Parkinson-Krankheit und Basalganglien

Parkinson's Disease

• Parkinson's Disease is a neurodegenerative disorder.
• It leads to the atrophy of dopamine neurons in the substantia nigra.
• The resulting dysfunction leads to problems with motor control.
• Symptoms include tremors, rigidity, bradykinesia (slow movement), and postural instability.
• Difficulties with initiating and executing voluntary movements are also common.
• The disease affects the cortico-striato-thalamic loop, impacting the activation and deactivation of particular neocortical regions during basic and higher cognitive processes.
• Damage to the substantia nigra affects the supplemental motor area (SMA), making coordinated movements difficult.

MPTP

• MPTP is a substance associated with Parkinson's disease.
• It is discussed in the context of Parkinson's disease as a toxin that may affect similar brain areas, and thus have a causal role in the development of Parkinson's.

Basal Ganglia

• The basal ganglia are a group of subcortical structures that play a critical role in movement initiation and control.
• They receive input from various cortical areas and send output to structures involved in motor control.
• The basal ganglia interact with the neocortex and diencephalon to modulate activation and deactivation in specific regions, especially during basic and complex movement, and cognitive functions.

Cortico-striato-thalamic loop

• The cortico-striato-thalamic loop is a neural circuit involving the cerebral cortex, the striatum, the thalamus, and the substantia nigra.
• This loop plays a major role in motor control and the initiation of voluntary movements, as well as aspects of cognitive function.
• In Parkinson's in this loop, the substantia nigra's diminished support impacts the normal activation of the SMA (supplementary motor area), leading to difficulties executing voluntary movements.

Motor Symptoms Related to PD

• PD patients experience difficulties initiating and executing voluntary movements.
• They also have trouble with complex multi-step tasks.
• Freezing of gait (freezing during walking) and other balance problems are also observed.
• Rigidity, tremors, and dyskinesia (abnormal movements) are common motor dysfunctions.
• A characteristic feature of Parkinson's is the reduced range of movements, and reduced flexibility.
• Difficulties with speech and facial expressions (reduced facial expressiveness) may also occur.

Treatment with L-Dopa

• L-Dopa, a precursor to dopamine, is used to treat Parkinson's.
• It supplements dopamine, helping to restore a portion of dopamine function.
• This helps the remaining dopamine-producing neurons function more effectively, and the substantia nigra to better engage with the putamen in initiation and coordinating movements.

Deep Brain Stimulation (DBS)

• Deep Brain Stimulation (DBS) is a surgical procedure for treating Parkinson's disease.
• DBS involves implanting electrodes in specific areas of the brain, typically the subthalamic nucleus (STN).
• DBS interrupts or modulates abnormal electrical signals in the STN in order to reduce related symptoms of the disease, helping to improve motor control problems.

Non-motor Symptoms related to PD

• PD patients frequently experience non-motor problems that involve impairments in non-declarative memory functions, including implicit memory formation.
• These aspects of cognitive impairments include attention and executive functions.
• Tasks related to shifting between tasks (executive function) pose difficulties for PD patients.

Neuropsychological Intervention

• Cognitive training can be effective in improving some of the non-motor cognitive deficits.
• Such therapy can address memory (particularly non-declarative memory), attention, and executive functions like shifting between tasks.

Meta-analysis of CT Effect

• Meta-analyses suggest a somewhat limited effect of cognitive training on executive functions and processing speed, but a moderate to strong effect on working memory tasks in Parkinson's patients.

Summary of PD

• Parkinson's disease is a neurodegenerative disorder causing dopamine neuron loss.
• This leads to motor problems like rigidity, tremors, and difficulty initiating movements.
• Cognitive deficits also occur, affecting areas like memory and executive functions.
• Treatments include L-Dopa and DBS to ease motor symptoms.
• Cognitive training can help improve some cognitive aspects.