Naming of newly learned objects: a PET activation study

The present study tracked the naming-related brain activity by positron emission tomography (PET) when successfully learned unfamiliar objects were named. Ten Finnish-speaking subjects participated in the study. Prior to the PET scan, each subject underwent a 4-day long training period in which 40 names of rare unfamiliar objects were taught. The stimulus categories were as follows: unfamiliar but real objects for which both the name and the definition were given during training, only the name was given, no information was given. In addition, familiar objects and visual noise patterns were used. The unfamiliar items mainly represented ancient domestic tools unknown to modern-day people. As semantic support did not affect the PET results, all trained items were pooled together. The trained objects vs. familiar objects contrast revealed rCBF increases in the left inferior frontal cortex (Broca's area), the left anterior temporal area, and the cerebellum. Likewise, the trained objects vs. unfamiliar objects (for which no information was given) contrast revealed more extensive left frontal (roughly Broca's area) and cerebellar rCBF increases, while anterior temporal activation was bilateral. Familiar objects, contrasted with both visual noise patterns and a rest condition, elicited activation increases in expected areas, i.e., bilateral occipital regions and the fusiform gyrus. Our results indicate that the naming of newly learned objects recruits more extensive brain areas than the naming of familiar items, namely a network that includes left-dominant frontotemporal areas and cerebellum. Its activity is tentatively related to enhanced lexical-semantic and lexical-phonological retrieval, as well as associative memory processes.     

Learning and forgetting new names and objects in MCI and AD

We studied how subjects with mild cognitive impairment (MCI), early Alzheimer's disease (AD) and age-matched controls learned and maintained the names of unfamiliar objects that were trained with or without semantic support (object definitions). Naming performance, phonological cueing, incidental learning of the definitions and recognition of the objects were tested during follow-up. We found that word learning was significantly impaired in MCI and AD patients, whereas forgetting patterns were similar across groups. Semantic support showed a beneficial effect on object name retrieval in the MCI group 8 weeks after training, suggesting that the MCI patients’ preserved semantic memory can compensate for impaired episodic memory. The MCI group performed equally well as the controls in the tasks measuring incidental learning and recognition memory, whereas the AD group showed impairment in this respect. Both the MCI and the AD group benefited less from phonological cueing than the controls. Our findings indicate that word learning is compromised in both MCI and AD, whereas long-term retention of newly learned words is not affected to the same extent. Incidental learning and recognition memory seem to be well preserved in MCI.     

Accessing newly learned names and meanings in the native language

Ten healthy adults encountered pictures of unfamiliar archaic tools and successfully learned either their name, verbal definition of their usage, or both. Neural representation of the newly acquired information was probed with magnetoencephalography in an overt picture-naming task before and after learning, and in two categorization tasks after learning. Within 400 ms, activation proceeded from occipital through parietal to left temporal cortex, inferior frontal cortex (naming) and right temporal cortex (categorization). Comparison of naming of newly learned versus familiar pictures indicated that acquisition and maintenance of word forms are supported by the same neural network. Explicit access to newly learned phonology when such information was known strongly enhanced left temporal activation. By contrast, access to newly learned semantics had no comparable, direct neural effects. Both the behavioral learning pattern and neurophysiological results point to fundamentally different implementation of and access to phonological versus semantic features in processing pictured objects.     

Naming of objects, faces and buildings in mild cognitive impairment

Accruing evidence suggests that the cognitive deficits in very early Alzheimer's Disease (AD) are not confined to episodic memory, with a number of studies documenting semantic memory deficits, especially for knowledge of people. To investigate whether this difficulty in naming famous people extends to other proper names based information, three naming tasks – the Graded Naming Test (GNT), which uses objects and animals, the Graded Faces Test (GFT) and the newly designed Graded Buildings Test (GBT) – were administered to 69 participants (32 patients in the early prodromal stage of AD, so-called Mild Cognitive Impairment (MCI), and 37 normal control participants). Patients were found to be impaired on all three tests compared to controls, although naming of objects was significantly better than naming of faces and buildings. Discriminant analysis successfully predicted group membership for 100% controls and 78.1% of patients. The results suggest that even in cases that do not yet fulfil criteria for AD naming of famous people and buildings is impaired, and that both these semantic domains show greater vulnerability than general semantic knowledge. A semantic deficit together with the hallmark episodic deficit may be common in MCI, and that the use of graded tasks tapping semantic memory may be useful for the early identification of patients with MCI.     

