The contribution of virtual reality to the diagnosis of spatial navigation disorders and to the study of the role of navigational aids: A systematic literature review.

INTRODUCTION: Spatial navigation, which involves higher cognitive functions, is frequently implemented in daily activities, and is critical to the participation of human beings in mainstream environments. Virtual reality is an expanding tool, which enables on one hand the assessment of the cognitive functions involved in spatial navigation, and on the other the rehabilitation of patients with spatial navigation difficulties. Topographical disorientation is a frequent deficit among patients suffering from neurological diseases. The use of virtual environments enables the information incorporated into the virtual environment to be manipulated empirically. But the impact of manipulations seems differ according to their nature (quantity, occurrence, and characteristics of the stimuli) and the target population. METHODS: We performed a systematic review of research on virtual spatial navigation covering the period from 2005 to 2015. We focused first on the contribution of virtual spatial navigation for patients with brain injury or schizophrenia, or in the context of ageing and dementia, and then on the impact of visual or auditory stimuli on virtual spatial navigation. RESULTS: On the basis of 6521 abstracts identified in 2 databases (Pubmed and Scopus) with the keywords « navigation ¼ and « virtual ¼, 1103 abstracts were selected by adding the keywords "ageing", "dementia", "brain injury", "stroke", "schizophrenia", "aid", "help", "stimulus" and "cue"; Among these, 63 articles were included in the present qualitative analysis. CONCLUSION: Unlike pencil-and-paper tests, virtual reality is useful to assess large-scale navigation strategies in patients with brain injury or schizophrenia, or in the context of ageing and dementia. Better knowledge about both the impact of the different aids and the cognitive processes involved is essential for the use of aids in neurorehabilitation.

Advances in user-training for mental-imagery-based BCI control: Psychological and cognitive factors and their neural correlates.

While being very promising for a wide range of applications, mental-imagery-based brain-computer interfaces (MI-BCIs) remain barely used outside laboratories, notably due to the difficulties users encounter when attempting to control them. Indeed, 10-30% of users are unable to control MI-BCIs (so-called BCI illiteracy) while only a small proportion reach acceptable control abilities. This huge interuser variability has led the community to investigate potential predictors of performance related to users' personality and cognitive profile. Based on a literature review, we propose a classification of these MI-BCI performance predictors into three categories representing high-level cognitive concepts: (1) users' relationship with the technology (including the notions of computer anxiety and sense of agency), (2) attention, and (3) spatial abilities. We detail these concepts and their neural correlates in order to better understand their relationship with MI-BCI user-training. Consequently, we propose, by way of future prospects, some guidelines to improve MI-BCI user-training.

Everyday-like memory and its cognitive correlates in healthy older adults and in young patients with traumatic brain injury: a pilot study based on virtual reality.

UNLABELLED: PURPOSE STATE: A pilot-study with a comparison approach between aging and traumatic brain injury (TBI) is proposed to investigate everyday object memory patterns using a virtual HOMES test. METHODS: Sixteen young controls, 15 older adults and 15 TBI patients underwent the HOMES test and traditional tests. RESULTS: Older adults and TBI patients exhibited similar HOMES performances: poor recall, a greater recognition benefit, high false recognitions, but intact clustering and proactive interference effects. The age-related differences for HOMES measures were mainly mediated by executive functioning, while the HOMES performances in the TBI group were correlated with memory measures. CONCLUSION: The differential cognitive mediating effects for a similar everyday-like memory pattern are discussed by highlighting the need for more cautious interpretations of cognitive mechanisms behind similar behavioral patterns in different populations especially in clinical and rehabilitation settings.

[AGGIR scale: a contribution to specifying the needs of disabled elders]. / Grille AGGIR et aide à la spécification des besoins des personnes âgées en perte d'autonomie.

