Aging-related differences in cerebral capillary blood flow in anesthetized rats.

Age-related decreases in baseline cerebral blood flow have been measured with various imaging modalities, however, the contribution of capillary flow to this phenomenon remain to elucidate. This study used 2-photon laser scanning fluorescence microscopy to measure capillary diameter, red blood cell speed, and flux in individual capillaries in the sensory-motor cortex of 12 adult (3-month-old) and 12 old (24-month-old) male Long-Evans rats under isoflurane anesthesia. The average (± standard deviation) diameter and speed over 921 capillaries were 6.

Multimodal study of the hemodynamic response to hypercapnia in anesthetized aged rats.

With aging, the brain undergoes changes in metabolism and perfusion, both of which influence the widely used blood-oxygenation-level-dependent (BOLD) MRI signal. To isolate the vascular effects associated with age, this study measured the response to a hypercapnic challenge using different imaging modalities in 19 young (3 months-old) and 13 old (24 months-old) Long-Evans rats. Intrinsic optical imaging was used to measure oxy (HbO), deoxy (HbR) and total (HbT) hemoglobin concentration changes, laser speckle for cerebral blood flow (CBF) changes, and MRI for the BOLD signal.

Functional electrical stimulation post-spinal cord injury improves locomotion and increases afferent input into the central nervous system in rats.

Background: Functional electrical stimulation (FES) has been found to be effective in restoring voluntary functions after spinal cord injury (SCI) and stroke. However, the central nervous system (CNS) changes that occur in as a result of this therapy are largely unknown.

Objective: To examine the effects of FES on the restoration of voluntary locomotor function of the CNS in a SCI rat model.

Characterization of the hemodynamic response in the rat lumbar spinal cord using intrinsic optical imaging and laser speckle.

Quantifying spinal cord functions is crucial for understanding neurophysiological mechanisms governing the intact and the injured spinal cord. Intrinsic optical imaging (IOI) and laser speckle provides measures of deoxyhemoglobin (HbR) and oxyhemoglobin (HbO(2)) concentrations, blood volume (BV) and blood flow (BF) at high spatial and temporal resolution. In this study we used IOI and laser speckle to characterize the hemodynamic response to neuronal activation in the lumbar spinal cord of anaesthetized rats (N=9).

Laminar optical tomography of the hemodynamic response in the lumbar spinal cord of rats.

Intrinsic optical imaging (IOI) has emerged as a very powerful tool to assess neuronal function in small animals. Although it has been used extensively in the brain, its application to the spinal cord is rare. The inability of intrinsic optical techniques to resolve different depths and embedded gray matter hampers their capacity to distinguish larger vasculature contributions of hemodynamic signals originating from motoneuron and interneuron activation.

Optical imaging of vascular and metabolic responses in the lumbar spinal cord after T10 transection in rats.

Neuronal and vascular reorganization after spinal cord injury (SCI) is scarcely known although its characterization has major implications in understanding the functioning of the altered spinal cord. Several electrophysiological and anatomical lines of evidence support plasticity caudal to the lesion site, but do not provide sufficient clues about neuronal and vascular reorganization after SCI. The aim of the present study was to compare neuronal activation in the lumbar spinal cord between uninjured and SCI rats with novel optical imaging technology.

Development of a multi-channel system for intrinsic cardiac neural recording.

Recent clinical evidence suggests that abnormal neural input can contribute to the onset perpetuation of atrial arrhythmias, such that neural elements have become potential targets for ablation. A better understanding of the influence of the cardiac autonomous nervous system is required to improve therapy. We have developed a multi-channel system to record neural activity simultaneously at different intra and pericardiac locations.