Enhancing picture naming with transcranial magnetic stimulation

The enhancement of cognitive function in healthy subjects by medication, training or intervention yields increasing political, social and ethical attention. In this paper facilitatory effects of single-pulse TMS and repetitive TMS on a simple picture naming task are presented. A significant shortening of picture naming latencies was observed after single-pulse TMS over Wernicke's area. The accuracy of the response was not affected by this speed effect. After TMS over the dominant motor cortex or over the non-dominant temporal lobe, however, no facilitation of picture naming was observed. In the rTMS experiments only rTMS of Wernicke's area had an impact on picture naming latencies resulting in a shortening of naming latencies without affecting the accuracy of the response. rTMS over the visual cortex, Broca's area or over the corresponding sites in the non-dominant hemisphere had no effect. Single-pulse TMS is able to facilitate lexical processes due to a general preactivation of language-related neuronal networks when delivered over Wernicke's area. Repetitive transcranial magnetic stimulation over Wernicke's area also leads to a brief facilitation of picture naming possibly by shortening linguistic processing time. Whether TMS or rTMS can be used to aid linguistic therapy in the rehabilitation phase of aphasic patients should be subject of further investigations.     

Speech sound errors in patients with conduction and Broca's aphasia

Speech sound errors exhibited by three conduction and three Broca's aphasic patients on naming and word-repetition tasks were subjected to phonemic and subphonemic analyses. In the conduction aphasic patients, errors occurred equally often on consonants and vowels in both the naming and word-repetition tasks, while in the Broca's aphasic patients errors occurred selectively on consonants. Transposition errors occurred almost as often as substitution errors in the conduction aphasic patients, while substitution errors constituted the majority of errors in the Broca's aphasic patients. The Broca's aphasic patients, as compared to the conduction aphasic patients, exhibited a markedly higher number of substitution errors occurring between phonemes separated by a single subphonemic feature on the naming task. On the basis of these findings, it was hypothesized that the differences in the error patterns of the two types of aphasia reflected differences in the underlying mechanisms of the impairment in each type.     

The naming of objects and symbols by children and aphasic patients

Three studies of naming in children and in aphasic patients were conducted in order to determine the kinds of errors made in the naming of objects, parts of objects, and various kinds of symbols, and to evaluate the contribution of operativity to the ease of naming such elements. Operativity refers to the extent to which elements can be transformed and involved in a variety of sensory and motor schemes. It was found that operativity of depicted elements makes a significant contribution to ease of naming for both groups of subjects. However, children and aphasic patients made different types of naming errors. In the case of naming of symbols, the categories easiest for aphasics to name proved the most difficult for children to name. It is suggested that the partial loss of an acquired ability can produce a different clinical picture than the partial acquisition of that ability in the normal child. The concept of operativity may be a less useful concept in the relatively figurative domain of symbols.The research cited in this report was supported in part by Harvard Project Zero (through Grant No. GB-31064 from the National Science Foundation), the Livingston Fund, and the Milton Fund of Harvard University.     

Comprehension of indirect requests by persons with fluent aphasia

This study examined the judgments and response latencies of 10 participants with aphasia and 10 participants without aphasia for responses to indirect requests. Modals such as can and should were drawn from 5 indirect request categories. There was a significant difference in judgment errors and response latency between participants with and without aphasia. There were no significant differences between aphasic participants' judgments for literal versus nonliteral contrasts. There was a significant effect among the modals and among the categories of indirect requests. Response latency reflected aphasic participants' understanding of these indirect requests.     

Tracing attention and the activation flow of spoken word planning using eye movements

The flow of activation from concepts to phonological forms within the word production system was examined in 3 experiments. In Experiment 1, participants named pictures while ignoring superimposed distractor pictures that were semantically related, phonologically related, or unrelated. Eye movements and naming latencies were recorded. The distractor pictures affected the latencies of gaze shifting and vocal naming. The magnitude of the phonological effects increased linearly with latency, excluding lapses of attention as the cause of the effects. In Experiment 2, no distractor effects were obtained when both pictures were named. When pictures with superimposed distractor words were named or the words were read in Experiment 3, the words influenced the latencies of gaze shifting and picture naming, but the pictures yielded no such latency effects in word reading. The picture-word asymmetry was obtained even with equivalent reading and naming latencies. The picture-picture effects suggest that activation spreads continuously from concepts to phonological forms, whereas the picture-word asymmetry indicates that the amount of activation is limited and task dependent.     

