ACQ Vol 12 no 1 2010

monkeys, firing of mirror neurones has been shown to increase learning and success in new motor activities without the monkey actually practising the task concerned (Rizzolatti & Craighero, 2004). The existence of these neurones would partially explain why modelling is an effective and natural part of many motor interventions and why imagining yourself completing an action can improve performance on this action, a concept well known in elite sports. Indeed, work in people with stroke has suggested that improved motor performance can be achieved through detailed imagining of movement (e.g., Yoo, Park, & Chung, 2001). In addition, one PML suggests that watching someone else learn how to do a task is more efficient than an expert modelling the behaviour (Hebert & Landin, 1994) and this principle may be explained by mirror neurones. It is possible that watching someone else learn leads the mirror neurones to simulate learning the action. Thus in the future we may develop a theoretical rather than economic justification for group intervention. Integral stimulation (Strand & Skinder, 1999) is an example of a treatment which uses these hypothesised mirror neurones to aid learning. Two principles of this approach that may utilise mirror neurones include: 1) the clinician should sit very close to and directly opposite the patient so that the clinician’s face occupies most of the patient’s visual field, and 2) in the early stages of treatment, the clinician and patient say the target sounds simultaneously. Conclusions There are other areas of emerging knowledge for which we do not have space in this paper, but which are equally fascinating. These include constraint induced change, transcranial magnetic stimulation (as described in Goozée, this issue), and the role of the undamaged hemisphere in inhibiting recovery from brain damage. It is exciting to see areas of speech pathology practice that have been relatively dormant changing through the newly available understanding of how skilled movement is learnt and how the brain functions. Watch this space. References Ballard, K.J., Robin, D.A., McCabe, P.J., & McDonald, J. (2009). Treating dysprosody in childhood apraxia of speech . Paper presented at Speech Pathology Australia Annual National Conference, May 2009, Adelaide. Doidge, N. (2007). The brain that changes itself . Melbourne: Scribe. Hebert, E. P., & Landin, D. (1994). Effects of a learning model and augmented feedback on tennis skill acquisition. Research Quarterly for Exercise & Sport , 65 , 250–257. Hodges, N. J., & Lee, T. D. (1999). The role of augmented information prior to learning a bimanual visual-motor coordination task: Do instructions of the movement pattern facilitate learning relative to discovery learning? British Journal of Psychology , 90 , 389–403. Iacobini, M. (2005). Neural mechanisms of imitation. Current Opinion in Neurobiology , 15 (6), 632–637. Maas, E., Robin, D. A., Austermann Hula, S. N., Freedman, S. E., Wulf, G., & Ballard, K. J. (2008). Principles of motor learning in treatment of motor speech disorders. American Journal of Speech-Language Pathology , 17 (3), 277–298.

carrier structure. In this way we can use recent theoretical research to guide practice in the absence of higher level evidence. Neural plasticity The two-cutting edge research areas presented here, neural plasticity and mirror neurones, underpin PML and provide new ways of thinking about motor based intervention across the board. The concept of neural plasticity is one which has emerged in neurology in the past few years and is the focus of a recent popular science book The Brain That Changes Itself (Doidge, 2007). As late as the early 1990s it was widely believed that the brain did not repair itself after stroke or head injury, but we now know that brains have both adaptive and maladaptive repair processes operating continuously which can be harnessed in the rehabilitation process. Neural plasticity refers to these constantly engaged adaptive processes which allow us to learn new skills as a result of sensory input. This sensory information comes from our five primary senses but also, and importantly for motor learning, from our proprioception system including stretch receptors in muscles. When we damage our brains, or the sensory inputs to them, these adaptive processes continue to function and react to the distorted sensory input produced by the damage. This means that in the absence of normal function (motor or otherwise), the brain starts to use the available, but incorrect, information as the input and thus to lay down new learning based on this distorted input. The result is shifting of allocation of neurological resources, learning of new and disabling motor patterns, and ongoing loss of function. The longer this disrupted learning continues, the “better” these maladapted motor patterns are learnt (Pascual-Leone, Amedi, Fregni, & Merabet, 2005). It now seems clear that rehabilitation should start on renewal of competent function as soon as possible and certainly within days of the initial neurological insult as the brain starts to change within 3–4 days of the changed input. To delay is to allow maladaptive learning to take place through reduced sensory input and through new motor patterns which may be created by compensatory strategies. In physiotherapy this means that comatose patients may have their limbs moved and muscles stretched and this not only helps prevent deep vein thrombosis (a medical goal) but also provides the brain with sensory input. This input is thought to help maintain brain function for the inert limbs and to prevent maladaptive neural plasticity from using the part of the sensory motor cortex allocated for the limb concerned for another function. So how will neural plasticity change speech pathology practice? We might hypothesise that research will show that in treatment of dysarthria, the sooner you start near normal behaviours the better, or that with adults we need to use errorless learning so that maladaptive neurological changes are suppressed. Neural plasticity is emerging as a strong argument for both early and continued high frequency intervention in all aspects of motor learning. Mirror neurones Researchers are interested in a neurological construct known as “mirror neurones”. Mirror neurones fire when we watch someone else do an action and when we hear a sound commonly associated with an action (Iacobini, 2005). In

4

ACQ Volume 12, Number 1 2010

ACQ uiring knowledge in speech, language and hearing