A new approach to diagnosing and researching developmental prosopagnosia: Excluded cases are impaired too.

Developmental prosopagnosia is characterized by severe, lifelong difficulties when recognizing facial identity. Unfortunately, the most common diagnostic assessment (Cambridge Face Memory Test) misses 50-65% of individuals who believe that they have this condition. This results in such excluded cases' absence from scientific knowledge, effect sizes of impairment potentially overestimated, treatment efficacy underrated, and may elicit in them a negative experience of research. To estimate their symptomology and group-level impairments in face processing, we recruited a large cohort who believes that they have prosopagnosia. Matching prior reports, 56% did not meet criteria on the Cambridge Face Memory Test. However, the severity of their prosopagnosia symptoms and holistic perception deficits were comparable to those who did meet criteria. Excluded cases also exhibited face perception and memory impairments that were roughly one standard deviation below neurotypical norms, indicating the presence of objective problems. As the prosopagnosia index correctly classified virtually every case, we propose it should be the primary method for providing a diagnosis, prior to subtype categorization. We present researchers with a plan on how they can analyze these excluded prosopagnosia cases in their future work without negatively impacting their traditional findings. We anticipate such inclusion will enhance scientific knowledge, more accurately estimate effect sizes of impairments and treatments, and identify commonalities and distinctions between these different forms of prosopagnosia. Owing to their atypicalities in visual perception, we recommend that the prosopagnosia index should be used to screen out potential prosopagnosia cases from broader vision research.

Progress in perceptual research: the case of prosopagnosia.

Prosopagnosia is an impairment in the ability to recognize faces and can be acquired after a brain lesion or occur as a developmental variant. Studies of prosopagnosia make important contributions to our understanding of face processing and object recognition in the human visual system. We review four areas of advances in the study of this condition in recent years. First are issues surrounding the diagnosis of prosopagnosia, including the development and evaluation of newer tests and proposals for diagnostic criteria, especially for the developmental variant. Second are studies of the structural basis of prosopagnosia, including the application of more advanced neuroimaging techniques in studies of the developmental variant. Third are issues concerning the face specificity of the defect in prosopagnosia, namely whether other object processing is affected to some degree and in particular the status of visual word processing in light of recent predictions from the "many-to-many hypothesis". Finally, there have been recent rehabilitative trials of perceptual learning applied to larger groups of prosopagnosic subjects that show that face impairments are not immutable in this condition.

Prosopagnosia: un caso de meningoencefalitis viral / Prosopagnosia: a case of viral meningoencephalitis

La prosopagnosia es un trastorno caracterizado por una incapacidad para reconocer caras conocidas. Su presencia aislada es infrecuente, sobre todo en el caso de meningoencefalitis virales sin otra alteración neuropsiquiátrica (AU)

Prosopagnosia is a disorder characterised by the inability to recognise known faces. Its presentation alone with no other neuropsychiatric disorder, especially in viral meningoencephalitis, is uncommon (AU)

Potenciales evocados de larga latencia y procesamiento mnésico de caras y palabras / Long-latency evoked potentials and mnemonic processing of faces and words

Introducción. Los potenciales evocados son marcadores electrofisiológicos en tiempo real de operaciones cognitivas y, en particular, de procesos mnésicos. La onda N400 se ha estudiado tradicionalmente para caracterizar los procesos de memoria de material verbal. Para investigar la existencia de procesos de memoria específicos de cada dominio de información,se investigan análogos funcionales de esta onda durante el procesamiento de estímulos no verbales, como las caras. Objetivo. Mediante un diseño intrasujeto, se compararon la onda N400 verbal clásica y su análogo funcional durante el procesamiento de caras en una tarea de preactivación contextual adaptada al dominio visual de las caras. Sujetos y métodos. Tras varias sesiones de aprendizaje de un conjunto de caras, se realizó una sesión de registro de potenciales evocados para analizarlos efectos de la presentación de incongruencias estructurales en estos estímulos y compararlos, en cuanto a su distribución topográfica y generadores neurales, con los observados en la tarea clásica de N400 verbal. Resultados. Se constató la existencia de una onda N400 verbal con una distribución centroparietal (ligeramente derecha), y se diferenció esta respuesta de otra onda negativa obtenida durante el procesamiento de incongruencias faciales en el mismo grupo de participantes, con una localización predominantemente occipital y generadores neurales diferenciados. Conclusiones. Estos resultados apoyan la hipótesis de la especificidad de los mecanismos neurales implicados en el procesamiento mnésico de caras y palabras, encongruencia con los modelos neurocognitivos que proponen la independencia o modularidad de los procesos de memoriaen diferentes dominios de información

