Motor Learning
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Motor learning refers broadly to changes in an organism's movements that reflect changes in the structure and function of the nervous system. Motor learning occurs over varying timescales and degrees of complexity: humans learn to walk or talk over the course of years, but continue to adjust to changes in height, weight, strength etc. over their lifetimes. Motor learning enables animals to gain new skills, and improves the smoothness and accuracy of movements, in some cases by calibrating simple movements like
reflex In biology, a reflex, or reflex action, is an involuntary, unplanned sequence or action and nearly instantaneous response to a stimulus. Reflexes are found with varying levels of complexity in organisms with a nervous system. A reflex occurs ...
es. Motor learning research often considers variables that contribute to motor program formation (i.e., underlying skilled motor behaviour), sensitivity of error-detection processes, and strength of movement schemas (see motor program). Motor learning is "relatively permanent", as the capability to respond appropriately is acquired and retained. Temporary gains in performance during practice or in response to some perturbation are often termed
motor adaptation Motor adaptation, a form of motor learning, is the process of acquiring and restoring locomotor patterns (e.g. leg coordination patterns) through an error-driven learning process. This type of adaptation is context-dependent and hence, is specifi ...
, a transient form of learning. Neuroscience research on motor learning is concerned with which parts of the brain and spinal cord represent movements and motor programs and how the nervous system processes feedback to change the connectivity and synaptic strengths. At the behavioral level, research focuses on the design and effect of the main components driving motor learning, i.e. the structure of practice and the feedback. The timing and organization of practice can influence information retention, e.g. how tasks can be subdivided and practiced (also see varied practice), and the precise form of feedback can influence preparation, anticipation, and guidance of movement.


Behavioural approach


Structure of practice and contextual interference

Contextual interference was originally defined as "function interference in learning responsible for memory improvement". Contextual interference effect is "the effect on learning of the degree of functional interference found in a practice situation when several tasks must be learned and are practiced together". Variability of practice (or varied practice) is an important component to contextual interference, as it places task variations within learning. Although varied practice may lead to poor performance throughout the acquisition phase, it is important for the development of the schemata, which is responsible for the assembly and improved retention and transfer of motor learning. Despite the improvements in performance seen across a range of studies, one limitation of the contextual interference effect is the uncertainty with regard to the cause of performance improvements as so many variables are constantly manipulated. In a review of literature, the authors identify that there were few patterns to explain the improvements in experiments that use the contextual interference paradigm. Although there were no patterns in the literature, common areas and limitations that justified interference effects were identified: :# Although the skills being learned required whole-body movements, most tasks had a common feature; they all contained components that could be isolated. :# Most of the studies supporting interference effect used slow movements that enabled movement adjustments during movement execution. :# According to some authors bilateral transfer may be elicited through alternate practice conditions, as a source of information can develop from both sides of the body. Despite improvements seen in these studies, interference effects would not be attributed to their improvements, and it would have been a coincidence of task characteristics and schedule of practice. :# The terminology of "complex skills" has not been well defined. Procedural manipulations, which vary between experiments (e.g., changing the similarity between tasks) has been cited as a contributor to skill complexity.


Feedback given during practice

Feedback Feedback occurs when outputs of a system are routed back as inputs as part of a chain of cause-and-effect that forms a circuit or loop. The system can then be said to ''feed back'' into itself. The notion of cause-and-effect has to be handled ...
is regarded as a critical variable for skill acquisition and is broadly defined as any kind of sensory information related to a response or movement. Intrinsic feedback is response-produced — it occurs normally when a movement is made and the sources may be internal or external to the body. Typical sources of intrinsic feedback include
vision Vision, Visions, or The Vision may refer to: Perception Optical perception * Visual perception, the sense of sight * Visual system, the physical mechanism of eyesight * Computer vision, a field dealing with how computers can be made to gain un ...
,
proprioception Proprioception ( ), also referred to as kinaesthesia (or kinesthesia), is the sense of self-movement, force, and body position. It is sometimes described as the "sixth sense". Proprioception is mediated by proprioceptors, mechanosensory neurons ...
and
audition An audition is a sample performance by an actor, singer, musician, dancer or other performer. It typically involves the performer displaying their talent through a previously memorized and rehearsed solo piece or by performing a work or piece giv ...
. Extrinsic feedback is augmented information provided by an external source, in addition to intrinsic feedback. Extrinsic feedback is sometimes categorized as knowledge of performance or knowledge of results. Several studies have manipulated the presentation features of feedback information (e.g., frequency, delay, interpolated activities, and precision) in order to determine the optimal conditions for learning. See Figure 4, Figure 6, and summary Table 1 for a detailed explanation of feedback manipulation and knowledge of results (see below).


