Presentation on theme: "Madeleine Wright. Structural and Functional nueroimaging Structural- refers to scanning techniques that show brain structure and anatomy.Scans produced."— Presentation transcript:
Structural and Functional nueroimaging Structural- refers to scanning techniques that show brain structure and anatomy.Scans produced by these techniques typically show cross sections of the brain and may look as if someone has sliced through the brain and taken a picture. Examples: MRI and CT Functional- refers to scanning techniques that provide views of some particular aspects of brain funtion by images of the brain ‘at work’. They also provide information about brain structure. Examples: PET,SPECT and FMRI
Direct electrode stimulation Involves using a device that emits a weak electric current to activate or disrupt the normal activity of neurons in a specific brain area. The brain area initiates a response which is then assumed the area controls or is involved in that responses. It may not just initiate the response it may also disrupt the functioning. A electrode is a small, electrified fine wire (or disc) that can be inserted into or placed onto a specific area of the brain, that stimulates a specific brain area. The brain does not contain pain receptors therefore patients can remain conscious during brain surgery.
Example : Penfield - Brain map which was used to identify areas of the cerebral cortex responsible for different functions. - Did a study with epilepsy in which he mapped cortical areas and related functions to see what area was responsible for the response. - Advantages: The research may promote futher experiments to test the possibilty of a brain pacemaker that regulates chrome (long-term) cases of depression
Advantages: The research may promote further experiments to test the possibility of a brain pacemaker that regulates chrome (long-term) cases of depression Limitations- Invasive, they had to enter the brain by opening the brain and activating or disrupting specific brain areas to observe any changes in behaviour.
Transcranial magnetic stimulation (TMS) Delivers a magnetic field impulse through the skull and temporally activates or disrupts the normal activity of neurons in a specific area of the cerebral cortex. - harmless electric current in time varying changes. - person fully awake - Non-invasive, no anaesthetic
2 types - Single pulse –involves the delivery of a single pulse - Repetive TMS (rTMS) – repeated but not necessarily rapid, delivery of a pulse. When rTMS is used, the consecutive pulses cause the neurons to lose their ability to fire. It can uses to study how the brain organises different functions such as language, memory, vision or attention - A bride single pulse can cause a burst of brain activity - The pulse does not directly affect the whole brain. It only affects that part of the brain that lies immediately below the skull
Used to study functions of specific areas of the cerebral cortex As with electrode stimulation, TMS can be used for mapping brain areas. This is performed by changing the coil position while observing its effects.
LimitationsAdvantages -Extremely invasive research procedure, which uses methods that ethical standards today would be considered unacceptable - Difficulties in generalising results - Cant be used with individuals who have and metal in their body -Very effective technique for brain research -The use of electrodes have been useful and reliable -Has advanced understanding of the role of the brain in mental processes and behaviour -Identify the locations and functions of numerous brain structures and areas, as well as hemispheric specialisation for different functions -Results are generally very consistent
EEG(electroencephalograph) Detects amplifies and records brain activity Assist with the diagnosis and psychological study of various brain related medial conditions, including brain damage and neurological disorders such as epilepsy and Parkinson's disease. Detect and identify distinctive patterns of electrical activity in the brain occurring in people with depression or schizophrenia Useful in providing general and overall info about brain activity without being non invasive. Also used to study ongoing activity in the brain while the participant perform long, complex tasks.
