Colour knowledge in semantic dementia: It is not all black and white

What we mean when we say semantic: Toward a multidisciplinary semantic glossary

Tulving characterized semantic memory as a vast repository of meaning that underlies language and many other cognitive processes. This perspective on lexical and conceptual knowledge galvanized a new era of research undertaken by numerous fields, each with their own idiosyncratic methods and terminology. For example, "concept" has different meanings in philosophy, linguistics, and psychology. As such, many fundamental constructs used to delineate semantic theories remain underspecified and/or opaque. Weak construct specificity is among the leading causes of the replication crisis now facing psychology and related fields. Term ambiguity hinders cross-disciplinary communication, falsifiability, and incremental theory-building. Numerous cognitive subdisciplines (e.g., vision, affective neuroscience) have recently addressed these limitations via the development of consensus-based guidelines and definitions. The project to follow represents our effort to produce a multidisciplinary semantic glossary consisting of succinct definitions, background, principled dissenting views, ratings of agreement, and subjective confidence for 17 target constructs (e.g., abstractness, abstraction, concreteness, concept, embodied cognition, event semantics, lexical-semantic, modality, representation, semantic control, semantic feature, simulation, semantic distance, semantic dimension). We discuss potential benefits and pitfalls (e.g., implicit bias, prescriptiveness) of these efforts to specify a common nomenclature that other researchers might index in specifying their own theoretical perspectives (e.g., They said X, but I mean Y).

Ageing- and dementia-friendly design: theory and evidence from cognitive psychology, neuropsychology and environmental psychology can contribute to design guidelines that minimise spatial disorientation

Many older people, both with and without dementia, eventually move from their familiar home environments into unfamiliar surroundings, such as sheltered housing or care homes. Age-related declines in wayfinding skills can make it difficult to learn to navigate in these new, unfamiliar environments. To facilitate the transition to their new accommodation, it is therefore important to develop retirement complexes and care homes specifically designed to reduce the wayfinding difficulties of older people and those with Alzheimer’s disease (AD). Residential complexes that are designed to support spatial orientation and that compensate for impaired navigation abilities would make it easier for people with dementia to adapt to their new living environment. This would improve the independence, quality of life and well-being of residents, and reduce the caregivers’ workload. Based on these premises, this opinion paper considers how evidence from cognitive psychology, neuropsychology and environmental psychology can contribute to ageing- and dementia-friendly design with a view to minimising spatial disorientation. After an introduction of the cognitive mechanisms and processes involved in spatial navigation, and the changes that occur in typical and atypical ageing, research from the field of environmental psychology is considered, highlighting design factors likely to facilitate (or impair) indoor wayfinding in complex buildings. Finally, psychological theories and design knowledge are combined to suggest ageing- and dementia-friendly design guidelines that aim to minimise spatial disorientation by focusing on residual navigation skills.

Cortical network underlying audiovisual semantic integration and modulation of attention: An fMRI and graph-based study

Many neuroimaging and electrophysiology studies have suggested that semantic integration as a high-level cognitive process involves various cortical regions and is modulated by attention. However, the cortical network specific to semantic integration and the modulatory mechanism of attention remain unclear. Here, we designed an fMRI experiment using “bimodal stimulus” to extract information regarding the cortical activation related to the effects of semantic integration with and without attention, and then analyzed the characteristics of the cortical network and the modulating effect of attention on semantic integration. To further investigate the related cortical regions, we constructed a functional brain network for processing attended AV stimuli to evaluate the nodal properties using a graph-based method. The results of the fMRI and graph-based analyses showed that the semantic integration with attention activated the anterior temporal lobe (ATL), temporoparietal junction (TPJ), and frontoparietal cortex, with the ATL showing the highest nodal degree and efficiency; in contrast, semantic integration without attention involved a relatively small cortical network, including the posterior superior temporal gyrus (STG), Heschl’s gyrus (HG), and precentral gyrus. These results indicated that semantic integration is a complex cognitive process that occurs not only in the attended condition but also in the unattended condition, and that attention could modulate the distribution of cortical networks related to semantic integration. We suggest that semantic integration with attention is a conscious process and needs a wide cortical network working together, in which the ATL plays the role of a central hub; in contrast, semantic integration without attention is a pre-attentive process and involves a relatively smaller cortical network, in which the HG may play an important role. Our study will provide valuable insights into semantic integration and will be useful for investigations on multisensory integration and attention mechanism at multiple processing stages and levels within the cortical hierarchy.

