Understanding the effects of task-specific practice in the brain: Insights from individual-differences analyses

We used functional magnetic resonance imaging to study practice effects in different mental imagery tasks. The study was designed to address three general questions: First, are the results of standard group-based analyses the same as those of a regression method in which brain activation changes over individual participants are used to predict task performance changes? With respect to the effects of practice, the answer was clear: Group-based analyses produced different results from regression-based individual-differences analyses. Second, are all brain areas that predict practice effects consistently activated across participants? Again, the answer was clear: Most areas that predicted the effects of practice on performance were not activated consistently over participants. Finally, does practice affect different areas in different ways for different people in different tasks? The answer was again clear: The areas that predicted changes in performance with practice varied for the different tasks, but this was more dramatically and clearly revealed by the individual-differences analyses. In short, individual-differences analyses provided insights into the relation between changes in brain activation and changes in accompanying performance, and these insights were not provided by standard group-based analyses.     

Imagery and Recognition: Dissociable Measures of Memory?

An assumption of many theories of visual cognition is that imagery tasks and picture recognition tasks tap the same kind of memory processes (i.e. visual), implying that these two types of tests can be used as interchangeable measures of visual memory. In this paper, we investigated whether articulatory suppression—a variable known to improve imagery performance—has a similar effect on picture recognition performance. In Experiment 1, subjects performed either an imagery task or a recognition task while engaging or not in articulatory suppression; in Experiment 2, the same subjects performed first the imagery task, and then the recognition task, while engaging or not in articulatory suppression. When the type of task was manipulated between subjects (Experiment 1), imagery performance was significantly improved by articulatory suppression. In contrast, recognition performance was significantly impaired by the introduction of articulatory suppression. In accordance with results of Experiment 1, in Experiment 2 imagery and recognition performance were found to be unrelated. However, when the same subjects performed both tasks, the opposite effect of articulatory suppression on imagery vs recognition performance was observed only on the first item. It does appear that when the imagery task and the picture recognition task are performed in isolation, performance is found to be independent, suggesting that the two tasks are mediated by different mechanisms. However, when a within-subjects design is used, performance in one task can be contaminated by the presence of the other task.     

Musicians processing music: Measurement of brain potentials with EEG

Abstract

In the present study, the EEG was recorded from the scalp of musicians while mentally active in their field. Analytic, creative and memory processes of the brain were observable using a special electrophysiological method called DC-potential recording. Music students listened to a sequence of four notes and subsequently were either to reverse the sequence (task 1 = analytic) or to compose a new continuation (task 2 = creative). In task 3, the initial segment of a well-known melody was presented and had to be continued (memory task). All tasks had to be solved mentally (imagery). In tasks 1 and 2, either tonal or atonal sequences were presented.

While processing, the results show that the analytic task elicited the highest brain activity. The analytic task involved mainly parieto-temporal areas of both hemispheres, the left hemisphere showing a tendency for domination. The memory task produced predominant activity over the right hemisphere. The creative task caused the lowest brain activation and elicited an unexpected lateralisation to the left, though we expected creativity to be a right hemispheric holistic-synthetic phenomenon.

Comparing listening with processing of the perceived music, we found a significant shift from an insignificant right hemispheric to an insignificant left hemispheric predominance (except with the memory task). This indicates that musicians do not lateralise to the left hemisphere per se when listening to music. Whether one finds a left hemispheric lateralisation in listening tasks or a right hemispheric one probably depends on the amount of simultaneous analytic-sequential processing the musician undertakes.     

Patterns and Predictors of Adult Age Differences in Mental Imagery

Adult age differences in, and predictors of, component imagery processes were examined across a broad elderly adult age range (65-86 years). Relative to younger adults, older adults were slower and less accurate on tasks of image generation, maintenance, scanning, and rotation. Ability to maintain mental images in particular was compromised by older age. Manipulations of stimulus complexity produced inconsistent differential age effects across tasks. Processing speed and sensorimotor functioning were prominent predictors of performance and age-related variance in all imagery components, with smaller contributions from working memory and executive function. These findings suggest that age-related decrements in individual imagery processes depend primarily on how quickly information can be processed and on the neurophysiological integrity of the ageing brain.     

