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B&B - TB9 - Tutorial
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- 1Parkinson's Disease.Long-term degenerative disorder of the central nervous system, that mainly affects the motor system.
- 2Parkinson's Disease, What are the motor problems?- Tremors, difficulty controlling timing of hand movements.
- Shuffling when walking - no knee movement, losing ability to process thought of what they are doing.
- Need help when moving. - 3Parkinson's Disease, Dopamine neurotransmitter is involved:- Dopamine = Main neurotransmitter.
- System breaks down.
- Areas of brain secreting it are drying up.
- Lack of dopamine in the brain.
- Around basal ganglia area of the brain.
- Thought process and telling things what to do is integral in movements. - 4Parkinson's Disease, Symptoms:- Dyskinesia - Abnormality or impairment of voluntary movement.
- Rigidity - Inability to be bent or forced out of shape.
- Slow Shuffle.
- Tremor - Involuntary muscle contraction, twitching movements. - 5Parkinson's Disease Test. Timed get up and go.- First system to break down = Movement.
- This test looks at walking gate. - 6Parkinson's Disease Test. Clock Drawing.- Know what a clock looks like, but it's the spatial awareness problem with putting pen to paper.
- Spatial awareness breaks down - Perception of where things need to go is distorted.
- 7Hyperkinesia.- Muscle spasm.
- Hyperactivity and inability to concentrate. - 8Hypokinesia.- Partial or complete loss of muscle movement due to a disruption in the basal ganglia.
- Patients with hypokinetic disorders like Parkinson's disease experience muscle rigidity and an inability to produce movement. - 9Brain Mechanisms of Action- The neurotransmitter system involved in the basal ganglia is mostly affected in Parkinson's Disease (PD).
- PD is associated with a degeneration of the dopamine producing cells in the substantia nigra. - 10—- Located in the cerebral hemisphere.
- Critical in starting and stopping movement and choosing appropriate timing and appropriate movement.
- 11Regions and Key Words in Basal Ganglia Loop: Cortex, Excitatory, and Inhibitory.Cortex - Where the movement is coming from.
Excitatory - Making involuntary movements, where the tremors come from.
Inhibitory - Can't perform the movements they want to. - 12Damage to the basal ganglia loop causes:- Excitation.
- Inhibition.
- The loop is what is degenerating over time. - 13Neuropathology. Nigro-striatal pathway degeneration.- Leading to a depletion of striatal dopamine (the system of dopamine involved).
- Some degeneration of other dopamine pathways too. - 14Another condition affecting this brain system where the opposite problem is found and movements are freely created even when not intended?Torretes:
- Involuntary noises or movements, believed to be to do with dopamine pathways.
- Not terminal - Behaviour disorder with some brain disruption.
- Symptoms can be suppressed depending upon mood.
- 15Another condition affecting this brain system where the opposite problem is found and movements are freely created even when not intended?Hemiballismus:
- Happens after brain loses a lot oxygen.
- Only effects one side of the body.
- No control over involuntary movements.
- Over stimulated.
- Had control over timing of arm movements. - 16Other dopamine systems?Loss of inhibition in this system can lead to:
- Compulsive gambling.
- Risk seeking behaviour. - 17Dopamine Action and Cognition: - Dopamine is associated with the reward system.- Loss of inhibition in the system can lead to compulsive gambling, risk seeking behaviour, and suicide.
- 18Dopamine Action and Cognition: - Drugs can also affect the pleasure/reward system.- Heroine, so low on the come down, so you take more heroine, abuse the system which results in drying up/changing the dopamine system.
- 19Parkinson's Disease Treatment: History.- Prior to the 1960s no effective treatment.
- Realisation of dopamine's involvement led to use of drugs which increase brain dopamine.
- Dopamine itself cannot cross the blood/brain barrier.
- Use L-DOPA, enters the brain and converted to dopamine. - 20Parkinson's Disease Treatment: Drugs. Drugs increasing dopamine levels - L-DOPA.- Can cause psychoticism, dyskinetic (involuntary muscle) movements, and excessive movements.
- L-DOPA targets all 4 dopamine systems.
- L-DOPA eventually stops working the longer you're on it. - 21Parkinson's Disease: Treatment. Surgically implanted implants, stimulating specific brain regions.- Facial expressions improved.
- Gate closer to normal.
- Better timing and control of specific movements.
- Bigger steps as opposed to shuffling.
- Give more fluid and specifically selected and timed movement, can stops movement when he wants to.
- Uses your own dopamine to stimulate the brain. - 22Parkinson's Disease Treatment: Implants. Area Stimulated - Subthalamic Brain Regions (STN).- High infection rates - Something in the brain that shouldn't be = infections.
- Sometimes electrodes slip and stimulate pleasure areas - Symptoms combined with hyper-sexuality.
- Complete elimination of tremor. - 23Deep Brain Stimulation (DBS).- When medication works insufficiently or has strong side effects.
- Stimulation is mostly applied to STN, and leads to disinhibition such that movements can be inhibited.
- 24Deep Brain Stimulation (DBS).- Legions of the subthalamic nucleus (STN) or internal segment of the globus pallidus (right) effectively reduce parkinsonian signs by respectively normalising or eliminating abnormal an excessive inhibitory output from the internal pallidal segment.
- 25Deep Brain Stimulation (DBS). Side Effects:- High infection rates.
Sometimes electrodes slip and stimulate pleasure area, symptoms combined with hypersexuality. - 26Parkinson's and Cognition: Dementia with Lewy bodies.- Lewy body dementia and Parkinson's combined.
- Decrease in expressions.
- Change in gate.
- No longer independent.
- Combination means also a problem with memory systems.
- The impairment in timing and readout of information sometimes generalises to memory and other aspects of cognition. - 27Why might timing mechanisms that are affected in Parkinson's give rise to cognitive problems?- Parkinson's can affect movement.
- Often underestimate time interval.
Area in basal ganglia loop is associated with time - develops when connecting neurons die. - 28—Failing inhibiting sensations.
- 29—Summary:
- Dopamingergic circuits in the basal ganglia are involved in the timing and the readout of movements.
- Dysfunction of these circuits can lead to hyper- or hypo- kinesias.
- An imbalance in the dopamine system is often associated with other cognitive problems as well:
Dementia vs Hallucinations.
Lack of motivation vs Risk seeking behaviour.