Developing a “hands-free” neuroprosthesis command system Peter Boord, Ashley Craig*, Andrew Barriskill, Hung Nguyen University of Technology, Sydney, NSW, Australia Introduction People with spinal cord injury (SCI) face significant lifestyle challenges. Loss of independence due to the SCI can often be associated with depressive illness, pain, high levels of anxiety, frequent hospitalisation, drug dependency and so on (Craig & Hancock, 1998; Craig et al., 2002). They face severe restrictions on their ability to perform basic activities of daily living such as eating and drinking, and being wheelchair-bound restricts the user to limited terrains. Functional Electrical Stimulation (FES) involves developing technology that has the potential to help overcome some of these problems. For example, FES has been used to restore standing and stepping in people with paraplegia (Triolo & Bogie, 1999). Restoring leg movement using FES raises the problem of how the restored function is to be operated by the user. In many cases it is not possible for the person to operate a command system using their hands. Brain-Computer Interfaces (BCIs) provide a “hands-free” means of controlling electrical devices and is believed to have significant potential for the operation of neuroprostheses. The purpose of this paper is to evaluate briefly the ability of BCI interfaces to fulfill the requirements of neuroprosthetic applications, and highlight the potential of an EEG 8-13 Hz wave (called the Mind Switch) interface with an FES application. FES command interface requirements All lower-body FES systems currently require the use of a walking frame or crutches, and frequently involve the application of large forces through both arms to support the body against collapse. With both hands involved in the demanding task of postural support it is difficult for the person to issue commands to the FES system using their hands. Furthermore, as developments reduce the need for postural support it will be desirable to keep the hands free to perform tasks while standing. This raises the possibility of switch interfaces that do not require or involve arm/hand activity. The status of development of lower extremity neuroprostheses has been reviewed by Triolo & Bogie (1999) and includes systems for standing, transfers, stepping, stair climbing/descending and bladder control. There are many degrees of freedom involved in the control of lower extremity FES tasks. Each function involves electrical stimulation applied to appropriate muscles in a specific sequence. Due to the complexity of this task, and the need to ensure user safety, the stimulation sequence is handled automatically, without the need for intervention from the user. However, the task of the user is to select a pre-programmed sequence to achieve a desired result, such as taking a step forward. Therefore, the primary nature of a lower extremity FES command system is to provide switches for selection, execution, and termination of these sequences. Graded or proportional command sources would also be useful for setting commands such as the angle of a turn, or the height of a step to be taken. Brain-computer interfaces (BCIs) BCIs offer “hands-free” control by allowing the user to employ their brain signals as a switch. The principle of BCI control is that a person can voluntarily change, or learn to change, neuronal activity in their brain. The brain activity generally used is the electroencephalogram (EEG) that is measured using surface electrodes. Detection of a specific change is then used to control some device. This general criterion has resulted in a wide variety of different strategies for BCIs (Wolpaw et al., 2000). BCI development has mainly focused on applications for