Process generalization and the prediction of performance on mental imagery tasks

Kosslyn (1980, 1983) theorized that performance measures on imagery tasks may vary as a function of the existence of independent processes in imaging ability. The present study determined whether improvement can be made in performance on such tasks with practice. It also considered whether performance on such tasks improves with practice and whether this improvement generalizes. Experiment 1 determined whether improvement in a mental rotation task generalizes to improvement in a geometric analogies task, with both tasks weighted in Kosslyn's find process, but not in a line drawing memory task weighted in Kosslyn's regenerate process. In Experiment 2, we examined generalization in improvement from a geometric analogies task to a mental rotation task. In Experiment 3, we tested whether improvement in an animal imagery task (Kosslyn, 1975) generalizes to improvement in a line drawing memory task, with both tasks weighted in Kosslyn's regenerate process, but not to improvement in a mental rotation task. Performance improved with practice on all tasks. Furthermore, performance improved from one task to another only if both tasks loaded on the same process.     

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.     

Imagery,rehearsal, and the compatibility of input-output tasks

Two experiments tested the proposition that recall in an imagery task would be facilitated when the processes instigated during original input and during a rehearsal interval were similar to (compatible with) processes assumed to be initiated by two retrieval formats. In both experiments the subjects listened to tape-recorded messages which described the placements of numbers in an imaginary mental matrix. Experiment 1 used four modes of presenting the original information about the placement of the numbers. Two of the input modes were expected to foster the use of imagery: listening to the tape-recorded messages (L), and listening while shadowing (vocalizing) the messages (LV). The other modes of presentation were expected to encourage verbalized rather than imaginal encoding: listening plus silent reading (LR), and listening plus reading aloud (LRV). Two types of recall tasks were used, one which emphasized imaginal coding (matrix recall) and one which emphasized verbal coding (direction recall). Recall was highest when the input and output tasks were assumed to involve similar types of processing. Thus, Groups L and LV showed higher recall than Groups LR and LRV on the matrix task, but the converse was true for the direction task. In addition, rotation of the information yielded different characteristics for the input-output conditions. Experiment 2 introduced rehearsal instructions. Visualizing rehearsal was more beneficial to matrix recall than verbalizing rehearsal or no explicit rehearsal instructions, and verbalizing rehearsal aided direction recall more than visualizing rehearsal. Various models were discussed.     

Time–Frequency Cross Mutual Information Analysis of the Brain Functional Networks Underlying Multiclass Motor Imagery

To study the physiologic mechanism of the brain during different motor imagery (MI) tasks, the authors employed a method of brain-network modeling based on time–frequency cross mutual information obtained from 4-class (left hand, right hand, feet, and tongue) MI tasks recorded as brain–computer interface (BCI) electroencephalography data. The authors explored the brain network revealed by these MI tasks using statistical analysis and the analysis of topologic characteristics, and observed significant differences in the reaction level, reaction time, and activated target during 4-class MI tasks. There was a great difference in the reaction level between the execution and resting states during different tasks: the reaction level of the left-hand MI task was the greatest, followed by that of the right-hand, feet, and tongue MI tasks. The reaction time required to perform the tasks also differed: during the left-hand and right-hand MI tasks, the brain networks of subjects reacted promptly and strongly, but there was a delay during the feet and tongue MI task. Statistical analysis and the analysis of network topology revealed the target regions of the brain network during different MI processes. In conclusion, our findings suggest a new way to explain the neural mechanism behind MI.     

Short-Term Kinesthetic Training for Sensorimotor Rhythms: Effects in Experts and Amateurs

The authors’ aim was to examine whether short-term kinesthetic training affects the level of sensorimotor rhythm (SMR) in different frequency band: alpha (8–12 Hz), lower beta (12.5–16 Hz) and beta (16.5–20 Hz) during the execution of a motor imagery task of closing and opening the right and the left hand by experts (jugglers, practicing similar exercises on an everyday basis) and amateurs (individuals not practicing any sports). It was found that the performance of short kinesthetic training increases the power of alpha rhythm when executing imagery tasks only in the group of amateurs. Therefore, kinesthetic training may be successfully used as a method increasing the vividness of motor imagery, for example, in tasks involving the control of brain–computer interfaces based on SMR.     