Porcelain for All - a nursing home study

PURPOSE

The Porcelain for All project was an initiative by Figgjo AS, a porcelain factory in Norway, which needed more research on different coloured porcelains. The paper aims to discuss this issue.

DESIGN/METHODOLOGY/APPROACH

The study aimed to gain new knowledge about how different décor and dinner plate colours can positively influence dementia sufferer food intake and appetite. The intervention period lasted three weeks. Four days were randomly picked during that period. Each plate was photographed before and after the resident had eaten, researchers conducted observations during mealtimes. Two CurroCus® group interviews were used to collect additional empirical data. In total, 12 dementia sufferers (five females) between 65 and 85 years were observed during dinnertime.

FINDINGS

Plates with a white well, yellow lip and red rim seemed to be preferred regarding food intake. Three main categories were noted from the observations and group interviews: mealtime dignity, porcelain design and appetite.

RESEARCH LIMITATIONS/IMPLICATIONS

Future research could incorporate well-being in people with dementia regarding food weight, testing different meal room environments, user involvement, food presentation and should include more nursing homes and residents.

PRACTICAL IMPLICATIONS

This study only encompasses a small sample (12 residents), all diagnosed with dementia.

SOCIAL IMPLICATIONS

Outcomes may help to prevent undernutrition among elderly people.

ORIGINALITY/VALUE

Combined coloured porcelain, food intake and residents with dementia is scarcely investigated.

Verbal and visual cognition: Individual differences in the lab, in the brain, and in the classroom

In many ways, individuals vary in their thought processes, and in their cognitive strengths and weaknesses. Among the findings revealed by individual differences research, one major dividing line highlighted recurrently by decades of experimental studies is that between linguistically-mediated cognitive operations (verbal cognition), versus cognition, which primarily operates on visual - or visuospatial - representations (visual cognition). In this article, we review findings from three research areas-cognitive abilities, working memory, and task strategies-focusing on individual differences in verbal and visual cognition. In each area we highlight behavioral, neuroimaging, and classroom-based findings, bridging the perspectives of these different methodologies.

Controlled semantic cognition relies upon dynamic and flexible interactions between the executive 'semantic control' and hub-and-spoke 'semantic representation' systems

Built upon a wealth of neuroimaging, neurostimulation, and neuropsychology data, a recent proposal set forth a framework termed controlled semantic cognition (CSC) to account for how the brain underpins the ability to flexibly use semantic knowledge (Lambon Ralph et al., 2017; Nature Reviews Neuroscience). In CSC, the ‘semantic control’ system, underpinned predominantly by the prefrontal cortex, dynamically monitors and modulates the ‘semantic representation’ system that consists of a ‘hub’ (anterior temporal lobe, ATL) and multiple ‘spokes’ (modality-specific areas). CSC predicts that unfamiliar and exacting semantic tasks should intensify communication between the ‘control’ and ‘representation’ systems, relative to familiar and less taxing tasks. In the present study, we used functional magnetic resonance imaging (fMRI) to test this hypothesis. Participants paired unrelated concepts by canonical colours (a less accustomed task – e.g., pairing ketchup with fire-extinguishers due to both being red) or paired well-related concepts by semantic relationship (a typical task – e.g., ketchup is related to mustard). We found the ‘control’ system was more engaged by atypical than typical pairing. While both tasks activated the ATL ‘hub’, colour pairing additionally involved occipitotemporal ‘spoke’ regions abutting areas of hue perception. Furthermore, we uncovered a gradient along the ventral temporal cortex, transitioning from the caudal ‘spoke’ zones preferring canonical colour processing to the rostral ‘hub’ zones preferring semantic relationship. Functional connectivity also differed between the tasks: Compared with semantic pairing, colour pairing relied more upon the inferior frontal gyrus, a key node of the control system, driving enhanced connectivity with occipitotemporal ‘spoke’. Together, our findings characterise the interaction within the neural architecture of semantic cognition – the control system dynamically heightens its connectivity with relevant components of the representation system, in response to different semantic contents and difficulty levels.

