Agnosia

Epilepsy in children leads to disorders in their psychomotor development or the loss of their acquired skills. Successful pharmacological treatment of epilepsy provides grounds for effective therapeutic measures. The goal of this article is to present the dynamics of neurodevelopmen-tal disorders in the course of the severe symptomatic epilepsy with status epileptici which affected a 10-year-old girl. As a result of longitudinal studies, four stages were distinguished which determined the dynamics of development of the disease: 1) up to the age of 10, when the child's psycho-motor development proceeded correctly, 2) between the ages of 10 and 15, when, because of epilepsy , the disorders in the cognitive, linguistic, emotional, behavioural, motor, and vegetative spheres occurred, which assumed the form of profound dementia, 3) between the ages of 16 and 17, when the balance of the bioelectric activity of the brain was achieved owing to the optimisation of pharmacological treatment, 4) between the ages of 17 and 25, when, after the multi-specialist therapy, there was a significant improvement in the functioning of all the disordered spheres, which enabled the patient to finish junior and senior high school, apply to a university, obtain very good results in learning, and to achieve spectacular successes in sport.

Colour agnosia concerns the inability to recognise colours despite intact colour perception, semantic memory for colour information, and colour naming. Patients with selective colour agnosia have been described and the deficit is associated with left hemisphere damage. Here we report a case study of a 43-year-old man who was referred to us with a stroke in his right cerebellar hemisphere. During the standard assessment it transpired that he was unable to name coloured patches. Detailed assessment of his colour processing showed that he suffers from a selective colour agnosia. As he claimed to have had this problem all his life, and the fact that the infratentorial infarct that he had incurred was in an area far away from the brain structures that are known to be involved in colour processing, we suggest that he is the first reported case of developmental colour agnosia.

Aunque no puedo asegurar qué fue lo que despertó mi interés
por los soportes neurales de la razón, recuerdo cuando me con�vencí de que tradicionalmente su naturaleza se enfocaba mal.
Desde niño había oído que las decisiones sensatas son el fruto de
una mente serena, que emociones y razón no se mezclan mejor
que el agua y el aceite. Crecí acostumbrado a pensar que los
mecanismos racionales existían en una provincia mental separa�da, a la que no debían tener acceso las emociones, y cuando
pensaba en el cerebro como parte de la mente, imaginaba siste�mas neurales. distintos para emoción y razón. Esa manera de
concebir las relaciones entre razón y emociones, ,en términos
mentales y neurales, estaba ampliamente difundida.
Pero ahora tenía ante mis ojos a un ser humano inteligente, el
más calmado y menos emotivo que uno pueda imaginar, y sin
embargo su razón práctica estaba tan disminuida que cometía
-en las distintas circunstancias de la vida diaria- errores sucesivos,
violaciones perpetuas de lo que se considera apropiado en la
sociedad y ventajoso en el plano personal. Tuvo una mente por
completo sana hasta que una dolencia neurológica estragó un
sector específico de su cerebro y, de un día para otro, le provocó
ese defecto profundo en su capacidad para tomar decisiones.

