Cognitive impairment and whole brain diffusion in patients with neuromyelitis optica after acute relapse

The objective of this study investigated cognitive impairments and their correlations with fractional anisotropy (FA) and mean diffusivity (MD) in patients with neuromyelitis optica (NMO) without visible lesions on conventional brain MRI during acute relapse. Twenty one patients with NMO and 21 normal control subjects received several cognitive tests to assess cognitive function. Head diffusion tensor imaging (DTI) of all patients with NMO were collected with a 3-T MR system. Correlations of cognitive test scores and whole brain FA and MD were examined by voxel-based analysis. Region-of-interest analysis was applied to the significantly correlated regions which the most frequently appeared. We found that NMO patients without visible brain lesions had significantly impaired learning and memory, decreased information processing speed, and damaged attention compared with normal control subjects. These impaired cognitive domains were significantly correlated with FA and MD in local regions of corpus callosum, anterior cingulate and medial frontal cortex. In corpus callosum of NMO patients, mean FA was significantly lower and mean MD higher than normal control subjects. Our findings suggest that cognitive impairments in learning and memory, information processing speed and attention occur in NMO patients without visible brain lesions during acute relapse. The impairments in immediate and short-term memory in NMO patients may be due to information encoding deficits in the process of information acquisition. The corpus callosum of such patients may have local microscopic damages that play a role in cognitive impairments during acute relapse.     

The 36th Sir Frederick Bartlett Lecture: An associative analysis of spatial learning

The ability of animals to find important goals in their environment has been said to require a form of learning that is qualitatively different from that normally studied in the conditioning laboratory. Such spatial learning has been said to depend upon the construction of a global representation of the environment, and the acquisition of knowledge about the position of goals with reference to this representation is said to be unaffected by the presence of other cues or landmarks. To evaluate the first of these claims, experiments are described that investigated the extent to which the effects of training in one environment transfer to another. To evaluate the second claim, experiments are described that investigated whether cue competition effects normally found in conditioning studies can be found in spatial tasks. Overall, the results indicate that most of the phenomena of spatial learning can be explained by the principles of associative learning. The implications of the reported results for an understanding of the neural mechanisms of spatial learning are considered.     

Ageing and attentional control

The research examines the structural bottleneck account and the resource account of the substantial dual-task deficits among older adults. Procedures from two common dual-task methodologies—the psychological refractory period and the relative-priority manipulation—were used to encourage maximization of the joint performance. Performance and time-sharing strategies from subjects between the ages of 20 and 70 years were examined. Age-related declines in time-sharing efficiency and in the precision of the executive control process were observed. The age-related effect was larger when two manual responses were required than when one manual and one vocal response were required, but no evidence for obligatory sequential processing was found. Except for the most demanding conditions, comparable practice effects were observed between the younger and older subjects, suggesting considerable cognitive plasticity in the older subjects. Implications for the two attentional accounts were discussed.     

Cognitive load while driving impairs memory of moving but not stationary elements within the environment

The negative impact of cognitive load, such as cell phone conversations, while driving is well established, but understanding the nature of this performance deficit is still being developed. To test the impact of load on awareness of different elements in a driving scene, memory for items within the environment was examined under load and no load conditions. Participants drove through two different scenarios in a driving simulator, were periodically interrupted by a pause in the driving during, and were asked questions regarding moving and stationary objects in the environment. Participants in the load condition drove while concurrently counting backwards by sevens. Results indicate that driving under load conditions led to diminished knowledge of moving, but not stationary, objects in the scene. This result suggests not all types of knowledge are equally impaired. Potential implications for current theories of cell phone use while driving and applied attention theory are discussed.     

Cognitive defusion and self-relevant negative thoughts: examining the impact of a ninety year old technique

Cognitive defusion techniques are designed to reduce the functions of thoughts by altering the context in which they occur, rather than the attempting to alter the form, frequency, or situational sensitivity of the thoughts themselves. Applied technologies designed to produce cognitive defusion seem to lead to reductions in the believability of negative thoughts, but defusion techniques are generally only parts of complex packages and the role of defusion techniques per se is note yet known. The present study examined the impact of a cognitive defusion technique first described by Titchener nearly 90 years ago: rapidly repeating a single word. In series of eight single-case alternating treatment designs, this defusion technique was compared to a distraction task, and to a thought control task on reductions in the discomfort and believability of self-relevant negative thoughts. The cognitive defusion technique reduced both discomfort and believability more so than the comparison approaches. Control studies showed that the effect was probably not due to demand characteristics.     