Semantic word category processing in semantic dementia and posterior cortical atrophy

There is general agreement that perisylvian language cortex plays a major role in lexical and semantic processing; but the contribution of additional, more widespread, brain areas in the processing of different semantic word categories remains controversial. We investigated word processing in two groups of patients whose neurodegenerative diseases preferentially affect specific parts of the brain, to determine whether their performance would vary as a function of semantic categories proposed to recruit those brain regions. Cohorts with (i) Semantic Dementia (SD), who have anterior temporal-lobe atrophy, and (ii) Posterior Cortical Atrophy (PCA), who have predominantly parieto-occipital atrophy, performed a lexical decision test on words from five different lexico-semantic categories: colour (e.g., yellow), form (oval), number (seven), spatial prepositions (under) and function words (also). Sets of pseudo-word foils matched the target words in length and bi-/tri-gram frequency. Word-frequency was matched between the two visual word categories (colour and form) and across the three other categories (number, prepositions, and function words). Age-matched healthy individuals served as controls. Although broad word processing deficits were apparent in both patient groups, the deficit was strongest for colour words in SD and for spatial prepositions in PCA. The patterns of performance on the lexical decision task demonstrate (a) general lexicosemantic processing deficits in both groups, though more prominent in SD than in PCA, and (b) differential involvement of anterior-temporal and posterior-parietal cortex in the processing of specific semantic categories of words.

The anterior temporal cortex is a primary semantic source of top-down influences on object recognition

Perception emerges from a dynamic interplay between feed-forward sensory input and feedback modulation along the cascade of neural processing. Prior knowledge, a major form of top-down modulatory signal, benefits perception by enabling efficacious inference and resolving ambiguity, particularly under circumstances of degraded visual input. Despite semantic information being a potentially critical source of this top-down influence, to date, the core neural substrate of semantic knowledge (the anterolateral temporal lobe – ATL) has not been considered as a key component of the feedback system. Here we provide direct evidence of its significance for visual cognition – the ATL underpins the semantic aspect of object recognition, amalgamating sensory-based (amount of accumulated sensory input) and semantic-based (representational proximity between exemplars and typicality of appearance) influences. Using transcranial theta-burst stimulation combined with a novel visual identification paradigm, we demonstrate that the left ATL contributes to discrimination between visual objects. Crucially, its contribution is especially vital under situations where semantic knowledge is most needed for supplementing deficiency of input (brief visual exposure), discerning analogously-coded exemplars (close representational distance), and resolving discordance (target appearance violating the statistical typicality of its category). Our findings characterise functional properties of the ATL in object recognition: this neural structure is summoned to augment the visual system when the latter is overtaxed by challenging conditions (insufficient input, overlapped neural coding, and conflict between incoming signal and expected configuration). This suggests a need to revisit current theories of object recognition, incorporating the ATL that interfaces high-level vision with semantic knowledge.

Functional magnetic resonance imaging adaptation reveals a noncategorical representation of hue in early visual cortex

Color names divide the fine-grained gamut of color percepts into discrete categories. A categorical transition must occur somewhere between the initial encoding of the continuous spectrum of light by the cones and the verbal report of the name of a color stimulus. Here, we used a functional magnetic resonance imaging (fMRI) adaptation experiment to examine the representation of hue in the early visual cortex. Our stimuli varied in hue between blue and green. We found in the early visual areas (V1, V2/3, and hV4) a smoothly increasing recovery from adaptation with increasing hue distance between adjacent stimuli during both passive viewing (Experiment 1) and active categorization (Experiment 2). We examined the form of the adaptation effect and found no evidence that a categorical representation mediates the release from adaptation for stimuli that cross the blue-green color boundary. Examination of the direct effect of stimulus hue on the fMRI response did, however, reveal an enhanced response to stimuli near the blue-green category border. This was largest in hV4 and when subjects were engaged in active categorization of the stimulus hue. In contrast with a recent report from another laboratory (Bird, Berens, Horner, & Franklin, 2014), we found no evidence for a categorical representation of color in the middle frontal gyrus. A post hoc whole-brain analysis, however, revealed several regions in the frontal cortex with a categorical effect in the adaptation response. Overall, our results support the idea that the representation of color in the early visual cortex is primarily fine grained and does not reflect color categories.

