Depression in multiple sclerosis: relationship to working memory capacity.

The study of working memory capacity is of outmost importance in cognitive psychology as working memory is at the basis of general cognitive function. Although the working memory capacity limit has been thoroughly studied, its origin still remains a matter of strong debate. Only recently has the role of visual saliency in modulating working memory storage capacity been assessed experimentally and proved to provide valuable insights into working memory function. In the computational arena, attractor networks have successfully accounted for psychophysical and neurophysiological data in numerous working memory tasks given their ability to produce a sustained elevated firing rate during a delay period. Here we investigate the mechanisms underlying working memory capacity by means of a biophysically-realistic attractor network with spiking neurons while accounting for two recent experimental observations: 1) the presence of a visually salient item reduces the number of items that can be held in working memory, and 2) visually salient items are commonly kept in memory at the cost of not keeping as many non-salient items.Our model suggests that working memory capacity is determined by two fundamental processes: encoding of visual items into working memory and maintenance of the encoded items upon their removal from the visual display. While maintenance critically depends on the constraints that lateral inhibition imposes to the mnemonic activity, encoding is limited by the ability of the stimulated neural assemblies to reach a sufficiently high level of excitation, a process governed by the dynamics of competition and cooperation among neuronal pools. Encoding is therefore contingent upon the visual working memory task and has led us to introduce the concept of effective working memory capacity (eWMC) in contrast to the maximal upper capacity limit only reached under ideal conditions.

Cerebrospinal fluid kynurenines in multiple sclerosis; relation to disease course and neurocognitive symptoms

It has been suggested that hearing-impaired listeners with a good working memory (WM) should be fitted with a compression system using short time constants (i.e., fast-acting compression [FAC]), whereas those with a poorer WM should be fitted with a longer time constant (i.e., slow-acting compression [SAC]). However, commercial hearing aids (HAs) seldom use a fixed speed of compression. The performance of a variable speed compression (VSC) system relative to a fixed speed compressor (FAC and SAC) on measures of speech intelligibility, recall, and subjective report of listening effort and tolerable time was evaluated. The potential interaction with the listeners' WM capacity (WMC) was also examined. A double-blinded, repeated measures design. Seventeen HA wearers (16 with greater than one year HA experience) with a bilaterally symmetrical, mild to moderately severe sensorineural hearing loss participated in the study. Participants wore the study HAs at three compression speeds (FAC, SAC, and VSC). Each listener was evaluated on the Office of Research in Clinical Amplification-nonsense syllable test (NST) at 50 dB SPL (signal-to-noise ratio [SNR] = +15 dB), 65 dB SPL (SNR = +5 dB), 80 dB SPL (SNR = 0 dB), and a split (80 dB SPL-50 dB SPL) condition. Listeners were also evaluated on a Repeat Recall Test (RRT), where they had to repeat six short sentences (both high- and low-context sentences) after each was presented. Listeners recalled target words in all six sentences after they were presented. They also rated their listening effort and the amount of time they would tolerate listening under the specific condition. RRT sentences were presented at 75 dB SPL in quiet, as well as SNR = 0, 5, 10, and 15 dB. A Reading Span Test (RST) was also administered to assess listeners' WMC. Analysis of variance using RST scores as a covariate was used to examine differences in listener performance among compressor speeds. Listener performance on the NST was similar among all three compression speeds at 50, 65, and 80 dB SPL. Performance with FAC was significantly better than SAC for the split condition; however, performance did not differ between FAC and VSC or between SAC and VSC. Performance on the NST was not affected by listeners' RST scores. On the RRT, there was no effect of compressor speed on measures of repeat, recall, listening effort, and tolerable time. However, VSC resulted in significantly lower (better) speech reception threshold at the 85% correct recognition criterion (SRT85) than FAC and SAC. Listener RST scores significantly affected recall performance on the RRT but did not affect SRT85, repeat, listening effort, or tolerable time. These results suggest that the VSC, FAC, and SAC yield similar performance in most but not all test conditions. FAC outperforms SAC, where the stimulus levels change abruptly (i.e., split condition). The VSC yields a lower SRT85 than a fixed compression speed at a moderately high level with a favorable SNR. There is no interaction between compression speed and the participants' WMC.

The effectiveness of post-reading word-focused activities and their associations with working memory

The present study was conducted to investigate the effects of background noise and working memory capacity on speechreading performance. The results displayed no differences in speechreading performance (i.e. on a word-test and on a sentence-test) due to background noise. When working memory capacity was correlated with speechreading, only one of the two tests of working memory capacity (i.e. the reading span task) was found to be related to speechreading performance. This relationship applies to both speechreading tests, but only to one specific background noise condition in the tests: meaningful noise. The results are discussed with respect to the demands of simultaneous storage and processing in working memory and how these demands apply to speech-based noise distractors. It was also concluded that although performance was similar across different background noise conditions, they apparently engage different components of the individual's cognitive system.