Long-term maintenance of novel vocabulary in persons with chronic aphasia

Background: The study of novel word learning in aphasia can shed light on the functionality of patients' learning mechanisms and potentially help in treatment planning. Previous studies have indicated that persons with aphasia are able to learn some new vocabulary. However, these learning outcomes appear short-lived and evidence for the ability to use the newly learned words in the long term is lacking.

Aims: Participants with aphasia and matched controls underwent short training where they were taught to name novel objects with novel names. We studied the participants' word learning and particularly their long-term maintenance. We also examined whether the language and verbal short-term memory impairments of the participants with aphasia related to their ability to acquire and maintain phonological and semantic information on novel words.

Methods & Procedures: Two participants with nonfluent aphasia, LL and AR, and two matched controls took part in the experiment. They were taught to name 20 unfamiliar objects by repeating the names in the presence of the object picture. Half of the items carried a definition that was used to probe incidental semantic learning. There were four training sessions, a post-training test, and follow-up tests up to 6 months post-training. Learning measures included recognition of the trained objects, as well as spontaneous and cued recall in visual confrontation naming. Incidental semantic learning was measured by spontaneous recall of the definitions.

Outcomes & Results: Combining spontaneous and phonologically cued responses, LL acquired 70% and AR 55% of the novel words. With phonological cueing, LL named 50% of the items correctly up to 6 months post-training (vs 95–100% for the controls) and AR 25% up to 8 weeks post-training. AR's lexical-semantic processing, pseudoword repetition and verbal short-term capacity were inferior to those of LL. In line with this, AR learned fewer words and showed more decline in recognition memory for the trained items, and weaker recall of the semantic definitions.

Conclusions: Our results support previous findings that people with aphasia can learn to name novel items. More importantly, the results show for the first time that, with phonological cueing, an individual with aphasia can maintain some of this learning up to 6 months post-training. Moreover the results provide further evidence for the significance of the functional status of lexical-semantic processing on word learning success.     

Learning and maintaining new vocabulary in persons with aphasia: Two controlled case studies

Background: Novel word learning of persons with aphasia is little studied, even though a better understanding of learning processes would inform development of effective treatment strategies. Recent evidence suggests some remaining verbal learning capacity in persons with aphasia. Long-term maintenance of newly learned active vocabulary has not been reported previously in persons with aphasia.

Aims: To explore learning and long-term maintenance of novel words in persons with aphasia.

Methods & Procedures: Two English-speaking males with chronic anomic aphasia and two age-matched controls were taught novel names of 20 unfamiliar objects. Half of the words were taught with semantic information (definition) and half without. Participants were instructed to learn the names. The experiment included four training sessions, one post-training test and four follow-up tests administered 1 week, 4 weeks, 8 weeks, and 6 months post-training. We tested explicit learning of the new names through visual confrontation naming. In addition, incidental learning of semantic information was probed over the follow-up period.

Outcomes & Results: The two participants with aphasia learned 6–8 of the 20 novel names during the training. However, this new vocabulary dissipated during the 6-month follow-up. As expected, the controls showed better performance both in acquisition and in maintenance of the new vocabulary over the follow-up period. As regards the accuracy of semantic information, the aphasic participant with semantic impairment demonstrated worse incidental learning of semantic information than controls and the participant with intact lexical semantics.

Conclusions: Some new vocabulary can be acquired even in chronic aphasia but the ability to spontaneously retrieve the newly learned words gradually dissipates over the weeks following learning. Our results also indicate an interaction between the level of lexical-semantic processing skills and incidental learning of new lexical-semantic knowledge in aphasia.     

