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| Frage | Antworten |
| What is a brain controlled interface? | A motor/effector which is controlled directly by the nervous system |
| Give the two different types of brain control interfaces, and describe each of them. | Detection of mental states- the subject makes a thought and the associated brain activity is recorded and given a label on a computer. the computer then knows to associate this thought with a certain action. Operant conditioning- the computer is looking for a specific brain pattern and the subject has to create this brain pattern as best they can until the computer picks it up. |
| Describe the general characteristics of a slow cortical potential | positive or negative change in cortical polarisation. Last between 300ms to 1-2 seconds. Influenced by movement and relaxation |
| Explain how someone might use slow cortical potentials to help with medical conditions | Epileptics can use this as a biofeedback mechanisms and learn to control unwanted activity |
| Give the type of EEG potential that would be used to set up communication with a 'locked in' patient. | Slow cortical potentials |
| What is a P300 evoked potential? | A change in EEG activity associated with a specific stimulus |
| Describe the process of how a P300 could be used to interpret a word people are thinking of. | Letters arranged into a grid are shown. An individual grid or column is flashed up and the subject must look for the next letter of their word. When the letter is flashed up a p300 potential is seen on the EEG reading so we know that letter was seen. From deduction we are able to make out what letter was chosen and eventually make a word. |
| Describe how EEG could be used to look movement related changes in beta activity, and give a paper which supports this and give its findings. | Use frequency analysis, as movements are associated with changes in EEG frequency content. Wolpaw et. al 2002, found that beta activity decreased just before movement was made, termed the event related desynchronisation |
| What evidence is there that movements could be controlled using a brain controlled interface? | when movements are just imagined, event related desynchronisation still occurs therefore changes in EEG can be used to start or stop movements of an external motor/effector |
| Give limitations for using EEG for brain control interfaces | Requires placement of electrodes before each session taking time and gell is messy. Low spatial resolution. Potential of artifacts forming when moving or speaking. noisy signals which needs averaging several time (takes time). Limited number of control commands can be setup. Relatively slow as participant needs time to form the image in their head |
| EEG has limitations for brain control interfaces, suggest two other techniques which is similar to EEG. Give positives and negatives of each alternative method and studies which assessed these techniques | ECoG - increased spatial resolution as no skull in the way, but potential for scar tissue to form between electrodes and brain damaging the connection. Leuthardt 2004 found ECoG showed positive results and activity changed with imagined movement or speech. Single unit recording- even better spatial resolution but only looks at small brain area. Need to have a good idea of the brain area that will be activated. Hochberg et al, 2006 looked at single unit recording paraplegic human Found there was still a drop in the beta frequency after a go signal was given. |
| Describe the Hochberg 2006 study. | Used single unit recording as a potential way of BCI in a paraplegic man. It has been 3 years since his injury, a 96 electrode array was used (really tiny) which provided single unit activity giving high resolution when put through a high pass filter. local field potential were seen, and beta activity decreased when go command was given. Neural tuning of cells was seen indicating different brain areas are linked with specific actions and therefore can be used to control BCI |
| What is directional tuning? | where specific neurones are associated with specific activies, e.g. one brain area is associated with movement of your little finger. This means we can associate neural activity with a motor/effector for BCI |
| Suggest what technique is used for mind reading, and define what mind reading actually is. | fMRI. The ability to make inferences about a persons state of mind based upon recorded neural signals (usually BOLD signals) |
| Give the principle behind neurofeedback. | We establish a 'good' EEG pattern associated with a good performance, and then make performers aware of what their EEG should look like so they are able to try and achieve this EEG signal in the hope it will mean they give a good performance. |
| Which study showed that brain activity can be modulated by neurofeedback. | Ros et. al 2010 |
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