Parkinson's Disease and Limb Kinetic Apraxia on Finger Dexterity

The Effect of Parkinson's Disease and Limb Kinetic Apraxia on Finger Dexterity

Bradykinesia vs. Limb- Kinetic Apraxia (lkA)

(Gebhardt et al., 2008; Quencer et. al, 2007)

Methods

Interpreting the Results

Hypotheses & Findings

- Insular & Secondary Somatosensory Cortices

- Overactivation of these areas in PD patients is described

as an enhancement of compensatory recruitment of

associative sensory areas in

the presence of basal

ganglia dysfunction

• Two major results:

1. tendency to overactivate corticol and subcortical structures

2. dissociative behaviour of the left perirolandic cortex

• The Hypotheses

1. fMRI activation patterns associated with right-handed coin

rotation will differ between PD patients and healthy individuals

2. fMRI differences between PD patients and healthy individuals

are most pronounced in the left perirolandic area

• Overactivation of Parietal regions

(BA 39, 40, 5, & 7) in PD subjects

- these regions are typically involved

in praxis performance tasks and

have been previously associated with

apraxic disorders

- overactivation of these areas seems to reflect a

physiological mechanism adapting to compensate for

impaired coin rotation performance

Green = Secondary Somatosensory Cortices

Brown = Insular Cortices

Interpreting the Results

Implications & Future Research

- Decreased activity in the left postcentral

perirolandic cortex in PD patients indicates

a regional dysfunction with the consequence

of decreased CR performance

- Decreased activation of the right occipito-parietal

and parastriate cortices in PD subjects

- These hemispheric regions are known for their

function in visuo-spatial processing

- PD patients are known to display impairments of

this visuo-spatial processing system

• Periolandic index described could help define specific markers of LkA in movement disorder patients
• Further investigations may clarify how brain activity varies with disease state and severity

Future investigations:

• possible morphometric changes in specific areas of the brain
• comparing ON and OFF conditions of PD medication

- Overactivation of PD patient's

Default-Mode Network (DMN)

results from the inability to

physiologically deactivate these

areas during task performance

- An active DMN during tasks

would result in the observed

decreased performance

- The perirolandic cortex seperates the frontal and

parietal lobes. Deactivation of this area may lead

to disruptions in communication between the

motor and sensory cortices

fMRI

Behavioural Results

fMRI Results

Overactive Regions in Patients

Patients

Controls

Active Areas in Healthy Subjects

- Cranial part of the vermis

- Posterior right putamen

- Healthy participants flipped the coin more frequently

(26 +/- 2 half turns per 20 sec vs. 13 +/- 6)

- Finger taps per reference period was comparable

(patients 20 +/- 2, healthy controls 19 +/- 1)

- No significant correlation between the two tasks

- Shows that patients can have LKA without bradykinesia

- Left precentral perirolandic cortex

- Parietal lobes

- "Default mode network"

- Primary motor cortex

- Right anterior cingulate cortex

- Bilateral posterior cingulate cortex

- Medial orbitofrontal cortices

- Premotor areas, SMA, CMA

-Dorsolateral prefrontal cortex

Active Areas in Patients

- Bilateral insular cortex

- Basal ganglia

- Right anterior

cingulate cortex

- Left dorsolateral

prefrontal cortex

- Right precentral and

inferior frontal gyrus

- Left caudate nucleus

- Superior temporal gyri

General Finding

- More brain activation in patients

Conclusion

• Overactivation
• PD patients showed a precentral overactivation and a postcentral underactivation when compared to healthy controls

Discussion

Perirolandic Indices

Perirolandic Cortex

Overactive Regions in Controls

Significance of Perirolandic Indices

- Left postcentral perirolandic cortex

- Right parastriate cortex

- Shows that a low perirolandic index

could be an indicator of LKA

- The index could be used to help

define specific markers of LKA

- Found patients indices to be significantly lower than controls

- All patients scored below 2.0, where 6 out of 10 controls scored above 2.0

- Better known as the Central sulcus

- Separates the parietal lobe from the frontal lobe and

the primary motor cortex from the primary somatosensory

cortex

- Plays a part in both sensory

and motor control

- Calculated as the difference

between postcentral

perirolandic cortex activation

and precentral perirolandic cortex

activation

- Postcentral activation/Precentral

activation

- Calculated for both patients and

controls and the results were

compared

Foki, T., Pirker, W., Klinger, N., Geiβler, A., Rath, J., Steinkellner, T., ... Beisteiner, R. (2010). FMRI correlates of apraxia in Parkinson's disease patients OFF medication. Experimental Neurology, 225, 416-422.

Michelle, Emilia, Nick, Colby

Hypothesis:

fMRI activation patterns associated

with right handed coin rotation

would differ between PD patients

and healthy controls, and, that this

difference would be more pronounced in

the left perirolandic area.

BRADYKINESIA

-

Limb-kinetic Apraxia (lkA)

Participants

Results from...

FMRI correlates of apraxia in Parkinson's

disease patients OFF medication (Foki, T. et al, 2010)

Parkinson's Disease (PD)

• 10 right-handed PD participants (6 male, 4 female)
• 10 right-handed healthy control participants (5 male, 5 female)
• Patients were off their PD medications at least 12 hours prior to fMRI scans

- movement

- muscle control

- balance

Decreased Ability

to Perform

Fine Motor Skills

fMRI Scan

- movement

- coordination

• 4 finger-tapping reference points that alternated with 3 coin rotation tasks, 20s each
• Head fixation device was used
• Functional images in A-C and P-C plane with coverage of the whole brain and brain stem
• Image pre-processing and statistical analysis

Finger Tapping Task

• Associated with Bradykinesia serving as the reference 'Bradykinesia' task
• Dissociation between simple and complex movements regarding Dopaminergic Therapy

Coin Rotation Task

• Associated with Apraxia serving as the target task
• Participants were told to flip (180° degrees) as fast as possible in 20s, the number of turns was monitored