Please write the answer as clear as possible with it is explanation. Q1)The figu
ID: 207730 • Letter: P
Question
Please write the answer as clear as possible with it is explanation.
Q1)The figure shows the MRI images of (a) 27 year old healthy male, (b) 27 year old male with first- episode psychosis, (c) 25 year old male with chronic schizophrenia brains. The white color corresponds to myelinated axons. t has been shown that the decrease in myelination is statistically correlated with the onset of schizophrenia. Speculate on the mechanism of the disease by referring to the functions of myelination. (9pts.)Explanation / Answer
Schizophrenia unfolds during the late stages of brain maturation, while the myelination is still continuing. Impaired myelination in schizophrenia could contribute to abnormalities of neural connectivity and persistent functional impairment in illness.
Any etiological theory of schizophrenia accounts for three distinctive features : 1] excessive dopamine neurotransmission.
2] its periadolescent onset i.e. the appearance of the symptoms in late adolesence or early adulthood [ between 18 to 30 years of age ].
3] the strange pathognomonic syptoms that appear in the patient .
It is speculated that all these abnormalities arise from the abnormal myelination of late-developing frontol white matter fasciculi. Abnormalities in frontal myelination result in conduction delays in the efference copies that are involved in predicting the neural consequences of self generated actions. These conduction delays lead to prediction errors which are directly responsible for certain psychotic symptoms.They also underpin the excessive phasic dopamine neurotransmission that is associated with psychotic symptoms of schizophrenia.
The white matter of the central nervous system is primarily made up of the phospholipids processes of a certain type of neuroglia known as oligodendrocytes. The compacted processes of these oligodendrocyte are known as myelin and they sheath the axons of nearby axons. The myelin acts as electrical insulation for the ensheathed axons . This helps to preserve the amplitude and increase the conduction velocity of the propagating axon potential.
Given its role as the primary infrastructure for long distance communication in the brain, it is not surprising that abnormalities in the white matter fasciculi lead to symptoms of schizophrenia.