Brain-Computer interfaces for communication:preferences of individuals with locked-in syndrome, caregivers and researchers

Objectives: The development of Brain-Computer Interfaces to restore communication (cBCIs) in people with severe motor impairment ideally relies on a close collaboration between end-users and other stakeholders, such as caregivers and researchers. Awareness about potential differences in opinion between these groups is crucial for development of usable cBCIs and access technology (AT) in general. In this study, we compared the opinions of prospective cBCI users, their caregivers and cBCI researchers regarding: (1) what applications would users like to control with a cBCI; (2) what mental strategies would users prefer to use for cBCI control; and (3) at what stage of their clinical trajectory would users like to be informed about AT and cBCIs.Methods: We collected data from 28 individuals with locked-in syndrome, 29 of their caregivers and 28 cBCI researchers. The questionnaire was supported with animation videos to explain different cBCI concepts, the utility of which was also assessed.Results: Opinions of the three groups were aligned with respect to the most desired cBCI applications, but diverged regarding mental strategies and the timing of being informed about cBCIs. Animation videos were regarded as clear and useful tools to explain cBCIs and mental strategies to end-users and other stakeholders.Conclusions: Disagreements were clear between stakeholders regarding which mental strategies users prefer to use and when they would like to be informed about cBCIs. To move forward in the development and clinical implementation of cBCIs, it will be necessary to align the research agendas with the needs of the end-users and caregivers.</p

GridLoc : An automatic and unsupervised localization method for high-density ECoG grids

Precise localization of electrodes is essential in the field of high-density (HD) electrocorticography (ECoG) brain signal analysis in order to accurately interpret the recorded activity in relation to functional anatomy. Current localization methods for subchronically implanted HD electrode grids involve post-operative imaging. However, for situations where post-operative imaging is not available, such as during acute measurements in awake surgery, electrode localization is complicated. Intra-operative photographs may be informative, but not for electrode grids positioned partially or fully under the skull. Here we present an automatic and unsupervised method to localize HD electrode grids that does not require post-operative imaging. The localization method, named GridLoc, is based on the hypothesis that the anatomical and vascular brain structures under the ECoG electrodes have an effect on the amplitude of the recorded ECoG signal. More specifically, we hypothesize that the spatial match between resting-state high-frequency band power (45–120 Hz) patterns over the grid and the anatomical features of the brain under the electrodes, such as the presence of sulci and larger blood vessels, can be used for adequate HD grid localization. We validate this hypothesis and compare the GridLoc results with electrode locations determined with post-operative imaging and/or photographs in 8 patients implanted with HD-ECoG grids. Locations agreed with an average difference of 1.94 ± 0.11 mm, which is comparable to differences reported earlier between post-operative imaging and photograph methods. The results suggest that resting-state high-frequency band activity can be used for accurate localization of HD grid electrodes on a pre-operative MRI scan and that GridLoc provides a convenient alternative to methods that rely on post-operative imaging or intra-operative photographs

Estimated Prevalence of the Target Population for Brain-Computer Interface Neurotechnology in the Netherlands

BACKGROUND: People who suffer from paralysis have difficulties participating in society. Particularly burdensome is the locked-in syndrome (LIS). LIS patients are not able to move and speak but are cognitively healthy. They rely on assistive technology to interact with the world and may benefit from neurotechnological advances. Optimal research and design of such aids requires a well-defined target population. However, the LIS population is poorly characterized and the number of patients in this condition is unknown. OBJECTIVE: Here we estimated and described the LIS patient population in the Netherlands to define the target population for assistive (neuro)technology. METHODS: We asked physicians in the Netherlands if they had patients suffering from severe paralysis and communication problems in their files. Physicians responding affirmatively were asked to fill out a questionnaire on the patients' status. RESULTS: We sent out 9570 letters to general practitioners (GPs), who reported 83 patients. After first screening, the GPs of 46 patients received the questionnaire. Based on the responses, 26 patients were classified as having LIS. Extrapolation of these numbers resulted in a prevalence of 0.73 patients per 100 000 inhabitants. Notable results from the questionnaire were the percentage of patients with neuromuscular disease (>50%) and living at home (>70%). CONCLUSIONS: We revealed an etiologically diverse group of LIS patients. The functioning and needs of these patients were, however, similar and many relied on assistive technology. By characterizing the LIS population, our study may contribute to optimal development of assistive (neuro)technology