The present study investigated the relationship between working memory capacity and brain activity in the dorsolateral prefrontal cortex (DLPFC) and the left ventrolateral prefrontal cortex (VLPFC) using functional near-infrared spectroscopy. We administered the reading span test language task to measure linguistic working memory, while we assessed brain activity reflected in the cerebral blood flow change during the task. The cerebral blood flow change in the DLPFC had a negative correlation with the reading span test score. Both focused regions exhibited different patterns of cerebral blood flow changes during the first and second halves of the task period in the high- and low-score groups. Our findings suggest that the brain activity correlates with the reading span test score, which is associated with linguistic working memory capacity. Therefore, brain activity measurement in the DLPFC with the functional near-infrared spectroscopy can be used to indirectly assess working memory capacity.

The effects of working memory (WM) capacity on mathematical ability are well known. This relationship is seen mainly for the capacity of visuospatial WM, while the capacity of the phonological loop of WM, which is associated with processing sound and speech information, has been suggested to have a minor effect on mathematical ability in adults. Nonetheless, involvement of the language neural networks in mathematical thought remains controversial. We have studied the effects of the capacity of the phonological loop of WM on the rate and correctness of solution of mathematical and verbal tasks in young, healthy, right-handed volunteers who either had higher education or were students at institutions teaching mathematics and humanities. Subjects in the mathematics group (N = 10) solved all tasks with measures of solution correctness (CA) and response time (RT) which were significantly better than values for subjects of the humanities group (N = 10). The capacity of the phonological loop of WM showed no difference between the two groups but had different effects on CA and RT values for tasks in mathematicians and humanities specialists. Spearman correlation analysis for each group separately showed that the capacity of WM had positive effects on CA for all mathematical tasks only in the mathematicians group, where it had no effect on RT, while the reverse tendency was seen in the humanities group. The capacity of WM in the mathematicians group correlated inversely with RT for logical tasks on arithmetic sequences. Our results provide indirect evidence that WM in the verbal domain can influence mathematical ability, especially when tasks require the involvement of logical thought.

This study investigated the role of working memory capacity on the making of reinstatement and causal elaborative inferences during the reading of natural texts. In order to determine participants' working memory capacity, they were asked to take the reading span task before they took part in the study. Those participants that were identified as high or low working memory capacity readers were asked to perform a lexical decision task in two conditions: pre-inference and inference. In the pre-inference condition, target words representing reinstatement or causal elaborative inferences were presented immediately before the sentences that were predicted to prompt them. In the inference condition, the target words were presented immediately after the sentences that were predicted to prompt the inferences. Results indicated that, for the high working memory capacity readers, lexical decision times were faster at the inference compared to the pre-inference locations for both types of inferences. In the case of low working capacity readers, lexical decision times were faster at the inference compared to the pre-inference locations only for reinstatement inferences. These findings suggest that working memory capacity plays a role in the making of causal inferences during the comprehension of natural texts.

This study investigated the extent to which textual enhancement in captions can draw a learner’s attention to the target linguistic construction and promote subsequent development in L2 collocation knowledge. The study also explored the extent to which individual difference in working memory (WM) is related to learners’ attentional allocation and L2 collocation knowledge development. A total of 34 L2 English learners in Korea were assigned into an enhanced captions group (n =18) and a captions group (n = 16). For the enhanced captions group, the target L2 construction was typographically enhanced using a different color (i.e., red color). Learners’ allocation of attentional resources to the target collocations was measured with an eye-tracking method. To assess L2 collocation knowledge development, a meaning recall and meaning recognition test were used. In addition, learners’ working memory capacity was assessed using a nonword span task and a reading span task. The results of this study showed that textual enhancement succeeded in directing a learner’s attention to the target linguistic constructions; however, it did not lead to learning gains in collocation knowledge. In addition, working memory was found to have meaningful relationships with learners’ allocation of attentional resources when they were exposed to textually enhanced input.

In learning to read, a condition is often encountered where a person has succeeded in reaching the last line of a reading, but he does not remember what he has read. Therefore, in learning dokkai besides requiring knowledge of kanji, vocabulary, grammar and understanding, it also requires working memory or momentary memory for each sentence that is read. The purpose of this research is to determine the correlation of Working Memory Capacity of Japanese learners based on the Dokkai ability test (reading span test, then to determine the increase in Working Memory capacity of Japanese learners after the use of ICT in Dokkai learning. The method used in this research is descriptive, with a descriptive-quantitative analysis which describes the correlation of working memory in Dokkai learning and the effectiveness of using ICT to improve Dokkai abilities.