Reprint of: Semantic impairment disrupts perception, memory, and naming of secondary but not primary colours

To investigate how basic aspects of perception are shaped by acquired knowledge about the world, we assessed colour perception and cognition in patients with semantic dementia (SD), a disorder that progressively erodes conceptual knowledge. We observed a previously undocumented pattern of impairment to colour perception and cognition characterized by: (i) a normal ability to discriminate between only subtly different colours but an impaired ability to group different colours into categories, (ii) normal perception and memory for the colours red, green, and blue but impaired perception and memory for colours lying between these regions of a fully-saturated and luminant spectrum, and (iii) normal naming of polar colours in the opponent-process colour system (red, green, blue, yellow, white, and black) but impaired naming of other basic colours (brown, gray, pink, and orange). The results suggest that fundamental aspects of perception can be shaped by acquired knowledge about the world, but only within limits.

Is cognition enough to explain cognitive development?

Traditional views separate cognitive processes from sensory-motor processes, seeing cognition as amodal, propositional, and compositional, and thus fundamentally different from the processes that underlie perceiving and acting. These were the ideas on which cognitive science was founded 30 years ago. However, advancing discoveries in neuroscience, cognitive neuroscience, and psychology suggests that cognition may be inseparable from processes of perceiving and acting. From this perspective, this study considers the future of cognitive science with respect to the study of cognitive development.

For richer or poorer? Imageability effects in semantic dementia patients' reading aloud

The degree to which a word's meaning evokes a mental image exerts an influence on performance across a variety of conceptual and linguistic tasks. In normal healthy participants, this effect takes the form of an advantage for high over low imageability words. Consideration of the influence of imageability on performance of patients with semantic dementia can provide information concerning its cognitive and neural bases. Semantic dementia patients show deficits in conceptual processing tasks, and an associated enhancement of the advantage for high over low imageability words. Semantic dementia patients also show deficits in linguistic processing tasks, including reading aloud words with inconsistent spelling-sound correspondences. This study provides the first systematic exploration of the influence of imageability on semantic dementia patients' reading aloud performance. Over 10 cases, the imageability effect seen for inconsistent words was actually reversed in reaction times, with faster performance for low than high imageability items. The same reversal was observed for inconsistent words when the frequency of legitimate alternative reading of components errors was considered, and this reversed effect grew larger with increasing semantic impairment. This result is interpreted in terms of the development of stronger connections along the direct pathway between spelling and sound for low than high imageability items that are then revealed under diminished semantic activation. This interpretation emphasises the interaction between form and meaning that occurs throughout learning in connectionist models.

Semantic impairment disrupts perception, memory, and naming of secondary but not primary colours

To investigate how basic aspects of perception are shaped by acquired knowledge about the world, we assessed colour perception and cognition in patients with semantic dementia (SD), a disorder that progressively erodes conceptual knowledge. We observed a previously undocumented pattern of impairment to colour perception and cognition characterized by: (i) a normal ability to discriminate between only subtly different colours but an impaired ability to group different colours into categories, (ii) normal perception and memory for the colours red, green, and blue but impaired perception and memory for colours lying between these regions of a fully-saturated and luminant spectrum, and (iii) normal naming of polar colours in the opponent-process colour system (red, green, blue, yellow, white, and black) but impaired naming of other basic colours (brown, gray, pink, and orange). The results suggest that fundamental aspects of perception can be shaped by acquired knowledge about the world, but only within limits.

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Study of colour perception and cognition in patients with semantic dementia.

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Colour discrimination is normal but categorization is impaired.

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Patients and controls show opposing accuracy patterns in memory and perception.

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Naming is more impaired for secondary than primary colours.