Several instruments are used for the assessment of the disability, and the scale AGGIR (Autonomie Gérontologie Groupes Iso-Ressources) is the one most commonly used in France. This scale covers so-called instrumental dimensions, that correspond to relatively complex activities with the dominating cognitive component (cooking, medication use, finances, etc.) as well as dimensions with the dominating physical component (so-called fundamental dimensions that are related to such activities as walking, dressing, toileting, etc.). However, at present, only the fundamental activities are taken into account while assessing the dependency of the elderly within the scale AGGIR. The aim of our study was to identify the relative importance of these two dimensions (fundamental and instrumental) in the definition and identification of difficulties that older people encounter in their everyday life. A principal components analysis was carried out using 525 AGGIR scales of non-institutionalized elders living at their homes. The results indicate that the inclusion of instrumental activities may improve the assessment of dependency of the elderly and thus facilitate the implementation of appropriate responses to the needs of disabled people.

[Virtual reality for clinical assessment of elderly people: early screening for dementia]. / La réalité virtuelle au service de l'évaluation clinique de la personne âgée: le dépistage précoce de la démence.

Today, there are 24.3 million people suffering from dementia worldwide, that is a new case every 7 seconds (Ferri et al., 2005) and more than 80 million cases expected in 2040. Aging-related morbidity is a real social problem making screening a major challenge. Currently, screening and diagnostic tools for dementia remain independent from each other, screening tools being non-specific and diagnostic tools non-naturalistic. With the technological possibilities offered by virtual reality, it is becoming easier to investigate cognition and behavior in elderly people. Virtual reality allows a better understanding and assessment, and perhaps could stimulate cognitive functioning of elderly people. Combining measurements of cognitive impairment and disability might help close the gap between structural and naturalistic validity.

Verbal fluency output in children aged 7-16 as a function of the production criterion: qualitative analysis of clustering, switching processes, and semantic network exploitation.

Developmental changes in children's verbal fluency were explored in this study. One hundred and forty children aged from 7 to 16 completed four verbal fluency tasks, each with a different the production criterion (letter, sound, semantic, and free). The age differences were analyzed both in terms of number of words produced, and clustering, switching, and semantic network exploration. Analysis of the number of words produced showed a larger difference between the 7-8- and the 9-10-year-olds in semantic than in letter fluency, but this difference gradually disappeared with increasing age for semantic fluency while remaining constant for letter fluency. In letter fluency production, age modified both the number of switches and clusters formed whereas in semantic fluency tasks, only cluster size changed with age. Concerning the semantic network exploration indicators derived from the supermarket fluency task, the number of categories sampled increased from 11 to 12 years, but efficient semantic exploitation occurred only after the age of 13-14 years. These results are discussed in terms of the development of strategic retrieval components and categorical knowledge.

Exploration of hemispheric specialization and lexico-semantic processing in unilateral temporal lobe epilepsy with verbal fluency tasks.

Verbal production has been shown to rely on both hemispheres differentially. To determine how lateralized brain lesions affect the generation of isolated words, we evaluated three subject groups: normal controls (n=22), and patients with right (n=23), and left (n=22) non-operated temporal lobe epilepsy (TLE) using three verbal fluency tasks (letter, phonetic, semantic). LTLE patients produced fewer words than controls in the phonetic, letter, semantic conditions, whereas RTLE patients were only impaired in the semantic task. Hence, there would be a hemispheric specialization in language where phonetic processing involves mostly the left temporal lobe and semantic aspects of production involve both temporal lobes. And, in order to study disruption of semantic lexicon involved in supermarket fluency (to name things which can be bought in a supermarket), specific indicators Tröster et al., (1998) [Tröster AI, Fields JA, Testa JA, Paul RH, Blanco CR, Hames KA, Salmon DP, Beatty WW. Cortical and subcortical influences on clustering and switching in the performance of verbal fluency Tasks, Neuropsychologia 1998;36:295-304.] were exploited. Our results indicated that TLE groups made fewer category shifts than controls. Also, RTLE patients used labels more frequently and produced fewer exemplars. Results show the specificity of processing according to cue, and suggest that the semantic fluency deficits due to TLE be primarily due to an alteration of the mental lexicon.

Age effect in recall performance according to the levels of processing, elaboration, and retrieval cues.