The semantic deficit hypothesis: Perceptual parsing and object classification by aphasic patients

Many aphasic patients are impaired in their ability to provide or to recognize the names of objects, but little is known about the processing deficits that underlie these difficulties. In this report, a model of object naming/name recognition is proposed, and a prediction is tested concerning one possible functional locus of impairment in name-recognition and object-naming disorders. A subgroup of aphasic patients is found to be impaired in the ability to perform perceptual similarity judgments for pairs of stimulus objects, and to be unable to classify the objects into one of two lexical categories. It is concluded that the classification disorder suffered by these patients results from an impairment at the level of the semantically guided perceptual parsing of objects.     

Locus of semantic priming effects in speeded naming

The locus of semantic priming effects was examined by measuring onset and rime durations as well as response latencies of words with consistent and inconsistent pronunciations, using the postvocalic naming task. We found that the effect of a semantic prime on naming duration was localized rather than spread across the entire word; onset durations were shorter in the related condition than in the unrelated condition, but rime durations were equal in the two prime conditions. Moreover, the priming effect on onset durations was larger for words with inconsistent than for those with consistent pronunciations. These duration results cannot be accounted for by previous proposals, but they can be accounted for by models in which phonemes are activated in parallel rather than serially from left to right and in which motor programs are based on phonemes rather than syllables. Contrary to previous reports of an interaction of prime and regularity (a factor closely related to consistency) on naming latency, we found no interaction of prime and consistency on response latency. We argue that this conflict is only apparent and arises because naming latency conflates response latency and initial phoneme duration for some targets.     

Enhancement of naming in nonfluent aphasia through gesture

In a number of studies that have examined the gestural disturbance in aphasia and the utility of gestural interventions in aphasia therapy, a variable degree of facilitation of verbalization during gestural activity has been reported. The present study examined the effect of different unilateral gestural movements on simultaneous oral-verbal expression, specifically naming to confrontation. It was hypothesized that activation of the phylogenetically older proximal motor system of the hemiplegic right arm in the execution of a communicative but nonrepresentational pointing gesture would have a facilitatory effect on naming ability. Twenty-four aphasic patients, representing five aphasic subtypes, including Broca's, Transcortical Motor, Anomic, Global, and Wernicke's aphasics were assessed under three gesture/naming conditions. The findings indicated that gestures produced through activation of the proximal (shoulder) musculature of the right paralytic limb differentially facilitated naming performance in the nonfluent subgroup, but not in the Wernicke's aphasics. These findings may be explained on the view that functional activation of the archaic proximal motor system of the hemiplegic limb, in the execution of a communicative gesture, permits access to preliminary stages in the formative process of the anterior action microgeny, which ultimately emerges in vocal articulation.     

Effects of imposed delay of response and item complexity on auditory comprehension by aphasics

Ten aphasic and five control subjects were administered an auditory comprehension task similar to Levels I-IV of the Revised Token Test under conditions of 0, 5, 10, and 20 sec of imposed response delay. Responses were evaluated in terms of performance accuracy and response time. Aphasic subjects' response accuracy was significantly effected by an interaction between the length of delay imposed and the complexity of the stimulus. The aphasic group also demonstrated a significant main effect for item complexity. Control subjects' accuracy was not influenced by the treatment conditions. Latency measures indicated the aphasic subjects were slower to respond across all treatment conditions. Both groups' latency scores were significantly effected by item complexity. A comparison of mean latencies by condition did, however, suggest different patterns of response for the two groups. Results are discussed in terms of theoretical and clinical implications for the auditory comprehension deficits of aphasia.     

Effect of surface characteristics and style of production on naming and verification of pictorial stimuli.

Theories of object recognition that are based purely on part decomposition do not take into account the role of textural, shading, and color information, nor do they differentiate between stylistic factors in the preparation of line-drawn pictorial stimuli. To investigate these factors, naming and verification experiments were performed using line drawings, monochrome photographs, and color photographs of common objects. For line drawings, it was shown that line width, exposure, and contrast affected naming latency, which increased for lines of narrow width and extremes of exposure. Naming latencies were compared for objects drawn by a professional artist, with varying degrees of surface detail, and objects produced by a computer-aided design (CAD) system, with no surface detail. The mean naming latencies for the artist set were faster than for the CAD set, though not significantly, with a significant degree of object correlation being observed. However, in certain cases there were significant differences between objects. These were investigated in a further experiment in which subsets with common properties of present or absent surface detail were selected from the artist-drawn stimuli. It was found that the presence of surface features resulted in lower response latencies even for those objects that intuitively could be recognized by parts alone. The time to name photographic and line-drawn stimuli was compared, and a progressive decrease in naming latency from line to monochrome to color stimuli was observed. In a verification task, no significant advantage for color or monochrome photographs over line drawings was found, either when comparing stimuli of equivalent or of different mode. However, there was a tendency for the comparison of different modes to take longer than the comparison of same modes. The results are discussed in terms of theories of human visual processing and cognitive and computational models of object recognition.     

