Sense of identity in advanced Alzheimer's dementia: a cognitive dissociation between sameness and selfhood?

We looked at whether sense of identity persists in patients with Alzheimer's disease (AD) and if its profile remains the same between two examinations. A specifically designed protocol was administered to 16 AD patients in the mild to severe stages of dementia and to 16 matched healthy controls, both living in the same institution. We showed that sense of identity was broadly preserved in AD patients. The patterns of their responses were similar to those of controls, and remained consistent over a two-week period. However, some qualitative characteristics of sense of identity in AD patients differed significantly from those of controls, suggesting that AD patients may not be able to update their self-knowledge, probably because of their episodic memory deficit. These results are discussed in the light of both current models of the self and philosophical concepts such as sameness and selfhood.

The neural substrates of musical memory revealed by fMRI and two semantic tasks.

Recognizing a musical excerpt without necessarily retrieving its title typically reflects the existence of a memory system dedicated to the retrieval of musical knowledge. The functional distinction between musical and verbal semantic memory has seldom been investigated. In this fMRI study, we directly compared the musical and verbal memory of 20 nonmusicians, using a congruence task involving automatic semantic retrieval and a familiarity task requiring more thorough semantic retrieval. In the former, participants had to access their semantic store to retrieve musical or verbal representations of melodies or expressions they heard, in order to decide whether these were then given the right ending or not. In the latter, they had to judge the level of familiarity of musical excerpts and expressions. Both tasks revealed activation of the left inferior frontal and posterior middle temporal cortices, suggesting that executive and selection processes are common to both verbal and musical retrievals. Distinct patterns of activation were observed within the left temporal cortex, with musical material mainly activating the superior temporal gyrus and verbal material the middle and inferior gyri. This cortical organization of musical and verbal semantic representations could explain clinical dissociations featuring selective disturbances for musical or verbal material.

Musical and verbal semantic memory: two distinct neural networks?

Semantic memory has been investigated in numerous neuroimaging and clinical studies, most of which have used verbal or visual, but only very seldom, musical material. Clinical studies have suggested that there is a relative neural independence between verbal and musical semantic memory. In the present study, "musical semantic memory" is defined as memory for "well-known" melodies without any knowledge of the spatial or temporal circumstances of learning, while "verbal semantic memory" corresponds to general knowledge about concepts, again without any knowledge of the spatial or temporal circumstances of learning. Our aim was to compare the neural substrates of musical and verbal semantic memory by administering the same type of task in each modality. We used high-resolution PET H(2)O(15) to observe 11 young subjects performing two main tasks: (1) a musical semantic memory task, where the subjects heard the first part of familiar melodies and had to decide whether the second part they heard matched the first, and (2) a verbal semantic memory task with the same design, but where the material consisted of well-known expressions or proverbs. The musical semantic memory condition activated the superior temporal area and inferior and middle frontal areas in the left hemisphere and the inferior frontal area in the right hemisphere. The verbal semantic memory condition activated the middle temporal region in the left hemisphere and the cerebellum in the right hemisphere. We found that the verbal and musical semantic processes activated a common network extending throughout the left temporal neocortex. In addition, there was a material-dependent topographical preference within this network, with predominantly anterior activation during musical tasks and predominantly posterior activation during semantic verbal tasks.

[The twenty-first century as a neuropsychology era]. / Le XXI(e) siècle sera neuropsychologique ou ne sera pas !

This article reviews how neuropsychology, in the French-speaking world, has evolved as a discipline focused on research, teaching and clinical work. The article targets the last 30 years as this corresponds to the time at which the Société de Neuropsychologie de Langue Française (French-Speaking Neuropsychological Society) was created. The review addresses how the cognitive neuropsychology approach and the advent of brain imaging have shaped the field of neuropsychology in recent years. It presents the status of the discipline in the main French-speaking countries (where neuropsychology is currently developed) including France, Belgium, Switzerland and Canada. It also analyzes a number of indicators that reflect the vitality of the discipline and its cohesion as a science and as a clinical domain. These indicators include the creation of specialized journals, organization of scientific meetings, accessibility to training programs in neuropsychology, development of discipline-oriented clinical programs, and the increase in scientific productivity. The Quebec academic environment is used as an illustration, whereby structured clinical doctoral training programs that meet national standards in neuropsychology were implemented to train clinical neuropsychologists. Finally, the authors emphasize the major role that the discipline is likely to play at different levels of society in the near future.

Characteristics and evolution of writing impairment in Alzheimer's disease.

Rapcsak et al. (Archs Neurol. 46, 65-67, 1989) proposed a hypothesis describing the evolution of agraphic impairments in dementia of the Alzheimer type (DAT): lexico-semantic disturbances at the beginning of the disease, impairments becoming more and more phonological as the dementia becomes more severe. Our study was conducted in an attempt to prove this hypothesis on the basis of an analysis of the changes observed in the agraphia impairment of patients with DAT. A writing test from dictation was proposed to 22 patients twice, with an interval of 9-12 months between the tests. The results show that within 1 year there was little change in the errors made by the patients in the writing test. The changes observed however were all found to develop within the same logical progression (as demonstrated by Correspondence Analysis). These findings made it possible to develop a general hypothesis indicating that the agraphic impairment evolves through three phases in patients with DAT. The first one is a phase of mild impairment (with a few possible phonologically plausible errors). In the second phase non-phonological spelling errors predominate, phonologically plausible errors are fewer and the errors mostly involve irregular words and non-words. The last phase involves more extreme disorders that affect all types of words. We observe many alterations due to impaired graphic motor capacity. This work would tend to confirm the hypothesis proposed by Rapcsak et al. concerning the development of agraphia, and would emphasize the importance of peripheral impairments, especially grapho-motor impairments which come in addition to the lexical and phonological impairments.

