The influence of gender and lesion location on naming disorders for animals, plants and artefacts

Gender Differences of Dementia in Response to Intensive Self-Administered Transcranial and Intraocular Near-Infrared Stimulation

Background

Transcranial near-infrared (tNIR) stimulation was proven to be a safe, reliable, and effective treatment for cognitive and behavioral symptoms of dementia. Dementia patients of different genders differ in terms of gross anatomy, biochemistry, genetic profile, clinical presentations, and socio-psychological status. Studies of the tNIR effect on dementia have thus far been gender-neutral, with dementia subjects being grouped based on diagnoses or dementia severity. This trial hereby investigated how dementia subjects of different sex respond to tNIR treatment.

Methods

A total of 60 patient-caregiver dyads were enrolled and randomized to this double-blind, sham-controlled clinical trial. The tNIR light has a wavelength of 1,060 nm to 1,080 nm and was delivered via a photobiomodulation (PBM) unit. The active PBM unit emits near-infrared (NIR) light while the sham unit does not. The treatment consists of a six-minute tNIR light stimulation session twice daily for eight weeks. Neuropsychological assessments conducted at baseline (week 0) and endline (week 8) were compared within the female and male group and between different sex, respectively.

Results

Over the course of treatment, active-arm female subjects had a 20.2% improvement in Mini‐Mental State Exam (MMSE) (mean 4.8 points increase, p < 0.001) and active-arm male cohort had 19.3% improvement (p < 0.001). Control-arm female subjects had a 6.5% improvement in MMSE (mean 1.5 points increase, p < 0.03) and control-arm male subjects had 5.9% improvement (p = 0.35) with no significant differences in the mean MMSE between female and male subjects in both arms respectively. Other comparison of assessments including Clock Copying and Drawing Test, Logical Memory Test - immediate and delayed recall yielded nominal but not statistically significant differences. No significant differences were observed in the mean MMSE between female and male subjects in both arms respectively before treatment implementation (active arm, p = 0.12; control arm, p = 0.50) at week 0, or after treatment completion (active arm, p = 0.11; control arm, p = 0.74) at week 8.

Conclusion

Despite differences between female and male dementia subjects, the response to tNIR light stimulation does not demonstrate gender-based differences. Further studies are warranted to refine the tNIR treatment protocol for subjects suffering from dementia or dementia-related symptoms.

A Chinese Conceptual Semantic Feature Dataset (CCFD)

Memory and language are important high-level cognitive functions of humans, and the study of conceptual representation of the human brain is a key approach to reveal the principles of cognition. However, this research is often constrained by the availability of stimulus materials. The research on concept representation often needs to be based on a standardized and large-scale database of conceptual semantic features. Although Western scholars have established a variety of English conceptual semantic feature datasets, there is still a lack of a comprehensive Chinese version. In the present study, a Chinese Conceptual semantic Feature Dataset (CCFD) was established with 1,410 concepts including their semantic features and the similarity between concepts. The concepts were grouped into 28 subordinate categories and seven superior categories artificially. The results showed that concepts within the same category were closer to each other, while concepts between categories were farther apart. The CCFD proposed in this study can provide stimulation materials and data support for related research fields. All the data and supplementary materials can be found at https://osf.io/ug5dt/ .

What a pooled data study tells us about the relationships between gender and knowledge of semantic categories

Introduction: Both the neuropsychological study of patients with category-specific semantic disorders (CSSD) and the experimental research on categorical processing in healthy subjects (HSs) have shown that men are mainly impaired with fruits and vegetables and women with animals and artifacts. Since this difference is more striking in patients with CSSD than in HSs, we hypothesized that the lack of power of some investigations conducted with HSs and the different methods used in studies conducted with HSs and patients with CSSD could explain some of these inconsistencies and that a study conducted with a very large number of HSs using visual naming tasks should strongly confirm the role of gender in categorical tasks. Methods: Picture naming data gathered during the last ten years with our category-specificity paradigm from a large number (702) of HSs were reanalyzed. Results: As predicted, men named significantly more animals and artifacts, while women named more plant life items. Discussion: These data confirm that, if different domains of knowledge are studied in a very large sample of HSs using a picture naming task equivalent to the naming tasks used in most anatomo-clinical studies on CSSD, then the gender effects are highly significant.

The left temporal pole is a convergence region mediating the relation between names and semantic knowledge for unique entities: Further evidence from a "recognition-from-name" study in neurological patients

Prior research has implicated the left temporal pole (LTP) as a critical region for naming semantically unique items, including famous faces, landmarks, and musical melodies. Most studies have used a confrontation naming paradigm, where a participant is presented with a stimulus and asked to retrieve its name. We have proposed previously that the LTP functions as a two-way, bidirectional convergence region brokering between conceptual knowledge and proper names for unique entities. Under this hypothesis, damage to the LTP should result in a "two way" impairment: (1) defective proper name retrieval when presented with a unique stimulus (as shown in prior work); and (2) defective concept retrieval when presented with a proper name. Here, we directly tested the second prediction using a "recognition-from-name" paradigm. Participants were patients with LTP damage, brain-damaged comparisons with damage outside the LTP, and healthy comparisons. Participants were presented with names of famous persons (e.g., "Marilyn Monroe"), landmarks (e.g., "Leaning Tower of Pisa"), or melodies (e.g., "Rudolph the Red-Nosed Reindeer") and were asked to provide conceptual knowledge about each. We found that individuals with damage to the LTP were significantly impaired at conceptual knowledge retrieval when given names of famous people and landmarks (but this finding did not hold for melodies). This outcome supports the theory that the LTP is a bidirectional convergence region for proper naming, but suggests that melody retrieval may rely on processes different from those supported by the LTP.