Narrative comprehension and production abilities of children with 22q11.2 deletion syndrome

Background: The 22q11.2 Deletion Syndrome (22q11DS) is associated with language deficits and weak intellectual functioning. In other clinical groups, linguistic and cognitive difficulties have been associated with impaired acquisition of narrative abilities. However, little is known about the narrative abilities of children with 22q11DS. Aims: To describe the ability of children with 22q11DS to produce and comprehend narrative macrostructure. Additionally, to examine the role of intellectual functioning in explaining their narrative difficulties. Methods and procedures: Narrative skills of 14 school-aged children with 22q11DS were compared to those of younger typically developing (TD) children matched on mental age and same-aged peers with Developmental Language Disorder (DLD). Outcomes and results: Children with 22q11DS had significantly lower scores on narrative comprehension than younger TD children. No significant differences emerged on narrative production. Children with 22q11DS and children with DLD did not differ significantly on any of the narrative measures. Conclusions and implications: Narrative comprehension in children with 22q11DS seems more affected than production. Narrative comprehension difficulties cannot be entirely explained by a low level of intellectual functioning. Narrative comprehension and production abilities in 22q11DS require further consideration

The opioid fentanyl affects light input, electrical activity and Per gene expression in the hamster suprachiasmatic nuclei

The suprachiasmatic nuclei (SCN) contain a major circadian pacemaker, which is regulated by photic and nonphotic stimuli. Although enkephalins are present in the SCN, their role in phase regulation of the pacemaker is largely unknown. The opioid agonist fentanyl, a homologue of morphine, is an addictive drug that induces phase shifts of circadian rhythms in hamsters. We observed that these phase shifts are blocked by naloxone, which is a critical test for true opioid receptor involvement, and conclude that opioid receptors are the sole mediators of the actions of fentanyl on the circadian timing system. A strong interaction between opioids and light input was shown by the ability of fentanyl and light to completely block each other's phase shifts of behavioural activity rhythms. Neuronal ensemble recordings in vitro provide first evidence that SCN cells show direct responses to fentanyl and react with a suppression of firing rate. Moreover, we show that fentanyl induces a strong attenuation of light-induced Syrian hamster Period 1 (shPer1) gene expression during the night. During the subjective day, we found no evidence for a role of shPer1 in mediation of fentanyl-induced phase shifts. Based on the present results, however, we cannot exclude the involvement of shPer2. Our data indicate that opioids can strongly modify the photic responsiveness of the circadian pacemaker and may do so via direct effects on SCN electrical activity and regulation of Per genes. This suggests that the pathways regulating addictive behaviour and the circadian clock intersect

Separate spatial and temporal frequency tuning to visual motion in human MT+ measured with ECoG

The human middle temporal complex (hMT+) has a crucial biological relevance for the processing and detection of direction and speed of motion in visual stimuli. Here, we characterized how neuronal populations in hMT+ encode the speed of moving visual stimuli. We evaluated human intracranial electrocorticography (ECoG) responses elicited by square-wave dartboard moving stimuli with different spatial and temporal frequency to investigate whether hMT+ neuronal populations encode the stimulus speed directly, or whether they separate motion into its spatial and temporal components. We extracted two components from the ECoG responses: (1) the power in the high-frequency band (HFB: 65-95 Hz) as a measure of the neuronal population spiking activity and (2) a specific spectral component that followed the frequency of the stimulus's contrast reversals (SCR responses). Our results revealed that HFB neuronal population responses to visual motion stimuli exhibit distinct and independent selectivity for spatial and temporal frequencies of the visual stimuli rather than direct speed tuning. The SCR responses did not encode the speed or the spatiotemporal frequency of the visual stimuli. We conclude that the neuronal populations measured in hMT+ are not directly tuned to stimulus speed, but instead encode speed through separate and independent spatial and temporal frequency tuning. Hum Brain Mapp, 2016. © 2016 Wiley Periodicals, Inc

