The document discusses the neuronal group selection theory (NGST) as a framework for understanding and treating motor development disorders in children. It outlines various theories of motor development, emphasizing the roles of genetic, experiential, and environmental factors in shaping motor behavior. The document also provides insights into intervention strategies aimed at improving motor function, particularly following early brain injuries.

1. 1
Neuronal Group Selection Theory
A framework for understanding and treating
disordered motor behavior in children
Mohsen Sarhady MSc. OT

2. Outline:
1. The importance of Theory
2. Theories of Motor Development:
Neuromaturation & Dynamic systems
3. NGST: Mechanisms and Processes
4. NGST: Typical Development
5. NGST: Atypical Development
6. NGST: Suggestions for Intervention
2

3. Theory and Practice
3
There is nothing as practical as a good theoryThere is nothing as practical as a good theory
Kurt Lewin

4. Theory and Practice
In General:
A way of seeing the world
A way for gathering an recording data
A way to Influence the world
In Therapy:
A specific way to define the Typical development.
A specific way to define the Atypical development.
A specific way to Intervene.
4

5. History of Developmental Theory
 Two Distinct Point of view:
Nativism: Behavioral (re)actions present at birth and
just need to be unfolded.
Environmentalism: Structure Derives from
experience.
 Different names for an old debate:
Nativism Vs. Epigenetism
Nature Vs. Nurture
Innateness Vs. Environmentalism
Instructionism Vs. Constructivism
Maturation Vs. Learning
5

6. Theories of Motor Development
 The Traditional:
Neuromaturation Theories
 The Contemporary:
Dynamic System Theories
 The Modern:
Neuronal Group Selection Theory
6

7. Neuromaturation Theory
 Typical Development:
 Most Primitive Reflexes to More Intentional Movements
 Lower centers control gradually replaces by Higher Centers
 Proximo-distal and Cephalo-caudal
 Stages and Milestones
 Atypical Development:
 Primitive motor behavior
 Removed higher control and released lower centers
 Delay or inability in acquiring milestones
 Intervention:
 Inhibition-Facilitation
 Sensory Stimulation
 Advancing milestones
7

8. Dynamic Systems Theory
 Dynamic System is Complex
 Dynamic System’s behavior is Non-Linear
 Dynamic System Self-Organizes
 Dynamic System Keep itself in Non-
Equilibrium
8

9. Dynamic System Theory
 Movement is produced from the interaction of multiple sub-systems
within the person, task and environment.
 All of the sub-systems spontaneously self-organize, or come together
and interact in a specific way, to produce the most efficient movement
solution for each specific task.
 No sub-system is most important.
 Development is a non-linear process. movement is not developed in a
continuous manner, at a steady rate. Rather, a small, but critical
change in one sub-system can cause the whole system to shift,
resulting in a new motor behaviour(phase shift).
9

10. Developmental Landscape
10

11. Attractors
11

12. Dynamic Systems Theory and Intervention
 Considering All Interacting systems
 Identifying Constraints
 Identifying Control Parameters
 Perturbing Stable Inefficient State attractors
 Creating new attractor states
 Activity-Focused, Task-Oriented, Function-Based
Intervention
12

13. Before Going Further…
The Bernstein’s Problem and Motor
Development
13

14. 14
Neuronal Group Selection Theory

15. 15
Basic Tenets
1.Development of brain species-specific yet unique
anatomy (Formation of Primary Repertoire(
2.Selection by Experience and formation of Secondary
Repertoire
3.Reentry and Global Mapping

16. 16
Tenet 1:Formation of Primary Repertoire
Genetic code and activity of specific molecules
determine borders of neural areas in the brain.
Neurons compete to make connection.
Diversity results.
The resulting system provides the infant with a primary
repertoire of species-specific yet unique behaviors.

17. 17
Tenet 1 (continued(
In newborns this repertoire includes:
1(orienting the head and eyes toward light
2(bringing the mouth to the hand
3(sucking and rooting on the fist or nipple
4(following moving objects with the eyes
5(preference for the human face
6(projecting the arms toward moving objects
7(kicking
8(orienting the head toward vertical and toward sound

18. 18
Tenet 2:Formation of Secondary
Repertoire by Selection
Experience of spontaneous movement activates sensory
receptors.
Secondary repertoire of functional circuits carve out from the
many existing possible neuronal groups.
Neuronal groups that receive input become more strongly
interconnected through enhancement of pre- and post-
synaptic efficacy.
Neuronal groups are selected that meet task requirements
efficiently.

19. 19
Tenet 3: Reentry and global
mapping
Multiple systems (networks or neuronal groups(
integrate in a distributed whole:
As a result of selection of neuronal groups and their
strengthening through use, maps develop.
These maps connect vast areas of the nervous system such
that perception, cognition, emotion and movement control
are interconnected in the organization of spontaneous
movements or movements in response to environmental
and task demands.

