Sound naming in neurodegenerative disease

Modern cognitive neuroscientific theories and empirical evidence suggest that brain structures involved in movement may be related to action-related semantic knowledge. To test this hypothesis, we examined the naming of environmental sounds in patients with corticobasal degeneration (CBD) and progressive supranuclear palsy (PSP), two neurodegenerative diseases associated with cognitive and motor deficits. Subjects were presented with 56 environmental sounds: 28 sounds were of objects that required manipulation when producing the sound, and 28 sounds were of objects that required no manipulation. Subjects were asked to provide the name of the object that produced the sound and also complete a sound-picture matching condition. Subjects included 33 individuals from four groups: CBD/PSP, Alzheimer disease, frontotemporal dementia, and normal controls. We hypothesized that CBD/PSP patients would exhibit impaired naming performance compared with controls, but the impairment would be most apparent when naming sounds associated with actions. We also explored neural correlates of naming environmental sounds using voxel-based morphometry (VBM) of brain MRI. As expected, CBD/PSP patients scored lower on environmental sounds naming (p < 0.007) compared with the controls. In particular, the CBD/PSP patients scored the lowest when naming sounds of manipulable objects (p < 0.05), but did not show deficits in naming sounds of non-manipulable objects. VBM analysis across all groups showed that performance in naming sounds of manipulable objects correlated with atrophy in the left pre-motor region, extending from area six to the middle and superior frontal gyrus. These results indicate an association between impairment in the retrieval of action-related names and the motor system, and suggest that difficulty in naming manipulable sounds may be related to atrophy in the pre-motor cortex. Our results support the hypothesis that retrieval of action-related semantic knowledge involves motor regions in the brain.     

The semantic category effect increases with worsening anomia in Alzheimer's type dementia

A large number of patients (n=72) with probable Alzheimer's type dementia (DAT) and mild cognitive impairment (MCI) carried out a picture naming task which comprised stimuli from biological and nonbiological categories. The results were stratified into five ranges of overall naming ability. Every group except those with scores within the range of elderly normal individuals demonstrated better nonbiological naming than biological naming, an effect which increased with worsening impairment. In general, patients diagnosed with other dementia (n=15) did not fit well within the pattern of the DAT/MCI participants, except those known to have a significant semantic impairment. A category effect favoring nonbiological items appears to be robust and produce a predictable pattern across progressive levels of impairment in AD.     

The organization of conceptual knowledge: the evidence from category-specific semantic deficits

Questions about the organization of conceptual knowledge in the human brain can be addressed by studying patients with category-specific semantic deficits: disproportionate and even selective impairment of conceptual knowledge of one category of objects compared with other categories. Recently, consensus has emerged regarding the basic facts of category-specific semantic deficits: (1) the categories that can be disproportionately impaired or spared are 'animals', 'fruit/vegetables', and 'artifacts'; and (2) category-specific semantic deficits are not associated with disproportionate deficits for a type or modality of knowledge. Together with findings in functional neuroimaging, these data indicate a complex organization of conceptual knowledge characterized by several independent dimensions of organization.     

Semantic category effect and emotional valence in female university students

The semantic category effect represents a category dissociation between biological and nonbiological objects in picture naming. The aim of this preliminary study was to further examine this phenomenon, and to explore the possible association between the effect and subjective emotional valence for the named objects. Using a speeded picture naming task, vocal reaction times for 45 items were divided into four categories based on emotional valence rating and semantic category, and examined in 36 female university students. Analyses of the data indicated an "animate/inanimate" category dissociation favouring animate objects, in tandem with a potential relationship between subjective emotional valence and semantic processing underlying picture naming.     

Memory for proper names in old age: A disproportionate impairment?

A common complaint of older adults is that they have trouble remembering names, even the names of people they know well. Two experiments examining this problem are reported in the present article. Experiment 1 tested episodic memory for surnames and occupations; older adults and younger adults under divided attention performed less well than did full attention younger adults, but showed no disproportionate loss of name information. Experiment 2 examined the ability to name photographs of public figures and of uncommon objects; this experiment therefore tested retrieval from semantic memory. In this case adults in their 70s did show an impairment in recall of names of known people, but not of known objects. Further analyses revealed systematic relations between naming, recognition, and rated familiarity of the categories used. Familiarity largely determined the proportions of recognizable items that were named in a prior phase. Overall, little evidence was found for a disproportionate age-related impairment in naming in either episodic or semantic memory.     

Ideational action impairments in Alzheimer's disease

We report data from a group of patients with mild Alzheimer's disease on a range of tasks requiring either stored semantic knowledge about objects (e.g., naming object use) or the execution of action to objects (e.g., miming and using objects). We found that the patients were impaired at miming in response to objects, even when they could describe the object's function. On the other hand, copying gestures was not impaired relative to naming gestures, indicating that an ideomotor deficit in action execution, per se, was unlikely to explain the impairments in object use. We suggest instead that the patients had an impairment in stored motor programmes for action, over and above their deficits in semantic knowledge. Despite this, the patients were better at using than at miming to objects, consistent with the view that proprioceptive input (when using objects) can directly constrain selection of the appropriate motor programme for action.     