Lack of semantic priming effects in famous person recognition in Mild Cognitive Impairment

IntroductionGrowing evidence indicates that individuals with Mild Cognitive Impairment (MCI) manifest semantic deficits that are often more severe for items that are characterized by a unique semantic and lexical association, such as famous people and famous buildings, than common concepts, such as objects. However, it is still controversial whether the semantic deficits observed in MCI are determined by a degradation of semantic information or by a deficit in intentional access to semantic knowledge. Here we used a semantic priming task in order to assess the integrity of the semantic system without requiring explicit access to this system. This paradigm may provide new insights in clarifying the nature of the semantic deficits in MCI.MethodsWe assessed the semantic and repetition priming effect in 13 individuals with MCI and 13 age-matched controls who engaged in a familiarity judgment task of famous names. In the semantic priming condition, the prime was the name of a member of the same occupation category as the target (Tom Cruise–Brad Pitt), while in the repetition priming condition the prime was the same name as the target (Charlie Chaplin–Charlie Chaplin).ResultsThe results showed a defective priming effect in MCI in the semantic but not in the repetition priming condition. Specifically, when compared to controls, MCI patients did not show a facilitation effect in responding to the same occupation prime-target pairs, but they showed an equivalent facilitation effect when the target was the same name as the prime.ConclusionThe present results provide support to the hypothesis that the semantic impairments observed in MCI cannot be uniquely ascribed to a deficit in intentional access to semantic information. Instead, these findings point to the semantic nature of these deficits and, in particular, to a degraded representation of semantic information concerning famous people.     

Optic Aphasia: Evidence of the Contribution of Different Neural Systems to Object and Action Naming

Visual stimulus naming was studied in a 66-year-old male patient with optic aphasia subsequent to left occipito-temporal infarction. While having difficulty in naming objects perceived visually, he was able to name objects by viewing gestures illustrating their use, and to name actions shown in pictures. These results suggest that naming performance depends on the kind of stimulus that is visually presented (object vs. action). The present findings lend support to cognitive models which postulate the existence of visual and functional semantic systems.     

Optic Aphasia: Evidence of the Contribution of Different Neural Systems to Object and Action Naming

Visual stimulus naming was studied in a 66-year-old male patient with optic aphasia subsequent to left occipito-temporal infarction. While having difficulty in naming objects perceived visually, he was able to name objects by viewing gestures illustrating their use, and to name actions shown in pictures. These results suggest that naming performance depends on the kind of stimulus that is visually presented (object vs. action). The present findings lend support to cognitive models which postulate the existence of visual and functional semantic systems.     

Anomia for people names in DAT--evidence for semantic and post-semantic impairments

Proper name anomia is a frequent finding among patients in the early stages of Alzheimer's disease. The present study investigates naming of famous persons in a group of DAT patients, a group of persons with mild cognitive impairment (MCI) and healthy controls. The study is aimed at distinguishing the relative contributions of semantic and post-semantic factors to difficulties in proper name retrieval. As shown by a significantly lower score in answering semantic questions, DAT patients retrieve less biographical knowledge related to famous persons than healthy elderly subjects and persons with mild cognitive impairment. This finding is in line with the frequent observation of semantic deficits in early and moderate DAT. The high number of Tip-of-the-Tongue (TOT) answers in DAT found in relation to few spontaneously named items shows that post-semantic deficits are as important as semantic deficits in determining anomia for people names in DAT. Moreover, DAT patients were less sensitive to phonological cueing than healthy persons or persons with mild cognitive impairment. These findings suggest that proper name anomia in DAT is not only due to semantic deficits, but also to problems in accessing the phonological representation, as well as to a degradation of phonological representations. Thus, naming deficits in DAT differ not only quantitatively, but also qualitatively from the difficulties of healthy elderly persons. No significant differences were found between persons with mild cognitive impairment and healthy controls in proper name retrieval.     