Agnosia (del griego ἀγνωσία: «desconocimiento») es la interrupción en la capacidad para reconocer estímulos previamente aprendidos, o de aprender nuevos estímulos, sin haber deficiencia en la percepción, lenguaje o intelecto. En la agnosia la dificultad para reconocer los estímulos no puede ser atribuido a defectos sensoriales, como pérdida de visión por alteración ocular, o a falta de familiaridad con el estímulo presentado. 
La agnosia es una afectación específica de la capacidad para reconocer estímulos previamente aprendidos o de reconocer estímulos que pueden habitualmente ser aprendidos, después de una exposición adecuada, sin que exista una alteración de la sensación, lenguaje o intelecto.
La agnosia aparece en presencia de lesiones que afectan las zonas asociativas temporoparioccipitales de ambos hemisferios; cuando se asocia con trastornos de actividad gestual toma el nombre de apratognosia, mientras que cuando afecta la percepción del propio cuerpo toma el nombre de somatoagnosia 
Los requisitos que se exigen para el diagnóstico de una agnosia son los siguientes:
a) Se produce pérdida de capacidad para el reconocimiento de objetos previamente conocidos por el sujeto.
b) Los receptores periféricos sensoriales tienen que estar indemnes, o si existe un déficit parcial, éste por sí sólo no justifica la dificultad para atribuir significado a los estímulos.
c) Las áreas primarias del córtex tienen que estar preservadas, sin que exista trastorno sensitivo o motor que justifique la incapacidad para comprender el significado.
d) No debe existir hipoestesia o anestesia que impida el reconocimiento de los estímulos.
e) No deben existir trastornos atencionales o psiquiátricos que limiten la capacidad para aprehender el significado del estímulo.
Para evaluar las agnosias, se usan métodos diversos de acuerdo al tipo de agnosia que la persona padezca. En términos generales, resulta más fácil la identificación de objetos reales de fotografías de objetos o figuras representadas pictóricamente, así como la identificación de objetos completos que objetos fragmentados. De igual modo, normalmente se perciben con mayor facilidad los objetos en movimiento que los que se encuentran en situación estática. Se pueden evaluar las agnosias visuales pidiendo al sujeto que realice:
 Identificación de objetos reales.  Identificación de dibujos y fotografías de objetos y formas.  Test de Popelreuter y Lilia Ghent.  Identificación de figuras enmascaradas.  Tests de figuras fragmentadas de Gollin.  Test de Ishihara.   Denominación de colores.  Asociación de formas y colores.  Reconocimiento de caras.  Identificación de objetos en movimiento.

Para la evaluación clínica de las agnosias auditivas se pueden utilizar las siguientes pruebas: 
 Identificación de melodías previamente conocidas por el sujeto.  Evaluación de las aptitudes musicales básicas, mediante el test de Aptitudes Musicales de Seshore, Lewis y Saetveit. Esta prueba incluye pruebas de evaluación de tono, intensidad, ritmo, tiempos, timbre y memoria tonal.  Audición de sonidos no verbales del entorno, para reconocimiento: cantos de pájaros, ruido de sirenas o el sonido de una locomotora.  Subtests de la prueba de Boston para la evaluación de la afasia o del Diagnóstico Neuropsicológico de Luria-DNA.  Identificación de sonidos verbales.  Escucha dicótica.





La evaluación del sistema somatosensorial debe realizarse unimanual y bimanualmente, mediante la utilización de:
Tests dicápticos.
 Evaluación de la orientación personal, pidiéndole al sujeto que identifique partes de su cuerpo, así como el lado derecho e izquierdo siguiendo órdenes verbales, imitando al examinador o identificando partes lateralizadas en éste.   Evaluación de la orientación extrapersonal, pidiéndole que identifique mapas, planos y recorridos y rutas que sean previamente conocidos.  Test de Piaget-Head para evaluar el esquema corporal.  Test de orientación espacial de Benton.

The mystical union with God is accomplished at the moment when the Intellect separates from itself, by entering into the Divine Darkness. This ecstasy of the Intellect and this accession to God are the ones who allow it to know God not by itself but by the union itself, to know God in God and through God. This is “the most divine knowledge” qua unknowing (cf. De divinis nominibus VII.3). There is a difference between ignorance (agnoia) and unknowing (agnōsia) which corresponds to the distinction between skotos (obscurity qua deprivation of light) and gnophos (darkness qua superabundance of light).

Keywords: Dionysius the Areopagite, experience of God, apophatic theology, agnōsia, henōsis.

https://www.researchgate.net/publication/315750725_AGNOSIA_The_Apophatic_Experience_of_God_in_Dionysius_the_Areopagite

Balint syndrome is a combination of symptoms including simultanagnosia, a disorder of spatial and object-based attention, disturbed spatial perception and representation, and optic ataxia resulting from bilateral parieto-occipital lesions. Fixation and ocular exploration of space are severely impaired, as are reading, writing, drawing and orientation as well as movement in space. Low-level visual impairments may be associated and difficult to evaluate but are not a necessary element of Balint syndrome. This review summarizes the relevant facts of the etiology, localization of lesions, and the core features as well as frequently associated disorders of the syndrome. Instructions for the examination of patients are given and approaches for the management and treatment outlined. Models of attention and space representation are described for the explanation of this multifaceted and exciting syndrome. Finally the key features of the syndrome are summarized in a table at the end of the pa...