Perceptual differentiation as a source of category effects in object processing: Evidence from naming and object decision

The locus of category effects in picture recognition and naming was examined in two experiments with normal subjects. Subjects carried out object decision (deciding whether the stimulus is a “real” object or not) and naming tasks with pictures of clothing, furniture, fruit, and vegetables. These categories are distinguished by containing either relatively many exemplars with similar perceptual structures (fruit and vegetables;structurally similar categories), or relatively few exemplars with similar perceptual structures (clothing and furniture;structurally dissimilar categories). In Experiment 1, responses to the stimuli from the structurally similar categories were slower than responses to stimuli from the structurally dissimilar categories, and this effect was larger in the naming than in the object decision task. Further, prior object decisions to stimuli from structurally similar categories facilitated their subsequent naming. In Experiment 2, we orthogonally manipulated object decision and naming as prime and target tasks, again with stimuli from the four categories. Category effects, with responses slower to objects from structurally similar categories, were again larger in naming than in object decision, and these category effects in naming were reduced by priming with both naming and object decision. We interpret the data to indicate that category effects in object naming can reflect visually based competition which is reduced by the preactivation of stored structural knowledge for objects.     

Semantic impairment and anomia in Alzheimer''s disease

Impairment in naming visually presented objects was investigated in patients with a clinical diagnosis of Alzheimer's disease. Impaired object naming correlated with difficulty listing the names of objects from a specified semantic category and with erroneous selection of words semantically related to the correct names for objects in a name recognition test. These results suggest that patients with Alzheimer's disease have a semantic impairment characterized by inability to distinguish among objects that are members of the same semantic category, and that this impairment is associated with difficulty producing the names for objects. Semantic impairment was present in patients with normal ability to discriminate visually presented shapes, indicating that the semantic deficit in Alzheimer's disease occurs independently of abnormalities of visuospatial function. Patients tended to make errors on the same items in both confrontation naming and name recognition tests, suggesting that the semantic impairment in Alzheimer's disease involves loss of information about specific objects and their names.     

Implicit learning of semantic category sequences: response-independent acquisition of abstract sequential regularities

Through the use of a new serial naming task, the authors investigated implicit learning of repeating sequences of abstract semantic categories. Participants named objects (e.g., table, shirt) appearing in random order. Unbeknownst to them, the semantic categories of the objects (e.g., furniture, clothing) followed a repeating sequence. Irrespective of whether participants were instructed to attend to the categories (Experiment 1) or whether no mention was made of the categories (Experiments 2 and 3), naming latencies reliably increased when the repeating category sequence was switched to a random sequence. This was the case even for participants showing no explicit knowledge in reproduction and recognition tests. Results indicate that abstract sequential structures are learned implicitly, even if neither the surface stimuli nor the responses follow a sequence.     

Semantic component of a cross-modal Stroop-like task

Three experiments showed that the pattern of interference of single-modality Stroop tests also exists cross-modally. Distractors and targets were either pictures or auditory words. In a naming task (Experiment 1), word distractors from the same semantic category as picture targets interfered with picture naming more than did semantically unrelated distractors; the semantic category of picture distractors did not differentially affect word naming. In a categorization task (Experiment 2), this Stroop-like effect was reversed: Picture distractors from the same semantic category as word targets interfered less with word categorization than picture distractors that were semantically unrelated; the semantic category of word distractors did not differentially affect picture categorization. Experiment 3 replicated these effects when each subject performed both tasks; the task, naming or categorizing, determined the pattern of interference between pictures and auditory words. The results thus support the existence of a semantic component of a cross-modal Stroop-like effect.     

Receptive vocabulary and semantic knowledge in children with SLI and children with Down syndrome

Receptive vocabulary and associated semantic knowledge were compared within and between groups of children with specific language impairment (SLI), children with Down syndrome (DS), and typically developing children. To overcome the potential confounding effects of speech or language difficulties on verbal tests of semantic knowledge, a novel task was devised based on picture-based semantic association tests used to assess adult patients with semantic dementia. Receptive vocabulary, measured by word-picture matching, of children with SLI was weak relative to chronological age and to nonverbal mental age but their semantic knowledge, probed across the same lexical items, did not differ significantly from that of vocabulary-matched typically developing children. By contrast, although receptive vocabulary of children with DS was a relative strength compared to nonverbal cognitive abilities (p < .0001), DS was associated with a significant deficit in semantic knowledge (p < .0001) indicative of dissociation between word-picture matching vocabulary and depth of semantic knowledge. Overall, these data challenge the integrity of semantic-conceptual development in DS and imply that contemporary theories of semantic cognition should also seek to incorporate evidence from atypical conceptual development.     

