Browsing by Author "Chen, Ziying"

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    Beta and Low Gamma Oscillation Dynamics in Primary Motor Cortex of 6-OHDA hemi-Parkinson’s Rat during Voluntary Movement Initiation
    (2020-05-27) Chen, Ziying; Kemere, Caleb
    The reduction in the number of dopamine (DA) cells in subthalamic nucleus (STN) is the pathological signature of the patients with Parkinson’s Disease. With the loss of DA regulation, abnormally high power of electrophysiological oscillations, from 20 to 45 Hz near beta and low gamma band, in primary motor cortex (M1) is observed and is believed to be the reason of bradykinesia in DA patients. Studies using 6-hydroxydopamine (6-OHDA) rat model showed the frequency and power modulation of the abnormal oscillation during movement. However, constrained environment, for instance, treadmill for forced movement , did not demonstrate the voluntary aspect or allow to target the transition between behavioral statuses of 6-OHDA-lesioned rats. And the temporal dynamics of the abnormal rhythm during behavior and how it is different from healthy rat’s M1 signal oscillation is still not understood. Here, we used simultaneous video tracking and electrocorticography (ECoG) recording of M1 in both hemispheres of 6-OHDA-induced hemiparkinsonian rats during free moving on customized tracks. Behavioral performance degradation of rats from early lesion stage to late lesion stage was showed with the change of defined movement initiation (MI) events. Based on the findings, we suggest that there are components in different frequency bands in the abnormal oscillation in M1 of 6-OHDA lesioned rats and they have different likelihoods to happen during the initiation of a behavior. The potential multiple types of rhythm inside M1 could help us understand the dynamics of lack of regulation of DA cells in STN.
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    Deep imaging in scattering media with selective plane illumination microscopy
    (SPIE, 2016) Pediredla, Adithya Kumar; Zhang, Shizheng; Avants, Ben; Ye, Fan; Nagayama, Shin; Chen, Ziying; Kemere, Caleb; Robinson, Jacob T.; Veeraraghavan, Ashok; Bioengineering; Electrical and Computer Engineering; Computer Science
    In most biological tissues, light scattering due to small differences in refractive index limits the depth of optical imaging systems. Two-photon microscopy (2PM), which significantly reduces the scattering of the excitation light, has emerged as the most common method to image deep within scattering biological tissue. This technique, however, requires high-power pulsed lasers that are both expensive and difficult to integrate into compact portable systems. Using a combination of theoretical and experimental techniques, we show that if the excitation path length can be minimized, selective plane illumination microscopy (SPIM) can image nearly as deep as 2PM without the need for a high-powered pulsed laser. Compared to other single-photon imaging techniques like epifluorescence and confocal microscopy, SPIM can image more than twice as deep in scattering media (∼10 times the mean scattering length). These results suggest that SPIM has the potential to provide deep imaging in scattering media in situations in which 2PM systems would be too large or costly.