the Virtual Multiple Errands Test

The role of Virtual Reality in neuropsychology: the Virtual Multiple Errands Test (VMET) for the assessment of executive functions in Parkinson’s disease Silvia Serinoa,c*, Elisa Pedrolia, Pietro Cipressoa,c, Federica Pallavicinia Giovanni Albanib, Alessandro Maurob, Giuseppe Rivaa,c a

Applied Technology for Neuro-Psychology Lab, IRCCS Istituto Auxologico Italiano, Via Pellizza da Volpedo 41, 20149 Milano, Italy b

Division of Neurology and Neurorehabilitation, San Giuseppe Hospital, IRCCS Istituto Auxologico Italiano, Piancavallo (VB), Italy.

c

Psychology Department, Università Cattolica del Sacro Cuore, Largo Gemelli 1, 20123 Milan, Italy

Abstract In recent years, Virtual Reality technologies have emerged as assessment and treatment tools in neuropsychology. In this chapter, we will explore the possibility of using VR to improve the traditional neuropsychological assessment of executive functions. First, we will discuss the advantages offered by Virtual Reality may over the more traditional approaches. Then, the chapter details the characteristics of the Virtual Multiple Errands Test (VMET), a virtual reality tool developed using NeuroVR (http://www.neurovr.org) - a free virtual reality platform for the assessment and neurorehabilitation - and used for the neuropsychological evaluation of executive functions. Specifically, the VMET is an assessment protocol of executive functions, where participants are required to navigate a virtual supermarket, completing tasks that abide by certain rules. In the chapter we will be present the detailed description of its clinical ra-

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tionale and its different phases. Furthermore, a systematic analysis of the results obtained in different studies using the VMET will be outlined. Finally, we will discuss the potentiality of the VMET for integrating the traditional neuropsychological evaluation of patients with Parkinson’s disease. Identification of early executive deficits in Parkinson’s disease could facilitate the identification of patients at risk to develop dementia, and could give the chance to develop early neurorehabilitation interventions.

Introduction The assessment and rehabilitation of impairments of cognitive functions (language, spatial perception, attention, and memory) following neurological damage of different etiology (for example, stroke and traumatic brain injury, and neurodegenerative disorders) has been the focus of considerable research interest. Neuropsychology has developed several measures to effectively evaluate both cognitive and motor abilities. Traditional neuropsychological measures are reliable and have adequate construct validity. Today, however, a critical challenge for neuropsychology has been to find new way to better measure, understand, and predict daily life abilities. Indeed, one of the most consistent issues with respect to neuropsychological assessment and rehabilitations techniques is the lack of the ecological validity of the actual protocols, that results in limitations to generalization of new abilities in daily life situations. The cognitive domain that is most affected by this problem is that of executive functions. It is more and more important to create new tools that better reflect the activities of everyday life to improve the traditional assessment and rehabilitation of executive functions. Virtual Reality (VR) may be very useful in the assessment and rehabilitation of executive functions since it may increase the ecological validity of

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actual protocols. In fact, VR is used in neuropsychology as "an advanced form of human-computer interface that allows the user to interact with and become immersed in a computer-generated environment in a naturalistic fashion.” (Schultheis & Rizzo, 2001). An interesting test for executive functions is the Multiple Errand Test (MET), which it has been developed to allow an analysis of the patient in an real-life context (Alderman, Burgess, Knight, & Henman, 2003; Shallice & Burgess, 1991). This test requires that the patient completes certain tasks in a real shopping center, following a few rules given by the examiner in a span of time. Unfortunately, it is very difficult to apply the MET in clinical practice, such as its economic costs. To overcome these problems and to maintain high ecological validity, we have adapted the software NeuroVR (http://www.neurovr.org) to create a virtual version of the MET (VMET). The VMET is a instrument to assess executive functions, where participants are asked to navigate in a virtual supermarket, comprising of tasks that abide by certain rules. This assessment protocol will be presented by the detailed description of its clinical rationale and its different phases. Furthermore, an analysis of the results obtained in different studies using the VMET will be fully discussed. On the basis of these clinical advantages, we propose that the VMET may be an useful tool to evaluate early executive deficits in Parkinson's disease (PD). Cognitive disorders in PD are not as evident as cognitive impairment in other neurological disorders, and their diagnosis tends to be delayed. Identification of early executive deficits in PD could facilitate the identification of patients at risk to develop dementia, and could give the chance to develop early neurorehabilitation interventions.