Do living and nonliving categories need further fractionation? A study of picture naming in a pathological sample

A group of 51 patients affected by possible semantic memory deficit were given a picture naming task for the purposes of a comparison between six categories, three of Nonliving nature (tools, furniture, vehicles) and three of a Living nature (animals, fruits, and vegetables). A logistic regression analysis was used for a multiple single case study, where also the items' basic difficulty was included in the model. Besides some patients showing a dissociation between Living and Nonliving categories, other patients showed a finer selectivity on naming, differentiating animals from fruits and vegetables, tools from nonmanipulable objects, and even vehicles from furniture. These results are examined in the light of current theories of semantic category specificity.     

Functional neuroimaging studies of category specificity in object recognition: a critical review and meta-analysis

Functional neuroimaging studies in which the cortical organization for semantic knowledge has been addressed have revealed interesting dissociations in the recognition of different object categories, such as faces, natural objects, and manufactured objects. The present paper critically reviews these studies and performs a meta-analysis of stereotactic coordinates to determine whether category membership predicts patterns of brain activation across different studies. This meta-analysis revealed that, in the ventral temporal cortex, recognition of manufactured objects activates more medial aspects of the fusiform gyrus, as compared with natural object or face recognition. Face recognition activates more inferior aspects of the ventral temporal cortex, as compared with manufactured object recognition. The recognition task used—viewing, matching, or naming—also predicted brain activation patterns. Specifically, matching tasks recruit more inferior occipital regions than do either naming or viewing tasks, whereas naming tasks recruit more anterior ventral temporal sites than do either viewing or matching tasks. These findings indicate that the cognitive demands of a particular recognition task are as predictive of cortical activation patterns as is category membership.     

Hierarchies, similarity, and interactivity in object recognition: "category-specific" neuropsychological deficits.

Category-specific impairments of object recognition and naming are among the most intriguing disorders in neuropsychology, affecting the retrieval of knowledge about either living or nonliving things. They can give us insight into the nature of our representations of objects: Have we evolved different neural systems for recognizing different categories of object? What kinds of knowledge are important for recognizing particular objects? How does visual similarity within a category influence object recognition and representation? What is the nature of our semantic knowledge about different objects? We review the evidence on category-specific impairments, arguing that deficits even for one class of object (e.g., living things) cannot be accounted for in terms of a single information processing disorder across all patients; problems arise at contrasting loci in different patients. The same apparent pattern of impairment can be produced by damage to different loci. According to a new processing framework for object recognition and naming, the hierarchical interactive theory (HIT), we have a hierarchy of highly interactive stored representations. HIT explains the variety of patients in terms of (1) lesions at different levels of processing and (2) different forms of stored knowledge used both for particular tasks and for particular categories of object.     

What is in a tool concept? Dissociating manipulation knowledge from function knowledge

Research on patients with apraxia, a deficit in skilled action, has shown that the ability to use objects may be differentially impaired relative to knowledge about object function. Here we show, using a modified neuropsychological test, that similar dissociations can be observed in response times in healthy adults. Participants were asked to decide which two of three presented objects shared the same manipulation or the same function; triads were presented in picture and word format, and responses were made manually (button press) or with a basic-level naming response (verbally). For manual responses (Experiment 1), participants were slower to make manipulation judgments for word stimuli than for picture stimuli, while there was no difference between word and picture stimuli for function judgments. For verbal-naming responses (Experiment 2), participants were again slower for manipulation judgments over word stimuli, as compared with picture stimuli; however, and in contrast to Experiment 1, function judgments over word stimuli were faster than function judgments over picture stimuli. These data support the hypotheses that knowledge of object function and knowledge of object manipulation correspond to dissociable types of object knowledge and that simulation over motor information is not necessary in order to retrieve knowledge of object function.     

Semantic facilitation with pictures and words

The present experiments explored the role of processing level and strategic factors in cross-form (word-picture and picture-word) and within-form (picture-picture and word-word) semantic facilitation. Previous studies have produced mixed results. The findings presented in this article indicate that semantic facilitation depends on the task and on the subjects' strategies. When the task required semantic processing of both picture and word targets (e.g., category verification), equivalent facilitation was obtained across all modality combinations. When the task required name processing (e.g., name verification, naming), facilitation was obtained for the picture targets. In contrast, with word targets, facilitation was obtained only when the situation emphasized semantic processing. The results are consistent with models that propose a common semantic representation for both picture and words but that also include assumptions regarding differential order of access to semantic and phonemic features for these stimulus modalities.     

Can residual lexical knowledge concern word form rather than word meaning?

We described a patient with a dramatic deficit of both word comprehension and naming but with good preservation of visual pictorial semantics. On word-picture matching, his performances were slightly better than expected based on the observed lexical semantic disorder; in addition, the patient, who maintained good preservation of his underlying phonology, showed a tendency to point to the picture phonologically related to the target. In order to interpret these data, we advanced the hypothesis that the patient, in spite of his virtually complete inability to name, would be able, in a word-picture matching task, to "covertly" (i.e., preverbally) retrieve the name from the picture and to use this name to attempt a match with the phonological form of the stimulus word. This mechanism, that we called "phonological" comprehension, would allow the identification of the correct target and would explain the choice of the phonologically related foil that was sometimes selected.