Human perceptual performance with nonliteral imagery: region recognition and texture-based segmentation

In this study the authors address the issue of how the perceptual usefulness of nonliteral imagery should be evaluated. Perceptual performance with nonliteral imagery of natural scenes obtained at night from infrared and image-intensified sensors and from multisensor fusion methods was assessed to relate performance on 2 basic perceptual tasks to fundamental characteristics of the imagery. Specifically, single-sensor imagery and fused multisensor imagery (both achromatic and false color) were used to test performance on a region recognition task and a texture segmentation task. Results indicate that the use of color rendering and type of scene content play specific roles in determining perceptual performance allowed by nonliteral imagery. The authors argue that the usefulness of various image-rendering methods should be evaluated with respect to multiple perceptual tasks.     

Kinetic and static imagery in sentence memory

This experiment investigates the possibility that two different kinds of imagery codes are used in sentence memory, one involving moving images (kinetic imagery) and the other involving stationary images (static imagery). Using a modality-specific interference task it was shown that only sentences involving kinetic imagery were affected by the visual interference task; neither static nor low imagery sentences were so affected. The results are interpreted as showing that some kind of imaginal code is used in memory, but that there are different kinds of code available. It is claimed that this result is inconsistent both with Paivio's (1971) ‘dual-coding’ hypothesis and with propositional accounts of sentence memory.     

Visual imagery and memory: Do retrieval strategies affect what the mind's eye sees?

A variety of visual mental imagery tasks have been shown to activate regions of visual cortex that subserve the perception of visual events. Here fMRI was used to examine whether imagery‐related visuocortical activity is modulated if imagery content is held constant but there is a change in the memory retrieval strategy used to invoke imagery. Participants were scanned while visualising common objects in two different conditions: (a) recalling recently encoded pictures and (b) based on their knowledge of concrete nouns. Results showed that retrieval‐related activations in frontal cortex were bilateral when pictures were visualised but left‐lateralised when nouns were visualised. In posterior brain regions, both imagery conditions led to activation in the same set of circumscribed areas in left temporal‐parietal cortex, including a region of the left fusiform gyrus that has previously been implicated in visual imagery. These findings suggest that the posterior network activated during imagery did not vary with strategic task‐related changes in the frontal network used to retrieve imagery content from memory.     

Imagery skill and preference in bilinguals

A number of studies have reported differences in the performance of bilinguals and monolinguals in verbal tasks. It has been suggested that one source of this difference is a greater tendency among bilinguals to use non-verbal ways of representing events, because of the potential for confusions between their two verbal codes. In the present study, bilingual and monolingual college students were compared on three dimensions of self-reported aspects of imagery—control, vividness and preference—as well as on a performance measure of spatial manipulation skill. When these tasks were preceded by a nominally verbal activity (prose comprehension), there were no group differences on the self-report or objective imagery measures. In contrast, when they were preceded by an imagery rating task, some evidence of a compensatory reliance on spatial codes among bilinguals was obtained. Implications of these task induction effects on both subjective and performance measures of a skill were discussed.     

Using Real‐World and Standardized Spatial Imagery Tasks: Convergence,Imagery Realism,and Gender Differences

Can realistic spatial scenarios be used to measure spatial mental imagery? Can people accurately evaluate their spatial imagery? Does gender moderate the relationship between performance on realistic spatial imagery tasks and ratings of imagery realism? Forty‐two female and 31 male undergraduates first rated the realism of their images after reading spatial scenarios based on actual spatial tasks. In phase 2, they solved closely related spatial scenario problems, and then completed the VZ‐2 Paper Folding test. Performance on realistic spatial scenarios predicted performance on the VZ‐2. Men's evaluation of their spatial imagery realism predicted their actual spatial performance, but women's did not. More task experience was positively related to more realistic images and higher scores on the VZ‐2. These results were generally consistent with those found with more artificial stimulus materials, but also demonstrated the importance of considering gender differences in spatial problem strategy and/or rating scale interpretation. Copyright © 2014 John Wiley & Sons, Ltd.     

