Skilled MovementDifferent exercises demand an array of different & (semi-?) skilled movements

Different sports demand a huge array of different & highly skilled movements

Specific sports skills are nothing more than highly controlled specific physical movements with specific demands:

precision . efficiency . repeatability

The more complex the sport, the greater demands for skill…

NEUROLOGICAL BASIS OF SKILL

Environmental stimuli – select behavior – activate pre-motor – primary motor – muscles

Some Important Parts of the Brain

Limbic (another very important) System of the Brain

The limbic system isresponsible for generatingour emotional feelings (pleasure, frustration, anger) based on our cognitive interpretation of our environment

Substantia nigra

Caudate

PutamemGlobus Pallidus

Basal Ganglia is part of the limbic system

Ventral tegmentalarea

Locus coeruleus

Kinesthetic PerceptionSensory areas of the brain receive input from nerve fibers which originate from different types of receptors (touch, visual, auditory, pain, taste).

Sensory nerves originating from Pacinian corpuscles in the skin (mechanoreceptors) respond to touch.

Sensory nerves originating from proprioceptors

in the joints respond to “angle-specific pressure”

A-delta nerves originating from free nerve endings (Noci receptors) respond to tissue damage.

Our sensory nerves inform our brain about our physical environment

Primary (SI) and secondary (SII) sensory cortex involved with the localization of pain

Anterior portion of insular is most likely concerned with pain perception

All sensory information is relayed throughout different parts of the brain and our conscious interpretation of the stimuli generates a physical and emotional response which we “feel”:

body/joint position, body and/or limb movement, well-being, nausea, pain …

happy, sad, frustration, disappointment, joy, ecstasy, anger …

Our CNS response to stimuli also includes (selective) changes in the (autonomic) sympathetic and parasympathetic nerve pathways; selective changes based on our interpretation of the stimuli.

Skill PerformanceEnvironmental stimulus

visual . auditory . kinesthetic .

Select skill from memoryhippocampus . cerebrum . cerebellum .

(conscious) (unconscious)

Initiate skillfrontal cortex . pre-motor cortex . motor cortex .caudate . substantia nigra .

Perform skillfrontal cortex . pre-motor cortex . motor cortex .basal ganglia . reticular formation .

Performance of a Skill

Analyze and activate memories of the array of possible motor responses to the current environmental stimuli.

Select appropriate motor response and activate the pre-motor cortex to initiate the selected movement patterns via the motor cortex.

Basal ganglia (esp. caudate nucleus and substantia nigra) help coordinate activation of the appropriate motor neurons.

Performance of a Skill

All sensory inputs are coordinated by reticular formationand basal ganglia and transmitted to frontal cortex.

Sensory input is unconsciously compared to sensory memory and adjustments are made “as-you-go”.

Simultaneously, conscious image of movement (based on sensory input) is compared to conscious memory of what we should look like while we do it and we make conscious adjustments to mimic the conscious memory of the skill.

Integration of conscious and subconscious adjustments based on conscious and subconscious memories of the performance result in the actual performance.

Learning and memory play a very important role in how we develop skills (and behaviors)

The most basic connection between behavior and memory is that we desire to perform behaviors which produce responses that we want….if we can’t remember that a particular behavior resulted in a desirable outcome, there is little chance we will seek out to repeat the same behavior.

In addition, if a particular behavior results in an unpleasant experience, there is a strong likelihood that we will avoid that behavior.

On the other hand, if a behavior is not particularly pleasant, but does result in a highly desirable outcome, there is a high likelihood that the unpleasant behavior will be continued in order to get the pleasant payoff.

Memory, Learning & Behavior

Memory

A “memory” is not a discrete location in the brain made up of a cluster of cells which are independent of other cells.

A “memory” is actually comprised of a “pattern” of nerve-cell activities made up of interconnected nerve cells which are scattered throughout the cerebral cortex. These cells are in turn interconnected to all other brain cells.

Memory/Learning

We do not remember facts as discrete pieces of independent information.

We have memories of “facts” only in association with other memories.

We develop new memories only in association with existing memories.

New memories are created by rearranging existing patterns of activated nerve cells into new patterns of activity.

This process demands synthesis of new proteins in “some” nerve cells to modify their ability to be activated by other nerves and thereby create a new patterns of activation.

Memory/Learning

Learning

Parts of the brainthat are importantfor learning.

Memory & Skill

Sensory memories of physical movements are stored as patterns of neural activity in the cerebellum and are developed in much the same way as factual memories.

Learning

Hippocampus coordinates and integrates all incoming environmental stimuli with existing memories that correspond to the stimuli so we can identify (threats?) and act accordingly;

activating ALL of them

– we then pay attention to those that we recognize and are “important” to us

Learning

New memory is constructedbased on novel stimulus incomparison to existingmemory.

“Strength” of the memory isdependent on the frequencyand strength of the neural activity.

The learning process demands synaptic remodeling: the development of “new active” synapses between existing nerves in order to produce the new patterns of neural activity.

In order to do this a host of proteins that stimulate nerve-growth must be produced and maintained for many hours:New Proteins: (synapsin I, synaptotagmin, syntaxin, and integrins, among others);

Activate enzymes of the signal transduction pathways: (Ca2+/calmodulin-dependent protein kinase II, CaM-KII; mitogen-activated/extracellular signal-regulated protein kinase, MAP-K/ERK I and II; protein kinase C, PKC-δ);

Activate DNA-binding proteins (transcription regulators): (cyclic AMP response element binding protein - CREB, Brain-derived neurotrophic factor - BDNF)

How Does this Work?