When concepts lose their color: a case of object-color knowledge impairment

Color is important in our daily interactions with objects, and plays a role in both low- and high-level visual processing. Previous neuropsychological studies have shown that color perception and object-color knowledge can doubly dissociate, and that both can dissociate from processing of object form. We present a case study of an individual who displayed an impairment for knowledge of the typical colors of objects, with preserved color perception and color naming. Our case also presented with a pattern of, if anything, worse performance for naming living items compared to non-living things. The findings of the experimental investigation are evaluated in light of two theories of conceptual organization in the brain: the Sensory/Functional Theory and the Domain-Specific Hypothesis. The dissociations observed in this case compel a model in which sensory/motor modality and semantic domain jointly constrain the organization of object knowledge.

Creating Concepts from Converging Features in Human Cortex

To make sense of the world around us, our brain must remember the overlapping features of millions of objects. Crucially, it must also represent each object's unique feature-convergence. Some theories propose that an integration area (or "convergence zone") binds together separate features. We report an investigation of our knowledge of objects' features and identity, and the link between them. We used functional magnetic resonance imaging to record neural activity, as humans attempted to detect a cued fruit or vegetable in visual noise. Crucially, we analyzed brain activity before a fruit or vegetable was present, allowing us to interrogate top-down activity. We found that pattern-classification algorithms could be used to decode the detection target's identity in the left anterior temporal lobe (ATL), its shape in lateral occipital cortex, and its color in right V4. A novel decoding-dependency analysis revealed that identity information in left ATL was specifically predicted by the temporal convergence of shape and color codes in early visual regions. People with stronger feature-and-identity dependencies had more similar top-down and bottom-up activity patterns. These results fulfill three key requirements for a neural convergence zone: a convergence result (object identity), ingredients (color and shape), and the link between them.

The role of conceptual knowledge in understanding synaesthesia: Evaluating contemporary findings from a "hub-and-spokes" perspective

Synesthesia is a phenomenon in which stimulation in one sensory modality triggers involuntary experiences typically not associated with that stimulation. Inducing stimuli (inducers) and synesthetic experiences (concurrents) may occur within the same modality (e.g., seeing colors while reading achromatic text) or span across different modalities (e.g., tasting flavors while listening to music). Although there has been considerable progress over the last decade in understanding the cognitive and neural mechanisms of synesthesia, the focus of current neurocognitive models of synesthesia does not encompass many crucial psychophysical characteristics documented in behavioral research. Prominent theories of the neurophysiological basis of synesthesia construe it as a perceptual phenomenon and hence focus primarily on the modality-specific brain regions for perception. Many behavioral studies, however, suggest an essential role for conceptual-level information in synesthesia. For example, there is evidence that synesthetic experience arises subsequent to identification of an inducing stimulus, differs substantially from real perceptual events, can be akin to perceptual memory, and is susceptible to lexical/semantic contexts. These data suggest that neural mechanisms lying beyond the realm of the perceptual cortex (especially the visual system), such as regions subserving conceptual knowledge, may play pivotal roles in the neural architecture of synesthesia. Here we discuss the significance of non-perceptual mechanisms that call for a re-evaluation of the emphasis on synesthesia as a perceptual phenomenon. We also review recent studies which hint that some aspects of synesthesia resemble our general conceptual knowledge for object attributes, at both psychophysical and neural levels. We then present a conceptual-mediation model of synesthesia in which the inducer and concurrent are linked within a conceptual-level representation. This “inducer-to-concurrent” nexus is maintained within a supramodal “hub,” while the subjective (bodily) experience of its resultant concurrent (e.g., a color) may then require activation of “spokes” in the perception-related cortices. This hypothesized “hub-and-spoke” structure would engage a distributed network of cortical regions and may account for the full breadth of this intriguing phenomenon.

