Interfacing brain with computer to improve communication and rehabilitation after brain damage.

Communication and control of the external environment can be provided via brain-computer interfaces (BCIs) to replace a lost function in persons with severe diseases and little or no chance of recovery of motor abilities (ie, amyotrophic lateral sclerosis, brainstem stroke). BCIs allow to intentionally modulate brain activity, to train specific brain functions, and to control prosthetic devices, and thus, this technology can also improve the outcome of rehabilitation programs in persons who have suffered from a central nervous system injury (ie, stroke leading to motor or cognitive impairment). Overall, the BCI researcher is challenged to interact with people with severe disabilities and professionals in the field of neurorehabilitation. This implies a deep understanding of the disabled condition on the one hand, and it requires extensive knowledge on the physiology and function of the human brain on the other. For these reasons, a multidisciplinary approach and the continuous involvement of BCI users in the design, development, and testing of new systems are desirable. In this chapter, we will focus on noninvasive EEG-based systems and their clinical applications, highlighting crucial issues to foster BCI translation outside laboratories to eventually become a technology usable in real-life realm.

Investigating the effects of a sensorimotor rhythm-based BCI training on the cortical activity elicited by mental imagery.

OBJECTIVE: It is well known that to acquire sensorimotor (SMR)-based brain-computer interface (BCI) control requires a training period before users can achieve their best possible performances. Nevertheless, the effect of this training procedure on the cortical activity related to the mental imagery ability still requires investigation to be fully elucidated. The aim of this study was to gain insights into the effects of SMR-based BCI training on the cortical spectral activity associated with the performance of different mental imagery tasks. APPROACH: Linear cortical estimation and statistical brain mapping techniques were applied on high-density EEG data acquired from 18 healthy participants performing three different mental imagery tasks. Subjects were divided in two groups, one of BCI trained subjects, according to their previous exposure (at least six months before this study) to motor imagery-based BCI training, and one of subjects who were naive to any BCI paradigms. MAIN RESULTS: Cortical activation maps obtained for trained and naive subjects indicated different spectral and spatial activity patterns in response to the mental imagery tasks. Long-term effects of the previous SMR-based BCI training were observed on the motor cortical spectral activity specific to the BCI trained motor imagery task (simple hand movements) and partially generalized to more complex motor imagery task (playing tennis). Differently, mental imagery with spatial attention and memory content could elicit recognizable cortical spectral activity even in subjects completely naive to (BCI) training. SIGNIFICANCE: The present findings contribute to our understanding of BCI technology usage and might be of relevance in those clinical conditions when training to master a BCI application is challenging or even not possible.

The Walking Corsi Test (WalCT): a normative study of topographical working memory in a sample of 4- to 11-year-olds.

We report normative data on topographical working memory collected through the Walking Corsi Test (WalCT; Piccardi et al., 2008 ) for developing a standard administration procedure to be used in clinical and educational practice. A total of 268 typically developing Italian children aged 4-11 years performed both WalCT and Corsi Block-Tapping Test (CBT; Corsi, 1972 ) a well-known visuo-spatial memory test. WalCT has already been validated in adults, demonstrating sensitivity in detecting topographical memory deficits even in individuals who have no other memory impairments. Our results showed that age, but not sex, affected performances. Both girls and boys had a larger span on the CBT than the WalCT. The youngest group did not differ in performing WalCT and CBT, but from 5.6 years of age children performed better on CBT than WalCT, suggesting that memory in reaching space develops before topographical memory. Only after 5 years of age do children learn to process specifically topographical stimuli, suggesting that this happens when their environmental knowledge becomes operational and they increase environmental independence. We also discuss the importance to introduce WalCT in the clinical assessment.

Time varying effective connectivity for describing brain network changes induced by a memory rehabilitation treatment.

In clinical practice, cognitive impairment is often observed after stroke. The efficacy of rehabilitative interventions is routinely assessed by means of a neuropsychological test battery. Nowadays, more evidences indicate that the neuroplasticity which occurs after stroke can be better understood by investigating changes in brain networks. In this study we applied advanced methodologies for effective connectivity estimation in combination with graph theory approach, to define EEG derived descriptors of brain networks underlying memory tasks. In particular, we proposed such descriptors to identify substrates of efficacy of a Brain-Computer Interface (BCI) controlled neurofeedback intervention to improve cognitive function after stroke. Electroencephalographic (EEG) data were collected from two stroke patients before and after a neurofeedback-based training for memory deficits. We show that the estimated brain connectivity indices were sensitive to different training intervention outcomes, thus suggesting an effective support to the neuropsychological assessment in the evaluation of the changes induced by the BCI-based cognitive rehabilitative intervention.

Advanced methods for time-varying effective connectivity estimation in memory processes.

Memory processes are based on large cortical networks characterized by non-stationary properties and time scales which represent a limitation to the traditional connectivity estimation methods. The recent development of connectivity approaches able to consistently describe the temporal evolution of large dimension connectivity networks, in a fully multivariate way, represents a tool that can be used to extract novel information about the processes at the basis of memory functions. In this paper, we applied such advanced approach in combination with the use of state-of-the-art graph theory indexes, computed on the connectivity networks estimated from high density electroencephalographic (EEG) data recorded in a group of healthy adults during the Sternberg Task. The results show how this approach is able to return a characterization of the main phases of the investigated memory task which is also sensitive to the increased length of the numerical string to be memorized.

The auditory p300-based SSBCI: a door to minimally conscious patients?

In this study we report on the evaluation of a novel auditory single-switch BCI in nine patients diagnosed with MCS. The task included a simple and a complex oddball paradigm, the latter uses the tone stream segregation phenomenon. In all patients a significant difference between deviant and frequent tones could be observed in EEG. However, in some cases the deviant tones produce a significant negative peak and in some a very late positive peak. These preliminary findings are relevant in order to address future customization of this auditory ssBCI-based paradigm for unresponsive patients.

Familiarity and environmental representations of a city: a self-report study.

"Sense of direction" is usually assessed by self-report. Several internal factors contribute to proficiency in navigation: spatial cognitive style, respondent's sex, and familiarity with the environment; however, questionnaires assessing sense of direction do not include all these factors. In a recent study, Nori and Piccardi reported that environmental familiarity was crucial for topographical orientation. Regardless of a person's spatial cognitive style (i.e., landmark, route, or survey), the greater their familiarity with the environment, the better their performance. In this study, a questionnaire was used, the Familiarity and Spatial Cognitive Style Scale, to measure 208 women's sense of direction and knowledge of their city of residence. Analysis showed that Spatial Cognitive Style predicted sense of direction but not town knowledge. By contrast, familiarity played a crucial role in both areas, confirming the importance of having a tool to assess this factor.