Convergence of distinct functional networks supporting naming and semantic recognition in the left inferior frontal gyrus

Naming individual objects is accompanied with semantic recognition. Previous studies examined brain‐networks responsible for these operations individually. However, it remains unclear how these brain‐networks are related. To address this problem, we examined the brain‐networks during a novel object‐naming task, requiring participants to name animals in photographs at a specific‐level (e.g., “pigeon”). When the participants could not remember specific names, they answered basic names (e.g., “bird”). After fMRI scanning during the object‐naming task, the participants rated familiarity of the animals based on their sense of knowing. Since participants tend to remember specific names for familiar objects compared with unfamiliar objects, a typical issue in an object‐naming task is an internal covariance between the naming and familiarity levels. We removed this confounding factor by adjusting the familiarity/naming level of stimuli, and demonstrated distinct brain regions related to the two operations. Among them, the left inferior frontal gyrus triangularis (IFGtri) contained object‐naming and semantic‐recognition related areas in its anterior‐ventral and posterior‐dorsal parts, respectively. Psychophysiological interaction analyses suggested that both parts show connectivity with the brain regions related to object‐naming. By examining the connectivity under control tasks requiring nonlexical semantic retrieval (e.g., animal's body color), we found that both IFGtri parts altered their targeting brain areas according to the required memory attributes, while only the posterior‐dorsal part connected the brain regions related to semantic recognition. Together, the semantic recognition may be processed by distinct brain network from those for voluntary semantic retrievals including object‐naming although all these networks are mediated by the posterior‐dorsal IFGtri.     

Episodic and semantic memory in mild cognitive impairment

Little is known about episodic and semantic memory in the early predementia stage of Alzheimer's disease (AD), which is referred to as mild cognitive impairment (MCI). To explore person knowledge, item recognition and spatial associative memory, we designed the Face Place Test (FPT). A total of 75 subjects participated: 22 patients with early AD, 24 with MCI and 29 matched controls. As predicted, AD patients showed significant deficits in person naming, item recognition and recall of spatial location (placing). Surprisingly, subjects with MCI were also impaired on all components. There was no significant difference between AD and MCI except on the placing component. Analysis of the relationship between semantic (naming) and episodic (recognition and placing) components of the FPT revealed a significant association between the two episodic tasks, but not between episodic and semantic performance. Patients with MCI show deficits of episodic and semantic memory. The extent of impairment suggests dysfunction beyond the medial temporal lobe. The FPT might form the basis of a sensitive early indicator of AD.     

Dissociation of color from object in amnesia.

A patient with persistent amnesia after bilateral medial temporal and left inferotemporo-occipital infarction could not match colors to objects in verbal, visual, or visuoverbal tasks. A severe naming disorder for objects was present but the patient could name colors and point to colors whose name was given. The matching disorder appeared to be a deficit in the semantic classification of objects rather than a problem in identifying colors.     

Real object use facilitates object recognition in semantic agnosia

In the present paper we show that, in patients with poor semantic representations, the naming of real objects can improve when naming takes place after patients have been asked to use the objects, compared with when they name the objects either from vision or from touch alone, or together. In addition, the patients were strongly affected by action when required to name objects that were used correctly or incorrectly by the examiner. The data suggest that actions can be cued directly from sensory-motor associations, and that patients can then name on the basis of the evoked action.     

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.     

