repeated-measures design to characterize the developmental trajectory of infant CFF thresholds between three and six months of age, based on the results of Experiment 1. Our results reveal a general increase in CFF from three to four and one-half months of age, with a high degree of variability within each age group. Infant CFF thresholds at 4.5months of age were not significantly different from the adult average, though a regression analysis of the data from Experiment 2 predicted that infants would reach the adult average closer to 6months of age. Developmental and clinical implications of these data are discussed.

Transferability of Dual-Task Coordination Skills after Practice with Changing Component Tasks.

Recent research has demonstrated that dual-task performance with two simultaneously presented tasks can be substantially improved as a result of practice. Among other mechanisms, theories of dual-task practice-relate this improvement to the acquisition of task coordination skills. These skills are assumed (1) to result from dual-task practice, but not from single-task practice, and (2) to be independent from the specific stimulus and response mappings during the practice situation and, therefore, transferable to new dual task situations. The present study is the first that provides an elaborated test of these assumptions in a context with well-controllable practice and transfer situations. To this end, we compared the effects of dual-task and single-task practice with a visual and an auditory sensory-motor component task on the dual-task performance in a subsequent transfer session. Importantly, stimulus and stimulus-response mapping conditions in the two component tasks changed repeatedly during practice sessions, which prevents that automatized stimulus-response associations may be transferred from practice to transfer. Dual-task performance was found to be improved after practice with the dual tasks in contrast to the single-task practice. These findings are consistent with the assumption that coordination skills had been acquired, which can be transferred to other dual-task situations independently on the specific stimulus and response mapping conditions of the practiced component tasks.

Learning-Related Brain-Electrical Activity Dynamics Associated with the Subsequent Impact of Learnt Action-Outcome Associations.

Goal-directed behavior relies on the integration of anticipated outcomes into action planning based on acquired knowledge about the current contingencies between behavioral responses (R) and desired outcomes (O) under specific stimulus conditions (S). According to ideomotor theory, bidirectional R-O associations are an integral part of this knowledge structure. Previous EEG studies have identified neural activity markers linked to the involvement of such associations, but the initial acquisition process has not yet been characterized. The present study thus examined brain-electrical activity dynamics during the rapid acquisition of novel bidirectional R-O associations during instructed S-R learning. Within a trial, we inspected response-locked and stimulus-locked activity dynamics in order to identify markers linked to the forward and backward activation of bidirectional R-O associations as they were being increasingly strengthened under forced choice conditions. We found that a post-response anterior negativity following auditory outcomes was increasingly attenuated as a function of the acquired association strength. This suggests that previously reported action-induced sensory attenuation effects under extensively trained free choice conditions can be established within few repetitions of specific R-O pairings under forced choice conditions. Furthermore, we observed the even more rapid development of a post-response but pre-outcome fronto-central positivity which was reduced for high R-O learners which might indicate the rapid deployment of preparatory attention towards predictable outcomes. Finally, we identified a learning-related stimulus-locked activity modulation within the visual P1-N1 latency range which might reflect the multi-sensory integration of the perceived antecedent visual stimulus the anticipated auditory outcome.

The neural basis of integrating pre- and post-response information for goal-directed actions

A fundamental prerequisite for goal-directed action is to encode the contingencies between responses (R) producing specific outcomes (O) in specific stimulus conditions (S). The present study aimed to characterize the functional neuroanatomy of different associational sub-components of such S–R–O contingencies during the first few trials of exposure. We devised a novel paradigm that was suited to distinguish BOLD activation patterns related to S–R, R–O, and the full S–R–O contingency. Different from previous studies our experimental design ensured that stimulus-related processes and outcome-related processes were maximally comparable, as both were learned incidentally and lacked intrinsic incentive value, and different from trial-and-error learning situations, outcomes did not serve a special role as performance feedback. We observed contingency-related dissociations between SMA, lateral OFC, and large parts of the reward system including central OFC, anterior striatum and midbrain areas. While the lateral OFC was involved in processing differential outcomes irrespective of a predictive stimulus context, the SMA was specifically engaged when differential outcomes could be predicted by the stimulus. By contrast, the activation pattern of reward system areas suggested that these regions serve a role in integrating non-incentive differential outcome information and incentive common outcome information. Together, these results support the notion that striatal and orbitofrontal regions are involved in outcome-related processes beyond trial-and-error S–R learning, that is, when outcomes are non-incentive and do not serve as reinforcing feedback that drives learning. Furthermore, our results clarify the role of the SMA in outcome-related processes thereby supporting current versions of ideomotor theory.

Low- but Not High-Frequency LFP Correlates with Spontaneous BOLD Fluctuations in Rat Whisker Barrel Cortex.