Correspondence between fMRI and electrophysiology during visual motion processing in human MT

Changes in brain neuronal activity are reflected by hemodynamic responses mapped through Blood Oxygenation Level Dependent (BOLD) functional magnetic resonance imaging (fMRI), a primary tool to measure brain functioning non-invasively. However, the exact relationship between hemodynamics and neuronal function is still a matter of debate. Here, we combine 3T BOLD fMRI and High Frequency Band (HFB) electrocorticography (ECoG) signals to investigate the relationship between neuronal activity and hemodynamic responses in the human Middle Temporal complex (hMT+), a higher order brain area involved in visual motion processing. We modulated the ECoG HFB and fMRI BOLD responses with a visual stimulus moving at different temporal frequencies, and compared measured BOLD responses to estimated BOLD responses that were predicted from the temporal profile of the HFB power change. We show that BOLD responses under an electrode over hMT+ can be well predicted not only be the strength of the neuronal response but also by the temporal profile of the HFB responses recorded by this electrode. Our results point to a linear relationship between BOLD and neuronal activity in hMT+, extending previous findings on primary cortex to higher order cortex

Separate spatial and temporal frequency tuning to visual motion in human MT+ measured with ECoG

The human middle temporal complex (hMT+) has a crucial biological relevance for the processing and detection of direction and speed of motion in visual stimuli. Here, we characterized how neuronal populations in hMT+ encode the speed of moving visual stimuli. We evaluated human intracranial electrocorticography (ECoG) responses elicited by square-wave dartboard moving stimuli with different spatial and temporal frequency to investigate whether hMT+ neuronal populations encode the stimulus speed directly, or whether they separate motion into its spatial and temporal components. We extracted two components from the ECoG responses: (1) the power in the high-frequency band (HFB: 65-95 Hz) as a measure of the neuronal population spiking activity and (2) a specific spectral component that followed the frequency of the stimulus's contrast reversals (SCR responses). Our results revealed that HFB neuronal population responses to visual motion stimuli exhibit distinct and independent selectivity for spatial and temporal frequencies of the visual stimuli rather than direct speed tuning. The SCR responses did not encode the speed or the spatiotemporal frequency of the visual stimuli. We conclude that the neuronal populations measured in hMT+ are not directly tuned to stimulus speed, but instead encode speed through separate and independent spatial and temporal frequency tuning. Hum Brain Mapp, 2016. © 2016 Wiley Periodicals, Inc

Correspondence between fMRI and electrophysiology during visual motion processing in human MT

Changes in brain neuronal activity are reflected by hemodynamic responses mapped through Blood Oxygenation Level Dependent (BOLD) functional magnetic resonance imaging (fMRI), a primary tool to measure brain functioning non-invasively. However, the exact relationship between hemodynamics and neuronal function is still a matter of debate. Here, we combine 3T BOLD fMRI and High Frequency Band (HFB) electrocorticography (ECoG) signals to investigate the relationship between neuronal activity and hemodynamic responses in the human Middle Temporal complex (hMT+), a higher order brain area involved in visual motion processing. We modulated the ECoG HFB and fMRI BOLD responses with a visual stimulus moving at different temporal frequencies, and compared measured BOLD responses to estimated BOLD responses that were predicted from the temporal profile of the HFB power change. We show that BOLD responses under an electrode over hMT+ can be well predicted not only be the strength of the neuronal response but also by the temporal profile of the HFB responses recorded by this electrode. Our results point to a linear relationship between BOLD and neuronal activity in hMT+, extending previous findings on primary cortex to higher order cortex