Knowledge of performance

Knowledge of performance (KP) or kinematic feedback refers to information provided to a performer, indicating the quality or patterning of their movement. It may include information such as displacement, velocity or joint motion. KP tends to be distinct from intrinsic feedback and more useful in real-world tasks. It is a strategy often employed by coaches or rehabilitation practitioners.


Knowledge of results

Knowledge of results Knowledge of results is a term in the psychology of learning. A psychology dictionary defines it as feedback of information: :"(a) to a subject about the correctness of heirresponses; (b) a student about success or failure in mastering material, o ...
(KR) is defined as extrinsic or augmented information provided to a performer after a response, indicating the success of their actions with regard to an environmental goal. KR may be redundant with intrinsic feedback, especially in real-world scenarios. However, in experimental studies, it refers to information provided over and above those sources of feedback that are naturally received when a response is made (i.e., response-produced feedback; Typically, KR is also verbal or verbalizable. The impact of KR on motor learning has been well-studied and some implications are described below.


= Experimental design and knowledge of results

= Often, experimenters fail to separate the relatively permanent aspect of change in the capability for responding (i.e. indicative of learning) from transient effects (i.e. indicative of performance). In order to account for this, transfer designs have been created which involve two distinct phases. To visualize the transfer design, imagine a 4x4 grid. The column headings may be titled "Experiment #1" and "Experiment #2" and indicate the conditions you wish to compare. The row headings are titled "Acquisition" and "Transfer" whereby: # The acquisition block (2 columns) contains the test conditions in which some variable is manipulated (i.e. different levels of KR applied) and different groups receive different treatments. This block represents the transient effects of KR (i.e. performance) # The transfer block (2 columns) contains the test conditions in which that variable is held constant (i.e. a common level of KR applied; normally a no-KR condition). When presented with a no-KR condition, this block represents the persistent effects of KR (i.e. learning). Conversely, if this block is given to subjects in a format where KR is available, transient and persistent effects of KR are convoluted and it is argued not interpretable for learning effects. After a rest period, the change in the capability for responding (i.e. effects) are argued to be those attributed to learning, and the group with the most effective performance has learned the most.


= Functional role of knowledge of results and potential confounding of effects

= KR seems to have many different roles, some of which can be viewed as temporary or transient (i.e. performance effects). Three of these roles include: 1) motivation, 2) associative function, and 3) guidance. The motivational influence can increase the effort and interest of the performer in the task as well as maintain this interest once KR is removed. Though important to create interest in the task for performance and learning purposes, however the extent to which it affects learning is unknown. The associative function of KR is likely to be involved in the formation of associations between stimulus and response (i.e.,
Law of Effect The law of effect is a psychology principle advanced by Edward Thorndike in 1898 on the matter of behavioral conditioning (not then formulated as such) which states that "responses that produce a satisfying effect in a particular situation become ...
). However, this additional effect is not able to account for findings in transfer tasks manipulating the relative frequency of KR; specifically, decreasing relative frequency results in enhanced learning. For an alternate discussion on how KR may calibrate the motor system to the outside world (see schema theory in motor program). The guidance role of KR is likely the most influential to learning as both internal and external sources of feedback play a guiding role in performance of a motor task. As the performer is informed of errors in task performance, the discrepancy can be used to continually improve performance in following trials. However, the ''guidance hypothesis'' postulates that provision of too much external, augmented feedback (e.g., KR) during practice may cause the learner to develop a harmful dependency on this source of feedback. This may lead to superior performance during practice but poor performance at transfer – an indication of poor motor learning. Additionally, it implies that, as the performer improves, the conditions of KR must be adapted according to the performer’s skill and difficulty of the task in order to maximize learning (see challenge point framework).


Specificity of learning hypothesis

The specificity of learning hypothesis suggests that learning is most effective when practice sessions include environment and movement conditions which closely resemble those required during performance of the task — replicating the target skill level and context for performance.p. 194 It suggests that the benefit of specificity in practice occurs because motor learning is combined with physical practice during the learned sport or skill.p. 90 Contrary to previous beliefs, skill learning is accomplished by alternating motor learning and physical performance, making the sources of feedback work together. The learning process, especially for a difficult task, results in the creation of a representation of the task where all relevant information pertaining to task performance is integrated. This representation becomes tightly coupled with increasing experience performing the task. As a result, removing or adding a significant source of information after a practice period where it was present or not, does not cause performance to deteriorate. Alternating motor learning and physical practice can ultimately lead to a great, if not better performance as opposed to just physical practice.