Why do herpes simplex encephalitis and semantic dementia show a different pattern of semantic impairment in spite of their main common involvement within the anterior temporal lobes?

A very challenging problem in the domain of the cognitive neurosciences is to explain why herpes simplex encephalitis and semantic dementia show, respectively, a category-specific semantic disorder for biological entities and an across-categories semantic disruption, despite highly overlapping areas of anterior temporal lobe damage. The aim of the present review consisted in trying to make a separate survey of anatomo-clinical investigations (single-case studies and group studies) and of activation studies, in order to analyse the factors that could explain these different patterns of semantic disruption. Factors taken into account in this review were laterality of lesions, disease aetiology, kind of brain pathology and locus of damage within the temporal lobes. Locus of damage within the temporal lobes and kind of brain pathology seemed to play the most important role, because in patients with herpes simplex encephalitis and category-specific semantic disorder for biological entities the lesions prevailed in the anteromedial temporal lobes. Furthermore, the neuropathology concerned both the anterior temporal cortices and the white matter pathways connecting these areas with the posterior visual areas, whereas in semantic dementia the inferior longitudinal fasciculus involvement was restricted to the rostral temporal lobe and did not extend into the cortically uninvolved occipital lobe.

Anomia for musical entities

BACKGROUND

Previous work has investigated extensively the neuroanatomical correlates of lexical retrieval for words for concrete entities. Musical entities, such as musical instruments, are often included in studies of category-specific naming deficits, but have rarely been the focus of such work.

AIMS

This article reviews a program of research investigating the neuroanatomical basis for lexical retrieval of words for unique (i.e., melodies) and non-unique (i.e., musical instruments) musical entities.

MAIN CONTRIBUTION

We begin by reporting findings on the retrieval of words for unique musical entities, including musical melodies. We then consider work focusing on retrieval of words for non-unique musical entities, specifically musical instruments. We highlight similarities between the two lines of work, and then report results from new analyses including direct comparisons between the two. These comparisons suggest that impairments in naming musical melodies and in naming musical instruments are both associated with damage to the left temporal pole (LTP). However, musical instrument naming appears to rely on a more distributed set of brain regions, possibly including those relating to sensorimotor interactions with such instruments, whereas melody naming relies more exclusively on the left temporal pole.

CONCLUSIONS

Retrieval of names for musical melodies appears to rely on similar neuroanatomical correlates as for other proper nouns, namely the LTP. Musical instrument naming seems to rely on a broader network of regions, including the LTP and sensorimotor areas. Overall, melody naming seems to coincide with naming of other proper nouns, while musical instrument naming appears distinct from other categories of non-unique items.

Measuring nonvisual knowledge about object categories: The Semantic Vanderbilt Expertise Test

How much do people differ in their abilities to recognize objects, and what is the source of these differences? To address the first question, psychologists have created visual learning tests including the Cambridge Face Memory Test (Duchaine & Nakayama, 2006) and the Vanderbilt Expertise Test (VET; McGugin et al., 2012). The second question requires consideration of the influences of both innate potential and experience, but experience is difficult to measure. One solution is to measure the products of experience beyond perceptual knowledge-specifically, nonvisual semantic knowledge. For instance, the relation between semantic and perceptual knowledge can help clarify the nature of object recognition deficits in brain-damaged patients (Barton, Hanif, & Ashraf, Brain, 132, 3456-3466, 2009). We present a reliable measure of nonperceptual knowledge in a format applicable across categories. The Semantic Vanderbilt Expertise Test (SVET) measures knowledge of relevant category-specific nomenclature. We present SVETs for eight categories: cars, planes, Transformers, dinosaurs, shoes, birds, leaves, and mushrooms. The SVET demonstrated good reliability and domain-specific validity. We found partial support for the idea that the only source of domain-specific shared variance between the VET and SVET is experience with a category. We also demonstrated the utility of the SVET-Bird in experts. The SVET can facilitate the study of individual differences in visual recognition.

