Chronic wide-field imaging of brain hemodynamics in behaving animals.

Peng Miao,Shihan Feng,Miao Li,Lingke Zhang,Yiguang Zhang,Nitish V Thakor,Qihong Wang

doi:10.1364/boe.8.000436

Peng Miao, Shihan Feng + Show 5 more

Open Access

https://doi.org/10.1364/boe.8.000436

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Abstract

Chronically monitoring cerebral activities in awake and freely moving status is very important in physiological and pathological studies. We present a novel standalone micro-imager for monitoring the cerebral blood flow (CBF) and total hemoglobin (HbT) activities in freely moving animals using the laser speckle contrast imaging (LSCI) and optical intrinsic signal (OIS) methods. A new cranial window method, using contact lens and wide field optics, is also proposed to achieve the chronic and wide-field imaging of rat's cerebral cortex. The hemodynamic activities of rats' cortex were measured for the first time without restriction of cables or fibers in awake and behaving animals. Chronic imaging showed the increase of CBF and HbT in motor cortex when the rats were climbing on the cage wall. Interestingly, the CBF activation of supplying vessel was smaller than that of parenchyma. Furthermore, after the climbing, CBF demonstrated fully return to the baseline while HbT showed a delayed recovery. The standalone micro-imager technology provides new possibilities of brain imaging in cognitive neuroscience studies.

Highlights

Monitoring brain activity during active and social behavioral conditions provides more relevant physiological information and realistic information on pathological conditions [1~3]
While the electrophysiological methods provide an instantaneous recording of neural activities in the brain, optical imaging methods probe the brain’s hemodynamics in a noncontact way and provide structural and functional information at high resolution
All experiments were performed in our Specific Pathogen-Free (SPF) Animal Research Facility (ARF)

Summary

Introduction

Monitoring brain activity during active and social behavioral conditions provides more relevant physiological information and realistic information on pathological conditions [1~3]. While the electrophysiological methods provide an instantaneous recording of neural activities in the brain, optical imaging methods probe the brain’s hemodynamics in a noncontact way and provide structural and functional information at high resolution. Traditional imaging system cannot be applied to investigate the brain activities in social behavior and social motivations of groups. Traditional methods for chronic imaging require a cranial window for a high-quality optical access [17,18]. The cranial window technique involves a full craniotomy with a cover glass filled with agarose [20]. Due to inflammation or physiological changes, the cover glass may apply additional pressure disrupting cerebrospinal fluid regulation and intracranial pressure levels [19]. The cover glass is rigid so that it cannot be used for covering lateral areas of rat’s cortex

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