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Biomedical subjects

N Ghanayim

Publications and source records attributed to N Ghanayim.

6 recordsLinked to original sources
PubMed2001

Self-initiation of EEG-based communication in paralyzed patients.

OBJECTIVES: Severely paralyzed patients could learn to voluntarily generate slow cortical potential (SCP) shifts in their electroencephalogram and to use these signals to operate a communication device. To enhance the patients' autonomy, the present study describes the development of a permanently available communication system that can be turned on and off by locked-in patients without external assistance. A skill necessary for turning the system on is the ability to regulate one's slow potentials in the absence of continuous feedback. METHODS: A stepwise learning approach was employed to train two paralyzed patients to regulate their SCPs without continuous feedback. Elements of the original communication system were gradually removed and elements of the new stand-by mode were introduced. RESULTS: At the end of the learning procedure, both patients achieved correct response rates of above 84% in training sessions without continuous feedback. This skill enabled them to turn the communication device on and off without assistance from others. CONCLUSIONS: These findings suggest that severely paralyzed individuals can learn to operate an EEG-based communication device autonomously.

Adult↗
PubMed2000

The thought translation device (TTD) for completely paralyzed patients.

The thought translation device trains locked-in patients to self-regulate slow cortical potentials (SCP's) of their electroencephalogram (EEG). After operant learning of SCP self-control, patients select letters, words or pictograms in a computerized language support program. Results of five respirated, locked-in-patients are described, demonstrating the usefulness of the thought translation device as an alternative communication channel in motivated totally paralyzed patients with amyotrophic lateral sclerosis.

Biofeedback, Psychology↗
PubMed1999

The thought translation device: a neurophysiological approach to communication in total motor paralysis.

A thought translation device (TTD) for brain-computer communication is described. Three patients diagnosed with amyotrophic lateral sclerosis (ALS), with total motor paralysis, were trained for several months. In order to enable such patients to communicate without any motor activity, a technique was developed where subjects learn to control their slow cortical potentials (SCP) in a 2-s rhythm, producing either cortical negativity or positivity according to the task requirement. SCP differences between a baseline interval and an active control interval are transformed into vertical or horizontal cursor movements on a computer screen. Learning SCP self regulation followed an operant-conditioning paradigm with individualized shaping procedures. After prolonged training over more than 100 sessions, all patients achieved self-control, leading to a 70-80% accuracy for two patients. The learned cortical skill enabled the patients to select letters or words in a language-supporting program (LSP) developed for inter-personal communication. The results demonstrate that the fast and stable SCP self-control can be achieved with operant training and without mediation of any muscle activity. The acquired skill allows communication even in total locked-in states.

Adult↗
PubMed1998

Self-regulation of slow cortical potentials in completely paralyzed human patients.

The study was intended to answer the question whether self-regulation of brain activity can be operantly learnt when the brain is disconnected from motor periphery. Two neurological patients with nearly complete motor paralysis learned bi-directional control of their slow cortical potentials (SCP) at vertex. After 4-6 weeks training both patients could reliably differentiate between SCP shifts in a negative versus positive direction. With one patient, training has been continued for a subsequent 4 months, which resulted in precise self-control, i.e. the patient was able to produce positive SCP shifts on command with an accuracy of about 95%. This indicates that self-regulation of cortical excitability (as manifested in the SCP) does not require feedback loops from the periphery. Although we cannot rule out that healthy subjects may employ behavioral strategies such as muscle contractions or changes in breathing, obviously humans can also control their SCP without using these strategies.

Adult↗