Are Sex-Related Category-Specific Differences in Semantic Tasks Innate or Influenced by Social Roles? A Viewpoint

In semantic tasks, sex-related categorical differences, in the form of better processing of fruits and vegetables by women and of artifacts (human-made objects) and animals by men, have been reported both in healthy participants and in brain-damaged patients. Researchers' interpretation of these sex-related categorical asymmetries has, however, been controversial, being connected with the more general (innatist versus experience-dependent) interpretations that had been given of the mechanisms subsuming the categorical organization of the brain. I begin this review with a brief reminder of the debate between supporters of the innatist and the experience-related accounts of categorical brain organization. Then I summarize results that have documented a preference by women for fruits and vegetables and a preference by men for artifacts and animals, and I discuss the innatist and social role-related interpretations that have been given of these results. I conclude that sex-related categorical effects disappear in generations in which the traditional social roles have almost completely disappeared, and these differences are not seen in young individuals raised in societies that emphasize sex equality.

Gender differences in category-specificity do not reflect innate dispositions

It is well established that certain categories of objects are processed more efficiently than others in specific tasks; a phenomenon known as category-specificity in perceptual and conceptual processing. In the last two decades there have also been several reports of gender differences in category-specificity. In the present experiments we test the proposition that such gender differences have an evolutionary origin. If they do, we would expect them to emerge even when the population tested comprises young individuals raised in a gender-equality oriented society. Contrary to this expectation we find no evidence of gender differences in category-specificity in a relatively large sample (N = 366) drawn from such a population; and this despite the fact that both tasks applied (object decision and superordinate categorization) gave rise to reliable category-effects. We suggest that a plausible account of this discrepancy is that previous reports of gender differences may have reflected differences in familiarity originating from socially-based gender roles.

Naming and Categorization in Healthy Participants: Crowded Domains and Blurred Effects of Gender

The study of category-specific effects has produced compelling insights into the structure, organization and functioning of cognitive processes. According to some accounts, the greater intra-category structural similarity for living things (LT) contributes to faster access to superordinate pictorial information, making LT easier to classify than structurally dissimilar items (i.e., nonliving things: NLT). Conversely, LT would be harder to name than NLT, as they must compete with within-domain structurally similar items in order to be properly discriminated. Additionally, it has been reported that men perform better with NLT than women, whereas women surpass men with LT but the reasons for this remain unclear. In the current study, we explored both the visual crowding hypothesis and the effects of gender by testing the performance of 40 healthy participants in classification and naming tasks. Analyses revealed that LT were classified significantly faster than NLT (η p 2 = .11), but named significantly slower (η p 2 = .25). Interestingly, the same results persisted after removing atypical categories that are known to distort the interpretation of data from the analyses. Moreover, we did not find the expected effects of gender. Men were more accurate than women naming NLT (η p 2 = .13), and women did not surpass men in any task.

Standardization, Clinical Validation, and Typicality Norms of a New Test Assessing Semantic Verbal Fluency

OBJECTIVE

Semantic verbal fluency (SVF) tests are widely used in clinical neuropsychology. We propose the standardization and clinical validation of a new SVF test based on the production of names of birds and articles of furniture (Birds and Articles of Furniture test-BAF).

METHODS

A sample of 268 subjects aged 40 years or more underwent the test. The clinical validation was conducted on subjects affected by amnesic Mild Cognitive Impairment (aMCI; N = 106), mild (N = 178), and moderate (N = 114) Alzheimer's disease (AD).

RESULTS

The BAF total score was influenced by both age and education, whereas the single scores obtained on BAF were also influenced by gender. The percentage of subjects with pathological score on BAF increased from aMCI (19%) to mild (45.5%) and moderate (71.1%) AD, and receiver operating characteristic curves analysis showed that the BAF may be highly reliable in distinguishing aMCI and AD patients from healthy subjects. We also provide typicality norms for birds and articles of furniture that could be useful in the assessment of qualitative features of words produced in semantic fluency tests.

CONCLUSIONS

The BAF test could be a valid and reliable tool in both clinical practice and research on subjects affected by cognitive impairment.

Inborn and experience-dependent models of categorical brain organization. A position paper

The present review aims to summarize the debate in contemporary neuroscience between inborn and experience-dependent models of conceptual representations that goes back to the description of category-specific semantic disorders for biological and artifact categories. Experience-dependent models suggest that categorical disorders are the by-product of the differential weighting of different sources of knowledge in the representation of biological and artifact categories. These models maintain that semantic disorders are not really category-specific, because they do not respect the boundaries between different categories. They also argue that the brain structures which are disrupted in a given type of category-specific semantic disorder should correspond to the areas of convergence of the sensory-motor information which play a major role in the construction of that category. Furthermore, they provide a simple interpretation of gender-related categorical effects and are supported by studies assessing the importance of prior experience in the cortical representation of objects On the other hand, inborn models maintain that category-specific semantic disorders reflect the disruption of innate brain networks, which are shaped by natural selection to allow rapid identification of objects that are very relevant for survival. From the empirical point of view, these models are mainly supported by observations of blind subjects, which suggest that visual experience is not necessary for the emergence of category-specificity in the ventral stream of visual processing. The weight of the data supporting experience-dependent and inborn models is thoroughly discussed, stressing the fact observations made in blind subjects are still the subject of intense debate. It is concluded that at the present state of knowledge it is not possible to choose between experience-dependent and inborn models of conceptual representations.

