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Lecture

Kinesiology 1080A/B Lecture Notes - Ideomotor Apraxia, Closed Head Injury, Combined Oral Contraceptive Pill


Department
Kinesiology
Course Code
Kinesiology 1080A/B
Professor
Matthew Heath

Page:
of 4
Kinesiology 1080 Feb. 6, 2013
Apraxia: a disorder of learned, skilled purposeful movement not related muscle paralysis or
comprehension deficits:
Ideational apraxia: it is the inability to evoke the appropriate action representation from
long-term memory; they are unable to produce memories to allow them to produce
movement (eg. Picking up a glass of water, they literally forget how to move)
Ideomotor apraxia: It is the inability to translate the appropriate innervatory patterns
into action (eg. Picking up a cup of water: they know exactly how to do it, but cannot
use their knowledge to produce the movement they can’t translate knowledge into
the neural signals to produce that movement
This can be both chronic (long-term) or short-term
New form of Apraxia: Case of CK
- This is due to a large stroke in the front parietal lobe from possibly taking birth control
pills
- The patient was able to demonstrate actions from memory and off of imitation, but as
soon as an object was placed in her hand to perform the movement, her movement
become unbalanced and uncontrolled
Somatosensory form of Apraxia
It is the most profound type of apraxia
This is because it has impaired her ability to perform movements in her left and right
hand
Since the parietal lobe is sensory to motor interface, it could be that her
somatosensory system is too highly tuned leading to amplified signals, thus, the
motor system does not know what to do and the movement becomes
uncoordinated and uncontrolled
Therefore, a lesion to the right parietal lobe leads to a deficit to the sensory motor
interface Apraxia is believed to be the result of closed head injury
Dyspraxia: Developmental in nature
- It is a developmental coordinate disorder (DCD) “clumsy children” dyspraxic
movement impairment
- It is a soft issue related to the development of the cortex; no stroke is involved
- DCD it is generally identified because of the characteristic deficit to the timing of
movement
- It is very evident in spoken language
- As the individual grows older, they are usually able to grow out of it as their system
develops
Cerebral Asymmetries in Down Syndrome
Down syndrome characteristics:
Individuals have a much smaller brain, probably to match their the size of the body
because they are generally smaller Too small for their age
The cerebellum is particularly smaller
Behavioural Characteristics:
Approximately 90% of the people are right-hand dominant
Out of those 90%, 99% of them are left-hemisphere dominant for speech and
language
90% of left-hand dominant also have speech and language lateralized to the left-
hemisphere
Approximately, 50% of the people with down syndrome are left-handed
Linkage between hand dominance and language lateralization?
It was studied using a FMRI
The Vernicke’s area in the left hemisphere activates when a
normal person hears speech sounds (speech perception)
Most people who have Down Syndrome, the right hemisphere is
activated during the perception of speech
Model of Reversed Cerebral Specialization
Everything lateralized to left or right is flipped in Down Syndrome
According to this, the speech production should be flipped to the
right side; however, just like the general population, the speech
production was lateralized to the left cerebral hemisphere
This model was quickly disproven, because everything else other
than speech perception was lateralized to the same side
Therefore, people with Down Syndrome have separation between speech production
and speech perception
They have to take the verbal information (process in the side), and transport it to the
left side to talk back or act (praxis also lateralized to the left side)
Model of Biological Dissociation
People with Down Syndrome have deficit in verbal-motor behaviours because of
separation between right hemisphere (speech perception) and left hemisphere
(speech production & movement praxis systems)
Corpus collosum
It is needed to communicate speech perception & speech production
information in Down Syndrome
The corpus collosum of people with DS is rounded, whereas in normal
individuals, it is flat
There is a thin (very little axons) area of the rounded corpus collosum, which is
called Rostral Fifth
This area is very critically involved between the integration of hemispheres of
verbal information. It is not optimized for communication
People with DS have a hard time learning new motor tasks through verbal
instructions due to the model of biological disassociation
However, these individuals are able to grasp information visually; and this is
probably due to the enhancement/overdevelopment of mirror neuron system in
the down syndrome
Spinal Cord Connections with Extrafusal Muscle
Extrafusal thick red fibre
Power producing
Intrafusal thin red fibre
Detects stretch
Information leaves the spinal cord through the ventral root ganglion (tangle of neurons)
There is an alpha motor neuron that extends from the ventral root ganglion and
connects to the extrafusal muscle fibre
The stretch information from the intrafusal fibres gets projected back to the spinal cord
through the dorsal root ganglion
There is a monosynaptic (direct) connection between alpha motor neuron and
incoming signal from the intrafusal muscle**
Gamma motor neuron/fusimotor neuron
It leaves the spinal cord via the ventral root ganglion and synapses onto the
intrafusal muscle fibre
Golgi tendon organ detects tension
It sends information back to the spinal cord through the dorsal root ganglion and
synapses onto an inter-neuron, which then synapses onto the alpha motor
neuron
This connection is referred to as an oligosynaptic connection
The red lines in the spinal cord (upper diagram) are the inhibitory interneuron
These interneurons allow the connections of one synapse with another synapse
that are at the same level/area/segment within the spinal cord
The class of neurons that allows connections between different segments/areas
of the spinal cord are called: propriospinal neurons