Amusia congénita y sus efectos en habilidades no musicales / Congenital amusia and its effects on non-musical skills

INTRODUCCIÓN: La amusia congénita es una condición específica en la que el individuo afectado es incapaz de reconocer variaciones tonales en las piezas musicales. Esto no puede explicarse por una lesión encefálica previa, una pérdida auditiva, un déficit cognitivo, un trastorno socioafectivo o una falta de estimulación ambiental. Actualmente se estima una prevalencia del 1,5% de la población mundial, con un importante componente genético entre los afectados. Se ha descrito que en las personas con amusia puede haber afectación de ciertas habilidades cognitivas en el campo emocional, espacial y del lenguaje. OBJETIVO: Revisar la bibliografía donde se describen los efectos en las habilidades no musicales que pueden coexistir en individuos con amusia congénita. DESARROLLO: Varios estudios de neuroimagen han permitido observar cambios morfológicos y funcionales en el lóbulo temporal, así como en las conexiones de la sustancia blanca entre el giro temporal superior y el giro frontal inferior. Partiendo de estas regiones afectadas, podría existir un déficit en habilidades cognitivas relacionadas con áreas adyacentes. CONCLUSIONES: La amusia congénita se ha relacionado con un pobre desempeño en diferentes habilidades cognitivas no musicales, como el procesamiento visuoespacial, el procesamiento del lenguaje, alteraciones de la lectura, el reconocimiento de rostros y aspectos emocionales

INTRODUCTION: Congenital amusia is a specific condition in which the individual is unable to recognise tonal variations in a piece of musical. This cannot be explained by a previous brain injury, hearing loss, cognitive deficit, socio-affective disorder or lack of environmental stimulation. The current estimated prevalence is 1.5% of the world population, with a significant genetic component among those who suffer from it. It has been claimed that certain cognitive abilities in the emotional, spatial and language fields may be affected in people with amusia. AIM: To review the literature describing the effects on non-musical skills that may coexist in individuals with congenital amusia. DEVELOPMENT: Several neuroimaging studies have observed morphological and functional changes in the temporal lobe, as well as in the white matter connections between the superior temporal gyrus and the inferior frontal gyrus. From these affected regions, there may be a deficit in cognitive skills related to adjacent areas. CONCLUSIONS: Congenital amusia has been associated with poor performance in different non-musical cognitive skills, such as visuospatial processing, language processing, reading difficulties, face recognition and emotional aspects

Visual agnosia and focal brain injury.

Visual agnosia encompasses all disorders of visual recognition within a selective visual modality not due to an impairment of elementary visual processing or other cognitive deficit. Based on a sequential dichotomy between the perceptual and memory systems, two different categories of visual object agnosia are usually considered: 'apperceptive agnosia' and 'associative agnosia'. Impaired visual recognition within a single category of stimuli is also reported in: (i) visual object agnosia of the ventral pathway, such as prosopagnosia (for faces), pure alexia (for words), or topographagnosia (for landmarks); (ii) visual spatial agnosia of the dorsal pathway, such as cerebral akinetopsia (for movement), or orientation agnosia (for the placement of objects in space). Focal brain injuries provide a unique opportunity to better understand regional brain function, particularly with the use of effective statistical approaches such as voxel-based lesion-symptom mapping (VLSM). The aim of the present work was twofold: (i) to review the various agnosia categories according to the traditional visual dual-pathway model; and (ii) to better assess the anatomical network underlying visual recognition through lesion-mapping studies correlating neuroanatomical and clinical outcomes.

Auditory agnosia.

