Absence of amusia and preserved naming of musical instruments in an aphasic composer.

M.M., a right-handed, 74 year old professional musician and composer, presented with a progressive aphasia with a severe anomia. His musical competence was apparently totally preserved, and he continued his activity as a composer. There was a striking discrepancy between his impaired naming of nonmusical stimuli and his normal naming of musical instruments' sounds. We suggest that the preservation of skills in the musical domain results from an expanded cortical representation of this function in the left hemisphere, secondary to his lifelong formal training, and to the high level of his professional competence. As for his preserved naming of musical instruments, we argue that the early age-of-acquisition and higher than "normal" frequency/familiarity for names of musical instruments facilitate the access to their lexical representation and/or their retrieval within the lexicon.

Discrimination of facial identity and of emotions in Alzheimer's disease.

OBJECTIVE: To investigate processing of human faces identity and of emotional expressions in patients with Alzheimer's Disease (AD). BACKGROUND: Mechanisms responsible for discriminating facial identity may be dissociated from those involved in discriminating facial expressions. Patients with prosopagnosia often have preserved capacities for processing emotional facial expressions and occasionally, patients with focal lesions may recognize human faces without being able to recognize their facial expression. Such a dissociation has not been clearly shown in groups of AD patients. METHODS: Thirty-one probable AD patients and 14 control subjects were administered tasks of discrimination of faces and of emotions. RESULTS: AD patients were significantly impaired in discriminating facial identities and in naming and pointing to named emotions, but were comparable to controls in discriminating facial expressions of emotion. The deficits of facial discrimination and of identification of emotions were, on the whole, correlated with the MMS and Raven scores. Discrimination of emotions was not correlated to either test, suggesting that this ability is based on cognitive processes different from those underlying the MMS and the PM47. CONCLUSIONS: This dissociation implies two separate systems, one dedicated to discrimination of facial identities and the other to discrimination of emotions. This is compatible with the modular organization of cognitive deficits in AD and may explain the well known experience that nonverbal communication often remains effective even in patients with severe dementia.

Language impairment and rate of cognitive decline in Alzheimer's disease.

There is growing evidence that AD consists of different subtypes, and that language is a pertinent factor to identify a subgroup with a fast rate of cognitive decline. We report the first results of a longitudinal study in which we compared two groups of patients with probable AD. The main result showed that a subgroup with stable MMSE scores during a 1-year follow-up period had an impairment in language domains which are usually preserved until an advanced stage of the disease. It is proposed that this group may correspond to a variety of AD who, in addition to symptoms of AD, present characteristics of primary progressive aphasia. In other respects, we underscore that the high loading in language-mediated tasks of the MMSE makes it a poor index to accurately measure the rate of cognitive decline.

Loss of topographic memory with learning deficits.

A case is reported in which a patient with a vascular accident involving the posterior portion of the minor hemisphere presented a topographic memory loss and also deficits in his ability to learn certain types of new material. The study of this case has led us to re-examine spatial functioning in light of both human and animal research. Based on clinical and experimental evidence we have proposed that a unitary interpretation can account for the various spatial deficits associated with posterior righ hemisphere lesions. We have also suggested that the establishment of a spatial map for orientation probably depends not only on posterior right hemisphere structures but also may require the participation of structures which are more specifically concerned with learning and memory, such as the hippocampus or at least the connections between the hippocampus and these structures.