Topographic EEG activations during timbre and pitch discrimination tasks using musical sounds.

Successive auditory stimulation sequences were presented binaurally to 18 young normal volunteers. Five conditions were investigated: two reference tasks, assumed to involve passive listening to couples of musical sounds, and three discrimination tasks, one dealing with pitch, and two with timbre (either with or without the attack). A symmetrical montage of 16 EEG channels was recorded for each subject across the different conditions. Two quantitative parameters of EEG activity were compared among the different sequences within five distinct frequency bands. As compared to a rest (no stimulation) condition, both passive listening conditions led to changes in primary auditory cortex areas. Both discrimination tasks for pitch and timbre led to right hemisphere EEG changes, organized in two poles: an anterior one and a posterior one. After discussing the electrophysiological aspects of this work, these results are interpreted in terms of a network including the right temporal neocortex and the right frontal lobe to maintain the acoustical information in an auditory working memory necessary to carry out the discrimination task.

Contributions of frontal and medial temporal regions to verbal episodic memory: a PET study.

Using PET, subtraction and correlation analysis were jointly employed to determine the specific and complementary contributions of frontal and medial temporal regions to verbal episodic encoding and retrieval processes. Subtraction analysis highlighted prefrontal rCBF increases which were predominantly left-sided during intentional encoding and exclusively right-sided during retrieval, the latter being moreover associated with bilateral precuneus activation. However, significant correlation between rCBF values obtained during intentional encoding and performance scores obtained during retrieval concerned, among other regions, the left parahippocampal gyrus, which indicated that the higher the neuronal activity in this medial temporal region during encoding, the better the retrieval performance.

[Neuropsychology of musical identification]. / Neuropsychologie de l'identification musicale.

Several neuropsychological observations have suggested that disturbances of the process involved in identifying music is related to lesions of the dominant cerebral hemisphere. The studies have been confirmed by different data from experimental psychology and functional brain imaging techniques. Based on these inference sources we propose different hypotheses to describe the cognitive processes involved in identifying music.

[A pneumatic transfusion accelerator]. / Un accélérateur pneumatique de transfusion.

A new simple device using piped medical gases for the inflation of pressure cuffs used for rapid intravenous infusions is described. The pressure cuffs are maintained inflated with piped medical oxygen delivered by an adjustable pressure regulator. Operating advantages of this device were: 1) inflation time for the cuff and infusion time for fluids kept in collapsible PVC bags (whole blood, plasma, cellular concentrates or other fluids) were considerably shortened, not requiring any manual manipulation throughout the infusion; 2) when the bag is emptied, the large bore tubing used allowed rapid deflation of the cuffs; 3) the procedure was as safe as manual acceleration of transfusion, and simpler, requiring a simple three-way stopcock.

Preservation of the attribute knowledge of concepts in normal aging groups.

The aim of this study was to detect possible alterations in semantic representation during normal aging. Forty young subjects (aged 20 to 30 years) and 40 elderly ones (divided into two groups of 60 to 70 years and 70 to 80 years), all in good health and with high education, completed a test protocol used for assessing semantic knowledge in the study of Alzheimer's disease. The same list of 42 words belonging to three different semantic categories was presented visually three times to the subjects, each time with different instructions: (a) find the words with one letter N (or more) (training task); (b) find the names of animals (test of categorical knowledge); (c) find the words representing something that prick (test of attribute knowledge of concepts). A two-way analysis of variance showed an effect of task (the times taken were significantly longer for the attribute-knowledge test), a group effect (the elderly subjects were slower) and an absence of interaction (the elderly subjects had the same profile as the young group). The results indicate the preservation of the semantic memory in normally aging groups and the usefulness is emphasized in the context of the data given in the literature on Alzheimer's disease.

Neural correlates underlying musical semantic memory.

Numerous functional imaging studies have examined the neural basis of semantic memory mainly using verbal and visuospatial materials. Musical material also allows an original way to explore semantic memory processes. We used PET imaging to determine the neural substrates that underlie musical semantic memory using different tasks and stimuli. The results of three PET studies revealed a greater involvement of the anterior part of the temporal lobe. Concerning clinical observations and our neuroimaging data, the musical lexicon (and most widely musical semantic memory) appears to be sustained by a temporo-prefrontal cerebral network involving right and left cerebral regions.

The structural components of music perception. A functional anatomical study.

This work explores the cerebral structures involved in the appreciation of music. We studied six young healthy subjects (right handed, French, without musical talent), using a high resolution PET device (CTI 953B) and 15O-labelled water. In three tasks, we studied the effects of selective attention to pitch, timbre and rhythm; a final task studied semantic familiarity with tunes (considered as divided attention for pitch and rhythm). These four tasks were performed on the same material (a tape consisting of 30 randomly arranged sequences of notes). We selected a paradigm, without a reference task, to compare the activations produced by attention to different parameters of the same stimulus. We expected that the activations recorded during each task would differ according to the differences in cognitive operations. We found activations preferentially in the left hemisphere for familiarity, pitch tasks and rhythm, and in the right hemisphere for the timbre task. The familiarity task activated the left inferior frontal gyrus, Brodmann area (BA) 47, and superior temporal gyrus (in its anterior part, BA 22). These activations presumably represent lexico-semantic access to melodic representations. In the pitch task, activations were observed in the left cuneus/precuneus (BA 18/19). These results were unexpected and we interpret them as reflecting a visual mental imagery strategy employed to carry out this task. The rhythm task activated left inferior Broca's area (BA 44/6), with extention into the neighbouring insula, suggesting a role for this cerebral region in the processing of sequential sounds.