20. 20
Reentry
These reciprocal connections, as they carry action potentials
and modify synaptic strengths, integrate and synchronize the
different activities of various specific brain areas.

21. 21
Principles and mechanisms
1.Epigenesis: development guided by evolution and genetics
but experience expectant
2.Redundancy: isomorphic and isofunctional networks
3.Degeneracy: non-isomorphic but isofunctional networks
4.Selection: experience-dependent or driven
Developmental: temporal correlation of input (neurons fire
together, wire together(
Experiential: change in synaptic power
5.Competition: readjustment of maps
6.Re-entry: process of global maps formation

22. 22
According to NGST:
There is no central controller or instructor.
There are no motor programs.
There are no computations.
Brain development occurs through movement activating sensory
receptors, not in a stimulus-response mode.
The brain is not hard-wired and as a result has both individual
uniqueness and lifelong plasticity.
The degrees of freedom problem in movement control is solved
through selection of the most appropriate neuronal groups, given
the task and current status of the body systems, not through a
computational process.

23. 23
Normal Motor Development
according to NGST
Development of motor behavior has three
phases:
1.Primary Variability
2.Selection
3.Secondary Variability

24. 24
Primary Variability
Non-adaptive or situation-independent activity of epigenetically
determined, grossly specified, primary Neuronal repertoires
Neural system exploration of all motor possibilities available within
neurological and anthropometric constraints set by evolution by
means of self-generated activity and consequently by self-
generated afferent information
Dissection of big networks into several small networks
Abundant variation in motor behavior
Occurring during fetal life and early infancy

25. 25
Selection
Experiential selection of most effective motor patterns and
their associated neuronal groups
Transient minor reduction in motor behavior
Time of selection and duration transition to secondary
variability is function-specific (dependent on task
difficulty(
Occurring during infancy at function-specific ages

26. 26
Secondary Variability
Creation of secondary neuronal repertoire with a large collection of
parallel channels due to exposure to a multitude of experiences
Extensive synaptic rearrangement as a result of synapse formation
and elimination
Variable repertoires with an effective motor solution for each specific
situation
Development of situation specific motor strategies guided by active
trial and error learning
Onset: function-specific from mid-infancy onwards, starting to bloom
at 2-3 years, matures in adolescence

27. 27
Secondary Variability (continued(
Mature Situation
High task constraints: Ability to adapt each movement exactly
and efficiently to task-specific conditions
Low task constraints: Multiple motor solutions or strategies for
a single motor task

28. 28
Development of a movement
repertoire
Schematic diagram of a developing movement repertoire contained in a movement space M. A single
movement within the space is specified by a combination of the movement variable Φ1 andΦ2; it is
represented as a small dot. The dot density represents the frequency with which movements are
executed in a particular region of M. The three frames depict different temporal stages. At the left is the
primary movement repertoire containing several preexistent (or "innate'( movement patterns. The shape
of the movement repertoire evolves with time to include previously unoccupied regions of M or to
exclude others. Hatched regions define movement patterns that correspond to a given task. Movements
within these regions θ meet with positive adaptive value. As a result, their frequency increases. With
time, due to changing environmental and biomechanical constraints, both the movement repertoire and
the regions θ will continue to change shape (see middle and right(.

29. 29
Normal motor development
Neural activity at early age at four
closely spaced points In time.
The filled circles (complete and crossed(
denote neurons genetically
determined to control a specific type
of motor behavior, that is, they
reflect a primary neuronal repertoire.
The open circles represent neurons
genetically linked to other types of
behavior. At the four different points
in time, the filled primary repertoire
is activated in four different
configurations (four different
neuronal groups( (completely filled
circle=active; crossed
circle=inactive(.
This in turn gives rise to primary
variability.

30. 30
Normal motor development
Development proceeds with selection of
the neuronal group, which produces
the most effective behavior
applicable in a wide variation of
conditions.

31. 31
Normal motor development
Next with increasing age, variation
returns, giving rise to the secondary
neuronal repertoire. The variation of
the secondary neuronal repertoire
can best be observed in conditions
lacking tight constraints. in the
absence of specific constraints the
nervous system has access to many
motor solutions for a motor problem.

32. 32
Normal motor development
Yet, in conditions with constraints, a specific
solution produced by the activity of a
specific neuronal group is selected, the
solution being geared to the specifics of
the situation.

33. 33
Normal motor development
Development of postural muscles activity in sitting
infants according to NGST

34. 34
Abnormal Motor Development
according to NGST

35. 35
Abnormal Motor Development
Two groups of developmental movement disorders:
1.Cerebral Palsy
2.Developmental Coordination Disorder
Evidence for damage exists only in 1/3 of DCDs▬► Border-line
CP
Remaining 2/3: dysfunction at the microscopic level of nervous
system (Neurotransmitters or Receptive system(

36. 36
Abnormal Motor Development
Early brain damage results in:
1.Reduced or lost neuronal repertoires:
Large brain damages can result in complete lose of primary
neuronal repertoires.
Small brain damage can result in reduction in primary neuronal
repertoires and in variability of motor behavior.
2.Impaired selection:
Due to deficit in proprioceptive, tactile, or visual information
processing.

