SENSOACT · From sensation to action; moving towards advanced neural rehabilitation devices

Final Activity Report Summary - SENSOACT (From sensation to action. Moving towards advanced neural rehabilitation devices)

Traumatic or non-traumatic injury to the neural systems at peripheral, spinal or cortical level may cause permanent loss of voluntary motor function and sensation. For instance, traumatic brain injury or stroke may result in lost sensation and motor functions in large parts of the body, e.g. like drop foot or hemiplegia. Within neural rehabilitation the goal is to replace the lost or impaired communication pathway between the central and the peripheral nervous systems. At the Centre for Sensory-Motor Interaction, Aalborg University, Denmark the aim has been to develop rehabilitation systems that work at the peripheral level to assist or to restore movement. These neural prosthetic systems operate by Functional electrical stimulation (FES) to activate the paralysed muscles and are controlled by interpreting and reacting on sensory information tapped from the peripheral nervous system. An alternative approach is to interface the neural system at cortical level. To restore movement, the systems work by interpreting neural signals derived directly from the motor cortex and turn these into e.g. movement commands for control of a prosthetic limb. To restore sensation, the cortical neural rehabilitation systems use artificially generated, electrical signals to stimulate brain tissue in the part of the sensory cortex. Groups are today working towards restoration of hearing, vision and the feeling of touch. In spite of the many excellent, however preliminary demonstrations of cortical neural rehabilitation devices, the systems are far from being fully optimized, i.e. the applied system technology must be fully implantable and be able to survive the harsh environment of the body for years. Further, the systems must be able to interact with surrounding world and must incorporate signals from intact neural pathways in the central and peripheral nervous system. The objective of this project his project was to assess how multiple sensory stimuli (natural and artificially generated stimuli) affect the sensory-motor transformation processes in awake, behaving rats performing controlled association-response tasks. Our main experimental objective was to investigate if rats were able to perform tactile discrimination based on a natural, tactile input or based on artificially generated sensations. The sensory areas in the brain were interfaced using chronically implanted wire-electrodes and several series of animal experiments were performed. An experimental paradigm was developed, and rats were first trained to touch a spinning wheel and to discriminate between two spinning velocities. Secondly, the tactile stimulation was replaced by direct, intra-cortical stimulation. We demonstrated that rats were able to correctly discriminate between the two spinning velocities (physical stimulation) and during microstimulation (artificial stimulation). The work shows that rats are able to perform tactile discrimination, and it provides further insight into which sensations may be generated by direct cortical stimulation. This work will be important for development of more robust cortical neural rehabilitation systems for e.g. brain or spinal cord injured, that will assist to restore sensation or movement and secure long-term survival, improve daily life quality and minimise hospitalisation costs. The outgoing phase took place between 1 April 2005 - 1 August 2006 at the University of Illinois at Chicago, United States under the supervision of Dr Patrick Rousche. The incoming phase took place between 1 February 2007 to 1 April 2008 at Centre for Sensory-Motor Interaction, Aalborg University under supervision of Dr Ken Yoshida.

Data: CORDIS, © European Union