A video showing the PRK laser eye surgery

The complex circuitry interconnecting different areas in the brain, known collectively as white matter, is composed of millions of axons organized into fascicles and bundles. Upon macroscopic examination of sections of the brain, it is difficult to discern the orientation of the fibers. The same is true for conventional imaging modalities. However, recent advancements in magnetic resonance imaging (MRI) make such task possible in a live subject. By sensitizing an otherwise typical MRI sequence to the diffusion of water molecules it is possible to measure their diffusion coefficient in a given direction1. Normally, the axonal membrane and myelin sheaths pose barriers to the movement of water molecules and, thus, they diffuse preferentially along the axon2. Therefore, the direction of white matter bundles can be elucidated by determining the principal diffusivity of water. The three-dimensional representation of the diffusion coefficient can be given by a tensor and its mathematical decomposition provides the direction of the tracts3; this MRI technique is known as diffusion tensor imaging (DTI). By connecting the information acquired with DTI, three-dimensional depictions of white matter fascicles are obtained4. The virtual dissection of white matter bundles is rapidly becoming a valuable tool in clinical research.

Our journey begins with a transverse section of tightly packed axons as seen through light microscopy. Although represented as a two-dimensional "slice", we see that these axons in fact resemble tubes. A simulation of water molecules diffusing randomly inside the axons demonstrates how the membranes and myelin hinder their movement across them and shows the preferred diffusion direction --along the axons. The tracts depicted through DTI slowly blend in and we ride along with them. As we zoom out even more, we realize that it is a portion of the corpus callosum connecting the two sides of the brain we were traveling on and the great difference in relative scale of the individual axons becomes evident. The surface of the brain is then shown, as well as the rest of the white matter bundles--a big, apparently chaotic tangle of wires. Finally, the skin covers the brain.

With the exception of the simulated water molecules, all the data presented in the animation is obtained through microscopy and MRI. Computer algorithms for the extraction of the cerebral structures and a custom-built graphics engine make our journey through the brain's anatomy possible in a living person.

Micrograph courtesy of Dr. Christian Beaulieu, University of Alberta.
Music by Mario Mattioli.

References:
1. Stejskal, E.O., et al., J. Chem. Phys., 1965. 42:
2. Beaulieu, C., NMR Biomed., 2002. 15:435-55.
3. Basser, P.J., et al., J. Magn. Reson. B, 1994. 103:247-54.
4. Mori, S., et al., NMR Biomed., 2002. 15:468-80.

Superficial Palpation of the Abdomen

Oral Surgery and Dental Implants

Dr.Vijay C. Bose from Apollo Speciality Hospital chennai perform Birmingham Hip Resurfacing Surgery procedure for a case of Avascular necrosis.The NCP ( Neck Capsule Preserving) approach is being used. Total hip replacement, hip resurfacing simply shaves and caps a few centimeters of bone within the joint. The bone-conserving approach of the Birmingham Hip Resurfacing System.

Liposuction for weight loss with Abdominoplasty and Body Lifting

Diagnose an abusive relationship and you will be on your way to ending domestic abuse. Getting a definitive, objective diagnosis can put you in the "stop-guessing" mode and into the "start-treating" mode in moments.

Laparoscopic repair of incisional hernia

A video showing Embryo and Fetal Development

Hip Replacement Surgery

Ingrown Toenail Surgery HD

Total Knee Replacement Surgery Video

Histology of GastroEsophageal Junction

Histology of Elastic Cartilage

Here we’ll explain the symptoms of pancreatitis, how alcohol causes the condition and the other health problems it can lead to. You probably don’t pay much attention to your pancreas. But that small, tadpole-shaped organ behind your stomach and below your ribcage is pretty important. It produces two essential substances: digestive juices which your intestines use to break down food, and hormones that are involved in digestion, such as insulin, which regulates your blood sugar levels. Pancreatitis is when your pancreas becomes inflamed and its cells are damaged. Heavy drinking can cause pancreatitis. But if you drink within the government’s low risk unit guidelines, you should avoid upsetting this important organ.

The annual incidence of primary intraspinal neoplasm is approximately five per million for females and three per million for males.[9] Spinal intradural extramedullary tumors account for two thirds of all intraspinal neoplasms and include neuromas and meningiomas.[1] Overall, meningiomas account for 25 to 46% of primary spinal neoplasms and are the second most common intradural spine tumor after neuromas.[9] Spinal meningiomas occur less frequently than intracranial ones and account for approximately 7.5 to 12.7% of all meningiomas.[25]

Bone pain: Pain is the most common sign of bone cancer, and may become more noticeable as the tumor grows. Bone pain can cause a dull or deep ache in a bone or bone region (e.g., back, pelvis, legs, ribs, arms). Early on, the pain may only occur at night, or when you are active.

There are 3 major parts of the respiratory system: the airway, the lungs, and the muscles of respiration. The airway, which includes the nose, mouth, pharynx, larynx, trachea, bronchi, and bronchioles, carries air between the lungs and the body's exterior.

This Unorthodox Procedure Makes Short People A Foot Taller

A small-bowel obstruction (SBO) is caused by a variety of pathologic processes. The leading cause of SBO in industrialized countries is postoperative adhesions (60%), followed by malignancy, Crohn disease, and hernias, although some studies have reported Crohn disease as a greater etiologic factor than neoplasia.