Parkinsons Disease – Neurobiology and Aetiology

This presentation covers aetiology of Parkinson’s disease.

Motor activity is controlled by projections that range from the primary motor cortex and the premotor cortical areas of the frontal lobe through to the brainstem and spinal cord.^{[Patestas & Gartner, 2016]} The primary motor cortex has an important function in the execution…

Normal motor function is the result of complex and intricate interactions between the basal ganglia, the cerebellum, and the cerebral cortex.^{[Patestas & Gartner, 2016]} The main function of the basal ganglia is to initiate motor activity and to control cortical outputs – i…

Direct motor pathway mechanism (facilitates movement)
The direct motor pathway goes from the striatum to the globus pallidus interna (GPi) via fibres that inhibit GPi activity.^{[DeLong, 2000]} When this occurs, the GPi no longer inhibits the thalamus, which is now able to s…

Cells of the nervous system communicate with each other at synapses, either via electrical signals or by the release of messenger molecules called neurotransmitters.^{[Patestas & Gartner, 2016]} Examples of neurotransmitters include: acetylcholine, adrenaline, dopamine, sero…

Dopamine is an excitatory neurotransmitter present in the neurons of several regions of the central nervous system.^{[Patestas & Gartner, 2016]} The major dopamine-containing area is the corpus striatum, which plays a central role in the coordination of body movements.^[Pates…

A Lewy body is largely composed of misfolded, insoluble α‑synuclein.^{[Halliday et al., 2014]} There are, however, many other components of Lewy bodies, including structural fibril proteins, α‑synuclein-binding proteins, and cellular components normally involved in the degra…

The protein α-synuclein was first isolated from human brain tissue during the early 1990s.^{[Burré, 2015]} Its role in PD only became apparent in 1997, when a mutation in the α-synuclein gene was discovered in groups affected by a rare, autosomal-dominant form of familial pa…

The overall level of atrophy of brain tissue does not seem to differ between patients with PD and age-matched controls.^{[Halliday et al., 2014]}
However, by the time a patient with PD develops motor symptoms, they will have suffered a moderate-to-severe loss of neuromelanin…

At a physiological level, PD is characterised by the loss of neurons in specific regions of the brain and a spreading of Lewy pathology.^{[Halliday et al., 2014]} However, these do not necessarily always go together; many regions with a concentration of Lewy pathology show o…

The Lewy pathology and aggregated α-synuclein proteins associated with PD are not confined to the central nervous system (CNS); they can also be found in the peripheral nervous system at various sites around the body, such as the skin, gastrointestinal tract, and salivary…

Neurons found in the enteric (gut) nervous system (ENS) require dopamine.^{[Rao & Gershon, 2016]} Without dopamine, these neurons cannot properly control gastrointestinal motility.^{[Rao & Gershon, 2016]} Animal studies have suggested that the ENS may be vulnerable to degenerat…