Techniques to Study the Brain

In the olden days… It was really difficult to study brain anatomy and function unless somebody died or an accident occurred. It was really difficult to study brain anatomy and function unless somebody died or an accident occurred. Luckily, with modern technology, we don’t necessarily have to wait for tragedy to get our answers! Luckily, with modern technology, we don’t necessarily have to wait for tragedy to get our answers!

Studying the Brain: Research Methods Clinical observations Clinical observations Damage studies/lesioning Damage studies/lesioning Electroencephalography (EEG) Electroencephalography (EEG) Electrical stimulation (ESB) Electrical stimulation (ESB) Transcranial magnetic stimulation (TMS) Transcranial magnetic stimulation (TMS) Brain imaging – Brain imaging – computerized tomography (CT “Cat” scan) computerized tomography (CT “Cat” scan) positron emission tomography (PET scan) positron emission tomography (PET scan) magnetic resonance imaging (MRI) magnetic resonance imaging (MRI)

Clinical Observation Clinical observations have shed light on a number of brain disorders. Alterations in brain morphology due to neurological and psychiatric diseases are now being catalogued. Tom Landers/ Boston Globe

Lesions Hubel (1990) A brain lesion involves experimentally damaging and removing sections of brain in animals, then observing their behaviors after such destruction A brain lesion involves experimentally damaging and removing sections of brain in animals, then observing their behaviors after such destruction

Electroencephalogram (EEG) An amplified recording of the electrical waves (neural activity) sweeping across the brain’s surface, measured by electrodes placed on the scalp.

Electrical Stimulation (ESB) Researchers electrically stimulate parts of the brain during brain surgery and note the effects Researchers electrically stimulate parts of the brain during brain surgery and note the effects There is a very cool video that shows a woman undergoing surgery whose brain is being electrically stimulated while she is conscious – you can see how the electricity affects her behavior. The video is called “Mapping the Brain through Electrical Stimulation” There is a very cool video that shows a woman undergoing surgery whose brain is being electrically stimulated while she is conscious – you can see how the electricity affects her behavior. The video is called “Mapping the Brain through Electrical Stimulation” g-the-brain-through-electrical-stimulation g-the-brain-through-electrical-stimulation g-the-brain-through-electrical-stimulation g-the-brain-through-electrical-stimulation

Abuse of ESB?

Transcranial Magnetic Stimulation (TMS) Involves delivering a large current through a wire coil on a person’s head. Involves delivering a large current through a wire coil on a person’s head. Can be used to: Can be used to: Produce motor responses Produce motor responses Temporarily inactivate an area of the brain Temporarily inactivate an area of the brain Treat depression Treat depression Also known as “virtual lesioning” Also known as “virtual lesioning” It can help demonstrate causality. A noninvasive mapping technique such as fMRI allows researchers to see what regions of the brain are activated when a subject performs a certain task, but this is not proof that those regions are actually used for the task; it merely shows that a region is associated with a task. If activity in the associated region is suppressed (i.e. 'knocked out') with TMS stimulation and a subject then performs worse on a task, this is much stronger evidence that the region is used in performing the task. It can help demonstrate causality. A noninvasive mapping technique such as fMRI allows researchers to see what regions of the brain are activated when a subject performs a certain task, but this is not proof that those regions are actually used for the task; it merely shows that a region is associated with a task. If activity in the associated region is suppressed (i.e. 'knocked out') with TMS stimulation and a subject then performs worse on a task, this is much stronger evidence that the region is used in performing the task.

Computerized Tomography (CT or “Cat” scan) CT scanning combines special x-ray equipment with sophisticated computers to produce multiple images or pictures of the inside of the body. These cross-sectional images of the area being studied can then be examined on a computer monitor or printed. CT scanning combines special x-ray equipment with sophisticated computers to produce multiple images or pictures of the inside of the body. These cross-sectional images of the area being studied can then be examined on a computer monitor or printed. Provides greater clarity and more details than regular x- ray exams. Provides greater clarity and more details than regular x- ray exams.

Positron Emission Topography (PET Scan) PET PET (positron emission tomography) Scan is a visual display of brain activity that detects a radioactive form of glucose (sugar) while the brain performs a given task. Active areas have increased blood flow Sensors detect radioactivity Different tasks show distinct activity patterns

Magnetic Resonance Imaging (MRI) An MRI is basically a picture of the brain from many angles and it provides clear 3D images An MRI is basically a picture of the brain from many angles and it provides clear 3D images It uses magnetic fields and radio waves to produce computer-generated images that distinguish among different types of brain tissue. The images to the right show ventricular enlargement in a schizophrenic patient. It uses magnetic fields and radio waves to produce computer-generated images that distinguish among different types of brain tissue. The images to the right show ventricular enlargement in a schizophrenic patient.

Homer Simpson’s MRI

Functional MRI (fMRI) Don’t confuse an MRI with a functional MRI Don’t confuse an MRI with a functional MRI A “functional” MRI enables doctors to see actual movement and activity in the brain. MRI just provides detailed pictures of the brain. A “functional” MRI enables doctors to see actual movement and activity in the brain. MRI just provides detailed pictures of the brain. The image to the The image to the right shows brain regions that are active when a participant lies.

Visual Function The functional MRI scan shows the visual cortex is active as the subject looks at faces. Courtesy of V.P. Clark, K. Keill, J. Ma. Maisog, S. Courtney, L.G. Ungerleider, and J.V. Haxby, National Institute of Mental Health

Auditory Function The functional MRI scan shows the auditory cortex is active in patients who hallucinate.

Specialization & Integration Brain activity when hearing, seeing, and speaking words

For more information… And check this out: a cool brain scan online tool where the user can choose the brain scan, choose the view, and choose the brain part(s) to be examined. In addition to the scans, you see the different views— coronal (front and back), sagittal (left and right) and axial/transverse (top and bottom): the-brain/mapping-the-brain.html And check this out: a cool brain scan online tool where the user can choose the brain scan, choose the view, and choose the brain part(s) to be examined. In addition to the scans, you see the different views— coronal (front and back), sagittal (left and right) and axial/transverse (top and bottom): the-brain/mapping-the-brain.html the-brain/mapping-the-brain.html the-brain/mapping-the-brain.html See /index.html See /index.html /index.html /index.html