A conceptual lemon: theta burst stimulation to the left anterior temporal lobe untangles object representation and its canonical color

Object recognition benefits greatly from our knowledge of typical color (e.g., a lemon is usually yellow). Most research on object color knowledge focuses on whether both knowledge and perception of object color recruit the well-established neural substrates of color vision (the V4 complex). Compared with the intensive investigation of the V4 complex, we know little about where and how neural mechanisms beyond V4 contribute to color knowledge. The anterior temporal lobe (ATL) is thought to act as a "hub" that supports semantic memory by integrating different modality-specific contents into a meaningful entity at a supramodal conceptual level, making it a good candidate zone for mediating the mappings between object attributes. Here, we explore whether the ATL is critical for integrating typical color with other object attributes (object shape and name), akin to its role in combining nonperceptual semantic representations. In separate experimental sessions, we applied TMS to disrupt neural processing in the left ATL and a control site (the occipital pole). Participants performed an object naming task that probes color knowledge and elicits a reliable color congruency effect as well as a control quantity naming task that also elicits a cognitive congruency effect but involves no conceptual integration. Critically, ATL stimulation eliminated the otherwise robust color congruency effect but had no impact on the numerical congruency effect, indicating a selective disruption of object color knowledge. Neither color nor numerical congruency effects were affected by stimulation at the control occipital site, ruling out nonspecific effects of cortical stimulation. Our findings suggest that the ATL is involved in the representation of object concepts that include their canonical colors.

Anterobasal temporal lobe lesions alter recurrent functional connectivity within the ventral pathway during naming

An increasing amount of evidence supports a crucial role for the anterior temporal lobe (ATL) in semantic processing. Critically, a selective disruption of the functional connectivity between left and right ATLs in patients with chronic aphasic stroke has been illustrated. The aim of the current study was to evaluate the consequences that lesions on the ATL have on the neurocognitive network supporting semantic cognition. Unlike previous work, in this magnetoencephalography study we selected a group of patients with small lesions centered on the left anteroventral temporal lobe before surgery. We then used an effective connectivity method (i.e., dynamic causal modeling) to investigate the consequences that these lesions have on the functional interactions within the network. This approach allowed us to evaluate the directionality of the causal interactions among brain regions and their associated connectivity strengths. Behaviorally, we found that semantic processing was altered when patients were compared with a strictly matched group of controls. Dynamic causal modeling for event related responses revealed that picture naming was associated with a bilateral frontotemporal network, encompassing feedforward and feedback connections. Comparison of specific network parameters between groups revealed that patients displayed selective network adjustments. Specifically, backward connectivity from anterior to posterior temporal lobe was decreased in the ipsilesional hemisphere, whereas it was enhanced in the contralesional hemisphere. These results reinforce the relevance of ATL in semantic memory, as well as its amodal organization, and highlight the role of feedback connections in enabling the integration of the semantic information.

Comparative semantic profiles in semantic dementia and Alzheimer's disease

Patients with the semantic variant of primary progressive aphasia, also known as semantic dementia, and Alzheimer's disease have deficits in semantic memory. However, few comparative studies have been performed to determine whether these patient groups have distinct semantic memory impairments. We asked 15 patients with semantic variant primary progressive aphasia and 57 patients with Alzheimer's disease to judge semantic category membership of coloured photos and printed words that are members of familiar natural and manufactured categories, and we related performance to grey matter atrophy. We found that both semantic variant primary progressive aphasia and Alzheimer's disease are significantly impaired on this task. Moreover, patients with semantic variant primary progressive aphasia had a significantly more prominent deficit for natural objects than their own deficit judging manufactured objects. Both semantic variant primary progressive aphasia and Alzheimer's disease had atrophy that included portions of the left temporal lobe. Regression analyses related performance in semantic variant primary progressive aphasia to ventral and medial portions of the left temporal lobe, while regression analyses in Alzheimer's disease related performance to these ventral and medial temporal areas as well as lateral temporal-parietal regions in the left hemisphere. We conclude that both semantic variant primary progressive aphasia and Alzheimer's disease are significantly impaired in a simple category membership judgement task and the selective impairment for natural kinds in semantic variant primary progressive aphasia is related in part to disease in visual association cortex in ventral-medial portions of the left temporal lobe. We discuss factors that may contribute to the semantic memory deficit in semantic variant primary progressive aphasia.