The influence of handedness on hemispheric representation of tools: a survey

An important debate exists in contemporary cognitive neuroscience about the innate or experience-dependent origin of the brain representation of conceptual categories. The 'domains of knowledge' hypothesis maintains that innate factors subsume the categorical organization at the brain level of animals, plant life and artefacts. On the other hand, the 'sensory-motor model of conceptual knowledge' and the embodied cognition theory attribute this categorical organization to experience-dependent factors. I tried to clarify this issue by surveying the influence that handedness could have on the lateralization of tools representation in the inferior fronto-parietal and posterior middle temporal cortices of the left hemisphere. The underlying assumption was that, if this lateralization results from innate mechanisms, then handedness should not influence this hemispheric asymmetry. If, on the other hand, this lateralization is due to the motor and somatosensory experiences made with the right dominant hand during the manipulation of tools and other artefacts, then this asymmetry should be inverted or strongly attenuated in left-handers. Results of the review strongly suggest that manual experience acquired during tool manipulation can influence the hemispheric representation of tools and other artefacts. They also suggest, however, that handedness-related embodiment is not fixed, but influenced by personal motor experiences (such as those made by left-handers who have been forced to use their right hand) and by social visual experiences (such as the fact that, living in a right-handed world, left-handers see more people in their environment who use the right rather than the left hand) during tool manipulation.

Why women see differently from the way men see? A review of sex differences in cognition and sports

The differences of learning and memory between males and females have been well documented and confirmed by both human and animal studies. The sex differences in cognition started from early stage of neuronal development and last through entire life span. The major biological basis of the gender-dependent cognitive activity includes two major components: sex hormone and sex-related characteristics, such as sex-determining region of the Y chromosome (SRY) protein. However, the knowledge of how much biology of sex contributes to normal cognitive function and elite athletes in various sports are still pretty limited. In this review, we will be focusing on sex differences in spatial learning and memory - especially the role of male- and female-type cognitive behaviors in sports.

Noun and knowledge retrieval for biological and non-biological entities following right occipitotemporal lesions

We investigated the critical contribution of right ventral occipitotemporal cortex to knowledge of visual and functional-associative attributes of biological and non-biological entities and how this relates to category-specificity during confrontation naming. In a consecutive series of 7 patients with lesions confined to right ventral occipitotemporal cortex, we conducted an extensive assessment of oral generation of visual-sensory and functional-associative features in response to the names of biological and nonbiological entities. Subjects also performed a confrontation naming task for these categories. Our main novel finding related to a unique case with a small lesion confined to right medial fusiform gyrus who showed disproportionate naming impairment for nonbiological versus biological entities, specifically for tools. Generation of visual and functional-associative features was preserved for biological and non-biological entities. In two other cases, who had a relatively small posterior lesion restricted to primary visual and posterior fusiform cortex, retrieval of visual attributes was disproportionately impaired compared to functional-associative attributes, in particular for biological entities. However, these cases did not show a category-specific naming deficit. Two final cases with the largest lesions showed a classical dissociation between biological versus nonbiological entities during naming, with normal feature generation performance. This is the first lesion-based evidence of a critical contribution of the right medial fusiform cortex to tool naming. Second, dissociations along the dimension of attribute type during feature generation do not co-occur with category-specificity during naming in the current patient sample.

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.

Revisiting domain-general accounts of category specificity in mind and brain

Theories about the neural basis of semantic knowledge have been strongly influenced by reports that particular semantic categories can be differentially impaired by neuropathology and can differentially activate particular regions of cortex in brain imaging studies. One well-known interpretation of these data is that the brain has evolved distinct functional and anatomical modules for storing and retrieving knowledge about different kinds of things. We review the evidence supporting an alternative view: that category specificity arises from many heterogeneous factors and so tells us little directly about the cognitive and neural architecture of semantic memory. We consider four general hypotheses about domain-general causes of category-specific patterns, their roots in early work, and their reemergence in contemporary research. We argue that there is compelling evidence supporting each hypothesis, and that the different hypotheses together can explain most of the interesting data. We further suggest that such a multifactor domain-general approach to category specificity is appealing partly because it explains the important findings with reference to theoretical claims that are already widely accepted, and partly because it resolves several puzzles that arise under the alternative view. For further resources related to this article, please visit the WIREs website.

CONFLICT OF INTEREST

The authors have declared no conflicts of interest for this article.