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The role of Virtual Reality in neuropsychology: Opportunities and Challenges In recent years the field of Virtual Reality (VR) has grown immensely. Practical applications for the use of this advanced technology encompass many fields, from aviation training and military applications, to medicine, where surgeons can be trained in surgical techniques using VR systems. One of the newest field to benefit from the advances in VR technology is that of neuropsychological assessment and rehabilitation (Bohil, Alicea, & Biocca, 2011; Riva, 2003; Riva & Gaggioli, 2009b; Rose, Brooks, & Rizzo, 2005; Schultheis & Rizzo, 2001) From a technological viewpoint, VR consists of a three-dimensional (3D) graphical environment where a user can interact with the environment through a variety of computer peripheral devices. Using visual, aural or haptic devices, the user can experience the environment as if it were a part of the real world. In neuropsychology, VR is used to offer a new human-computer interaction paradigm in which patients are no longer simply external observers of images on a computer screen but are active participants within realistic virtual worlds (Riva, Mantovani, & Gaggioli, 2004). VR appears to be a suitable medium that offers several requirements for effective neuropsychological assessment and neurorehabilitation interventions: repetitive practice, feedback about performance, multimodal stimulation, controlled and secure environments (Bohil et al., 2011; Riva et al., 2004; Schultheis & Rizzo, 2001). Specifically, it is possible to control and manipulate tailored exercises within meaningful, ecologically valid and motivating environments using Virtual Environments (VEs) (Riva & Gaggioli, 2009a). Indeed, VR simulations can be highly engaging by supporting a process known as transformation of flow, defined as a person’s ability to exploit an optimal (flow) experience to identify and use new and unexpected psychological resources as sources of involvement (Riva,

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Castelnuovo, & Mantovani, 2006). From a psychological perspective, motivation is particularly important for patients to consistently engage in demanding and practice-heavy cognitive exercises. Besides the opportunity for experiential, active learning which motivates the participant, it is crucial to objectively measure behavior in challenging but safe and ecologically valid environments, while maintaining strict experimental control over stimulus delivery and measurement (Brooks & Rose, 2003; Riva, 2003; Rose et al., 2005). However, in a recent review, Riva (Riva, 2009) has identified four major issues that may limit the use of the VR system in the assessment and rehabilitation of cognitive impairments: • The limited possibility of tailoring virtual environments to the specific requirements of the clinical or experimental setting. • The low availability of standardized protocols that can be shared by the community of clinicians and researchers. • The high costs (up to $200,000) required for designing and testing a clinical VR application. • The expensive technical support often required for maintaining a VR system. To address these challenges, Riva and his team developed NeuroVR http://www.neurovr.org) in 2007 – a free virtual reality platform based on open-source elements, and the updated version in 2011: NeuroVR 2 (Riva et al., 2011).

A new platform for neuropsychological assessment and rehabilitation: NeuroVR NeuroVR is a software allows non-expert users to adapt the content of several pre-designed virtual environments to the specific needs of the

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clinical setting. The key characteristics that make NeuroVR suitable as cognitive assessment and rehabilitation tool are the high level of control over interaction and the enriched experience provided to the patient. NeuroVR is composed of several virtual environments, that used by the neuropsychologist within a session with the patient. The environments present daily life situations (e.g., Home, Supermarket, Pub, Restaurant, Swimming Pool, Beach, Gymnasium). Using the NeuroVR Editor, the specific stimulus can be chosen from a rich database of 2D and 3D objects, and easily placed into the pre-designed virtual scenario by using an icon-based interface (no programming skills are required).

Fig. 1. The NeuroVR Editor

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In addition to static objects, the NeuroVR Editor allows both to add audio object and to overlay on the 3D scene video composited with a transparent alpha channel. The editing of the scene is performed in real time, and effects of changes can be checked from different views (frontal, lateral and top). The edited scene is then visualized and experienced using the NeuroVR Player.