Introduction. Evoked potentials are real-time electrophysiological markers of cognitive operations and especially mnemonic processes. The N400 wave has traditionally been studied to characterise the processes involved in memorising verbal material. To investigate the existence of specific memory processes for each information domain, functional analoguesof this wave were examined during the processing of non-verbal stimuli, such as faces. Aim. Using an inter-subject design, the classic verbal N400 wave was compared with its functional analogue during the processing of faces in a contextual preactivation task adapted to the visual domain of faces. Subjects and methods. After several sessions dedicated to learning aset of faces, another evoked potential recording session was held in order to analyse the effects of the existence of structural inconsistencies in these stimuli and to compare them, with regard to their topographic distribution and neural generators, withthose observed in the classic verbal N400 task. Results. A verbal N400 wave was observed with a (slightly right) centroparietal distribution, and this response was distinguished from another negative wave obtained during the processing of facial inconsistencies in the same group of participants, with a predominantly occipital localisation and differentiated neural generators. Conclusions. These findings support the hypothesis of the specificity of the neural mechanisms involved in themnemonic processing of faces and words, which is in line with the neurocognitive models that suggest the independence or modularity of memory processes in different domains of information

Functional plasticity in ventral temporal cortex following cognitive rehabilitation of a congenital prosopagnosic.

We used functional magnetic resonance imaging (fMRI) and electroencephalography (EEG) to measure neural changes associated with training configural processing in congenital prosopagnosia, a condition in which face identification abilities are not properly developed in the absence of brain injury or visual problems. We designed a task that required discriminating faces by their spatial configuration and, after extensive training, prosopagnosic MZ significantly improved at face identification. Event-related potential results revealed that although the N170 was not selective for faces before training, its selectivity after training was normal. fMRI demonstrated increased functional connectivity between ventral occipital temporal face-selective regions (right occipital face area and right fusiform face area) that accompanied improvement in face recognition. Several other regions showed fMRI activity changes with training; the majority of these regions increased connectivity with face-selective regions. Together, the neural mechanisms associated with face recognition improvements involved strengthening early face-selective mechanisms and increased coordination between face-selective and nonselective regions, particularly in the right hemisphere.

Overview of impaired facial affect recognition in persons with traumatic brain injury.

PRIMARY OBJECTIVE: To review the literature of affect recognition for persons with traumatic brain injury (TBI). It is suggested that impairment of affect recognition could be a significant problem for the TBI population and treatment strategies are recommended based on research for persons with autism. MAIN OUTCOMES AND RESULTS: Research demonstrates that persons with TBI often have difficulty determining emotion from facial expressions. Studies show that poor interpersonal skills, which are associated with impaired affect recognition, are linked to a variety of negative outcomes. Theories suggest that facial affect recognition is achieved by interpreting important facial features and processing one's own emotions. These skills are often affected by TBI, depending on the areas damaged. Affect recognition impairments have also been identified in persons with autism. Successful interventions have already been developed for the autism population. Comparable neuroanatomical and behavioural findings between TBI and autism suggest that treatment approaches for autism may also benefit those with TBI. CONCLUSIONS: Impaired facial affect recognition appears to be a significant problem for persons with TBI. Theories of affect recognition, strategies used in autism and teaching techniques commonly used in TBI need to be considered when developing treatments to improve affect recognition in persons with brain injury.