Auditory agnosia refers to impairments in sound perception and identification despite intact hearing, cognitive functioning, and language abilities (reading, writing, and speaking). Auditory agnosia can be general, affecting all types of sound perception, or can be (relatively) specific to a particular domain. Verbal auditory agnosia (also known as (pure) word deafness) refers to deficits specific to speech processing, environmental sound agnosia refers to difficulties confined to non-speech environmental sounds, and amusia refers to deficits confined to music. These deficits can be apperceptive, affecting basic perceptual processes, or associative, affecting the relation of a perceived auditory object to its meaning. This chapter discusses what is known about the behavioral symptoms and lesion correlates of these different types of auditory agnosia (focusing especially on verbal auditory agnosia), evidence for the role of a rapid temporal processing deficit in some aspects of auditory agnosia, and the few attempts to treat the perceptual deficits associated with auditory agnosia. A clear picture of auditory agnosia has been slow to emerge, hampered by the considerable heterogeneity in behavioral deficits, associated brain damage, and variable assessments across cases. Despite this lack of clarity, these striking deficits in complex sound processing continue to inform our understanding of auditory perception and cognition.

Visual form-processing deficits: a global clinical classification.

INTRODUCTION: Patients who have difficulties recognising visual form stimuli are usually labelled as having visual agnosia. However, recent studies let us identify different clinical manifestations corresponding to discrete diagnostic entities which reflect a variety of deficits along the continuum of cortical visual processing. DEVELOPMENT: We reviewed different clinical cases published in medical literature as well as proposals for classifying deficits in order to provide a global perspective of the subject. Here, we present the main findings on the neuroanatomical basis of visual form processing and discuss the criteria for evaluating processing which may be abnormal. We also include an inclusive diagram of visual form processing deficits which represents the different clinical cases described in the literature. Lastly, we propose a boosted decision tree to serve as a guide in the process of diagnosing such cases. CONCLUSIONS: Although the medical community largely agrees on which cortical areas and neuronal circuits are involved in visual processing, future studies making use of new functional neuroimaging techniques will provide more in-depth information. A well-structured and exhaustive assessment of the different stages of visual processing, designed with a global view of the deficit in mind, will give a better idea of the prognosis and serve as a basis for planning personalised psychostimulation and rehabilitation strategies.

Agnosias: recognition disorders in patients with brain tumors.

Two main varieties of recognition disorders are distinguished in neuropsychology: agnosias and semantic disorders. The term agnosias is generally used to denote recognition defects limited to a single perceptual modality (which is itself apparently intact), whereas the term semantic disorders is used to denote recognition defects involving all the sensory modalities in a roughly similar manner. Brain tumors can be one of the aetiologies underlying agnosias and semantic disorders. However, due to the heterogeneity and the rarity of recognition disorders, their investigation can be useful only to suggest or exclude the oncological nature of a brain lesion, but not to systematically monitor the clinical outcome in tumor patients. Furthermore, the relevance of recognition disorders as a hint toward a diagnosis of brain tumor varies according to the type of agnosia and of semantic disorder and the localization of the underlying brain pathology. The hypothesis that a variety of agnosia (or of semantic disorder) may be due to a neoplastic lesion can, therefore, be advanced if it is consistent with our knowledge about the usual localization and the growing patterns of different types of brain tumors.

[Progressive visual agnosia].

Progressive visual agnosia was discovered in the 20th century following the discovery of classical non-progressive visual agnosia. In contrast to the classical type, which is caused by cerebral vascular disease or traumatic injury, progressive visual agnosia is a symptom of neurological degeneration. The condition of progressive visual loss, including visual agnosia, and posterior cerebral atrophy was named posterior cortical atrophy (PCA) by Benson et al. (1988). Progressive visual agnosia is also observed in semantic dementia (SD) and other degenerative diseases, but there is a difference in the subtype of visual agnosia associated with these diseases. Lissauer (1890) classified visual agnosia into apperceptive and associative types, and it in most cases, PCA is associated with the apperceptive type. However, SD patients exhibit symptoms of associative visual agnosia before changing to those of semantic memory disorder. Insights into progressive visual agnosia have helped us understand the visual system and discover how we "perceive" the outer world neuronally, with regard to consciousness. Although PCA is a type of atypical dementia, its diagnosis is important to enable patients to live better lives with appropriate functional support.

