Objective assessment of the functional role of spike train correlations using information measures

The functional role of correlations between neuronal spike trains remains strongly debated. This debate partly stems from the lack of a standardized analysis technique capable of accurately quantifying the role of correlations in stimulus encoding. We believe that information theoretic measures may represent an objective method for analysing the functional role of neuronal correlations. Here we show that information analysis of pairs of spike trains allows the information content present in the firing rate to be disambiguated from any extra information that may be present in the temporal relationships of the two spike trains. We validate and illustrate the method by applying it to simulated data with variable degrees of known synchrony, and by applying it to recordings from pairs of sites in the primary visual cortex of anaesthetized cats. We discuss the importance of information theoretic analysis in elucidating the neuronal mechanisms underlying object identification.     

Demands,resources, and work ability: A cross-national examination of health care workers

Understanding work ability, with the goal of promoting it, is important for individuals as well as organizations. It is especially important to study work ability in health care workers, who face many work-related challenges that may threaten work ability. We studied various job demands, job resources, and interactions of demands and resources relating to work ability using the Job Demands–Resources model as a framework. Acute care health care workers from six nations (US, Australia, UK, Brazil, Croatia, and Poland) completed a survey. Role demands related to work ability in the Australia sample only, and supervisor support related to work ability in the Australia sample only. Yet, high levels of supervisor support significantly moderated (buffered) negative relationships between physical demands and work ability in the US sample, along with negative relationships between role demands and work ability in both the Croatia and UK samples. Skill discretion related to work ability in every nation sample, and therefore appears to be particularly important to work ability perceptions. In addition, skill discretion moderated (buffered) a negative relationship between role demands and work ability in the Australia sample. We therefore recommend that interventions to help preserve or improve work ability target this important job resource.     

Frankfurt versus Frankfurt: a new anti-causalist dawn

There is an important anomaly to the causalist/compatibilist paradigm in the philosophy of action and free will. This anomaly, which to my knowledge has gone unnoticed so far, can be found in the philosophy of Harry Frankfurt. Two of his most important contributions to the field – his influential counterexample to the Principle of Alternate Possibilities and his ‘guidance’ view of action – are incompatible. Frankfurt's counterexample to the Principle works only if we do not understand action as Frankfurt does in his guidance account. If, on the other hand, we understand agency in terms of the agent's guidance, then his counterexample to the Principle fails because, then, counterfactual scenarios of Frankfurt-type counterexamples are such that what happens does not count as the relevant agent's action. So Frankfurt-type counterexamples do not show that the agent could not have avoided acting as she did: so they fail to offer a scenario in which the agent is intuitively responsible even though she could not have avoided acting as she did. Therefore, Frankfurt-type counterexamples do not challenge the Principle, according to which ‘a person is morally responsible for what he has done only if he could have done otherwise’. The importance of this inconsistency goes far beyond the issue of coherence within Frankfurt's philosophy. I shall argue that this inconsistency represents an important anomaly within the causalist/compatibilist framework; so that we should start to seriously consider having to move on from the established paradigm.     

What clocks tell us about the neural correlates of spatial imagery

We review a series of experimental studies aimed at answering some critical questions about the neural basis of spatial imagery. Our group used functional magnetic resonance imaging (fMRI) to explore the neural correlates of an online behaviourally controlled spatial imagery task without need for visual presentation—the mental clock task. Subjects are asked to imagine pairs of times that are presented acoustically and to judge at which of the two times the clock hands form the greater angle. The cortical activation elicited by this task was contrasted with that obtained during other visual, perceptual, verbal, and spatial imagery tasks in several block design studies. Moreover, our group performed an event‐related fMRI study on the clock task to investigate the representation of component cognitive processes in spatial imagery. The bulk of our findings demonstrates that cortical areas in the posterior parietal cortex (PPC), along the intraparietal sulcus, are robustly involved in spatial mental imagery and in other tasks requiring spatial transformations. PPC is bilaterally involved in different kinds of spatial judgement. Yet the degree to which right and left PPC are activated in different tasks is a function of task requirements. From event‐related fMRI data we obtained evidence that left and right PPC are activated asynchronously during the clock task and this could reflect their different functional role in subserving cognitive components of visuospatial imagery.     