Physiological approach

The
cerebellum The cerebellum (Latin for "little brain") is a major feature of the hindbrain of all vertebrates. Although usually smaller than the cerebrum, in some animals such as the mormyrid fishes it may be as large as or even larger. In humans, the cerebel ...
and
basal ganglia The basal ganglia (BG), or basal nuclei, are a group of subcortical nuclei, of varied origin, in the brains of vertebrates. In humans, and some primates, there are some differences, mainly in the division of the globus pallidus into an extern ...
are critical for motor learning. As a result of the universal need for properly calibrated movement, it is not surprising that the cerebellum and
basal ganglia The basal ganglia (BG), or basal nuclei, are a group of subcortical nuclei, of varied origin, in the brains of vertebrates. In humans, and some primates, there are some differences, mainly in the division of the globus pallidus into an extern ...
are widely conserved across
vertebrates Vertebrates () comprise all animal taxa within the subphylum Vertebrata () ( chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, ...
from
fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of li ...
to
humans Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, culture, ...
. Through motor learning the human is capable of achieving very skilled behavior, and through repetitive training a degree of automaticity can be expected. And although this can be a refined process much has been learned from studies of simple behaviors. These behaviors include
eyeblink conditioning Eyeblink conditioning (EBC) is a form of classical conditioning that has been used extensively to study neural structures and mechanisms that underlie learning and memory. The procedure is relatively simple and usually consists of pairing an audi ...
, motor learning in the vestibulo-ocular reflex, and
birdsong Bird vocalization includes both bird calls and bird songs. In non-technical use, bird songs are the bird sounds that are melodious to the human ear. In ornithology and birding, songs (relatively complex vocalizations) are distinguished by func ...
. Research on '' Aplysia californica'', the sea slug, has yielded detailed knowledge of the cellular mechanisms of a simple form of learning. A type of motor learning occurs during operation of a
brain–computer interface A brain–computer interface (BCI), sometimes called a brain–machine interface (BMI) or smartbrain, is a direct communication pathway between the brain, brain's electrical activity and an external device, most commonly a computer or robotic l ...
. For example,
Mikhail Lebedev Mikhail Ivanovich Lebedev (russian: link=no, Михаил Иванович Лебедев) (4 November 1811 – 13 July 1837) was a Russian painter. Biography Lebedev was born in Dorpat into the family of an impoverished serf. In the 1820s, se ...
,
Miguel Nicolelis Miguel Ângelo Laporta Nicolelis, M.D., Ph.D. (, born March 7, 1961), is a Brazilian scientist, physician and Duke School of Medicine Professor in Neuroscience at Duke University, best known for his pioneering work surrounding brain-computer i ...
and their colleagues recently demonstrated
cortical plasticity Neuroplasticity, also known as neural plasticity, or brain plasticity, is the ability of neural networks in the brain to change through growth and reorganization. It is when the brain is rewired to function in some way that differs from how it ...
that resulted in incorporation of an external actuator controlled through a brain–machine interface into the subject's neural representation. At a cellular level, motor learning manifests itself in the
neurons A neuron, neurone, or nerve cell is an electrically excitable cell that communicates with other cells via specialized connections called synapses. The neuron is the main component of nervous tissue in all animals except sponges and placozoa. N ...
of the
motor cortex The motor cortex is the region of the cerebral cortex believed to be involved in the planning, control, and execution of voluntary movements. The motor cortex is an area of the frontal lobe located in the posterior precentral gyrus immediately ...
. Using single-cell recording techniques, Dr. Emilio Bizzi and his collaborators have shown the behavior of certain cells, known as " memory cells," can undergo lasting alteration with practice. Motor learning is also accomplished on the
musculoskeletal The human musculoskeletal system (also known as the human locomotor system, and previously the activity system) is an organ system that gives humans the ability to move using their muscular and skeletal systems. The musculoskeletal system prov ...
level. Each
motor neuron A motor neuron (or motoneuron or efferent neuron) is a neuron whose cell body is located in the motor cortex, brainstem or the spinal cord, and whose axon (fiber) projects to the spinal cord or outside of the spinal cord to directly or indirectl ...
in the body innervates one or more muscle cells, and together these cells form what is known as a motor unit. For a person to perform even the simplest motor task, the activity of thousands of these motor units must be coordinated. It appears that the body handles this challenge by organizing motor units into modules of units whose activity is correlated.


