6 / 60
4
ACQ
Volume 12, Number 1 2010
ACQ
uiring knowledge in speech, language and hearing
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