The present study was conducted to investigate the incidence of several factors contributing to age-related memory decrement. Variables manipulated include quality (level of processing encoding conditions), the degree of effort and encoding quantitative elaboration (active/passive encoding conditions), and the influence of retrieval support (free-/cued recall conditions). In support of the environmental support hypothesis, middle-old and old subjects benefited more than young ones from cued recall in all the memory tests. Moreover, the results showed a differential (qualitative vs. quantitative) impairment of conceptual processing between the middle-old and the old-age groups. In the middle-olds, age differences were abolished by deep processing in old adults, age differences were attentuated only with deep and active processing associated with retrieval support. These gradual memory impairments are evaluated according to Mandler's model of memory (1979, In L. G. Nilsson [Ed.], Perspective in memory research. Hillsdale: Lawrence-Erlbaum), and the environmental support hypothesis is discussed in terms of the involvement of encoding and retrieval operations required by the memory task.

Location of the epileptic zone and its physiopathological effects on memory-related activity of the temporal lobe structures: a study with intracranial event-related potentials.

PURPOSE: Neuropsychological research with epileptic patients has suggested that the location of seizure focus may be an important variable determining the nature and severity of memory impairments. According to this assumption, this study was designed to investigate the effects of the location of the epileptic zone on the memory-related activity recorded directly from different temporal lobe structures. METHODS: Intracranial event-related potentials (ERPs) were recorded during a continuous recognition memory task, which is known to elicit the modulation of N400 and P600 components (i.e., the ERP old/new effect). The patients were separated into three groups according to the location of their epileptic zone: unilateral temporal (UTE), temporal plus extratemporal (TEE), and bitemporal (BTE). Recordings were obtained from three temporal lobe structures: hippocampus, amygdala, and lateral temporal cortex. RESULTS: The results showed that in the hippocampus, the ERP old/new effect was abolished in the TEE group only. In the amygdala, although largely unaffected, the ERP modulation appeared to be more impaired in UTE patients. Contrasting with these data is the observation that the magnitude and reliability of the ERP old/new effect recorded at the neocortical level increases as the epileptic zone extends to the temporal lobes (i.e., BTE>TEE>UTE). CONCLUSIONS: It is concluded that the memory-related activity modulation of memory ERPs recorded from different temporal lobe structures is affected differently by the presence of an epileptic zone as a function of its location. The possible clinical implications of these findings in surgery planning are also discussed.

Differential involvement of the human temporal lobe structures in short- and long-term memory processes assessed by intracranial ERPs.

Intracranial event-related potentials (ERPs) elicited during a recognition memory task were recorded in 25 epileptic patients by using depth electrodes sampling four different regions within the temporal lobe (amygdala, hippocampus, anterior and posterior temporal cortices). The task was a continuous recognition memory task in which repeated items were presented after 6 or 19 intervening items following their first presentation. This study was performed to investigate the respective role of the different temporal lobe structures in short-term memory (STM) and long-term memory (LTM) processing. Subregions of the temporal lobe were differently involved in these two memory systems. The posterior temporal cortex is specifically involved in STM processing, whereas the amygdala, hippocampus, and anterior temporal cortex contribute to both STM and LTM. Moreover, it appeared that the latter structures play their own role in LTM. The anterior temporal cortex and amygdala may contribute to recency discrimination, and the hippocampus seems rather to be involved in maintaining memory traces. These findings suggest that the temporal lobe structures may function in a complementary way by subserving different aspects of information processing.

Functional heterogeneity of the frontal lobe: evidence from intracranial memory ERPs.

Intracranial event-related potentials (ERPs) elicited during a recognition memory task were recorded in 17 epileptic patients by using depth electrodes sampling different regions within the frontal lobe. The task was a continuous recognition memory task in which repeated items were presented after six or 19 intervening items following their first presentation. Such a paradigm is one of the experimental tasks requiring both short-term memory and interference control processes which are thought to be subserved by the frontal lobe. The results provide electrophysiological support for the classical view that the frontal lobe is heterogeneous region encompassing a number of functional systems subserving different aspects of memory processing. The anterior dorsolateral and cingulate cortices were found to contribute to short-term memory and recency judgment. The orbital region is more likely to be involved in interference control. The posterior part of the frontal cortex plays a role in some processes related to the control of the motor response.

