The brain is the most powerful organ in the human body. It is the center of our nervous system and controls all of our voluntary and involuntary bodily functions. The brain controls all other organ functions, generates muscle activity, and controls the secretion of hormones. From simple reflexes to complex sensory input, the brain and its billions of neurons are always in control. Due to advances in optics and medical diagnostics, how each neuron and glial cell interact is now better understood than ever, but how millions of neural networks operate as a single unit for complex tasks remains a mystery for researchers. More tools than ever before are available to image brain slices and utilize less invasive fiber-coupled imaging systems to understand how the brain works electrically, chemically, and physically. The key components to imaging brain slices and fiber-coupled imaging systems are infinity corrected, apochromatic microscope objectives with high magnifications and high numerical apertures.
Below are common ailments of the brain that are detected by advanced diagnostic techniques such as fluorescence microscopy. Advancements in microscope objectives and other optical components allow these ailments to be more easily detected and treated.
Medical condition caused when blood supply to the brain is interrupted for an extended period of time, resulting in muscle weakness on one side of the body, loss of face control, numbness, and speech issues.
Progressive and incurable type of dementia that destroys memory and other important mental functions, beginning slowly and worsening over time.
Incurable disorder of the central nervous system (CNS) that affects movement and includes uncontrollable tremors.
Inherited, incurable condition that causes nerve cells in the brain to break down over time, causing jerky body movements and eventually the inability to talk.
Severe inflammation of the brain and spinal cord membranes that is typically onset by an infection and leads to fever, headache, and neck stiffness.
Condition characterized by recurring seizures mainly due to abnormal and increased electrical activity in the brain.
The most common type of traumatic brain injury, onset by heavy impact resulting in the brain shaking or moving inside the skull.
Cancerous or non-cancerous growths of abnormal cells in the brain with a variety of severity levels and types including astrocytoma, blastoma, ependymoma, and meningioma.
Fluorescence microscopy is one of the primary techniques used to study the functional or morphological dynamics of synaptic structures, including dendritic spines and axon terminals, and to characterize circuit connectivity and dynamics. Typically, a laser beam is focused into a pinhole, acting as a point source illuminator. Spatially filtered light is reflected by a dichroic filter, which may or may not require a beam expander to fill the entire aperture of the objective. The objective then focuses excitation energy onto the sample, which emits a weaker fluorescence signal collected by the same objective. This emission light is transmitted through the dichroic filter into the secondary tube lens and then passes through a final pinhole before detection by a CCD or CMOS sensor. Ideally, both pinholes are located in conjugate image plans on the optical axis, which allows the images to overlap perfectly on the object plane. Since confocal microscopes observe a very thin, small spot in the object plane, it is important to sample light via a scanning system or motorized actuator to collect an array of images. These images are then reconstructed into 2D or 3D images.
Learn more about how to assemble a fluorescence microscopy system.
--Stephan Briggs, Biomedical Engineer and Advanced Diagnostics Expert