Verb-noun double dissociation in aphasic lexical impairments: the role of word frequency and imageability

Neurolinguistic studies have provided important evidence regarding the organization of lexical representations and the structure of underlying conceptual knowledge; in particular, it has been shown that the retrieval of verbs and nouns can be damaged selectively. Dissociated lexical damage is proof of an independent mental organization of lexical representations and/or of the underlying processes. The aim of the present study is to estimate the rate of dissociated impairments for nouns and verbs on a large sample of mild to moderate aphasic patients and to investigate the mechanisms underlying such phenomena. In addition, the authors wished to verify to what degree the impairment for nouns and verbs is related to a specific type of language disorder. A confrontation naming task for verbs and nouns was administered to 58 aphasic patients. The major lexical (word frequency and age of acquisition) and semantic variables (familiarity and imageability of the underlying concept) were considered for each noun and verb used in the task. Verbs were distinguished by major functional classes (transitive, intransitive, and ergative verbs). The data collected from this task were analyzed twice: (i) as a group study comparison of major aphasic subgroups and (ii) as a multiple single case study to evaluate the differences on the naming of verbs and nouns and the effect of the lexical semantic variables on each individual patient. The results confirm the existence of dissociated naming impairments of verbs and nouns. Selective impairment of verbs is more frequent (34%) than that of nouns (10%). In many cases, the dissociated pattern of naming impairment disappeared when the effect of the concomitant variables (word frequency and imageability) was removed, but in approximately one-fifth of the cases the noun or verb superiority was preserved. Noun superiority emerged in five of six agrammatic patients. Both the naming of verbs (n = 9) or of nouns (n = 6) could be impaired selectively in fluent aphasic patients. The results lend support to the hypothesis of an independent mental organization of nouns and verbs, but a substantial effect of imageability and word frequency suggests an interaction of the naming impairment with underlying lexical and semantic aspects.     

Mimicking aphasic semantic errors in normal speech production: evidence from a novel experimental paradigm

Semantic errors are commonly found in semantic dementia (SD) and some forms of stroke aphasia and provide insights into semantic processing and speech production. Low error rates are found in standard picture naming tasks in normal controls. In order to increase error rates and thus provide an experimental model of aphasic performance, this study utilised a novel method- tempo picture naming. Experiment 1 showed that, compared to standard deadline naming tasks, participants made more errors on the tempo picture naming tasks. Further, RTs were longer and more errors were produced to living items than non-living items a pattern seen in both semantic dementia and semantically-impaired stroke aphasic patients. Experiment 2 showed that providing the initial phoneme as a cue enhanced performance whereas providing an incorrect phonemic cue further reduced performance. These results support the contention that the tempo picture naming paradigm reduces the time allowed for controlled semantic processing causing increased error rates. This experimental procedure would, therefore, appear to mimic the performance of aphasic patients with multi-modal semantic impairment that results from poor semantic control rather than the degradation of semantic representations observed in semantic dementia [Jefferies, E. A., & Lambon Ralph, M. A. (2006). Semantic impairment in stoke aphasia vs. semantic dementia: A case-series comparison. Brain, 129, 2132-2147]. Further implications for theories of semantic cognition and models of speech processing are discussed.     

Age of acquisition and name agreement as predictors of mean response latencies in picture naming of French adults

We studied the influence of five variables on picture naming latencies in French adult subjects: frequency, age of acquisition and length of words, name agreement in oral naming, and visual complexity of pictures. 140 pictures were presented to 56 subjects with control of individual factors (age, educational level, gender). Naming latency was measured as the time from picture onset until keystroke corresponding to the begin of verbal production. The results of simple and multiple regression analyses show that only two variables make independent contributions to mean response latency: age of acquisition and name agreement. Such state of affairs confirms similar findings obtained with English speaking subjects.     

