How can we study the brain?

Scanning the Brain Do This: 66-69 Read through the descriptions of the different types of brain scans Rank the scans in order of most useful and least useful Provide an example to help explain your ranking choices

Brain Scans 66-69 Method How it works Used for CAT or CT scans Computerized axial tomography PET scan Positron emission tomography MRI scan Magnetic Resonance Imagine EEG Electroencephalogram

Brain Scans Method How it works Used for CAT or CT scans Computerized axial tomography Fancy x-ray Several xrays around the brain for a 3D picture Shows structure but not function or activity of the brain PET scan Positron emission tomography Measures chemical usage in the brain Measures brain activity Can scan for different chemicals, neurotransmitters, and blood flow MRI scan Magnetic Resonance Imagine Uses magnetic fields to measure the density and location of brain material Shows structure and not function (fMRI uses PET type scan to combine structure and function) Indicates damage Does not expose patient to radiation like an xray EEG Electroencephalogram Device detects brain waves Researchers can see the type of waves the brain produces during different stages of consciousness Study activity and function

Techniques for Studying Human Brain Function and Structure

EEG (Electroencephalography) Technique: Multiple electrodes are pasted to outside of head What it shows: A single line that charts the summated electrical fields resulting from the activity of billions of neurons

EEG (Electroencephalogram) Advantages Detects very rapid changes in electrical activity, allowing analysis of stages of cognitive activity Disadvantages Provides poor spatial resolution of source of electrical activity

PET (Positron Emission Tomography) SPECT (Single Photon Emission Computed Tomography) Technique: Positrons and photons are emissions from radioactive substances What it shows: An image of the amount and localization of any molecules that can be injected in radioactive form, such as neurotransmitters, drugs, tracers for blood flow or glucose use (which indicates specific changes in neuronal activity) PET Scan

PET (Positron Emission Tomography) SPECT (Single Photon Emission Computed Tomography) Advantages Allows functional and biochemical studies Provides visual image corresponding to anatomy Disadvantages Requires exposure to low levels of radioactivity Provides spatial resolution better than that of EEG, but poorer than that of MRI Cannot follow rapid changes (faster than 30 seconds)

MRI (Magnetic Resonance Imaging) Technique: Exposes the brain to magnetic field and measures radio frequency waves What it shows: Traditional MRI provides high resolution image of brain anatomy, and newer functional images of changes in blood flow (which indicate specific changes in neuronal activity)

Advantages of MRI Requires no exposure to radioactivity Provides high spatial resolution of anatomical details (<1 mm) Provides high temporal resolution (<1/10 of a second)

fMRI-Functional MRI Functional magnetic resonance imaging, or fMRI, is a technique for measuring brain activity. It works by detecting the changes in blood oxygenation and flow that occur in response to neural activity – when a brain area is more active it consumes more oxygen and to meet this increased demand blood flow increases to the active area. fMRI can be used to produce activation maps showing which parts of the brain are involved in a particular mental process.

MEG (Magnetoencephalography) What it shows: Detects the magnetic fields produced by electrical currents in neurons Detects and localizes brain activity, usually combined with structural image from MRI Advantages Detects very rapid changes in electrical activity, allowing analysis of stages of cognitive activity

MEG (Magnetoencephalography) Advantages (cont.) Allows millimeter resolution of electrical activity for surface sources such as cerebral cortex Disadvantages Poor spatial resolution of brain activity in structures below cortex Equipment is very expensive

Scanning the Brain Do This: 66-69 Read through the descriptions of the different types of brain scans Rank the scans in order of most useful and least useful Provide an example to help explain your ranking choices

Questions 1) Blindness could result from damage to which cortex and lobe of the brain? Visual cortex in the frontal lobe Visual cortex in the temporal lobe Sensory cortex in the parietal lobe Visual cortex in the occipital lobe Cerebral cortex in the occipital lobe

answer 1) D visual cortex in the occipital lobe

Question Paralysis of the left arm might be explained by a problem in the A) motor cortex in the frontal lobe in the left hemisphere B) motor cortex in the frontal lobe in the right hemisphere C) sensorimotor cortex in the temporal lobe in the left hemisphere D) motor cortex in the parietal lobe in the left hemisphere E) motor cortex in the occipital lobe in the right hemisphere

answer 2) B motor cortex in the frontal lobe in the right hemisphere

question Which chemicals pass across the synaptic gap and increase the possibility the next neuron in the chain will fire? Synaptic peptides Inhibitory neurotransmitters Adrenaline – type exciters Excitatory neurotransmitters Potassium and sodium

answer 3) D Excitatory neurotransmitters

question Which sentence most closely describes neural transmission? An electric charge is created in the neuron, the charge travels down the cell, and chemicals are released that cross the synapse to the next cell. A chemical change occurs within the cell, the change causes an electric charge to be produced, and the charge jumps the gap between the nerve cells. The electric charge produced chemically inside a group of neurons causes chemical changes in surrounding cells. Neurotransmitters produced in the hindbrain are transmitted to the forebrain, causing electric changes in the cerebral cortex. Neural transmission is an electrochemical process both inside and outside the cell

answer 4) An electric charge is created in the neuron, the charge travels down the cell, and chemicals are released that cross the synapse to the next cell.

question Dr. Fuller, a brain researcher, is investigating the connection between certain environmental stimuli and brain processes. Which types of brain scans is he most likely to use? MRI and CAT CAT and EKG PET and EEG EKG and CAT Lesioning and MRI

answer C) PET and EEG