What the study of voice recognition in normal subjects and brain-damaged patients tells us about models of familiar people recognition.

In recent years it has been shown that a disorder in recognizing familiar people can be observed in patients with lesions affecting the anterior parts of the temporal lobes and that these disorders can be multi-modal, simultaneously affecting the visual, auditory and linguistic channels that allow person identification. Several authors have also shown that patients with right anterior temporal atrophy are more impaired in assessing familiarity and in retrieving person-specific semantic information from faces than from names, whereas the opposite pattern of performance can be observed in patients with left temporal lobe atrophy. Voice recognition disorders have been studied much less even despite their clinical and theoretical importance. The aim of the present review, therefore, was to compare recognition of familiar faces and voices, taking into account not only results obtained in individual patients with right anterior temporal lesions, but also those of group studies of unselected right- and left brain-damaged patients and results of experimental investigations conducted on face and voice recognition in normal subjects. Results of the review showed that: (1) voice recognition disorders are mainly due to right temporal lesions, similarly to face recognition disorders; (2) famous voice recognition disorders can be dissociated from unfamiliar voice discrimination impairments; (3) although face and voice recognition disorders tend to co-occur, they can also dissociate and in these patients there is a prevalent involvement of the right fusiform gyrus when face recognition disorders are on the foreground, and of the right superior temporal gyrus when voice recognition disorders are prominent; (4) normal subjects have greater difficulty evaluating familiarity and drawing semantic information from the voices than from the faces of celebrities. These data are at variance with models which assume that familiarity feelings may be generated at the level of person identity nodes (PINs) and that the latter may be considered as modality-free gateways to single semantic systems in which information about people is stored in an amodal format.

Primary and secondary anosognosia for memory impairment in patients with Alzheimer's disease.

The neuropsychology of anosognosia for memory impairment in Alzheimer's disease (AD) was examined in 92 AD patients and 92 case matched individuals for comparison, using three quantitative methods of assessment: Experimenter Rating Scale (ERS), Objective Judgement Discrepancy (OJD) and Subjective-Rating Discrepancy (SRD). The OJD showed significant domain specific correlations with memory functioning as well as a significant correlation with susceptibility to intrusional errors. Memory or executive dysfunction may affect the immediate ability to judge cognitive performance in a domain specific manner (secondary anosognosia). Longer-term awareness of cognitive deficit appears less influenced by impaired basic cognitive functions, than by the decline of metacognitive function (primary anosognosia).

Detection of feigned tactile sensory loss using a forced-choice test of tactile discrimination and other measures of tactile sensation.

OBJECTIVE: Intentional exaggeration of disability is a risk in work injuries but is hard to reliably detect clinically. This study examined the accuracy of tactile sensory threshold and forced-choice discrimination measures in detecting feigned sensory loss. METHODS: Participants (n = 80) were randomly assigned to one of four sensory loss groups: (1) none; (2) partial; (3) full; or (4) feigned. Sensory data were collected for the upper extremities. RESULTS: Tactile thresholds greater than 0.5 g, discriminability less than 0.50, or forced-choice scores less than 90% were associated with a very low probability of false-positive errors. CONCLUSIONS: Below-chance scores are definitive evidence that the sensory loss is intentionally feigned. Scores beyond cut-offs should raise the clinician's suspicion of malingering if there is no physical basis for sensory loss.

Patient Schn: has Goldstein and Gelb's case withstood the test of time?

The current manuscript takes a critical look at the case of Goldstein and Gelb's patient, Schn, reported to be the first well-defined example of apperceptive visual agnosia. While doubts have been cast on the validity of the original investigations, we propose that perhaps the case of Schn should be reclassified as an example of integrative agnosia. Be that as it may, what is not in doubt is that the case of Schn has had a lasting impact on the development of neuropsychological theorem.