Fig. 2. The NeuroVR Player Through the VR experience, patients practice several different exercises. By directly practicing these cognitive exercises within the VR environment, the patient is helped in developing specific cognitive strategies within a realistic and safe environment. The use of NeuroVR in cognitive rehabilitation provides the opportunity to create tailored interventions in which the duration, intensity and feedback can be manipulated according to the specific patient’s needs.

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NeuroVR platform allow infinite repetitions of the same assessment or training task: thanks to its flexibility, it is possible to easily modify stimulus presentations, task complexity, response requirements, and type of feedback according to patients’ cognitive disabilities. An example of the potentiality of NeuroVR as effective tool for a new class of neuropsychological applications for improving the traditional neuropsychological evaluation of cognitive functions is the virtual version of the Multiple Errands Test (VMET). The different techniques used in the VR sessions for the assessment of executive functions in the VMET are detailed in the following paragraphs.

The role of Virtual Reality in the assessment of executive functions: from Multiple Errands Test to Virtual Multiple Errands Test In the recent decades, neuropsychology, cognitive psychology and cognitive neuroscience have been worked together to understand the complexity of cognitive processes, the functional neuroanatomy underpinning those cognitive domains, and the implications of cognitive impairments in neurological patients for models of normal cognitive functioning. One of the most complex ability of the human mind is its ability in continuously orienting cognitive resources to effectively respond both to environmental and internal demands. Traditionally, these high-level cognitive abilities have been called executive functions, and they have been the focus of considerable research interest. As suggested by Chan and colleagues (Chan, Shum, Toulopoulou, & Chen, 2008), the term “executive functions” is an umbrella term including a wide range of cognitive processes and behavioral competencies. They include problem-solving, planning, sequencing, the ability to sustain attention, resistance to interference, utilization of feedback, multitasking, cog-

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nitive flexibility, and the ability to deal with novelty (Burgess, Veitch, Costello, & Shallice, 2000; Grafman & Litvan, 1999; Shallice, 1988; Stuss & Benson, 1986; Stuss, Shallice, Alexander, & Picton, 1995) Impairments of executive functions are common in neurological patients, specifically in those presenting frontal cortex injury (for example, see Bechara, Damasio, Damasio, & Anderson, 1994; Burgess & Shallice, 1996a, 1996b; Robertson, Manly, Andrade, Baddeley, & Yiend, 1997). As summarized by Chan and colleagues (Chan et al., 2008), an increasing number of neuropsychological tests have been developed to assess the presence of executive deficits in different clinical population. The assessment of executive functions has been generally performed in clinical settings, usually via paper-and pencil questionnaires or laboratory tasks. For example, neuropsychological assessment may include the Cambridge Neurological Inventory (Chen et al., 1995), the Design Fluency Test (JonesGotman & Milner, 1977), and different types of Tower tests (Humes, Welsh, Retzlaff, & Cookson, 1997; Shallice, 1982). However, there are some critical issues in the traditional neuropsychological evaluation of executive functions (Chan et al., 2008): a more ecological and prompt neuropsychological evaluation of executive functions is essential to evaluate the specific cognitive profile of different individuals. Indeed, the lack of ecological validity is a critical issue of neuropsychological evaluation (Chaytor & Schmitter-Edgecombe, 2003; Goldstein, 1996), especially as regards the executive functions. Furthermore, even if many patients with frontal lobe lesions have shown scores on traditional neuropsychological tests similar to controls, they are characterized by several difficulties in daily life activities (Shallice & Burgess, 1991). More, the traditional assessment does not reflect the complexity of executive functions in ecological contexts. In fact, a more detailed assessment may evaluate if individuals are able to formulate,