老年人轻度认知功能损害的神经心理测验研究

目的;用神经心理测验研究老年人轻度认知功能损害的特点。方法;为横断面比较研究。研究对象分为两组,即有轻度认知功能损害的老年人（ＭＣＩ组）和认知功能正常的老年人（对照组,ＮＣ组）。以世界卫生组织老年认知功能介成套神经心理测验（ＷＨＯ－ＢＣＡＩ）为主要研究工具。     

The "hidden" semantic category dissociation in mild-moderate Alzheimer's disease patients

In patients manifesting mild-moderate Alzheimer's disease (AD), lexical semantic tasks are known to be influenced by several variables which should be adequately taken into account when studying semantic category dissociations. The following study provides indexes of three new variables (imageability (I), percentage of name agreement (pNA) and number of target alternatives (nTA)) and investigates their role in naming in a group of people with AD and in matched older adults controls. Forty young healthy participants rated I, pNA and nTA of 155 stimuli (including living and non-living items) from and sets. Forty-eight people with mild-moderate AD and 40 older adults were given the two naming tests and their naming ratings were analysed with a two-way ANOVA (two groupsxtwo categories) to assess category specificity and the effect of interaction. The influence of relevant concomitant variables in naming was measured using a multiple regression analysis. Semi-partial correlations were carried out to assess the independent contribution of each variable to naming. We found that living items were more imageable and had fewer lexical alternatives and higher name agreement than non-living items. We also found that controls significantly named better than AD patients (F=37.551, p<.001), whilst the two-way ANOVA showed no significant effect of category (F=.649, p=.423). Notably category effect emerged when assessing its independent contribution performing a semi-partial correlation (beta=-.278, p<.001) which kept the effect of relevant concomitant variables under control. Our results confirm that category dissociation does emerge in mild-moderate AD patients when the effect of relevant concomitant variables is adequately taken into account. The hypothesis that the highly correlated properties of items from biological categories may play a protective effect on living things, making them less prone to impairment in the early stages of AD, is discussed.     

Multidimensional measures of person knowledge and spatial associative learning: can these be applied to the differentiation of Alzheimer's disease from frontotemporal and vascular dementia?

Patients with early stage Alzheimer's disease (AD) show deficits in person knowledge and spatial associative memory. The current investigation examined the ability of impairment in these domains to differentiate AD from other overlapping conditions. In experiment 1, 14 AD patients, 21 vascular dementia (VaD) patients, 11 frontal variant frontotemporal dementia (fvFTD) patients and 41 controls were administered a graded faces test. VaD patients demonstrated a level of impairment comparable to the AD group on both the naming and person identification elements of the task. A mild naming deficit was revealed in the fvFTD group. In experiment 2, 22 AD patients, 23 patients with mild cognitive impairment (MCI), 11 fvFTD patients, 13 semantic dementia (SD) patients, and 23 elderly controls were administered the face-place test, a newly developed task that combines naming of famous faces, item recognition and spatial location. The naming component of the face-place test clearly differentiated SD patients from all dementia groups. All patient groups, except those with fvFTD, showed substantial deficits in the item recognition and spatial components. Consistency analyses indicated a fairly robust association between the two episodic components (item recognition and placing), but not between semantic and episodic elements of the FPT. Person knowledge deficits are, therefore, not specific to AD and the employment of face stimuli may influence the performance of SD patients on tasks of episodic memory.     

The nature of lexico-semantic processing deficits in mild cognitive impairment

Lexico-semantic impairments in Alzheimer disease (AD) have been attributed to abnormalities in both intentional and automatic access to semantic memory. However, the order in which these impairments appear during the course of the disease is unclear. We sought to answer this question by documenting lexico-semantic impairments in 61 subjects with mild cognitive impairment (MCI), a pre-AD stage, and by comparing them to those of 39 AD and 60 normal elderly (NE) subjects. All subjects were tested with intentional access tasks (picture naming and semantic probes), automatic access tasks (lexical decision and priming), and executive function tasks (Stroop and Stroop-Picture naming). Results indicated that the MCI group was only impaired on tasks of intentional access relative to the AD group who was impaired on both types of tasks. Because most MCI subjects eventually develop AD, these results suggest that intentional access to semantic memory is impaired before automatic access. Further, impairments on the Stroop-Picture naming task but not on the Stroop task, suggest that lexico-semantic impairments in the MCI group may be related to inhibition deficits during semantic search. Findings are discussed in light of executive dysfunctions within the framework of semantic memory theories.