Controversies over the mechanisms underlying the crucial role of the left fronto-parietal areas in the representation of tools

Anatomo-clinical and neuroimaging data show that the left fronto-parietal areas play an important role in representing tools. As manipulation is an important source of knowledge about tools, it has been assumed that motor activity explains the link between tool knowledge and the left fronto-parietal areas. However, controversies exist over the exact mechanisms underlying this relationship. According to a strong version of the “embodied cognition theory,” activation of a tool concept necessarily involves re-enactment of the corresponding kind of action. Impairment of the ability to use tools should, therefore, lead to impairment of tool knowledge. Both the “domains of knowledge hypothesis” and the “sensory-motor model of conceptual knowledge” refute the strong version of the “embodied cognition hypothesis” but acknowledge that manipulation and other action schemata play an important role in our knowledge of tools. The basic difference between these two models is that the former is based on an innate model and the latter holds that the brain’s organization of categories is experience dependent. Data supporting and arguing against each of these models are briefly reviewed. In particular, the following lines of research, which argue against the innate nature of the brain’s categorical organization, are discussed: (1) the observation that in patients with category-specific disorders the semantic impairment does not respect the boundaries between biological entities and artifact items; (2) data showing that experience-driven neuroplasticity in musicians is not confined to alterations of perceptual and motor maps but also leads to the establishment of higher-level semantic representations for musical instruments; (3) results of experiments using previously unfamiliar materials showing that the history of our sensory-motor experience with an object significantly affects its neural representation.

The evaluation of sources of knowledge underlying different conceptual categories

According to the “embodied cognition” theory and the “sensory-motor model of semantic knowledge”: (a) concepts are represented in the brain in the same format in which they are constructed by the sensory-motor system and (b) various conceptual categories differ according to the weight of different kinds of information in their representation. In this study, we tried to check the second assumption by asking normal elderly subjects to subjectively evaluate the role of various perceptual, motor and language-mediated sources of knowledge in the construction of different semantic categories. Our first aim was to rate the influence of different sources of knowledge in the representation of animals, plant life and artifact categories, rather than in living and non-living beings, as many previous studies on this subject have done. We also tried to check the influence of age and stimulus modality on these evaluations of the “sources of knowledge” underlying different conceptual categories. The influence of age was checked by comparing results obtained in our group of elderly subjects with those obtained in a previous study, conducted with a similar methodology on a sample of young students. And the influence of stimulus modality was assessed by presenting the stimuli in the verbal modality to 50 subjects and in the pictorial modality to 50 other subjects. The distinction between “animals” and “plant life” in the “living” categories was confirmed by analyzing their prevalent sources of knowledge and by a cluster analysis, which allowed us to distinguish “plant life” items from animals. Furthermore, results of the study showed: (a) that our subjects considered the visual modality as the main source of knowledge for all categories taken into account; and (b) that in biological categories the next most important source of information was represented by other perceptual modalities, whereas in artifacts it was represented by the actions performed with them. Finally, age and stimulus modality did not significantly influence judgment of relevance of the sources of knowledge involved in the construction of different conceptual categories.

The role of body-related and environmental sources of knowledge in the construction of different conceptual categories

CONTROVERSIES EXIST REGARDING: (a) the relationships between perceptual and conceptual activities and (b) the format and neuro-anatomical substrates of concepts. Some authors maintain that concepts are represented in the brain in a propositional, abstract way, which is totally unrelated to the sensory-motor functions of the brain. Other authors argue that concepts are represented in the same format in which they are constructed by the sensory-motor system and can be considered as activity patterns distributed across different perceptual and motor domains. The present paper examines two groups of investigations that support the second view. Particular attention is given to the role of body movements and somatosensory inputs in the representation of artifacts and, respectively, of visual and other perceptual sources of knowledge in the construction of biological categories. The first group of studies aimed to assess the weight of various kinds of information in the representation of different conceptual categories by asking normal subjects to subjectively evaluate the role of various perceptual, motor, and encyclopedic sources of knowledge in the construction of different semantic categories. The second group of studies investigated the neuro-anatomical correlates of various types of categorical disorders. These last investigations showed that the cortical areas damaged in patients with a disorder selectively affecting a given category have a critical role in processing the information that has contributed most to constructing the affected category. Both lines of research suggest that body movements and somatosensory information have a major role in the representation of actions and artifacts mainly known through manipulations and other actions, whereas visual and other perceptual information has a dominant role in the representation of animals and other living things.

The Vanderbilt Expertise Test reveals domain-general and domain-specific sex effects in object recognition

Individual differences in face recognition are often contrasted with differences in object recognition using a single object category. Likewise, individual differences in perceptual expertise for a given object domain have typically been measured relative to only a single category baseline. In Experiment 1, we present a new test of object recognition, the Vanderbilt Expertise Test (VET), which is comparable in methods to the Cambridge Face Memory Task (CFMT) but uses eight different object categories. Principal component analysis reveals that the underlying structure of the VET can be largely explained by two independent factors, which demonstrate good reliability and capture interesting sex differences inherent in the VET structure. In Experiment 2, we show how the VET can be used to separate domain-specific from domain-general contributions to a standard measure of perceptual expertise. While domain-specific contributions are found for car matching for both men and women and for plane matching in men, women in this sample appear to use more domain-general strategies to match planes. In Experiment 3, we use the VET to demonstrate that holistic processing of faces predicts face recognition independently of general object recognition ability, which has a sex-specific contribution to face recognition. Overall, the results suggest that the VET is a reliable and valid measure of object recognition abilities and can measure both domain-general skills and domain-specific expertise, which were both found to depend on the sex of observers.