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store and check all the goals and sub-goals in order to effectively respond to environmental and/or internal demands. These aspects led clinicians and researchers to develop a more ecological evaluation of executive functions. In this direction, there are some instruments developed to measure executive deficits in situations similar to daily ones, such as the Behavioral Assessment of Dysexecutive Syndrome (Wilson, Alderman, Burgess, Emslie, & Evans, 1996) and the Multiple Errands Test (MET) (Alderman et al., 2003; Shallice & Burgess, 1991). More specifically, the MET is a functional test for evaluating executive functions in daily life originally developed by Shallice and Burgess (Shallice & Burgess, 1991) specifically for high functioning patients. Specifically, it was also adapted into the simple (Alderman et al., 2003) and the hospital version (Knight, Alderman, & Burgess, 2002). Contrary to the Behavioral Assessment of Dysexecutive Syndrome or other laboratory-based tasks, MET is performed at a real shopping mall or in a hospital environment, and it requires the completion of various tasks without breaking a series of arbitrary rules. In the simplified version, the test is composed of three main tasks. The first involved purchasing six items (e.g., small brown loaf). The second involved locating and recording four items of information (e.g., the closing time of the library on Saturday). The third was meeting the clinician at a designated point (under the clock) and stating the time 20 minutes after beginning the test. While performing the exercise, participant have to follow some rules, such as for instance: "Do not speak to the person observing you unless this is part of the exercise.” The clinician follows the participant, recording different kind of errors, from a task failure (e.g., failed to purchase keying) to a rule breaking (e.g., shouted question to shop staff). As explained, the procedure is, as many situations outside of the laboratory, "open" or "ill-structured" (Goel, Grafman, Tajik, Gana, & Danto,

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1997): there are many possible courses of actions. In this way, the executive functions stimulated are several since participants have to decide how to plan the actions, how to list the steps necessary to achieve the main task, how to formulate, store and check all the goals and sub-goals, and how to compare the outcome of action with the desired goal Being a “real-life” test requires the performance in very common daily activities, the MET has good ecological validity (Burgess et al., 2006). However, to adequately perform the Multiple Errands Test, the patient should go with the clinician to a real mall, and this necessarily requires good motor skills. This procedure can be particularly demanding for a patient whose cognitive system is failing. Furthermore, this protocol is particularly time consuming, both for the patient and therapist. Finally, the "real world" is not a controlled and secure environment, and it is not possible to maintain a strict experimental control over stimulus delivery and measurement. To address these issues, a virtual version of the Multiple Errands Test has been developed and tested.

The Virtual Multiple Errands Test (VMET) Rand and colleagues (Rand, Rukan, Weiss, & Katz, 2009) have developed a first version of the Virtual Multiple Errands Test as an assessment tool for executive functions, within the virtual mall (Rand, Katz, Kizony, Shahar, & Weiss, 2005), a functional virtual environment consisting of a large supermarket which was programmed via GestureTek’s IREX video capture virtual reality system. The VMall has been developed to provide an engaging task which can offer post-stroke participants an opportunity to practice different shopping tasks without leaving the treatment room (Rand, Katz, & Weiss, 2007).

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On these premises, Riva and his team exploited the potentiality of NeuroVR previously described to develop and test an advanced assessment tool of executive functions, namely the VMET. From a technical point of view, the VMET consists of a Blender-based application that enables active exploration of a virtual supermarket where participants are requested to select and buy various products presented on shelves. The user enters the virtual supermarket and he/she is presented with virtual objects of the various items to be purchased. Moreover, using a joypad, the participant is able to freely navigate in the various aisles (using the up-down joypad arrows), and to collect products (by pressing a button placed on the right side of the joypad), after having selected them with the viewfinder. The virtual supermarket contains products grouped into the main grocery categories including beverages, fruits and vegetables, breakfast foods, hygiene products, frozen foods, garden products, and animal products. Signs at the top of each section indicate the product categories as an aid to navigation.

