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Disorders that mainly affect the central nervous system and the peripheral nervous system are called as neurological disorders. Parkinson disease (Anila M & Dr. G. Pradeepini, 2020) is one of the examples of this disorder and is second most common. PD begins in the middle or late in life. The exposure of pesticide (P. M. Shah et al., 2018) and Deoxyribonucleic acid (DNA) variation in genes like Leucine-rich repeat kinase 2 (LRRK2) can also cause the PD.
The substantia nigra (Aprajita Sharma & Mr. Ram Nivas Giri, 2013) helps to calibrate and fine tune the movement. It is a part of basal ganglia that controls the movement and connect to motor cortex. Substantia nigra is a latin term for black substance, it consists of two parts: pars reticula and pars compacta. Pars reticula receive signals from the striatum (which is also a part of basal ganglia) and relays messages to the thalamus via neurons rich in neurotransmitter Gamma aminobutyric acid (GABA). Pars compacta transmit messages to the striatum via neurons rich in neurotransmitter dopamine. This forms a nigrostriatal pathway, which help stimulate the cerebral cortex and initiate movement. Therefore, when substantia nigra pars compacta neurons, i.e., dopamine, die the hypokinetic state can be seen which is a common symptom (Tamanna Sood & Padmavati Khandnor, 2019) of PD. There are many motor and non-motor symptoms of PD that helps in detection of this disease. Some primary motor symptoms are tremors, rigidity, stooped posture, bradykinesia, hypokinesia, akinesia and postural instability. Whereas depression, dementia, sleep disturbances and anosmia are some of the non-motor symptoms which are caused by the dysfunction in dopaminergic signalling in other parts of brain. Various modalities have been proposed by the researchers to analyse these symptoms of PD such as Finger Tapping Test (FTT), handwritten test and voice samples. Some other neuroimaging technique such as: Magnetic Resonance Imaging (MRI), Computed Tomography (CT scan), Single Photon Emission Computed Tomography (SPECT), Positron Emission Tomography (PET), functional MRI (fMRI) are also suggested.
In FTT, the candidates are instructed to tap their index finger on the thumb fastly for a particular number of times. Initially the candidate is instructed to open their fingers widely and then their movements are analysed and the candidate is asked to stop. The score is generated on the 5-point scale.
Handwritten test as the name suggests, in this test the hand written datasets from PD. PD patients exhibit a reduction in amplitude of writing size. These patients also show slowness, irregular muscle contractions and tremors which leads to instability in patient's movements. The micrographia and impairments in writing helps in discrimination of a PD patient from a healthy individual. Therefore, when compared to healthy individuals, the PD patients apply less pressure, write small letters and spend more time acting. The patient's handwriting capability in language and their educational level will mostly differ from each other, for this reason the researchers focus on measuring the motor signs of hand writing while writing basic words, single letters or drawing Archimedean spirals.
Voice samples are used for detection of Parkinson’s, though the voice modulation occurs gradually, the PD candidate can suffer from hypokinetic dysarthria. Collective or individual movements of jaws, lips and tongue are analysed (Pedro Gómez-Vilda et al., 2017). Various features like phonation, articulation, prosody and phonological are extracted for the classification of PD and HC.