Age-related deficits in generation and manipulation of mental images: II. The role of dorsolateral prefrontal cortex.

The authors investigated neural substrates of age-related declines in mental imagery. Healthy adult participants (ages 19 to 77) performed a series of visual-spatial mental imagery tasks that varied in apparent difficulty and involved stimuli of varying graphic complexity. The volumes of the dorsolateral frontal cortex (DLPFC) and posterior visual processing areas were estimated from magnetic resonance imaging scans. The volume of the DLPFC and the fusiform cortex, working-memory capacity, and performance on the tasks involving image generation and manipulation were significantly reduced with age. Further analyses suggested that age-related deficits in performance on mental imagery tasks may stem in part from age-related shrinkage of the prefrontal cortex and age-related declines in working memory but not from age-related slowing of sensorimotor reaction time. The volume of cortical regions associated with modality-specific visual information processing did not show a consistent relationship with specific mental imagery processes.     

没听到？“听”到！——来自听觉表象神经机制研究的证据

近年来听觉表象开始得到关注,相关研究包括言语声音、音乐声音、环境声音的听觉表象三类。本文梳理了认知神经科学领域对上述三种听觉表象所激活的脑区研究,比较了听觉表象和听觉对应脑区的异同,并展望了听觉表象未来的研究方向。     

Valence of Affective Verbal Fluency: fMRI Studies on Neural Organization of Emotional Concepts <Emphasis Type="Italic">Joy</Emphasis> and <Emphasis Type="Italic">Fear</Emphasis>

The present study was designed to examine the underlying brain mechanisms of positive and negative emotional verbal fluency. Three verbal fluency tasks (one non-emotional phonemic task, two emotional tasks: Joy and Fear) were used in this study. The results were analyzed for 35 healthy, Polish-speaking, right-handed adults aged 20–35. Functional magnetic resonance imaging (3T) was used to show brain activity during active participation in emotional verbal fluency tasks. The results reported for emotional fluency confirmed activation of different brain regions for the negative and positive emotional verbal fluency: in positive emotional verbal fluency Joy elicits greater activation in the frontal regions and the cingulate cortex, while in negative verbal fluency Fear is reflected in activation of parietal and temporal areas. The study provides an evidence for differentiation in neural mechanisms between positive and negative emotional verbal fluency and/or positive and negative retrieving processes, and differentiation in brain-related determinants of the emotional concepts organization.     

Hemispheric differences for semantically and phonologically primed nouns: A tachistoscopic study in normals

Normal individuals performed two matching tasks. In one task, semantic processing, synonyms had to be recognized. Half the stimuli were picturable and half were nonpicturable nouns. In this task, recognition of picturable synonyms was found to have hemifield symmetry, whereas recognition of nonpicturable synonyms yielded a left-hemisphere superiority, indicating that semantic matching itself did not reveal equal performance of both hemispheres. It is concluded that picturable synonyms might be recognized either by processes of visual imagery, which pertain to right-hemisphere function, or by their phonological or phonic features, which are processed by the left hemisphere. The other task, shown in previous research to exhibit a left-hemisphere superiority, was to decide if two nouns (homophones) were equally pronounced. Here a distinct left-hemisphere advantage was revealed.     

Object‐spatial imagery: a new self‐report imagery questionnaire

A new instrument, the Object‐Spatial Imagery Questionnaire (OSIQ), was designed to assess individual differences in visual imagery preferences and experiences. The OSIQ consists of two scales: an object imagery scale that assesses preferences for representing and processing colourful, pictorial, and high‐resolution images of individual objects and a spatial imagery scale that assesses preferences for representing and processing schematic images, spatial relations amongst objects, and spatial transformations. Across a series of studies, the object imagery scale was significantly correlated with the performance on object imagery tasks; the spatial imagery scale was significantly correlated with the performance on spatial imagery tasks; but neither correlated with measures of intelligence. Additionally, compared to visual artists and humanities professionals, scientists reported higher spatial imagery ratings; however, compared to scientists and humanities professionals, visual artists reported higher object imagery ratings. Thus, the results from the studies supported the predictive, discriminant, and ecological validity of the OSIQ. Copyright © 2006 John Wiley & Sons, Ltd.