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Fig. 3. The VMET The procedure has been adapted by Shallice and Burgess (Alderman et al., 2003; Shallice & Burgess, 1991). After an initial training phase with an another virtual supermarket, the examiner shows the virtual supermarket shop and illustrates the different sections. Participants are given a shopping list, a supermarket's map, some information about the supermarket (opening and closing time, products in sales, etc.), a pen, and a wrist watch. The instructions are illustrated to the participants and the rules are explained with reference to the instruction sheet. The VMET test is composed of four main tasks. The first involved purchasing six items (e.g., one product in sales). The second involved asking examiner information about one item to be purchased. The third involved writing the shopping list 5 minutes after beginning the test. The third involved responding of

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some questions at the end of virtual session by using useful material (e.g., the closing time of the virtual supermarket). This is the list of rules: • you have to execute all the proposed tasks, but you can run them in any order; • you cannot go in a place unless this is a part of a task; • you cannot pass through the same passage more than once; • you cannot buy more than two items per categories (look at the chart); • take as few time as possible to complete this exercise however without hurry; • do not talk to the researcher unless this is a part of the task; • go to your "shopping cart" after 5 minutes from the beginning of the task and make a list of all the products that you bought. The examiner started clocking without talking with participant not even to answer to the questions. The time stopped when the participant said "I finished". During the task, the examiner took notes about participant’s behaviors in the virtual environment. As suggested by Shallice and Burgess (Shallice & Burgess, 1991), the errors were categorized as following: • task failure, namely a task not completed satisfactorily; • inefficiencies and strategies, where a more effective strategy could have been applied to accomplish the task; • rule Breaks, where a specific rule listed in the instructions has been violated; • interpretation failures, where the requirements of a particular task are not misunderstood. An analysis of the results obtained in different studies using the VMET will be deeply described in the following paragraph.

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The potentiality of the VMET for neuropsychology The VMET has good psychometric properties. In a first experiment, two independent researchers scored 11 videos, each one of a subject running the VMET. In a second experiment 7 researchers scored two videos, each one of a subject running the VMET. Results showed a good reliability of the VMET (Cipresso, Serino, Pedroli, Albani, & Riva, 2013). Furthermore, the VMET has been validated with different clinical population. Raspelli and colleagues (Raspelli et al., 2011) demonstrated the ecological validity and initial construct validity of the VMET. The study population included three groups: 9 post-stroke participants, 10 healthy young participants, and 10 healthy older participants. Correlations between VMET variables and some traditional executive functions measures provide preliminary support for the ecological and construct validity of the VMET; further performance obtained at the VMET provided a distinction between the clinical and healthy population, and between the two age control groups. La Paglia and colleagues (La Paglia, La Cascia, Rizzo, Riva, & La Barbera, 2012) used the VMET to evaluate the executive functions in daily life in 10 patients suffering from obsessive-compulsive disorder (OCD) and 10 controls. The execution time for the whole virtual task was higher in patients with OCD compared to controls, suggesting that patients with OCD need more time in planning than controls. Furthermore, patients showed more difficulties in following the rules and sustaining attention than controls. These results provide initial support for the feasibility of the VMET as assessment tool of executive functions in OCD patients. Specifically, the significant correlation found between the VMET and the neuropsychological battery support the ecological validity of VMET as an instrument for the evaluation of executive functions in patients with OCD. Cipresso and colleagues (Cipresso et al., 2013) used the VMET to investigate deficits of volition in OCD patients. The study involved thirty partici-

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pants (15 OCD patients and 15 controls) during task execution and the relative interferences. Results showed specific deficits in OCD patients, as defined in the following classification: 1. break in time: to go to the shopping chart after 5 min; 2. break in choice: to buy two products instead of just one; 3. break in social rules: “to go into a specific place and to ask the examiner what to buy.” Albani and colleagues (Albani et al., 2011) used the VMET to investigate decision-making ability in 12 patients with Parkinson’s disease as compared to 14 controls. In the early-middle stages of Parkinson's disease, polysomnographic studies show early alterations of the structure of the sleep, which may explain frequent symptoms reported by patients, such as daytime drowsiness, loss of attention and concentration, feeling of tiredness. Five of 12 patients with Parkinson’s disease showed abnormalities in the polysomnographic recordings associated to significant differences in the VMET performance. However, as underlined by Chan and colleagues (Chan et al., 2008) (2008), this advanced technology should be carefully used in clinical setting, in particular with regard to those patients who are not familiar with computerized test. To address this issue, Pedroli and colleagues (Pedroli, Cipresso, Serino, Albani G., & G., 2013) tested the usability of the VMET with 21 healthy participants and 3 patients with Parkinson’s disease. To evaluate usability, they used The System Usability Scale (SUS), a "quick and easy to use" measure developed by Brooke (Brooke, 1996). He defines usability as "the subjective perception of interaction with a system." Healthy participants gave a good usability for the VMET. As regards patients, results showed that a good training phase before the test is crucial to apply the virtual protocol.

