Attenuation of Information by Oscillatory Firing of Cerebellar Cortical Neurons
Date Issued
2013
Date
2013
Author(s)
Huang, Jina-Jia
Abstract
Neuronal oscillations have been shown to contribute to the cerebral cortical functions by coordinating the neuronal activities of distant cortical regions via a temporal synchronization of neuronal discharge patterns. This can occur regardless whether these regions are linked by cortico-cortical pathways or not. Less is known concerning the role of neuronal oscillations in the cerebellum. Literatures showed that Golgi and Purkinje cells are both principle cell types in the cerebellum. The Purkinje cell is the sole output cell of the cerebellar cortex while the Golgi cell contributes to information processing at the input stage of the cerebellar cortex. Both cell types have large cell bodies, as well as dendritic structures, that can generate large currents. The discharge patterns of both cell types also exhibit oscillations. In view of the massive afferent information conveyed by the mossy-fiber-granule-cell system to different and distant areas of the cerebellar cortex, it is relevant to inquire the role of cerebellar neuronal oscillations in information processing. In this thesis, we firstly compared the discharge patterns of Golgi cells and Purkinje cells in conscious rats and in rats anesthetized with urethane. We assessed neuronal oscillations by analyzing the regularity in the timing of individual spikes within a spike train by using auto-correlograms and FFT (Fast-Fourier transform) in different levels of consciousness (urethane-anesthetized, EtOH-treated, and sleeping states). The differences of neuronal oscillations and the amount of information content in a spike train (defined by Shannon entropy processed per unit time) were measured from Long-Evans rats in anesthetized and conscious states. Next, alcohol-treated rats were used as animal model with a lower unconscious level comparing to the anesthetized state due to the cerebellum is one of the EtOH action targets and the precise mechanisms underlying ethanol (EtOH)’s actions in the central nervous system (CNS) remain elusive. Finally, we tested the oscillatory Purkinje cell’s activity using the natural unconsciousness behavior (sleeping). we studied the cerebellar cortical neuronal oscillation using EtOH induced ataxia in the rat as an animal model. We also compared the neuronal oscillation under different states, which were sleeping, urethane anesthetizing, and conscious resting. Our results showed that: 1) in the input stage of cerebellar cortex, the EtOH increases the firing frequency in the Golgi cells and induces a neuronal oscillation; 2) in the output stage of the cerebellar cortex, EtOH significantly decreased and regulated the simple spike firing patterns in the Purkinje cells and induced a weaker neuronal oscillation in conscious unconstrained freely moving rats; 3) the neuronal oscillation in the cerebellar cortex was induced in the urethane anesthetized state in both Purkinje cells and Golgi cells, however in the conscious state the neuronal oscillations were weak; 4) the Purkinje cells firing frequency in the conscious state was higher than in the urethane anesthetized state, but in the Golgi cells, there was no significant difference in both states; 5) in the Purkinje cells during the neuronal oscillation period, the firing rate was slower than under weak oscillation states; 6) Using information entropy, the information count during the neuronal oscillation period is lower than weak oscillations. In conclusion, we examined the neuronal oscillatory activity of cerebellar Golgi cell and Purkinje cell in different states that may attenuate the capability of information processing. Our data support those in the previous studies made in the anesthesia experiment and provide additional experimental data for understanding the neuronal oscillation in the cerebellar cortex participating in a more natural conditions.
Subjects
神經元震盪性放電
Purkinje細胞
Golgi 細胞
信息熵
小腦皮質
Type
thesis
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