Terminology and procedures for studying the brain

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brain map, brain mapping,

A map of the brain identifies the areas of the brain where different parts of the body and their related activities are represented. Like geographical maps, which are topographical - i.e., adjacent areas on the map correspond to adjacent areas in the world, adjacent areas on brain maps are next to each other on the body. Mental activities, memories, and dreams, etc., are also mapped on the brain.

The borders and sizes of different brain map areas vary from person to person, and change daily according to everyday activities.

Brain mapping refers to different neuroscience techniques aimed at identifying where specific areas of the body and brain functions are represented in the brain. Like geographical maps, areas next to each other on the body's surface are generally next to each other on the map of the brain. Memories can also be mapped on the brain.

Deafferentation

An "afferent nerve" is a sensory nerve that sends information from the peripheral nervous system to the spinal cord and then to the brain. Deafferentation is a surgical procedure that cuts an incoming sensory nerve so that sensory imput cannot be conveyed from that nerve to the spine and brain. This is an old technique used since 1895 in experiments involving animals. A deafferented animal will not be able to feel any sensation or pain in the affected limb nor sense where that limb is in space. We owe much of what we have learned about brain maps and recovery from brain damage from various kinds of experiments using animals.

Electrode

An electrode is a device that carries an electrical current to probe, measure, or map brain activity. Neurosurgeon Wilder Penfield used an electric probe in the 1930s to create brain maps by relating specific areas of the brain to corresponding parts of the body, activities, and processes. Using the advanced technology of the 1960s, Michael Mezenich was able to micromap using pin-shaped microelectrodes, which are small enough to be inserted inside or beside a single neuron.

fMRI - functional magnetic resonance imaging

Functional magnetic resonance imaging (fMRI, or functional MRI), is an MRI procedure that enables the processing of information by areas of the brain to be captured in images. Instead of creating images of organs and tissues, fMRI measures and maps brain activity by detecting changes in blood flow. Researches identify areas in the brain that are active during different types of activities because they "light up" on the scan. Functional MRI has dominated brain mapping research since the 1990s, probably because injections, surgery, ingestion of substances, or exposure to radiation are not involved.

microelectrodes

An electrode is a device that carries an electrical current to probe, measure, or map brain activity. Neurosurgeon Wilder Penfield used an electric probe in the 1930s to create brain maps by relating specific areas of the brain to corresponding parts of the body, activities, and processes. Using the advanced technology of the 1960s, Michael Mezenich was able to micromap using pin-shaped microelectrodes, which are small enough to be inserted inside or beside a single neuron.

Neuroimaging

The term neuroimaging includes various techniques that either directly or indirectly create images of the structure, function, or chemistry of the brain. They include MRI, fMRI, and PET scans.

PET Scan - positron emission tomography

A positron emission tomography (PET) scan is an imaging test that shows how the organs and tissues of your body are functioning. It involves injecting a radiotracer, a small dose of radioactive chemical, into the vein of your arm. The tracer travels through your body and is absorbed by the organs and tissues being studied. The patient being tested lies on an examination table that is moved into the center of the PET scanner, which detects and records the energy emitted by the tracer. A computer converts this energy into three-dimensional pictures. Cross-sectional images of the organs and tissues can then be viewed from any angle so that functional problems may be detected. A PET scan can often reveal changes at very early stages of a disease because it detects changes occurring in an organ or tissue at the cellular level. Tests like MRI detect changes that occur in later stages, after the disease begins to cause changes in the structure of organs or tissues.

Recommended Resources

Stuart Firestein - TED Talk- The Pursuit of Ignorance

Allan Jones - TED Talk - A map of the brain

MIT News - article on Alzheimer's research

PBS - Scanning the Brain

Vilayanur Ramachandran - TED Talk - 3 Clues to Understanding Your Brain

Oliver Sacks - TED Talk - What Hallucination Reveals About Our Minds

U of Utah - Brain Imaging Technologies