Valuable information about: -Different levels of brain activity associated with various -Thoughts -Feelings -Behaviours -Hemispheric specialisation AdvantagesLimitations - Provides a summary of all the activity of neurons firing within the brain. Using an EGG to understand the workings of the brain. -Does not provide a summary of all the activity of neurons firing within the brain are activated and what their specific functions might be -Difficult to pinpoint the specific area of the brain that is the source of the brain wave activity
Computerised tomography (CT) or Computerised axial tomography (CAT) A neuroimaging technique that produces a computer enhanced image of a cross section (‘slice’) of the brain from X-rays taken from different angles. The procedure involves moving an X-ray source in an arc around the head while a computer complies different ‘snapshots’ of the brain area being investigated
Procedure The patient must be given an injection of a substance into the vein of their arm or hand. - used to highlight the brains blood vessel The patient is required to lie very still on the CT scan bed with their head inserted into the scanner opening An X-ray source is slowly moved in a circular path around the head, at each position delivering a small amount of radiation, which passes through the head and brain An X-ray detector opposite the X-ray source analyses the amount of radiation that has passed through the brain. The X-ray source and detectors are than moved to a new position, and this is repeated many times. A computor then combines the many cross-sectional images taken from all the different angles around the head into a composite cross-sectional, two-dimensional or 3D image
AdvantagesLimitations -Is a way of looking a live intact human brain without using invasive, often dangerous procedure -Radiation dosage, relatively harmless -Useful for spotting and identifying the precise location and extent of damage to or abnormalities in various brain structures or area. -Identify the location and size of tumours -Identify abnormalities in brain structures among people with a mental illness, schizophrenia and depression -Requires an injection but is considered non-invasive - It shows only brain structure or anatomy. It does not provide information about the activity of the brain; that is, brain function
Magnetic resonance imaging (MRI) A neuroimaging technique that uses harmless magnetic fields and radio waves to vibrate atoms in the brain neurons to produce an image of the brain These vibrations are detected by a huge magnet in the chamber surrounding the motionless person, and are channelled into a computer - which then assembles them into a coloured image that indicates areas of high and low brain activity MRI provides an image of the brain and structures that is clearer and more detailed than CT Structure
CT and MRI are used for diagnosing structural abnormalities if the brain. However a MRI can be used to detect and display extremely small changes in the brain Clearly distinguish between brain tissue that is cancerous and non- cancerous. AdvantagesLimitations -Enabled even more precision in the study of the structure of the live human brain in a non-invasive and harmless way -Provides detailed and clearer images of the brain -Doesn't use X-rays or radioactive substances -Can not be used with people who have internal metallic devices -It only shows brain structure, or anatomy, and not funtion -Does not reveal whether the structures are invloved in any given mental process or behaviour
Positron emission tomography (PET) Is a neuroimaging technique that uses a radioactive tracer to enable production of a computer-generated image that provides information about brain structure, activity and function during various tasks PET is used to record the levels of activity in different areas of the brain while the patient is involved in a cognitive or behavioural activity if some kind, such as thinking, imagining, remembering etc. Provides images of the ‘working brain’ by tracking blood flow around the brain - brain areas that require increased blood flow have increased neuronal activity.
Prior to the PET procedure, a harmless radioactive substance is injected into the participants blood vessels - Substance enters the bloodstream it travels to the brain Each PET scan uses a colour code to indicate different levels of brain activity:
AdvantagesLimitations -Useful technique for brain study -Enable researches to obtain valuable info about the role of the brain in behaviour and mental processes -Enables detailed images of the functioning brain; ‘brain at work’ -Observe different brain areas that interact when a person is required to do certain task -More sensitive in detecting areas of brain damage than CT and MRI -Colour coding in PET scans makes it relatively simple to identify areas of the brain that are more active and inactive -Researches can not determine whether an active brain area is actually involved in the mental process or behaviour under investigation -No scope for suggesting cause-effect relationship between active or inactive areas -Limited to studying relativley short tasks -Require an injection of radioactive substance but harmless
Single photon emission computed tomography (SPECT) Variation of the PET Uses a longer lasting radioactive tracer and a scanner to record data that a computer uses to construct two or three-dimensional images of active brain regions SPECT images are not as good as PET images- have a lower resolution Advantages Can also be given longer lasting tasks in research studies Less expensive to uses than PET
Functional magnetic resonance imaging (fMRI) Structure and funtion Is a nureoimaging technique that enables the identification of brain areas that are particularly active during a given task by detecting changes in oxygen levels in the blood flowing through the brain Bases on MRI and measures subtle changes in blood oxygen levels in the functioning brain The colour variations reflect the level of activity of different brain areas and structures while the participant engages in various experimental tasks fMRI images of the brain structure and activity are highly detailed and more precise
AdvantagesLimations -It can take numerous pictures of the brain in rapid succession and therefore can detect brain changes from moment to moment -Unlike PET, SPECT, the fMRI does not require exposure to radiation -Enables detailed images of behavioural responses -The uses of colour makes it easier to interpret images - Their is no scope for suggesting cause-effect relationship between active and inactive areas and mental processes and behaviours under investigation