Speculation about behavior, brain damage, and self-organization: the other way to herd a cat

This article contrasts aphasic patients' performance of word naming and lexical decision with that of intact college-aged readers. We discuss this contrast within a framework of self-organization; word recognition by aphasic patients is destabilized relative to intact performance. Less stable performance shows itself as an increase in the dispersion of patients' response times compared to college students'. Dispersion is also more pronounced for low-frequency words than for high frequency words. We speculate, that increased dispersion originates in a reduction of constraints that support naming and lexical decision performances. A sufficient reduction of constraints yields qualitative changes in performance such as the production of semantic errors in deep dyslexia. These hypotheses are offered as alternatives to postulating distinct modules.     

Naming times for the Snodgrass and Vanderwart pictures in Spanish

We present new Spanish norms for object familiarity and rated age of acquisition for 140 pictures taken from Snodgrass and Vanderwart (1980), together with data on visual complexity, image agreement, name agreement, word length (in syllables and phonemes), and five measures of word frequency. The pictures were presented to a group of 64 Spanish subjects, and oral naming latencies were recorded. In a multiple regression analysis, age of acquisition, object familiarity, name agreement, word frequency, and word length made significant independent contributions to predicting naming latency.     

Comprehending homographs in aphasia

This study assessed 13 aphasic subjects' knowledge of the multiple meanings of homographs. The results indicated that the various meanings were less available to aphasic subjects than to normal subjects. In addition, specific meanings became less available as they became less typical although the number of meanings associated with a homograph did not influence performance. Aphasia type also did not influence performance. Performance on the experimental test was significantly correlated with auditory comprehension level and picture naming ability. The results were related to recent findings on semantic organization in aphasia.     

The mental representation of verb-noun compounds in Italian: evidence from a multiple single-case study in aphasia

This study seeks information on the mental representation of Verb–Noun (VN) nominal compounds through neuropsychological methods. The lexical retrieval of compound nouns is tested in 30 aphasic patients using a visual confrontation naming task. The target names are VN compounds, Noun–Noun (NN) compounds, and long morphologically simple nouns (LSN). In order to check the ability to produce simple nouns and verbs in the same participants, a further visual confrontation naming task of objects and actions is used. Results of the study confirm that several patients with disproportionate verb deficit are also impaired in naming VN compounds. Data are in favor of a (de)compositional processing of compound words. A further group of patients is selectively more impaired with compound nouns than with comparably long simple nouns, irrespective of their VN or NN morphological structure. It is suggested that this impairment is to be ascribed to a specific disorder in retrieving two different lexemes with a single lexical entry.     

Toward a functional classification of naming impairments

Three experiments involving confrontation naming and nonverbal classification tasks establish that impaired naming is relatively common in elderly cardiac patients, but that it can be distinguished functionally from aphasic dysnoia. The results suggest that while the aphasics' failures often reflected failure to retrieve the verbal labels of objects which were appropriately perceived, naming failures in cardiac patients were frequently precipitated by failure to éstablish the semantic identity of the target and were more sentitive to reductions in visual quality of the target picture.     

The effects of semantic and phonemic prestimulation cues on picture naming in aphasia.

In this study of auditory prestimulation cues, picture naming performances under phonemic and semantic conditions were compared to picture naming performance under a neutral condition. Twenty aphasic subjects named 324 pictures (108 pictures x 3 conditions) each. Responses were scored using a coding system adapted by the investigator from classification systems used by Williams and Canter (1982) and Kohn and Goodglass (1985). Results indicated that naming accuracy was facilitated by phonemic and semantic cues. An examination of the distribution of errors under the three conditions revealed systematic effects of phonemic and semantic cues on the frequency of occurrence of specific error types. Increases in semantic paraphasia proportion scores and decreases in unrelated word error proportion scores were associated with the semantic condition, while increases in phonemic paraphasia proportion scores were associated with the phonemic condition. The finding that naming performance of aphasic adults varies as a function of the type of information provided by the cue is discussed in relation to cascade visual confrontation naming models.     

Action naming in anomic aphasic speakers: effects of instrumentality and name relation

Many studies reveal effects of verb type on verb retrieval, mainly in agrammatic aphasic speakers. In the current study, two factors that might play a role in action naming in anomic aphasic speakers were considered: the conceptual factor instrumentality and the lexical factor name relation to a noun. Instrumental verbs were shown to be better preserved than non-instrumental verbs in a group of anomic aphasic speakers but not in a group of Broca's aphasic speakers. Name relation to a noun improved the performance of the anomic aphasic speakers as well. Again, no effect was found in the group of Broca's aphasic speakers. Verbs with a name relation to a noun were better retrieved in action naming than verbs without a name relation. These findings are discussed in terms of the spreading activation theory of Dell. (Dell, G. S. (1986). A spreading activation theory of retrieval in sentence production. Psychological Review 93, 283-321.).