Memory for action sequences in semantic dementia

Semantic dementia (SD) is associated with a progressive, relatively selective, degeneration of semantic memory (both verbal and nonverbal facts and knowledge). Episodic memory, however, is thought to be relatively preserved. This study aimed to further assess the nonverbal, incidental, episodic memory profile associated with SD using deferred imitation, which measures recall by the nonverbal imitation of novel action sequences after a 24-h delay. The performance of six individuals with SD was compared to that of 10 healthy age- and education-matched controls. After a baseline phase, where sets of objects were presented for manipulation to measure the spontaneous production of relevant action sequences, participants were shown eight novel three-step action sequences with the sets of objects. The component actions of the sequences were causally related in four of the eight series and arbitrarily related in the remaining four, to investigate the influence of sequence structure on memory performance. All participants produced more target actions and pairs in the arbitrary sequences 24-h after demonstration compared to baseline, indicating memory for the sequences, but only the control group showed significant memory for the order of the causal sequences (pairs). Furthermore, and perhaps more strikingly, only the control participants showed a recall advantage for the causal relative to the arbitrary sequences, indicating that they, but not the patients, could take advantage of the semantic nature of these sequences. Together these findings suggest that individuals with SD show some nonverbal episodic memory, even after a 24-h delay, and that new anterograde memory can to some extent be established without significant support from semantic memory.

The neurobiology of semantic memory

Semantic memory includes all acquired knowledge about the world and is the basis for nearly all human activity, yet its neurobiological foundation is only now becoming clear. Recent neuroimaging studies demonstrate two striking results: the participation of modality-specific sensory, motor, and emotion systems in language comprehension, and the existence of large brain regions that participate in comprehension tasks but are not modality-specific. These latter regions, which include the inferior parietal lobe and much of the temporal lobe, lie at convergences of multiple perceptual processing streams. These convergences enable increasingly abstract, supramodal representations of perceptual experience that support a variety of conceptual functions including object recognition, social cognition, language, and the remarkable human capacity to remember the past and imagine the future.

Validation of the Literacy Independent Cognitive Assessment

BACKGROUND

Low education and illiteracy are associated with an increased risk of dementia. This study aimed to develop a neuropsychological test battery applicable to both illiterate and literate elderly and to assess its reliability and validity for a diagnosis of dementia.

METHODS

We developed the Literacy Independent Cognitive Assessment (LICA), which consists of 13 subtests assessing memory, language, visuoconstruction, executive function, attention and calculation. We investigated its reliability and validity on 152 patients with dementia, 66 with mild cognitive impairment and 639 normal controls.

RESULTS

The subtests were found to be applicable to most of the illiterate normal controls (97.3%) and were found to have high inter-rater reliabilities (r = 0.85-1.00, p < 0.001) and moderate to high test-retest reliabilities (r = 0.50-0.86, p < 0.001). The LICA performed well in discriminating participants across Clinical Dementia Rating stages and showed excellent internal consistency and good concurrent validity with the Korean Mini-mental State Examination in both literate and illiterate participants. The area under the curve of the receiver operating characteristic was 0.985 in each of the two literacy groups. Sensitivity and specificity of the LICA to make a diagnosis of dementia was 91.9% and 91.8% at the cutoff point of 186.0 in the literate subjects and 96.2% and 91.1% at the cutoff point of 154.5 in the illiterate subjects. The battery was factored into two separate factors consisting of verbal memory tests and tests for other cognitive domains.

CONCLUSION

The LICA is a valid and reliable instrument for a diagnosis of dementia in both illiterate and literate elderly.

The importance of multiple assessments of object knowledge in semantic dementia: the case of the familiar objects task

Semantic dementia (SD) is characterized by a dramatic loss of conceptual knowledge about the meaning of words and the identity of objects. Previous research has suggested that SD patients' knowledge is differentially influenced by the disease and may decline at different degrees depending on a patient's everyday familiarity with certain items. However, no study has examined (a) semantic knowledge deterioration and (b) the potential significance of autobiographical experience for the maintenance of object concepts in the same cohort of SD patients by using comprehensive assessments of different aspects of object knowledge across an experience-based, distributed semantic memory network. Here, we tested four SD patients and three Alzheimer's disease (AD) control patients using a range of tasks - including naming, gesture generation, and autobiographical knowledge - with personally familiar objects or perceptually similar or different object analogs. Our results showed dissociations between performance on naming relative to other assessments of object knowledge between SD and AD patients, though we did not observe a reliable familiar objects advantage. We discuss different factors that may account for these findings, as well as their implications for research on SD.