Order of strokes writing as a cue for retrieval in reading chinese characters

Abstract

Chinese characters are composed of a number of strokes, varying from 1 to 23. The strokes of each character have to be written in a precise order, which is codified in a number of rules, and which is learned in the process of literacy acquisition. The present study tested the hypothesis that stroke writing order has been coded in memory as an essential component of the orthographic knowledge of a character, and that this specific motor schema is used as a cue in lexical retrieval. In the first experiment reported here, fragments of Chinese characters consisting of “early” or of “late” strokes (namely strokes which are written first or last during writing) were pre-exposed to target characters to be named as fast as possible. The results indicated that “early” strokes were better retrieval cues for character names than “late” strokes. In the second experiment, subjects were requested to make same-different judgements about two characters which had in common either “early” or “late” strokes. Different characters sharing “early” strokes were more frequently erroneously judged as being identical than characters sharing “late” strokes.     

Forgetting curves in long-term memory: evidence for a multistage model of retention.

An experimental study with 20 normal healthy young adult subjects was performed to evaluate the interaction of type of memory tasks, type of learning modalities, and length of acquisition/recall interval. Four different tasks were employed (serial learning, paired learning, rote learning, and visuolinguistic transfer), some requiring a single trial learning modality others a multitrial learning modality. Acquisition/recall intervals were immediate, intermediate (3 min), and delayed. The experimental design allowed for the comparison of effects from five different delayed recall intervals (2, 8, 12, 24, and 48 hr). Results demonstrated a specific interaction on learning rates due to different ceiling effects for the different types of memory tasks. Forgetting rates, on the other hand, demonstrated a specific effect due to type of memory tasks and learning modalities only for differences between immediate and intermediate recall. These differences remained stable during the longer intervals and were not affected by length of interval. A multistage composition of long-term retention was suggested to explain these results, and a practical indication to build experimental procedures to study memory in the clinical field was evidenced.     

Randomized Controlled Trials for Diagnostic Imaging: Conceptual and Pratical Problems

Topoi - We raise a problem of applicability of RCTs to validate nuclear diagnostic imaging tests. In spite of the wide application of PET and other similar techniques that use radiopharmaceuticals...     

On the paradox of reversible processes in thermodynamics

This paper discusses an argument by Norton (in: European Philosophy of Science—Philosophy of Science in Europe and the Viennese Heritage, Vienna Circle Institute Yearbook, vol 17, Springer, Dordrecht, pp 197–210, 2014, 2016) to the effect that reversible processes in thermodynamics have paradoxical character, due to the infinite-time limit. For Norton, one can “dispel the fog of paradox” by adopting a distinction between idealizations and approximations, which he himself puts forward. Accordingly, reversible processes ought to be regarded as approximations, rather than idealizations. Here, we critically assess his proposal. In doing so, we offer a resolution of his alleged paradox based on the original work by Tatiana Ehrenfest-Afanassjeva on the foundations of thermodynamics.

     

Risk Factors for Attempting Suicide in Prisoners

We wished to examine determinants of suicidal behavior in prisoners. 903 male prisoners had a psychiatric interview which included various psychometric tests. Suicide attempters were compared with prisoners who had never attempted suicide. Significantly more of the attempters had a history of psychiatric disorder, substance abuse, a family history of suicidal behavior, convictions for violent crime, had exhibited aggressive behavior in jail, and had higher BGLHA aggression scores. A similar pattern of risk factors was found for prisoners with suicidal ideation. A lifetime history of attempting suicide, or of having suicidal ideation, is frequent in prisoners. Risk factors include family, developmental, aggression, personality, psychiatric, and substance abuse factors.