Effects of temporal versus temporal plus extra-temporal lobe epilepsies on hippocampal ERPs: physiopathological implications for recognition memory studies in humans.

The present experiment was designed to investigate the incidence of temporal and extra-temporal epileptogenic lesions on hippocampal activity related to recognition memory. Hippocampal event-related potentials (ERPs) were recorded during a recognition memory task for pictures in patients with unilateral temporal lobe epilepsy and in patients with combined temporal and extra-temporal (frontal or parietal) epileptogenic foci. In the first group, the comparison between correctly recognized pictures and new distractors revealed that the usual ERP (N400/P600) 'old/new' effects were not dramatically affected by the presence of a temporal epileptogenic lesion. In contrast, these effects were absent in multifocal epilepsy patients, indicating that frontal and parietal brain regions play a part in the modulation of hippocampal ERP and related memory processing. These results suggest that ERP 'old/new' effects are dependent on interactions between frontal, parietal and medial temporal structures. Together with the results of other recent studies devoted to locating the neural sources of N400 and P600, the present findings provide physiopathological evidence that ERP 'old/new' effects are subtended by distributed yet interconnected brain regions that are known to play an important role in recognition memory processing.

Intracranial topography of event-related potentials (N400/P600) elicited during a continuous recognition memory task.

To isolate the anatomical locus of the neural activity most important for generating or modulating the scalp-recorded N400 and P600 components elicited during continuous recognition memory tasks, intracranial event-related potentials (ERPs) were recorded from medial and lateral aspects of the temporal, frontal, parietal, and occipital lobes in 25 patients undergoing stereoelectroencephalography for seizure localization. Large-amplitude and polarity-inverted ERPs were recorded from various temporal, frontal, and parietal structures, whereas the memory-related ERP modulation assessed by the ERP repetition effect was present only in those brain areas that play the most important role in memory processing. These data suggest that the scalp-recorded N400 and P600 components may represent the most readily observable aspect of synchronous activity occurring across widely distributed brain structures and neural systems underlying different cognitive mechanisms, which all contribute to some aspect of information processing during recognition memory.

[P3on and P3off in a passive visual protocol]. / P3on et P3off dans un protocole visuel passif.

This study shows the possibility of obtaining visual event-related potentials without active discrimination instructions. The components are similar to the P3 components obtained in classic active protocol. The (P3off) of simple images indicates an interpretation in terms of information processing and change in mental state.

[Slow hippocampal potentials (200-600 ms) and short-term recognition of images in humans: study of the effect of context]. / Potentiels lents (200-600 ms) hippocampiques en reconnaissance à court terme d'images chez l'homme: étude de l'effet de contexte.

The activity of the hippocampic structures recorded during a semantic picture recognition task (Signoret's test) is modified by physical contextual changes. This contextual effect seems to be supported by the left hippocampus.

[Cerebral psychophysiologic study of the processes brought into action by physical context modifications in the short-term recognition of images]. / Etude psychophysiologique cérébrale des processus mis en jeu par les modifications contextuelles physiques en reconnaissance à court terme d'images.

The study of P300 waves and reaction times during the acquisition and recognition of simple symbolic pictures (Signoret's test) shows the extent of "contextual effect" in visual short-term recognition. These results support the "encodage spécifique" theory according to which contextual changes between acquisition and restitution reduce memory efficiency.

[P 300 wave and additive or self-terminated processes in short-term image recognition]. / Onde P 300 et processus exhaustifs ou autoterminés en reconnaissance à court terme d'images.

The study of the P 300 wave during the acquisition and the recognition of simple symbolic pictures shows a self-terminated treatment in short-term visual recognition processes. The results of this study plead in favour of a general principle of psychobiological economy and of a decrease of the mental charge. This principle is at variance with one of the postulates of Sternberg's additive processes theory.