37. 37
Abnormal Motor Development
Reduced primary repertoire
Impaired selection due to
disturbed sensory
information processing
Secondary repertoire is equally
reduced as primary
repertoire
Condition specific selection is
hampered

38. 38
NGST and Developmental Motor Disorders
Nervous system Motor dysfunction
Clinical
diagnoses
Deficit in primary variability
No appropriate functional activity in
primary neuronal networks
Very stereotyped motor behavior with virtually no
variation
Postural control: absence of direction specificity
Severe CP
Reduced repertoire of primary
networks
Stereotyped motor behavior with little variation
Postural control: presence of direction specificity,
reduced number of postural variations
Mild to moderate
CP
Complex MND
Deficit in selection
Inappropriate processing of afferent
information
Prolonged persistence of non-adaptive primary
variation in motor behavior
CP (all forms(
Complex MND
Deficit in secondary variability
Inappropriate coordination of
parallel networks of secondary
repertoires
Inappropriate selection of best motor solution for
specific motor tasks
Non-adaptive variations in motor performance
due to non-optimal temporal and quantitative
scaling of motor output
CP (all forms(
Complex MND
Simple MND

39. 39
Characteristics of motor behavior in
developmental motor disorders
First phase: stereotypy with no or little variation;
observable in General movements (GMs( and in
infantile reactions
Second phase: longer duration of and limitation in
selection processes
Last phase: stereotypy, problem in fine tuning and
scaling of motor output, inefficient adaptation to
task conditions

40. 40
Suggestions for Therapeutic Intervention
Interventions based on the NGST aim to
reduce Sensorimotor Dyscoordination

41. 41
Plasticity and recovery after early brain damage
Brain damage at an early age is followed by considerable plastic changes:
The changes are thought to contribute to functional recovery.
The changes vary with the age of the insult and the size of the lesion.
Large plasticity and recovery when the lesion is small and when the lesion
occurs after the completion of neural migration, during the period of
highly active process of dendritic outgrowth and synapse formation.
Considerable plasticity can be expected when lesions occur between
2 to 3 months before and 6 to 8 months after term age

42. 42
Plasticity and recovery after early brain damage
In terms of NGST plasticity could mean that:
The neurons neighboring a lesioned and thus reduced primary
neuronal repertoire change function and become incorporated
into the affected repertoire.
Recovery of the lesion affected function occurs in the form of a
less reduced primary repertoire.

43. 43
Phases of Intervention according to NGST
Two possible phases of intervention:
1.Intervention aiming at an increase of primary
variability and improved selection
2.Intervention aiming at selection out of the variation
of secondary repertoires

44. 44
Putative mechanisms of intervention after brain lesion at early age
NGST suggests that at early age intervention
should focus on augmentation of primary
repertoires.
Plastic changes induced a functional change of
3 neighboring circles with double margins.
Thus, the reorganization resulted in a
restoration of a part of the lost variation.
At older ages, the focus of intervention should
be on the provision of ample opportunities
for active practice, as a richness in
practice might form a compensation for the
impaired selection processes (point of
focus indicated by star symbol(

45. 45
Implications for Practice
Provision of variable but not excessive sensorimotor experiences (e.g. varying
infant’s posture( will increase the primary repertoires.
Frequent and ample opportunities of trial and error experience with considerable
repetition of developmentally appropriate motor skills enhances selection.
Active intensive practice (5 to 7 times per week( results in an enhanced secondary
variability and thus better adapted motor behavior.

46. 46
Implications for Practice (continued(
Repeated experience is necessary to create functional maps than can easily be
accessed by selection for reliable yet flexible motor performance to achieve
multiple functional outcomes.
Movement is the means of activating sensory receptors.
Activity correlates the requirements of body stability, movement strategies, cognition,
memory, experience, and changing environmental demands into a wide variety of
functional, secondary repertoires.
Active self-generated movement strengthens and creates individual neural maps and
more strongly links requirements of postural stability, sensory processing, and
movement patterns to develop flexible action for various tasks.

47. 47
Implications for Practice (continued(
Selection acts to match possible motor commands to constraints posed by body
structure and environment. Varying the environmental constraints and
requirements of various body systems provides increased opportunity for
individuals to select their own strategy to solve motor problems.
Brain damaged children develop only a limited set of global maps with strongly
linked motor synergies that then apply to all tasks. the repeated use of these
limited movement synergies hinders progress in functional skills.
The earlier intervention begins the less likely is the possibility that the child will
form global maps with limited repertoires with poorly organized connections
among selected multiple maps.

48. Thanks to professor Hadders-Algra for reviewing the
presentation slides and useful suggestions.
AND
Thank you ALL for your Attention.
48
Any Question…?

49. 49
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