A computational model of the lexical-semantic system based on a grounded cognition approach

This work presents a connectionist model of the semantic-lexical system based on grounded cognition. The model assumes that the lexical and semantic aspects of language are memorized in two distinct stores. The semantic properties of objects are represented as a collection of features, whose number may vary among objects. Features are described as activation of neural oscillators in different sensory-motor areas (one area for each feature) topographically organized to implement a similarity principle. Lexical items are represented as activation of neural groups in a different layer. Lexical and semantic aspects are then linked together on the basis of previous experience, using physiological learning mechanisms. After training, features which frequently occurred together, and the corresponding word-forms, become linked via reciprocal excitatory synapses. The model also includes some inhibitory synapses: features in the semantic network tend to inhibit words not associated with them during the previous learning phase. Simulations show that after learning, presentation of a cue can evoke the overall object and the corresponding word in the lexical area. Moreover, different objects and the corresponding words can be simultaneously retrieved and segmented via a time division in the gamma-band. Word presentation, in turn, activates the corresponding features in the sensory-motor areas, recreating the same conditions occurring during learning. The model simulates the formation of categories, assuming that objects belong to the same category if they share some features. Simple exempla are shown to illustrate how words representing a category can be distinguished from words representing individual members. Finally, the model can be used to simulate patients with focalized lesions, assuming an impairment of synaptic strength in specific feature areas.

Brain damage and semantic category dissociations: is the animals category easier for males?

Semantic dissociations show that biological stimuli present a further dissociation between animals and plant life. Almost all cases of greater impairment of plant life knowledge were males, suggesting a higher male familiarity with animals possibly derived from different daily activities. To verify this hypothesis, we collected familiarity ratings for normal males and females, for 288 animals, subdivided according to whether they were hunted/fished, or were used as food. The overall familiarity was almost identical between males and females. Males were more familiar with hunted animals, but for them also food animals were more familiar. There was not a consistent effect of hunting/fishing independently of the food/not food classification. The claim that males are generally more proficient with animals knowledge because most hunters/fishers are males seems rather simplistic, and the familiarity structure of the animals category is more complex. An evolution-based account is suggested for the category by sex interaction.

Neuroanatomical and cognitive mediators of age-related differences in perceptual priming and learning

Our objectives were to assess age differences in perceptual repetition priming and perceptual skill learning and to determine whether they are mediated by cognitive resources and regional cerebral volume differences. Fragmented picture identification paradigm allows the study of both priming and learning within the same task. The authors presented this task to 169 adults (ages 18-80), assessed working memory and fluid intelligence, and measured brain volumes of regions that were deemed relevant to those cognitive skills. The data were analyzed within a hierarchical path modeling framework. In addition to finding age-related decrease in both perceptual priming and learning, the authors observed several dissociations with regards to their neural and cognitive mediators. Larger visual cortex volume was associated with greater repetition priming, but not perceptual skill learning, and neither process depended upon hippocampal volume. In contrast, the volumes of the prefrontal gray and white matter were differentially related to both processes via direct and indirect effects of cognitive resources. The results indicate that age-related differences in perceptual priming and skill learning have dissociable cognitive and neural correlates.

Nature and facts about natural and artifactual categories: Sex differences in the semantic priming paradigm

There is abundant evidence from behavioral and neurophysiological experiments for the distinction of natural versus artifactual categories and a gender-specific difference: women's performances in cognitive tasks increase when natural categories are used, whereas men's performances increase with artifactual categories. Here, we used the semantic priming paradigm to study retrieval processes by presenting category labels as primes and exemplars as targets. Overall, in two experiments we found larger priming effects for natural than for artifactual categories. In addition, females showed positive priming effects for natural but negative effects for artifactual categories, whereas males showed positive priming effects for both categories. This pattern matches with that from other tasks and can be interpreted as evidence that the findings from these other tasks are, at least partially, indeed due to different representations or processing modes for males and females and not (exclusively) due to-for example-different familiarity with a category. In a further experiment, we showed that the found pattern for females can be manipulated by focusing on perceptual vs. functional features. The results can be interpreted as first evidence that there are (eventually in addition to different "crystallized" semantic structures) specific default processing modes that differ for males and females.

Does sex influence the age of acquisition of common names? A contrast of different semantic categories

The literature reports a sex-related asymmetry in the ability to process different semantic categories: women are more proficient with biological categories and men with man-made objects. The origin of this asymmetry is still debated. In this study, we directly checked whether the acquisition of names belonging to different semantic categories differs according to sex. We carried out our inquiry on 202 children aged 3-5 years, who were given a coloured picture naming task using a battery of 60 stimuli belonging to different semantic categories. Boys differed from girls only on naming of stimuli belonging to the categories of tools and vehicles, where they showed an earlier name acquisition. No sex differences were found for animals or plant life, notwithstanding evidence in the literature of an overrepresentation of males among patients affected by biological categories impairment. Our findings suggest that the male advantage for tools and vehicles reported in the literature on verbal fluency and naming tasks is strongly related to the earlier age in males of name acquisition for these categories, and possibly to their higher familiarity. On the contrary, the female advantage for plant life knowledge, which becomes evident later in life, has a still undefined nature and only a dubious relationship to familiarity, although it is sufficient to cause an overrepresentation of males among patients affected by a category specific impairment of biological categories, especially of plant life knowledge.