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This encouraging results led us to consider the VMET as an useful tool to evaluate executive deficits in Parkinson's disease. Cognitive disorders in PD are not as evident as cognitive impairment in other neurological disorders and their diagnosis tends to be delayed. Identification of early executive deficits in PD could facilitate the identification of patients at risk to develop dementia and could give the chance to develop early neurorehabilitation interventions.

The potentiality of the VMET in the assessment of executive functions in Parkinson’s disease: a possible approach Contrary to what firstly described James Parkinson (Parkinson, 1817), the evidence is that the cognitive impairment is extremely common in Parkinson's disease (PD) and affects a variety of cognitive domains, including memory, language, executive functions, visuospatial abilities. Besides on the characteristic motor signs, a number of different cognitive deficit has been received a relevant clinical attention in PD (Foltynie, Brayne, Robbins, & Barker, 2004; Kehagia, Barker, & Robbins, 2010; Levy et al., 2002; Muslimovic, Post, Speelman, & Schmand, 2005; Vingerhoets, Verleden, Santens, Miatton, & De Reuck, 2003; Williams-Gray et al., 2009). Similar to motor symptoms, the characteristics of cognitive impairments in PD can be extremely variable, both in terms of what cognitive functions are impaired and the timing of onset and rate of progression (for example, see Verleden, Vingerhoets, & Santens, 2007). As cognitive deficit is a common complication of PD, and since it is associated with significant disability for patients and burden for caregivers, it is crucial to be fully evaluated. There are convincing evidence demonstrating the clinical importance of cognitive impairment for the quality of life of patients and their caregivers, as well as the health-economic impact (Aarsland, Larsen, Karlsen, Lim, & Tandberg, 1999; Aarsland, Larsen, Tandberg, & Laake, 2000; Schrag,

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Jahanshahi, & Quinn, 2000). Impairment of executive functions constitutes the core feature of neuropsychological profile dysfunction in PD (Ceravolo, Pagni, Tognoni, & Bonuccelli, 2012; McKinlay, Grace, Dalrymple-Alford, & Roger, 2010). In PD, indeed, executive dysfunctions are similar, but not identical to those seen in frontal lobe patients, and are conceived to represent a dysfunction of the fronto-striatal neural circuitry (Rogers et al., 1998; Rowe et al., 2002). Because of the impact on the patient’s quality of life, early detection and rehabilitation of executive dysfunctions is crucial in the management of PD. So, it is fundamental that we improve our understanding, for this common and disabling complication in PD, both in terms of neuropsychological assessment and rehabilitation strategies. Based on these premises, we argue that the VMET could be an useful tool for evaluating executive deficits in PD.

The Virtual Multiple Errands Test (VMET) for the assessment of executive functions in Parkinson’s disease As the PD progresses, a relevant proportion of patients will develop dementia (Aarsland, Andersen, Larsen, Lolk, & Kragh-Sorensen, 2003; Bosboom, Stoffers, & Wolters, 2004; Dubois et al., 2007; Hely, Reid, Adena, Halliday, & Morris, 2008). The focus is now to identify patients with a potentially higher risk of dementia with the possibility to implement an early and individualized cognitive rehabilitation treatment to improve their quality of life. As previously underlined, executive deficits constitute the core clinical marker of neuropsychological profile of PD patients. Particularly, an increasing number of longitudinal studies suggests that early executive dysfunction is predictive of the conversion to dementia (Azuma, Cruz, Bayles, Tomoeda, & Montgomery, 2003; Janvin, Aarsland,