Resting-state magnetic resonance imaging (rsMRI) is thought to reflect ongoing spontaneous brain activity. However, the precise neurophysiological basis of rsMRI signal remains elusive. Converging evidence supports the notion that local field potential (LFP) signal in the high-frequency range correlates with fMRI response evoked by a task (e.g., visual stimulation). It remains uncertain whether this relationship extends to rsMRI. In this study, we systematically modulated LFP signal in the whisker barrel cortex (WBC) by unilateral deflection of rat whiskers. Results show that functional connectivity between bilateral WBC was significantly modulated at the 2 Hz, but not at the 4 or 6 Hz, stimulus condition. Electrophysiologically, only in the low-frequency range (<5 Hz) was the LFP power synchrony in bilateral WBC significantly modulated at 2 Hz, but not at 4- or 6-Hz whisker stimulation, thus distinguishing these 2 experimental conditions, and paralleling the findings in rsMRI. LFP power synchrony in other frequency ranges was modulated in a way that was neither unique to the specific stimulus conditions nor parallel to the fMRI results. Our results support the hypothesis that emphasizes the role of low-frequency LFP signal underlying rsMRI.

Repeated valproate treatment facilitates fear extinction under specific stimulus conditions

Single dose treatment with histone deacetylase inhibitor (HDACi) agents has been shown to enhance extinction learning in rodent models under certain conditions. The present novel studies were designed to examine the effects of repeated HDACi treatment, with valproate or sodium butyrate, on the extinction of conditioned fear. In Experiments 1 and 2, short duration CS exposure (30s) in combination with vehicle administration progressively attenuated conditioned fear responses over 40 or more sessions. This effective extinction training was not augmented by HDACi treatments. In Experiment 3, we used a long duration CS exposure (120s) to weaken extinction training. With these extinction parameters, repeated valproate treatment substantially facilitated the acquisition and retention of fear extinction. Results of this study extend previous work suggesting that HDACi's have utility in augmenting the efficiency of fear extinction, although their apparent benefits are critically dependent upon specific parameters of extinction training.

Thinking in spatial terms: decoupling spatial representation from sensorimotor control in monkey posterior parietal areas 7a and LIP

Perhaps the simplest and most complete description of the cerebral cortex is that it is a sensorimotor controller whose primary purpose is to represent stimuli and movements, and adaptively control the mapping between them. However, in order to think, the cerebral cortex has to generate patterns of neuronal activity that encode abstract, generalized information independently of ongoing sensorimotor events. A critical question confronting cognitive systems neuroscience at present therefore is how neural signals encoding abstract information emerge within the sensorimotor control networks of the brain. In this review, we approach that question in the context of the neural representation of space in posterior parietal cortex of non-human primates. We describe evidence indicating that parietal cortex generates a hierarchy of spatial representations with three basic levels: including (1) sensorimotor signals that are tightly coupled to stimuli or movements, (2) sensorimotor signals modified in strength or timing to mediate cognition (examples include attention, working memory, and decision-processing), as well as (3) signals that encode frankly abstract spatial information (such as spatial relationships or categories) generalizing across a wide diversity of specific stimulus conditions. Here we summarize the evidence for this hierarchy, and consider data showing that signals at higher levels derive from signals at lower levels. That in turn could help characterize neural mechanisms that derive a capacity for abstraction from sensorimotor experience.

A chronic pain: Inflammation-dependent chemoreceptor adaptation in rat carotid body

Experiments in recent years have revealed labile electrophysiological and neurochemical phenotypes in primary afferent neurons exposed to specific stimulus conditions associated with the development of chronic pain. These studies collectively demonstrate that the mechanisms responsible for functional plasticity are primarily mediated by novel neuroimmune interactions involving circulating and resident immune cells and their secretory products, which together induce hyperexcitability in the primary sensory neurons. In another peripheral sensory modality, namely the arterial chemoreceptors, sustained stimulation in the form of chronic hypoxia (CH) elicits increased chemoafferent excitability from the mammalian carotid body. Previous studies which focused on functional changes in oxygen-sensitive type I cells in this organ have only partially elucidated the molecular and cellular mechanisms which initiate and control this adaptive response. Recent studies in our laboratory indicate a unique role for the immune system in regulating the chemo-adaptive response of the carotid body to physiologically relevant levels of hypoxia.

Pre-participation cardiac screening: Considerations for young athletes

This article is the first of two focusing on the utility and evidence base for pre-participation cardiac screening in competitive athletic populations. The second article will focus on the diagnostic value of different screening modalities used in the large-scale screening of athletic populations. The current article, however, focuses on the incidence of sudden cardiac death (SCD) in young athletic populations and goes on to consider the effectiveness of cardiac screening programmes for reducing the risk of SCD. Cardiac screening in athletic populations is problematic as it may be difficult to distinguish between physiological adaptations resulting from a specific exercise training stimulus and pathological conditions. Different types of chronic exercise training can induce eccentric or concentric myocardial hypertrophy, which may mimic pathological conditions. The final section discusses some of the practical issues that a clinician may face when needing to advise a young athlete to either stop or modify his/her habitual patterns of physical activity including future exercise considerations.