The impact of dementia, age and sex on category fluency: greater deficits in women with Alzheimer's disease

A category specific effect in naming tasks has been reported in patients with Alzheimer's dementia. Nonetheless, naming tasks are frequently affected by methodological problems, e.g., ceiling effects for controls and "nuisance variables" that may confound results. Semantic fluency tasks could help to address some of these methodological difficulties, because they are not prone to producing ceiling effects and are less influenced by nuisance variables. One hundred and thirty-three participants (61 patients with probable AD; and 72 controls: 36 young and 36 elderly) were evaluated with semantic fluency tasks in 14 semantic categories. Category fluency was affected both by dementia and by age: while in nonliving-thing categories there were differences among the three groups, in living thing categories larger lexical categories produced bigger differences among groups. Sex differences in fluency emerged, but these were moderated both by age and by pathology. In particular, fluency was smaller in female than male Alzheimer patients for almost every subcategory.

Category-specific semantic deficits in Alzheimer's disease: a semantic priming study

Category-specific semantic deficits in individuals suffering brain damage after relatively focal lesions provide an important source of evidence about the organization of semantic knowledge. However, whether Alzheimer's disease (AD), in which the brain damage is more widespread, affects semantic categories to a different extent is still controversial. In the present study, we assess this issue by means of the semantic priming technique. AD patients with a mild impairment of their semantic knowledge showed comparable priming effects to that of controls for the categories of animals and artifacts. Interestingly, however, patients with a moderate impairment of their semantic knowledge showed a normal priming effect for animals but a very reduced priming effect (if any) for artifacts. These results reveal that AD may affect the semantic knowledge of different semantic categories to a different extent. The implications of this observation for current theoretical accounts of semantic representation in the brain are discussed.

The Different Neural Correlates of Action and Functional Knowledge in Semantic Memory: An fMRI Study

Previous reports suggest that the internal organization of semantic memory is in terms of different "types of knowledge," including "sensory" (information about perceptual features), "action" (motor-based knowledge of object utilization), and "functional" (abstract properties, as function and context of use). Consistent with this view, a specific loss of action knowledge, with preserved functional knowledge, has been recently observed in patients with left frontoparietal lesions. The opposite pattern (impaired functional knowledge with preserved action knowledge) was reported in association with anterior inferotemporal lesions. In the present study, the cerebral representation of action and functional knowledge was investigated using event-related analysis of functional magnetic resonance imaging data. Fifteen subjects were presented with pictures showing pairs of manipulable objects and asked whether the objects within each pair were used with the same manipulation pattern ("action knowledge" condition) or in the same context ("functional knowledge" condition). Direct comparisons showed action knowledge, relative to functional knowledge, to activate a left frontoparietal network, comprising the intraparietal sulcus, the inferior parietal lobule, and the dorsal premotor cortex. The reverse comparison yielded activations in the retrosplenial and the lateral anterior inferotemporal cortex. These results confirm and extend previous neuropsychological data and support the hypothesis of the existence of different types of information processing in the internal organization of semantic memory.

A predominance of category deficits for living things in Alzheimer's disease and Lewy body dementia

Although semantic memory impairment is well documented in patients with dementia of the Alzheimer's type, questions remain as to whether the deficit extends to other forms of dementia and whether it differentially affects different domains of knowledge. We examined category naming on two tasks (picture naming and naming-to-description) in patients with Alzheimer's disease (AD: n = 11), Lewy body dementia (DLB: n = 11) and healthy elderly matched controls (n = 22). The DLB and AD groups showed significantly worse naming on both tasks, although the AD patients were more impaired than the DLB patients. Like some AD patients, some DLB patients showed evidence of category-specific naming deficits, and strikingly, all 25 significant category dissociations were for living things. The latter finding accords with the preponderance of living deficits previously documented for AD patients, but extends this finding to DLB patients. The implications of this category bias is discussed in relation to relevant models of category specificity.

A meta-analytic review of category naming in Alzheimer's disease

Patients with Alzheimer's disease (AD) experience word-finding difficulties that become increasingly pronounced as pathological changes accrue in the brain. One question that has received increasing attention over the last two decades concerns whether the anomia in AD is category-specific, i.e. differentially affects the ability to name living things (LT) and non-living things (NLT). The current meta-analysis systematically reviewed the effect sizes for naming pictures of LT and NLT in comparisons of AD patients and healthy controls in 21 studies with over 1000 participants (557 patients and 509 healthy controls). A random effects model analysis revealed no significant difference in the large weighted effect sizes for naming pictures of LT and NLT (d=1.76 and 1.49, respectively). Moderator variable analyses revealed a significant impact of stimulus colour on the effect size for LT, indicating that using colour stimuli significantly increases the impairment of naming LT in AD patients. Additionally, we found that LT and the NLT effect sizes were larger for samples with proportionally more female patients; smaller samples produced larger LT effect sizes. In contrast, effect sizes were not significantly related to dementia severity, patient age, the number of stimuli, years of education, or the number of matching variables controlled.