ActiveSynapse

InactiveSynapse Synaptic Remodeling

Synapse

After sufficient amounts of new growth signals have been produced …

&

… they remain elevated long enough in the “stimulus-memory specific” activated nerve pathways:

… a new memory is formed

How Does this Work?

The new memory can now be activated either through the “novel” stimulus or through the associated memory.

We remember facts as pieces of “information” in relation to other pieces of “information” which in turn are related to other …

Learning & Memory

Because we construct and remember “facts” in relation to other “facts” that in turn are related to other “facts” …

The greater the number of interconnected pathways that “intersect” the “new memory” – the easier it is to recall the “new memory”

Learning & Memory

Put it all together and you get …

Analyze and activate memories of the array of possible motor responses to the current environmental stimuli.

Select appropriate motor response and activate the pre-motor cortex to initiate the selected movement patterns via the motor cortex.

Basal ganglia (esp. caudate nucleus and substantia nigra) help coordinate activation of the appropriate motor neurons.

All sensory inputs are coordinated by reticular formationand basal ganglia and transmitted to frontal cortex.

Sensory input is unconsciously compared to sensory memory and adjustments are made “as-you-go”.

Simultaneously, conscious image of movement (based on sensory input) is compared to conscious memory of what we should look like while we do it and we make conscious adjustments to mimic the conscious memory of the skill.

Integration of conscious and subconscious adjustments based on conscious and subconscious memories of the performance result in the actual performance.

So…

Skills such as running & cycling (and a whole lot more) are actually just programmed memories that are activated by a variety of stimuli; such as:

got to catch the bus…

starters pistol goes off at the beginning of a race…

PE teacher tells you to run for a standardized test… and so on.

Physical exercise is important for learning as illustrated in the following slides…

But… how do things work when there isno memory of a skill to recall???

Well… Here are some thoughts:And some important brain areas that might relate…

Frontal lobe of cerebral cortex- conscious thought- voluntary initiation of movement

Basal ganglia: caudate nucleus, substantia nigra, putamen, globus pallidus, (and the reticular formation)

- subconscious initiation of movement- subconscious control of movement- learning of habits- part of limbic system

Limbic system: amygdala, hippocampus, hypothalmus, nucleus accumbens, piriform cortex, olfactory tubercle, striatum, septum

- generation of emotional responses based on:- integration of unconscious sensory input and conscious interpretation of sensory input and conscious interpretation of the appropriateness of the feelings

Some Norepinephrine - Releasing Pathways

LocusCoeruleusHippocampus

Amygdala

CerebralCortex

Cerebellum

Hypothalmus

Arousal

Neurotransmitter Release

Some Dopamine - ReleasingPathways

VentralTegmental

Area

CaudateNucleus

Putamen

Globus Pallidus

Substantia Nigra

Piriform Cortex

NucleusAccumbens

Amygdala

Septum

Hypothalmus Pituitary

Some FrontalCortex

Striatum

What’s up with all this stuff about neurotransmitters?…

What do they have to do with a lack of skill?

Well …They affect membrane potentials and cell function …

Dopamine release into the nucleus accumbens by neurons originating in the ventral tegmental area usually leads to inhibition (Cl- influx = IPSP) and feelings of mild pleasure or reduced anxiety and frustration…

Enhanced norepinephrine release by nerves originating in the locus coeruleus leads to stimulation (usually Na+ influx = EPSP) of a variety of brain areas associated with arousal (heightened ability to focus), pleasure, and maybe even enhanced learning.

Norepinephrine (or the hormone; epinephrine) makes nerve cells easier to be stimulated and dopamine makes cells harder to be stimulated.

Dopamine release into the caudate, globus pallidus, and putamen inhibits the activation of motor pathways to prevent unwanted movement. When the dopaminergic pathways are damaged and dopamine cannot be released, Parkinson’s Disease is the result – a condition when motor pathways are not properly inhibited; producing less-than-perfect motor control.

When too much epinephrine is present, inappropriate activation of the motor pathways may occur, again, resulting in less-than-perfect motor control.

Now consider a new-born… obviously there is no skill…

Imagine the mostly random arm, leg and head movements whenever there is any stimulation (no selective inhibition by dopamine). Now imagine the much faster random movements when excited (epinephrine effects); say, when mommy or daddy are successfully entertaining the little thing.

It takes many months for the random arm movements to be refined into grabbing and pointing movements and each time attempts are made, conscious efforts to figure out how to control the movements also are made.

This self-discovery of more efficient movements eventually leads to an array of somewhat efficient movements that are stored as motor memories and integrated with the sensory memories of those movements.

These initial motor memories form the building blocks of various motor skills such as standing, creeping, walking, and grabbing anything and putting it in your mouth.

From the preceding, there is essentially a progression from:

Complete conscious control over movements as they are being discovered – a time-consuming and inefficient process…

To

A combination of mostly conscious with some subconscious control as new movement skills are developed on the basis of learned ones…

To

A combination of conscious and subconscious control as complex movement skills are developed on the basis of learned complex skills…

To

A combination of subconscious control with some conscious control as complex movement skills are refined…

In other words… learning of motor skills is a constant dynamic process of continually modifying learned motor memories in order to develop more refined motor memories that are easily recalled and efficiently executed.