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& Larsen, 2005). In this perspective, it has been recently proposed to use the term "mild cognitive impairment in PD" (Litvan et al., 2011; Litvan et al., 2012). Although the term “mild cognitive impairment” applied to PD is controversial (Troster, 2008), it is more frequently used and more widely accepted than alternative terms. Mild cognitive impairment in PD may be an useful clinically concept to define a cognitive decline that is not normal for age, but it is essentially associated with normal functional activities. Several studies demonstrated that mild cognitive impairment predicts the development of dementia, which can occur in up to 80% of PD patients over the long term (Azuma et al., 2003; Janvin, Larsen, Aarsland, & Hugdahl, 2006). Evaluation of early executive deficits in PD could facilitate the identification of patients at risk to develop dementia, and may give the chance to develop early neurorehabilitation interventions. In such context, we argue that the VMET may significantly improve the traditional assessment of executive functions in patients suffering from mild cognitive impairment due to PD. Thanks to the VMET, it will be possible to evaluate: • the real functional status of mild cognitive impairment due to PD , as manifested in terms of executive dysfunctions, that had not been fully acknowledged in everyday life scenarios; • the ability of patients with mild cognitive impairment due to PD in formulating, storing and checking all the goals and sub-goals in order to effectively respond to environmental demands in ecological situations.

Conclusion In recent years, Virtual Reality (VR) technologies have emerged as assessment and treatment tools in neuropsychology. Neuropsychology is

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one of the most promising field, where the advantages of using VR are still to be further explored. Neuropsychology is a field of great interest, in which the integration of new technologies may improve the ecological validity of the current approaches. Today, in fact, a critical challenge for neuropsychology has been to find new way to better measure, understand, and predict everyday abilities. Indeed, one of the most consistent issues with respect to neuropsychological assessment and rehabilitations techniques has been limits in the ecological validity of the actual protocols, that results in limitations to generalization of new abilities in daily life situations. In this chapter, we have explored the possibility of using VR to improve the traditional neuropsychological evaluation of executive functions. First, as the VR may have an important role in neuropsychology, it is important that it is extensively defined within its specific features. Indeed, in order to ensure an adequate development of virtual assessment tools, we have discussed the opportunities and challenges that Virtual Reality may provide to more traditional approaches. Specifically, to solve some limitations in the use of VR in clinical practice, Riva and his team developed NeuroVR, a new open- source platform for neuropsychological assessment and rehabilitation. Then, we have detailed the characteristics of the Virtual Multiple Errands Test (VMET) for the assessment of executive deficits, that tries to enhance the traditional approaches used in the neuropsychological evaluation of executive functions by means of VR. In fact, it is crucial to create new tools that better reflect the activities of everyday life to improve the traditional assessment and rehabilitation of cognitive functions. The cognitive domain that is most affected by this problem is that of executive functions. VR may be very useful in the assessment and rehabilitation of executive functions since it may increase the ecological validity of actual protocols. The VMET is an assessment protocol of executive functions, where participants are required to navigate in virtual supermarket, comprising of tasks that abide by certain rules. This assessment protocol has been pre-

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sented by the detailed description of its clinical rationale and its different phases. Furthermore, a systematic analysis of the results obtained in different studies using the VMET has been fully described. Finally, we discussed the potentiality of the VMET for integrating the traditional neuropsychological evaluation of patients with PD. As the PD progresses, a relevant proportion of patients will develop dementia (Aarsland et al., 2003; Bosboom et al., 2004; Dubois et al., 2007; Hely et al., 2008). The focus is now to identify patients with a potentially higher risk of dementia with the possibility to implement an early and individualized cognitive rehabilitation treatment to improve their quality of life. Identification of early executive deficits in PD with the VMET could facilitate the identification of patients at risk to develop dementia, and could give the chance to develop early neurorehabilitation interventions. Obviously, much more researches are needed to evaluate the potentiality of the VMET, especially in terms of its temporal stability, namely test– retest reliability, and criterion validity for Parkinson’s disease. However, a recently Italian funded project "VRehab. Virtual Reality in the Assessment and TeleRehabilitation of Parkinson's Disease and Post-Stroke Disabilities"will offer the right context to test the potentiality of the VMET as an assessment tool of executive deficits in PD.

Acknowledgments This work was supported by the Italian funded project "VRehab. Virtual Reality in the Assessment and TeleRehabilitation of Parkinson's Disease and Post-Stroke Disabilities" - RF-2009-1472190.

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