Characterizing Simpler Recognizable Sets of Integers

For a given numeration system U, a set X of integers is said to be U-star-free if the language of the normalized U-representations of the elements in X is star-free. Adapting a result of McNaughton and Papert, we give a first-order logical characterization of these sets for various numeration systems including integer base systems and the Fibonacci system. For k-ary systems, the problem of the base dependence of this property is also studied. Finally, the case of k-adic systems is developed.     

On Modal μ-Calculus and Non-Well-Founded Set Theory

A finitary characterization for non-well-founded sets with finite transitive closure is established in terms of a greatest fixpoint formula of the modal -calculus. This generalizes the standard result in the literature where a finitary modal characterization is provided only for wellfounded sets with finite transitive closure. The proof relies on the concept of automaton, leading then to new interlinks between automata theory and non-well-founded sets.     

Alien voices and inner dialogue: towards a developmental account of auditory verbal hallucinations

The phenomenon of auditory verbal hallucinations (AVHs) is one of the most intriguing features of the psychiatric literature. Two alternative models of the development of AVHs in both normal and psychotic populations are proposed. In the disruption to internalisation (DI) model, AVHs result from a disruption to the normal processes of internalisation of inner speech. In the re-expansion (RE) model, AVHs result when normal inner speech is re-expanded into inner dialogue under conditions of stress and cognitive challenge. Both models draw on Vygotsky's (The Collected Works Of L.S. Vygotsky, New York, Plenum Press, 1987) ideas about the development of inner speech. On this view, normal inner speech is considerably abbreviated relative to external speech, and also undergoes some important semantic transformations. In both the DI and RE models, AVHs arise when the subject's inner speech involves inappropriately expanded inner dialogue, leading the subject to experience the voices in the dialogue as alien. The two models may prove useful in explaining some of the social-developmental evidence surrounding the phenomenon, and also make a number of testable predictions which are suggested as priorities for future research.     

Faceted Thesauri

The basic elements of faceted thesauri are described, together with a review of their origins and some prominent examples. Their use in browsing and searching applications is discussed. Faceted thesauri are distinguished from faceted classification schemes, while acknowledging the close similarities. The paper concludes by comparing faceted thesauri and related knowledge organization systems to ontologies and discussing appropriate areas of use.     

A Computational Evaluation of Sentence Processing Deficits in Aphasia

Individuals with agrammatic Broca's aphasia experience difficulty when processing reversible non‐canonical sentences. Different accounts have been proposed to explain this phenomenon. The Trace Deletion account (Grodzinsky, 1995, 2000, 2006) attributes this deficit to an impairment in syntactic representations, whereas others (e.g., Caplan, Waters, Dede, Michaud, & Reddy, 2007; Haarmann, Just, & Carpenter, 1997) propose that the underlying structural representations are unimpaired, but sentence comprehension is affected by processing deficits, such as slow lexical activation, reduction in memory resources, slowed processing and/or intermittent deficiency, among others. We test the claims of two processing accounts, slowed processing and intermittent deficiency, and two versions of the Trace Deletion Hypothesis (TDH), in a computational framework for sentence processing (Lewis & Vasishth, 2005) implemented in ACT‐R (Anderson, Byrne, Douglass, Lebiere, & Qin, 2004). The assumption of slowed processing is operationalized as slow procedural memory, so that each processing action is performed slower than normal, and intermittent deficiency as extra noise in the procedural memory, so that the parsing steps are more noisy than normal. We operationalize the TDH as an absence of trace information in the parse tree. To test the predictions of the models implementing these theories, we use the data from a German sentence—picture matching study reported in Hanne, Sekerina, Vasishth, Burchert, and De Bleser (2011). The data consist of offline (sentence‐picture matching accuracies and response times) and online (eye fixation proportions) measures. From among the models considered, the model assuming that both slowed processing and intermittent deficiency are present emerges as the best model of sentence processing difficulty in aphasia. The modeling of individual differences suggests that, if we assume that patients have both slowed processing and intermittent deficiency, they have them in differing degrees.