If asked directly, anosognosic patients deny or seriously underestimate their motor difficulties. However explicit denial of hemiplegia does not necessarily imply a lack of insight of the deficit. In this study we explored explicit and implicit awareness for upper limb motor impairment in a group of 30 right-brain damaged patients. Explicit awareness was assessed using a questionnaire (the VATAm) in which patients are asked to rate their motor abilities, whereas implicit awareness was assessed by means of a newly developed test (BMT – bimanual task). This test requires the performance of a series of bimanual tasks that can be better performed using two hands, but could also be performed using one hand only. With the BMT, patients’ performance rather than their verbal reports is evaluated and scored as an index of awareness. Paretic patients with anosognosia tend to approach these tasks as if they could use both hands. Our findings showed that explicit and implicit awareness for motor deficits can be dissociated, and they may be differently affected by feedback suggesting that different underlying mechanisms may account for the multi-factorial phenomenon of anosognosia.

Neuropsychologia (2004), 42(5), 597-612.

Associative visual agnosia is classically defined as normal visual perception stripped of its meaning (Lissauer, 1890): these patients cannot access to their stored visual memories to categorize the objects nonetheless perceived correctly. However, according to an influential theory of visual agnosia (Farah, 1990), visual associative agnosics necessarily present perceptual deficits that are the cause of their impairment at object recognition Here we report a detailed investigation of a patient with bilateral occipito-temporal lesions strongly impaired at object and face recognition. NS presents normal drawing copy, and normal performance at object and face matching tasks as used in classical neuropsychological tests. However, when tested with several computer tasks using carefully controlled visual stimuli and taking both his accuracy rate and response times into account, NS was found to have abnormal performances at high level visual processing of objects and faces. Albeit presenting a different pattern of deficits than previously described in integrative agnosic patients such as HJA and LH, his deficits were characterized by an inability to integrate individual parts into a whole percept, as suggested by his failure at processing structurally impossible 3D objects, an absence of face inversion effect and an advantage at detecting and matching single parts. Taken together, these observations question the idea of separate visual representations for object/face perception and object/face knowledge derived from investigations of visual associative (prosop)agnosia, and they raise some methodological issues in the analysis of single case studies of (prosop)agnosic patients .

Paintings produced spontaneously by patients with neurological lesions represent a fascinating opportunity to analyze some aspects of the underlying disease and involved brain mechanisms. Many cases of artists who have suffered spatial neglect following a neurological disease have been reported in the literature. However, only a few studies evaluating the different subtypes of graphic neglect and aspects related to the construction of perspective (three dimensionality) in works of art have been published. In the present article, we present the case of an artist who, after resection of a central neurocytoma that affected the right thalamo-parietal connections, suffered an impairment of the ability to create perspective in his paintings and involuntary omission of only shapes in the left side of his paintings, although colors and contours were preserved.

Early studies suggested visual form perception impairment in schizophrenia. To re-examine this claim and characterise the deficit neuropsychologically, 41 schizophrenic patients were administered tests sensitive to different levels of visual object perception and recognition. Intellectually well-preserved patients were examined separately on these and additional tests. Single case analysis was also applied to four patients showing varying degrees of general intellectual impairment. As a group, the patients showed little impairment on tests of early visual object perception, but greater impairment on higher-level visual processing tests, in particular object recognition and naming. This held true for patients with preserved general intellectual function. Single case analysis suggested that patients with schizophrenia have a selective deficit affecting object recognition and identification, with a pattern similar to visual associative agnosia in neurological patients