Formal concepts expressed by compositional hierarchical Hebbian cell assemblies

Hebbian cell assemblies can be formalised as sets of tightly connected cells in autoand hetero-associative memories. Direct evidence for such has recently been obtained in multiple-unit recordings from rat hippocampal neurons [1,2]. These experiments suggest a hierarchical organisation where cliques are embedded in each other such that larger cliques represent less specific stimulus conditions. We here suggest an extended interpretation stating that the firing patterns may not just reflect nested categories but a lattice of concepts about stimulus-response mappings in the sense of formal concept analysis, an applied branch of set theory. We present an implementation of formal concept lattices in bidirectional associative memories that, in contrast to previous work by Belohlavek [3], satisfies Dale's principle and uses balanced excitation and inhibition [4]. Inhibitory cells have fixed, non-plastic synapses even if the model learns new concepts. As an extreme case a single global inhibitory cell is enough that controls the total level of activation. The excitatory cells can further learn incrementally using a Hebbian coincidence learning rule. A spiking neuron variant of the model is further presented and implications of the model for retrieval in auto-associative memories are outlined. Overall the model is well suited for representing hierarchical compositional relationships between entities in the form of correlated memory traces in the brain. Acknowledgements The author acknowledges support by the Engineering and Physical Sciences Research Council of the United Kingdom (EP/C010841/1, COLAMN – A Novel Computing Architecture for Cognitive Systems based on the Laminar Microcircuitry of the Neocortex) and the European Community (IST2001-35282, FACETS – Fast Analog Computing with Emergent Transient States).

On the Natural Hierarchical Composition of Cliques in Cell Assemblies

Hebbian cell assemblies can be formalised as sets of tightly connected cells in auto- and hetero-associative memories. Direct evidence for such “cliques” has recently been obtained in multiple-unit recordings from rat hippocampal neurons. These experiments suggest a hierarchical organisation where cliques are embedded in each other such that larger cliques represent less specific stimulus conditions. We here suggest an interpretation stating that the firing patterns may not just reflect nested categories but a lattice of concepts about stimulus–response mappings in the sense of formal concept analysis, an applied branch of set theory. We present an implementation of formal concept lattices in bidirectional associative memories that in contrast to previous work satisfies Dale’s principle and uses balanced excitation and inhibition. Inhibitory cells have fixed, non-plastic synapses even if the model learns new concepts. As an extreme case a single global inhibitory cell is enough that controls the total level of activation. The excitatory cells can further learn incrementally using a Hebbian coincidence learning rule. Implications of the model for retrieval in auto-associative memories are further outlined. Overall the model is well suited for representing hierarchical compositional relationships between entities in the form of correlated patterns in technical cognitive systems and potentially the brain.

Implications of Functionally Different Synaptic Inputs for Neuronal Gain and Computational Properties of Fly Visual Interneurons

Neurons embedded in networks are thought to receive synaptic inputs that do not drive them on their own, but modulate the responsiveness to driving input. Although studies on brain slices have led to detailed knowledge of how nondriving input affects dendritic integration, its origin and functional implications remain unclear. We tackle this issue using an ensemble of fly wide-field visual interneurons. These neurons offer the opportunity not only to combine in vivo recording techniques and natural sensory stimulation but also to interpret electrophysiological results in a behavioral context. By targeted manipulation of the animal's visual input we find a pronounced modulating impact of nondriving input, whereas functionally important cellular properties like direction tuning and the coding of pattern velocity are left almost unaffected. We propose that the integration of functionally different synaptic inputs is a mechanism that immanently equalizes the ensemble's sensitivity irrespective of the specific stimulus conditions.

The role of personality in cognitive-behavioral therapies

Trait-based theories of personality explain behavior across situations based on a set of broad personality attributes or dimensions. In contrast, recent social-cognitive theories of personality emphasize the importance of context and take a combined nomothetic/idiographic approach to personality. The social-cognitive perspective on personality resembles cognitive-behavioral therapies, which explain behavior in particular situations based on interactions of specific cognitions, mood states, and stimulus conditions. This article considers how contemporary personality theory and research might be integrated into the study of the outcomes and processes associated with cognitive-behavioral therapies. We propose that applying the social-cognitive perspective on personality to the study of how cognitive-behavioral therapies work provides both validation of current theories and promising directions for additional research. We review the research literatures on cognitive theories of psychopathology and cognitive-behavioral treatments to examine how the topic of personality has been addressed in those literatures to date. We then explore some commonalities between cognitive theories of psychopathology and psychotherapy and recent social-cognitive approaches to personality, suggesting that an integration of the two areas is overdue.

Evaluation of interaction between liposome membranes induced by stimuli responsive polymer and protein

Immobilized liposome chromatography was utilized as a novel method for the quantitative evaluation of the interaction between liposome membranes. The capacity factors evaluated from the elution profile showed that interaction between 1-palmitoyl-2-oleoyl- sn-glycero-3-phosphocholine (POPC) liposome membranes occurred in the presence of a stimuli responsive polymer and protein under specific stimulus conditions. The occurrence of such interaction was supported by experimental results for POPC liposome membrane fusion under corresponding stimuli conditions.