Task 7 Flashcards
What is the functional principle of fNIRS?
- within near-infrared spectrum, light can penetrate skull and reach considereable depth to allow investigation of the cerebral metabolism
- characterises aletration in intensity of attenuated light at differnet wave lengths (based on changes in oxy-/ and deoxyhemoglobin during neural activity
- limited spatial resolution
What are optodes (in fNIRS)?
- corrosive free sensors
- the lioght source (attached to the participants head)
what are advantages of fNRIS?
- good protability + affordability
- metabolic specificity
- uses corrosive free sensors
- non invasive
- not sensitive to movements
What is the light absorption spectra (in fNIRS)?
- most tissues are transparent to light in the near infrared range (700-1000nm) -> hemoglobin and water absorption are relatively small
- spectral band (= optical window) describes some wave length that is reflected by hemoglobin
What is the relevance of (de)-oxygenated haemoglobin (in fNIRS)?
- in optical imaging changes in optical properties of tissues are tracked using light in the near-infrared range
- oxy/ deoxyhemoglobin have characteristic optical properties in the visible and near-infrared light range
- the change in concentration of these molecules during neurovascular coupling can be measured with optical methods
What is the spatial resolution (in fNIRS)?
- around 1 cm3
- limited depth penetration (max sensitivity at the cortical surface)
What is the temporal resolution (in fNIRS)?
- medium
- hundrets of ms
- limited through hemodynamicdelays (= fMRI)
What are limitations of fNIRS?
- limited spatial resolution
- optode size requires space for emitting and detecting IR light sources
- noise through hair
What is the purpose of BCIs?
- hard/ software system that provides a direct communication link between neural activity of brain and computer sofware components
- can be invasive
What are functional principles of BCI?
replaces involvement of the descending motor pathways, PNS and muscles in the execution of motor tasks
- functional data
- rule-based alogrithms
- machine learning algorithm
- input commands
- sensory feedback
What are suitable brain measures of BCI ?
- EEG
- MEG
- fMRI
- NIRS
What are suitable tasks for BCI?
- EEG - P3 (non-inavsive communication)
- MEG - motor task (real-time BCI)
- FMRI - Prothese (activity in 2 differnet locations) -> challenge = latency of hemodynamic response
- Nirs - P3 (ohne gel) -> TMS as alternatvie
What are paradigms of BCI?
What are encoding strategies of BCI
In BCI: What is the signal to noise ratio?
- in MEG bCI better
What are the data processing steps of BCI?
- multivariate pattern analysis
- machine learning
- statistics
WHat are the relevant outcome measures of BCI?
- decoding accuracy
- speed
What is the practical value of BCIs?
What is the relevance of locked-in-syndrome/ control of external equipment?
- mental drawing article
- BCI rely on brain signals intentionally generated to encode and intention -> communicate yes/no
- fNIRS + mental imagery
- locked in = no body movement + no brain impairment
