Neuroscience: Modern Technology & Research (part 2)
Brain Mapping
Goal= to achieve a 3 dimensional (3D) map of the brain, representing the surface, the structures within, and the functions performed by components of structures.
Brain Mapping Techniques: Structural
X-ray Techniques
Cerebral Angiography
Computed Tomography
Computer Axial Tomography (CAT)
Magnetic Resonance Imaging (MRI)
Brain Mapping Techniques: Functional
Electrophysiological Techniques
Electroencephalography
Event-Related Potentials (EPRs)
Blood-Flow Techniques
Positron Emission Tomography (PET)
Single Photon emission Computed Tomography (SPECT)
Functional Magnetic Resonance Imaging (fMRI)
Useful in detecting disorders associated with abnormalities in brain arteries
A procedure that uses a special dye (contrast material) and x-rays to see how blood flows through the brain
An image slice through an organ without the interference of all layers of tissue present in X-ray images
X-ray films appear blurry because they are 2-D rendition of our 3-D body
Less radiation than traditional x-ray
Enable 'deblurring' of picture & reconstruction of a complete brain image from multiple views
Enable process of imaging brain internal structure to become safer & more precise-3D
Advantages
safer- The fan shaped beam exposes the body to less radiation than traditional x-rays
more precise- only takes a cross section of an organ, avoiding problem of interference of all the layers of tissue present in x-ray images
clearer image of brain structures-'deblurring' by computer technology 3D
Disadvantages
Doesn't indicate when an activity is occurring in the brain
Uses a magnetic field to take images of the inside of your body
Advantages
No X-rays or radioactive material is used (unlike CAT or PET)
Resolution of the image is shape / clearer than CAT scans
Flexibility- allows the researches to distinguish different structures of the brain- gray/white matter and cerebrospinal fluid
Disadvantages
slow- for an image to be generated
cannot be used in patients with metallic devices, like pacemakers
may cause claustrophobic reaction in some patients
A test of the function of the brain itself
records the electrical activity on the brain's surface
image the brain while it is performing cognitive task
detect the location and magnitude of brain activity involved in the various types of cognitive functions
Non-invasive and painless procedure
Take brief patient history
Apply electrode leads to the patient's scalp
Run the test
Tracings/ Recordings of patterns of electrical activity in the brain
Provide fine-tuned reading of rapidly occurring changes (MRI too slow to do this)
Advantages
Able to trace rapid changes in neural activity
Can record activations in brains of people who are fully conscious & engaged in various activities in natural environment
Disadvantages
Invasiveness- relative
Possible interference from movement, heartbeats- blue reading
Subject presented with a stimulus during EEG process
Record voltage change around the stimulus (before and after it ends)
Repetitions of event- average the values
Evoked response provides a picture of neural activity changing over time as the brain processes information
Method of measuring cerebral blood flow while subject carries out cognitive tasks
PET scans look at bodily process by detecting the decay products from radioactive tracers injected into the body.
Advantages
Provides an image of brain activity as a cognitive task is occurring - locate activity in specific parts of the brain
Disadvantages
Requires the use of cyclotron, an expensive equipment to provide the radioactive isotopes (decay easily and needs to be produced each day)
Not as sensitive to changes over milliseconds (in comparison to electrophysiological techniques)
Radioactive material used
Detect changes in magnetic state of blood using MRI scanners with fast imaging techniques- record changes in oxygen level & blood flow in various brain locations as subjects perform various cognitive tasks
Determine which parts of the brain are activated by different types of physical sensation or activity
Advantages
Provides information about brain structure and function
safer- less harm to patients as no-X-rays or radioactive material is used
allows researchers to infer which locations are involved in specific activities
Insights into Human Cognition
Language
Memory
Concept categories
Disorders
Aphasia (ALS)
Localization of brain
Brain Plasticity
Processing of content & function words
Functions of working memory
Role of Hippocampus
Implicit & Explicit memory
LTM
Categorization task
Name fiding
Bipolar & Unipolar disorder
Schizophrenia
Autism
Dyslexia