Disordered motor learning


Developmental coordination disorder

Impairments associated with
developmental coordination disorder Developmental coordination disorder (DCD), also known as developmental motor coordination disorder, developmental dyspraxia or simply dyspraxia from the word 'praxis' meaning to do or act, is a neurodevelopmental disorder characterized by impair ...
(DCD) involve difficulty in learning new motor skills as well as limited postural control and deficits in sensorimotor coordination. It appears that children with DCD are not able to improve performance of complex motor tasks by practice alone. However, there is evidence that task-specific training can improve performance of simpler tasks. Impaired skills learning may be correlated with brain activity, particularly, a reduction of brain activity in regions associated with skilled motor practice.


Apraxia

Motor learning has been applied to stroke recovery and neurorehabilitation, as rehabilitation is generally a process of relearning lost skills through practice and/or training. Although rehabilitation clinicians utilize practice as a major component within an intervention, a gap remains between motor control and motor learning research and rehabilitation practice. Common motor learning paradigms include robot arm paradigms, where individuals are encouraged to resist against a hand held device throughout specific arm movements. Another important concept to motor learning is the amount practice implemented in an intervention. Studies regarding the relationship between the amount of training received and the retention of the memory a set amount of time afterwards have been a popular focus in research. It has been shown that over learning leads to major improvements in long term retention and little effect on performance. Motor learning practice paradigms have compared the differences of different practice schedules, and it has proposed that repetition of the same movements is not enough in order to relearn a skill, as it is unclear whether true brain recovery is elicited through repetition alone. It is suggested that compensation methods develop through pure repetition and to elicit cortical changes (true recovery), individuals should be exposed to more challenging tasks. Research that has implemented motor learning and rehabilitation practice has been used within the stroke population and includes arm ability training,
constraint-induced movement therapy Constraint-induced movement therapy (CI, CIT, or CIMT) is a form of rehabilitation therapy that improves upper extremity function in stroke and other central nervous system damage patients by increasing the use of their affected upper limb.
, electromyograph-triggered neuromuscular stimulation, interactive robot therapy and virtual reality-based rehabilitation. A recent study ischemic conditioning was delivered via blood pressure cuff inflation and deflation to the arm, to facilitate learning. It showed for the first time in humans and animals, that ischemic conditioning can enhance motor learning and that the enhancement is retained over time. The potential benefits of ischemic conditioning extend far beyond stroke to other neuro-, geriatric, and pediatric rehabilitation populations. These findings were featured on Global Medical Discovery news.


See also

*
Apraxia Apraxia is a motor disorder caused by damage to the brain (specifically the posterior parietal cortex or corpus callosum), which causes difficulty with motor planning to perform tasks or movements. The nature of the damage determines the disorde ...
* Bayesian inference in motor learning *
Brain–computer interface A brain–computer interface (BCI), sometimes called a brain–machine interface (BMI) or smartbrain, is a direct communication pathway between the brain, brain's electrical activity and an external device, most commonly a computer or robotic l ...
* Cephalocaudal and proximodistal trends * Cognitive science *
Motor skill A motor skill is a function that involves specific movements of the body's muscles to perform a certain task. These tasks could include walking, running, or riding a bike. In order to perform this skill, the body's nervous system, muscles, and br ...
*
Motor coordination Motor coordination is the orchestrated movement of multiple body parts as required to accomplish intended actions, like walking. This coordination is achieved by adjusting kinematic and kinetic parameters associated with each body part involved in t ...
*
Muscle memory Muscle memory is a form of procedural memory that involves consolidating a specific motor task into memory through repetition, which has been used synonymously with motor learning. When a movement is repeated over time, the brain creates a long-t ...
*
Procedural memory Procedural memory is a type of implicit memory ( unconscious, long-term memory) which aids the performance of particular types of tasks without conscious awareness of these previous experiences. Procedural memory guides the processes we perform ...
*
Sequence learning In cognitive psychology, sequence learning is inherent to human ability because it is an integrated part of conscious and nonconscious learning as well as activities. Sequences of information or sequences of actions are used in various everyday tas ...


References


Further reading

* * * * * * * *
Iaroslav Blagouchine and Eric Moreau. ''Control of a Speech Robot via an Optimum Neural-Network-Based Internal Model With Constraints.'' IEEE Transactions on Robotics, vol. 26, no. 1, pp. 142—159, February 2010.


External links


Center For Integration Of Medicine And Innovative Technology

New Schema Perspectives
* Speech-Language Pathology/Stuttering/Fluency-Shaping Therapy/Motor Learning and Control - Wikibooks {{DEFAULTSORT:Motor Learning Memory Cognition Motor skills Nervous system Motor control