The emergence of semantic categorization in early visual processing: ERP indices of animal vs. artifact recognition

BACKGROUND

Neuroimaging and neuropsychological literature show functional dissociations in brain activity during processing of stimuli belonging to different semantic categories (e.g., animals, tools, faces, places), but little information is available about the time course of object perceptual categorization. The aim of the study was to provide information about the timing of processing stimuli from different semantic domains, without using verbal or naming paradigms, in order to observe the emergence of non-linguistic conceptual knowledge in the ventral stream visual pathway. Event related potentials (ERPs) were recorded in 18 healthy right-handed individuals as they performed a perceptual categorization task on 672 pairs of images of animals and man-made objects (i.e., artifacts).

RESULTS

Behavioral responses to animal stimuli were ~50 ms faster and more accurate than those to artifacts. At early processing stages (120-180 ms) the right occipital-temporal cortex was more activated in response to animals than to artifacts as indexed by posterior N1 response, while frontal/central N1 (130-160) showed the opposite pattern. In the next processing stage (200-260) the response was stronger to artifacts and usable items at anterior temporal sites. The P300 component was smaller, and the central/parietal N400 component was larger to artifacts than to animals.

CONCLUSION

The effect of animal and artifact categorization emerged at ~150 ms over the right occipital-temporal area as a stronger response of the ventral stream to animate, homomorphic, entities with faces and legs. The larger frontal/central N1 and the subsequent temporal activation for inanimate objects might reflect the prevalence of a functional rather than perceptual representation of manipulable tools compared to animals. Late ERP effects might reflect semantic integration and cognitive updating processes. Overall, the data are compatible with a modality-specific semantic memory account, in which sensory and action-related semantic features are represented in modality-specific brain areas.

Domain-specific deficits in schizophrenia

INTRODUCTION

Object recognition deficits are well documented in certain neurological disorders (e.g., Alzheimer's disease, herpes simplex encephalitis). Although agnosic problems have been documented in some patients with schizophrenia (Gabrovska et al., 2003), no study has investigated whether such deficits differentially affect specific categories of information (as they sometimes do in neurological cases).

METHOD

In Part I of this study, we compared object recognition in 55 patients with chronic schizophrenia and 22 age- and NART IQ-matched healthy controls. In Part II, we present a detailed case study of one patient with schizophrenia (DH) who displays a severe category specific semantic knowledge for living things.

RESULTS

Of the patients with schizophrenia, 75% had object recognition below the 5th percentile, and in 11% of cases, a highly specific classical category dissociation emerged (5 cases with nonliving deficit and 1 with living deficit); and two other patients showed strong dissociation for living things. These findings provide convincing evidence of a classical double dissociation across the two categories. In Part II, the in-depth case study of one schizophrenic patient (DH), documented a profound agnosia for living things. While DH displayed intact low level perceptual and spatial ability and could copy drawings, he was severely impaired at naming, picture-name matching, semantic fluency, and could not describe or draw items from memory.

CONCLUSIONS

The presence of impaired object recognition in most schizophrenic patients, along with highly selective category specific deficits in a minority, is discussed with reference to similar findings in neurological patients.

The impact of colour, spatial resolution, and presentation speed on category naming

Studies of neurological patients with category-specific agnosia have provided important contributions to our understanding of object recognition, although the meaning of such disorders is still hotly debated. One crucial line of research for our understanding of category effects, is through the examination of category biases in healthy normal subjects. This approach has, however, led to contradictory findings with advantages both for natural kinds and for man-made things being documented in healthy subjects. It has been proposed that task conditions may influence the direction of advantage (Gerlach, 2001) and in particular, that sub-optimal viewing conditions underpin natural kinds advantages, while man-made advantages emerge under more optimal viewing conditions. In two experiments with normal subjects, we examined the roles played by spatial resolution (blurring), stimulus type (colour and texture), and speed of presentation in picture naming across category. In both experiments, healthy subjects showed a natural kind advantage for original stimuli and for blurred colour stimuli (at slow and fast presentation speeds), while an advantage for man-made things emerged for line-drawings that were blurred and presented slowly. The implications for category-specific object recognition deficits are discussed.

Anatomical functional and cognitive determinants of semantic memory disorders

Contemporary debates on the 'semantic memory' construct revolve around three main topics: (1) the functional and anatomical relationships between episodic and semantic memory; (2) the format of semantic representations and their relationships with the underlying sensory-motor processes; (3) the categorical organization of semantic memory. The aim of the present review is to demonstrate that there is a common thread linking these different aspects of semantic memory. This thread is represented by the interdependence of mechanisms involved in the construction of semantic memory and the content of semantic representations. In particular, I suggest there is a continuity between: (a) the mechanisms of acquisition of episodic and semantic memory; (b) semantic representations and sensory-motor processes preliminary to the acquisition of these representations. This continuity has important implications for the format of semantic representations and the brain structures subserving the organisation of various categories of knowledge.