"Pre-semantic" cognition revisited: critical differences between semantic aphasia and semantic dementia

Patients with semantic dementia show a specific pattern of impairment on both verbal and non-verbal "pre-semantic" tasks, e.g., reading aloud, past tense generation, spelling to dictation, lexical decision, object decision, colour decision and delayed picture copying. All seven tasks are characterised by poorer performance for items that are atypical of the domain and "regularization errors" (irregular/atypical items are produced as if they were domain-typical). The emergence of this pattern across diverse tasks in the same patients indicates that semantic memory plays a key role in all of these types of "pre-semantic" processing. However, this claim remains controversial because semantically impaired patients sometimes fail to show an influence of regularity. This study demonstrates that (a) the location of brain damage and (b) the underlying nature of the semantic deficit affect the likelihood of observing the expected relationship between poor comprehension and regularity effects. We compared the effect of multimodal semantic impairment in the context of semantic dementia and stroke aphasia on the seven "pre-semantic" tasks listed above. In all of these tasks, the semantic aphasia patients were less sensitive to typicality than the semantic dementia patients, even though the two groups obtained comparable scores on semantic tests. The semantic aphasia group also made fewer regularization errors and many more unrelated and perseverative responses. We propose that these group differences reflect the different locus for the semantic impairment in the two conditions: patients with semantic dementia have degraded semantic representations, whereas semantic aphasia patients show deregulated semantic cognition with concomitant executive deficits. These findings suggest a reinterpretation of single-case studies of comprehension-impaired aphasic patients who fail to show the expected effect of regularity on "pre-semantic" tasks. Consequently, such cases do not demonstrate the independence of these tasks from semantic memory.

Going beyond LTM in the MTL: a synthesis of neuropsychological and neuroimaging findings on the role of the medial temporal lobe in memory and perception

Studies in rats and non-human primates suggest that medial temporal lobe (MTL) structures play a role in perceptual processing, with the hippocampus necessary for spatial discrimination, and the perirhinal cortex for object discrimination. Until recently, there was little convergent evidence for analogous functional specialisation in humans, or for a role of the MTL in processes beyond long-term memory. A recent series of novel human neuropsychological studies, however, in which paradigms from the animal literature were adapted and extended, have revealed findings remarkably similar to those seen in rats and monkeys. These experiments have demonstrated differential effects of distinct stimulus categories on performance in tasks for which there was no explicit requirement to remember information across trials. There is also accruing complementary evidence from functional neuroimaging that MTL structures show differential patterns of activation for scenes and objects, even on simple visual discrimination tasks. This article reviews some of these key studies and discusses the implications of these new findings for existing accounts of memory. A non-modular view of memory is proposed in which memory and perception depend upon the same anatomically distributed representations (emergent memory account). The limitations and criticisms of this theory are discussed and a number of outstanding questions proposed, including key predictions that can be tested by future studies.

Figuras de atividades funcionais: concordância de nomeação e familiaridade

O objetivo do estudo foi verificar a concordância de nomeação e familiaridade de um conjunto de figuras de objetos/animais e de atividades funcionais. Participaram 26 crianças entre 5 e 7 anos e 24 estudantes universitários entre 18 e 25 anos, de ambos os sexos. Os participantes observaram 90 figuras, 45 de atividades funcionais e 45 de objetos/animais, nomearam uma a uma e referiram o grau de familiaridade. Os dados foram analisados pelo coeficiente de Kappa, correlação de Spearman e teste de Mann-Whitney. Os resultados mostraram que a concordância com o nome original foi maior do que a freqüência de outras nomeações. As crianças tiveram mais dificuldades em fazer a nomeação. As figuras de objetos/animais foram consideradas mais familiares. O estudo mostrou diferenças significativas entre as figuras e entre as crianças e adultos, sugerindo o uso de figuras de atividades funcionais em estudos neuropsicológicos.