Brain Imaging Brain Imaging TechniquesTechniques

Figure 2.1 A wrongheaded theoryMyers: Psychology, Eighth EditionCopyright © 2007 by Worth Publishers

Phrenology

X-Ray Transmission ImagingX-Ray Transmission Imaging

Shoot x-rays through Shoot x-rays through the patient onto the patient onto detector film.detector film.

Different tissues Different tissues absorb and deflect x-absorb and deflect x-rays to different rays to different degrees. The film is degrees. The film is exposed less when x-exposed less when x-rays encounter higher rays encounter higher density material like density material like bone. bone.

Low resolution. Hard Low resolution. Hard to distinguish between to distinguish between blood vessels and blood vessels and tissue without an tissue without an injection of iodine or injection of iodine or bariumbarium

ElectroencephalogElectroencephalographyraphy

Electrodes on the scalp Electrodes on the scalp record electrical activityrecord electrical activity

Each electrode provides a Each electrode provides a signal from a particular signal from a particular regionregion

The electrode can then The electrode can then provide unique electrical provide unique electrical activity in that regionactivity in that region

Figure 2.12 An electroencephalograph providing amplified tracings of waves of electrical activity in the brainMyers: Psychology, Eighth EditionCopyright © 2007 by Worth Publishers

Computerized TomographyComputerized Tomography

Imaging of a cross sectional Imaging of a cross sectional slice of the body using X-slice of the body using X-rays.rays.

Invented by Dr. G. N. Invented by Dr. G. N. Housfield in 1971. Received Housfield in 1971. Received the Nobel prize in medicine the Nobel prize in medicine in 1979.in 1979.

The method is constructing The method is constructing images from large number images from large number of measurements of x-ray of measurements of x-ray transmission through the transmission through the patient. patient.

Example of cross-sections through several Example of cross-sections through several parts of the body: skull, thorax, and parts of the body: skull, thorax, and

abdomen,abdomen,obtained by computed tomography.obtained by computed tomography.

Computerized TomographyComputerized Tomography

Magnetic resonance imaging Magnetic resonance imaging (MRI)(MRI)

Magnetic resonance imaging exploits Magnetic resonance imaging exploits the existence of induced nuclear the existence of induced nuclear magnetism in the patient. magnetism in the patient. Magnets with an odd number of Magnets with an odd number of photons or neutrons possess a photons or neutrons possess a weak but observable nuclear weak but observable nuclear magnetic momentmagnetic moment

MR images provide MR images provide excellent contrast excellent contrast between various between various forms of soft forms of soft tissues.tissues.

Planes of Image Planes of Image AcquiredAcquired

CoronalCoronal

HorizontalHorizontal

SagitalSagital

Brain section Spinal cordBrain section Spinal cord

Positron Emission Positron Emission TomographyTomography

Positron emission tomography measures Positron emission tomography measures cerebral cerebral glucose metabolismglucose metabolism, using a , using a radioactive tracker/ marker of neuronal radioactive tracker/ marker of neuronal activity (usually radioactive glucose or even activity (usually radioactive glucose or even oxygen)oxygen)

Measures the amount of glucose present in Measures the amount of glucose present in general locations of the brain, general locations of the brain, shows relative shows relative activity levelsactivity levels

Not very clear resolutions, only shows general Not very clear resolutions, only shows general areasareas

Whole body PETWhole body PET

Functional MRIFunctional MRIffMRI MRI is a technique that images intrinsic blood signal change with magnetic is a technique that images intrinsic blood signal change with magnetic

Resonance imagers.Resonance imagers.Changes in neuronal activity are accompanied by focal changes in cerebral Changes in neuronal activity are accompanied by focal changes in cerebral blood flow (CBF), blood volume (CBV), blood oxygenation and metabolism. blood flow (CBF), blood volume (CBV), blood oxygenation and metabolism.

These physiological changes can be used to produce These physiological changes can be used to produce functionalfunctional maps of mental operations. maps of mental operations.

Figure 2.28 New technology shows the brain in actionMyers: Psychology, Eighth EditionCopyright © 2007 by Worth Publishers

Figure 2.20 The hypothalamusMyers: Psychology, Eighth EditionCopyright © 2007 by Worth Publishers

LesionLesion

Electrical Electrical StimulationStimulation

(Open-brain surgery)(Open-brain surgery)

Case StudyCase Study