The effects of structured input and working memory on the acquisition of English causative forms

This literature review aims to analyze the role of individual differences in working memory capacity in following instructions based on theoretical perspectives and empirical evidence. Individual differences in working memory capacity have an impact on the encoding, and retrieval stage. In general, the output from the review stated that the performance difference between individuals relates to the experimental design and treatment, which include delivery of the instructions, presentation of objects, the length of instructions, involvement of dual tasks, and retrieval methods. In addition, the contents of instructions can be transferred into working memory space if the individuals can give a high level of attention and control the attention to suppress the distractors. Therefore, the ability to follow instructions depends on the individual's understanding of the instructions' meaning and matching them with the available space of their working memory (capacity). This review also adds value and suggestions to the need to conduct more research on the role of working memory capacity in following instructions.

It is unclear whether brain MRI lesions are associated with depression in multiple sclerosis (MS). Neurological dysfunction in depressed (n= 19) and non-depressed (n = 29) MS patients was rated by expanded disability status scale (EDSS). EDSS was weakly predictive of the presence of (p = 0.03) and severity of (p = 0.01) depression. After correcting for EDSS, the presence of depression was predicted by superior frontal and superior parietal hypointense TI lesions (p<0.01); the severity of depression was predicted by superior frontal, superior parietal and temporal TI lesions, lateral and third ventricular enlargement, and frontal atrophy (p<0.01). Depression was not related to bright T2 lesions or enhancement. We conclude that atrophy and cortical-subcortical disconnection due to frontal and parietal white matter destructive lesions may contribute to depression in MS.

Despite the evidence of a positive relationship between task demands and listening effort, the Framework for Understanding Effortful Listening (FUEL) highlights the important role of arousal on an individual’s choice to engage in challenging listening tasks. Previous studies have interpreted physiological responses in conjunction with behavioral responses as markers of task engagement. The aim of the current study was to investigate the effect of potential changes in physiological arousal, indexed by the pupil baseline, on task engagement over the course of an auditory recall test. Furthermore, the aim was to investigate whether working memory (WM) capacity and the signal-to-noise ratio (SNR) at which the test was conducted had an effect on changes in arousal. Twenty-one adult hearing aid users with mild to moderately severe symmetrical sensorineural hearing loss were included. The pupil baseline was measured during the Sentence-final Word Identification and Recall (SWIR) test, which was administered in a background noise composed of sixteen talkers. The Reading Span (RS) test was used as a measure of WM capacity. The findings showed that the pupil baseline decreased over the course of the SWIR test. However, recall performance remained stable, indicating that the participants maintained the necessary engagement level required to perform the task. These findings were interpreted as a decline in arousal as a result of task habituation. There was no effect of WM capacity or individual SNR level on the change in pupil baseline over time. A significant interaction was found between WM capacity and SNR level on the overall mean pupil baseline. Individuals with higher WM capacity exhibited an overall larger mean pupil baseline at low SNR levels compared to individuals with poorer WM capacity. This may be related to the ability of individuals with higher WM capacity to perform better than individual with poorer WM capacity in challenging listening conditions.

Although the existing literature has explored the link between cognitive functioning and speech recognition in noise, the specific role of fluid intelligence still needs to be studied. Given the established association between working memory capacity (WMC) and fluid intelligence and the predictive power of WMC for speech recognition in noise, we aimed to elucidate the mediating role of fluid intelligence. We used data from the n200 study, a longitudinal investigation into aging, hearing ability, and cognitive functioning. We analyzed two age-matched samples: participants with hearing aids and a group with normal hearing. WMC was assessed using the Reading Span task, and fluid intelligence was measured with Raven's Progressive Matrices. Speech recognition in noise was evaluated using Hagerman sentences presented to target 80% speech-reception thresholds in four-talker babble. Data were analyzed using mediation analysis to examine fluid intelligence as a mediator between WMC and speech recognition in noise. We found a partial mediating effect of fluid intelligence on the relationship between WMC and speech recognition in noise, and that hearing status did not moderate this effect. In other words, WMC and fluid intelligence were related, and fluid intelligence partially explained the influence of WMC on speech recognition in noise. This study shows the importance of fluid intelligence in speech recognition in noise, regardless of hearing status. Future research should use other advanced statistical techniques and explore various speech recognition tests and background maskers to deepen our understanding of the interplay between WMC and fluid intelligence in speech recognition.