Real-time fMRI and EEG neurofeedback: A perspective on applications for the rehabilitation of spatial neglect.

Spatial neglect is a neuropsychological syndrome characterized by a failure to orient, perceive, and act toward the contralesional side of the space after brain injury. Neglect is one of the most frequent and disabling neuropsychological syndromes following right-hemisphere damage, often persisting in the chronic phase and responsible for a poor functional outcome at hospital discharge. Different rehabilitation approaches have been proposed over the past 60 years, with a variable degree of effectiveness. In this point-of-view article, we describe a new rehabilitation technique for spatial neglect that directly targets brain activity and pathological physiological processes: namely, neurofeedback (NFB) with real-time brain imaging methodologies. In recent proof-of-principle studies, we have demonstrated the potential of this rehabilitation technique. Using real-time functional MRI (rt-fMRI) NFB in chronic neglect, we demonstrated that patients are able to upregulate their right visual cortex activity, a response that is otherwise reduced due to losses in top-down attentional signals. Using real-time electroencephalography NFB in patients with acute or chronic condition, we showed successful regulation with partial restoration of brain rhythm dynamics over the damaged hemisphere. Both approaches were followed by mild, but encouraging, improvement in neglect symptoms. NFB techniques, by training endogenous top-down modulation of attentional control on sensory processing, might induce sustained changes at both the neural and behavioral levels, while being non-invasive and safe. However, more properly powered clinical studies with control groups and longer follow-up are needed to fully establish the effectiveness of the techniques, identify the most suitable candidates, and determine how the techniques can be optimized or combined in the context of rehabilitation.

Using real-time fMRI neurofeedback to restore right occipital cortex activity in patients with left visuo-spatial neglect: proof-of-principle and preliminary results.

Hemineglect is common after right parietal stroke, characterised by impaired awareness for stimuli in left visual space, with suppressed neural activity in the right visual cortex due to losses in top-down attention signals. Here we sought to assess whether hemineglect patients are able to up-regulate their right visual cortex activity using auditory real-time functional magnetic resonance imaging (rt-fMRI) neurofeedback. We also examined any effect of this training procedure on neglect severity. Two different neurofeedback methods were used. A first group of six patients was trained to up-regulate their right visual cortex activity and a second group of three patients was trained to control interhemispheric balance between their right and left visual cortices. Over three sessions, we found that the first group successfully learned to control visual cortex activity and showed mild reduction in neglect severity, whereas the second group failed to control the feedback and showed no benefit. Whole brain analysis further indicated that successful up-regulation was associated with a recruitment of bilateral fronto-parietal areas. These findings provide a proof of concept that rt-fMRI neurofeedback may offer a new approach to the rehabilitation of hemineglect symptoms, but further studies are needed to identify effective regulation protocols and determine any reliable impact on clinical symptoms.

A combined cognitive and gait quantification to identify normal pressure hydrocephalus from its mimics: The Geneva's protocol.

OBJECTIVES: Idiopathic normal pressure hydrocephalus (iNPH) is very prevalent in aging, underdiagnosed, and represents a rare cause of reversible neurological condition. The clinical triad of iNPH - gait, cognitive and urinary symptoms - and its neuroradiological features (i.e. ventriculomegaly) are not specific and found a various neurodegenerative and/or vascular conditions. We present our iNPH standardized protocol at the Geneva University Hospitals involving a multispecialty team of behavioral neurologists, neurosurgeons, neuropsychologists, engineers, and physical therapists. Based on a pragmatic approach, the goal of this protocol is to improve the identification of older patients with iNPH from its mimics (i.e. vascular dementia or other parkinsonian syndromes). PATIENTS AND METHODS: We used a novel standardized paradigm with a simultaneous quantification of cognition and gait (dual task gait assessment and mental imagery of locomotion) before and 24h after CSF tapping. RESULTS: We assessed 125 patients with suspicion of iNPH (age: 75.9±7.4years; 34.4% female) in 5 years: 54.4% of probable/possible iNPH and 45.6% of mimics. Among the mimics, vascular dementia (24.6%) and patients with multifactorial conditions (19.9%) were the two most common diagnoses. A total of 27 patients with iNPH (39.7%) accepted the neurosurgical shunt procedure. CONCLUSION: This report shows that a quantified gait and cognitive assessment - using dual-task paradigms - before and after CSF tapping is feasible among older adults with suspicion of iNPH and that this multidisciplinary approach contributes to the identification of patients with iNPH from its mimics.

Increased Alpha-Rhythm Dynamic Range Promotes Recovery from Visuospatial Neglect: A Neurofeedback Study.

Despite recent attempts to use electroencephalogram (EEG) neurofeedback (NFB) as a tool for rehabilitation of motor stroke, its potential for improving neurological impairments of attention-such as visuospatial neglect-remains underexplored. It is also unclear to what extent changes in cortical oscillations contribute to the pathophysiology of neglect, or its recovery. Utilizing EEG-NFB, we sought to causally manipulate alpha oscillations in 5 right-hemisphere stroke patients in order to explore their role in visuospatial neglect. Patients trained to reduce alpha oscillations from their right posterior parietal cortex (rPPC) for 20 minutes daily, over 6 days. Patients demonstrated successful NFB learning between training sessions, denoted by improved regulation of alpha oscillations from rPPC. We observed a significant negative correlation between visuospatial search deficits (i.e., cancellation test) and reestablishment of spontaneous alpha-rhythm dynamic range (i.e., its amplitude variability). Our findings support the use of NFB as a tool for investigating neuroplastic recovery after stroke and suggest reinstatement of intact parietal alpha oscillations as a promising target for reversing attentional deficits. Specifically, we demonstrate for the first time the feasibility of EEG-NFB in neglect patients and provide evidence that targeting alpha amplitude variability might constitute a valuable marker for clinical symptoms and self-regulation.

Disturbed mental imagery of affected body-parts in patients with hysterical conversion paraplegia correlates with pathological limbic activity.

Patients with conversion disorder generally suffer from a severe neurological deficit which cannot be attributed to a structural neurological damage. In two patients with acute conversion paraplegia, investigation with functional magnetic resonance imaging (fMRI) showed that the insular cortex, a limbic-related cortex involved in body-representation and subjective emotional experience, was activated not only during attempt to move the paralytic body-parts, but also during mental imagery of their movements. In addition, mental rotation of affected body-parts was found to be disturbed, as compared to unaffected body parts or external objects. fMRI during mental rotation of the paralytic body-part showed an activation of another limbic related region, the anterior cingulate cortex. These data suggest that conversion paraplegia is associated with pathological activity in limbic structures involved in body representation and a deficit in mental processing of the affected body-parts.

Spatial hyperschematia without spatial neglect after insulo-thalamic disconnection.

Different spatial representations are not stored as a single multipurpose map in the brain. Right brain-damaged patients can show a distortion, a compression of peripersonal and extrapersonal space. Here we report the case of a patient with a right insulo-thalamic disconnection without spatial neglect. The patient, compared with 10 healthy control subjects, showed a constant and reliable increase of her peripersonal and extrapersonal egocentric space representations - that we named spatial hyperschematia - yet left her allocentric space representations intact. This striking dissociation shows that our interactions with the surrounding world are represented and processed modularly in the human brain, depending on their frame of reference.