Modeling responses of macaque and human retinal ganglion cells to natural images using a convolutional neural network.

Linear-nonlinear (LN) cascade models provide a simple way to capture retinal ganglion cell (RGC) responses to artificial stimuli such as white noise, but their ability to model responses to natural images is limited. Recently, convolutional neural network (CNN) models have been shown to produce light response predictions that were substantially more accurate than those of a LN model. However, this modeling approach has not yet been applied to responses of macaque or human RGCs to natural images.

Decomposition of retinal ganglion cell electrical images for cell type and functional inference.

Identifying neuronal cell types and their biophysical properties based on their extracellular electrical features is a major challenge for experimental neuroscience and the development of high-resolution brain-machine interfaces. One example is identification of retinal ganglion cell (RGC) types and their visual response properties, which is fundamental for developing future electronic implants that can restore vision. The electrical image (EI) of a RGC, or the mean spatio-temporal voltage footprint of its recorded spikes on a high-density electrode array, contains substantial information about its anatomical, morphological, and functional properties.

Unified classification of mouse retinal ganglion cells using function, morphology, and gene expression.

Classification and characterization of neuronal types are critical for understanding their function and dysfunction. Neuronal classification schemes typically rely on measurements of electrophysiological, morphological, and molecular features, but aligning such datasets has been challenging. Here, we present a unified classification of mouse retinal ganglion cells (RGCs), the sole retinal output neurons.

An offset ON-OFF receptive field is created by gap junctions between distinct types of retinal ganglion cells.

In the vertebrate retina, the location of a neuron's receptive field in visual space closely corresponds to the physical location of synaptic input onto its dendrites, a relationship called the retinotopic map. We report the discovery of a systematic spatial offset between the ON and OFF receptive subfields in F-mini-ON retinal ganglion cells (RGCs). Surprisingly, this property does not come from spatially offset ON and OFF layer dendrites, but instead arises from a network of electrical synapses via gap junctions to RGCs of a different type, the F-mini-OFF.

Premotor and Motor Cortices Encode Reward.

Rewards associated with actions are critical for motivation and learning about the consequences of one's actions on the world. The motor cortices are involved in planning and executing movements, but it is unclear whether they encode reward over and above limb kinematics and dynamics. Here, we report a categorical reward signal in dorsal premotor (PMd) and primary motor (M1) neurons that corresponds to an increase in firing rates when a trial was not rewarded regardless of whether or not a reward was expected.

Neurogenic vasoreactivity of human internal thoracic artery is unaffected by endothelial cell integrity.

Background: The role of internal thoracic artery (ITA) nervous supply has not been previously considered as a potential factor influencing excellent long-term patency of an ITA graft. To define the interaction between the primary afferent neurons and endothelial cells of ITA, we investigated the effects of acute capsaicin administration in vitro on the isometric tension of human ITAs.

Methods: Vessels were obtained from patients undergoing coronary bypass or from multi-organ transplant donors.

Association of osteopontin with calcification in human mitral valves.

Background: Little is known about the long-standing inflammation leading to calcification within heart valves. Osteopontin, a phosphorylated glycoprotein, is present within atheromatous calcific plagues in response to vascular endothelial injury. The purpose of the study was to investigate whether osteopontin exists in calcific mitral valve leaflets in human beings, and to determine a link between chronic inflammation leading to mitral stenosis and the osteopontin status of mitral valvular tissue.

The influence of cardiopulmonary function on outcome of veterans undergoing resectional therapy for lung cancer.

Background: The unknown but presumably poor preoperative cardiopulmonary function of U.S. Armed Forces veterans with bronchogenic cancer may dissuade surgeons performing necessary major lung resection.

Filtration of diaspirin crosslinked hemoglobin into lung and soft tissue lymph.

Diaspirin crosslinked hemoglobin (DCHb) is a new blood substitute manufactured from human blood. To evaluate its microvascular filtration properties, we infused DCLHb into unanesthetized sheep (10%, 20 ml/kg) and measured the flow and composition of lung and soft tissue lymph. For comparison, we also infused human serum albumin (HSA; 10%, 20 ml/kg).

Long-term survival benefit of internal thoracic artery grafting is negligible in a patient with bad ventricle.

Background: Although the internal thoracic artery (ITA) graft is well known for its benefit of enhancing patient longevity after coronary artery bypass grafting (CABG), whether its superior patency is associated with improved patient survival at all levels of left ventricular function is unknown. The purpose of this study was to determine whether the use of ITA grafting during CABG confers improved survival benefit to patients with impaired preoperative left ventricular function.

Methods: A retrospective chart review was performed in 966 patients who had undergone isolated primary CABG between 1984 and 1995.

Neurogenic vasoreactive response of human internal thoracic artery smooth muscle.

The interaction between primary afferent neurons containing neuropeptides and the vascular smooth muscle is incompletely understood. To explore the function of perivascular afferent neurons and to determine whether they produce local effects on vascular smooth muscle cells, we investigated the effects of acute capsaicin and substance P administration in vitro on human internal thoracic arteries (ITA). Vessels were obtained from patients undergoing coronary bypass or from multiorgan transplant donors.

Clinical importance of measuring coronary graft flows in the revascularized heart. Ultrasonic or electromagnetic?

Background: In the past, routine coronary graft flow measurement at the end of coronary artery bypass grafting (CABG) was not universally adopted by cardiac surgeons due to the lack of reliable flow measurement techniques. The purpose of this study was to investigate the efficacy of ultrasonic and electromagnetic techniques in coronary graft flow measurements and to determine the relationship, if any, between intraoperative ultrasonic or electromagnetic coronary graft flows and postoperative early clinical outcome.

Methods: We studied 66 consecutive patients who underwent elective CABG using internal thoracic artery (ITA) and reversed saphenous vein graft (SVG) conduits.

Assessment of internal thoracic artery vasoreactivity in response to sublingual nitroglycerin.

Background: We have previously shown the feasibility of assessing internal thoracic artery (ITA) size and blood flow hemodynamics before and after coronary artery bypass grafting using color-flow duplex ultrasound. This noninvasive method would be an ideal diagnostic tool for the evaluation of ITA graft status after therapeutic interventions in a patient with angina after coronary artery bypass grafting. The purpose of this study was to investigate the effects of nitroglycerin on the diameter and blood flow velocities of the left native ITA before coronary artery bypass grafting and the ITA graft postoperatively.

Lung lymph oncotic pressure may not modulate pulmonary vascular filtration in sheep.

We tested the hypothesis that plasma oncotic pressure alone, not the plasma-to-lymph oncotic pressure difference, modulates pulmonary transvascular fluid filtration. To do this we measured lung lymph flow after raising left atrial pressure (by inflating a balloon) in sheep that were receiving a continuous (32 h) infusion of dextran 40. For comparison, we also raised left atrial pressure elevation, plasma oncotic pressures in dextran and control sheep, respectively, were 39.

Influence of increasing age on long-term survival after coronary artery bypass grafting.

Background: Despite the steady increase in the number of elderly patients undergoing coronary artery bypass grafting (CABG), skepticism still exists as to whether this operation is justified in older people with a reduced life expectancy. The purpose of this study was to examine the effects of increasing age on outcome after CABG.

Methods: A retrospective chart review was performed on 1,689 consecutive veterans of the United States Armed Forces undergoing isolated primary CABG from January 1972 through December 1994.