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Chapter 1
What is Behavioural Neuroscience?
Question | Answer |
---|---|
What is neuroscience? | A scientific study of the brain and nervous system. |
Layers of analysis, smallest to largest | Molecular - Cellular - Synaptic - Network - Behavioural |
Computational Neuroscience | Produce models of nervous system at desired layer of analysis to be tested |
Three Eras of Neuroscience | Ancient Times, Enlightenment, Modern Neuroscience |
Trepanation Purpose | Release demons or relieve pressure |
Edwin Smith Surgical Papyrus | Showed understanding that paralysis and lack of sensation in the body resulted from nervous system damage |
Hippocrates | Identified correctly that epilepsy originated in the brain |
Galen | Dissected animals, believed ventricles transmitted messages to and from brain (incorrectly) |
Rene Descartes | Argued for mind-body dualism - believe that mind was neither physical nor could be physically studied |
Anton von Leeuwenhoek | Invented light microscope in 1674 |
Luigi Galvani and Emils du Bois-Reymond | Showed that electricity was used as the mode of communication in the nervous system |
Charles Bell and Francois Magendie | Showed that information only traveled in one direction in the sensory and motor nerves |
Camillo Golgi | Supported concept of nervous system as vast, interconnected network of continuous fibers |
Santiago Ramon y Cajal | Supported the Neuron Doctrine |
Neuron Doctrine | Nervous system was composed of an array of seperate, independent cells |
Franz Josef Gall and Johann Gasper Spurzheim | Developed phrenology, which developed the concept of localization of function |
Phrenology | Structure of an individual's skull (bumps on the skull) could be correlated with his or her personality and abilities |
Localization of Function | Certain body functions are controlled by certain areas of the brain |
Paul Broca | Concluded that language was localized in the brain (broca's area) |
Gustave Theodor Fritch and Eduard Hitzig | Electrically stimulating motor cortex on one side resulted in movement on opposite side of body |
Charles Sherrington | Coined the term 'synapse', conducted extensive research on reflexes and the motor systems of the brain |
Otto Loevi | Demonstrated chemical signalling at the synapse |
Sir John Eccles, Andrew Huxley and Alan Hodgkin | Advanced information of the way neurons communicate |
Bernard Katz | Advanced understanding of chemical transmission at the synapse. |
Histology | The study of microscopic structures and tissues |
How is tissue prepared for viewing under a microscope? | 1. It is "fixed" with formalin, hardening the tissue and preserving it from breakdown. 2. It is sliced by a special machine called a microtome. 3. The fragile slices are mounted on slides for viewing 4. Tissue is stained with a stain |
Thickness of slices produced by microtome | Between 10 mm to 80 mm |
Types of specialized stains used for tissue | Golgi silver stain, Nissl stain, myelin stain, horseradish peroxidase |
Golgi silver stain | Used for detailed structural analysis of a small number of single cells |
Nissl stain | Used to identify clusters of cell bodies |
Myelin Stain | Used to follow neural pathways by staining myelin |
Horseradish peroxidase | Used to find the point of origin of a neural pathway by tracing it back towards the cell body |
Immunohistochemistry (IHC) | Antibodies are combined with a variety of dyes to highlight particular proteins |
Gene identified by IHC | c-Fos gene. it indicates brain activity in response to many stimuli |
Autopsy | Examination of the body following death |
Simon LeVay | Used autopsy to identify INAH-3: the size of which indicated that differences in brain structure are correlated with sexual orientation |
Types of Imaging | CT, PET (-> SPECT), MRI, fMRI, DTI |
Full name of CT | Computerized Tomography |
Wilhelm Rontgen | Discovered X-rays in 1896, laying the foundation for CT |
Godfrey Hounsfield and Allan Cormack | Invented CT in 1972 |
Advantages of CT | Provides high-resolution look at a living brain (first technology to do so), allows construction of highly-detailed 3D images |
Disadvantages of CT | Cannot distinguish between living and dead brain -> cannot provide information about activity levels in the brain -> Cannot answer questions about behaviour |
Full name of PET | Positron Emission Tomography |
Why is PET better than CT | It is able to observe brain activity |
Gamma camera | Used to detected radiation released by radioactive atoms that are decaying or breaking up |
Michael Phelps and Edward Hoffman of Washington University | Began to apply the gamma camera to observe brain activity and function in mid 1970s |
How is a PET study conducted? | 1. Radioactive tracers are combined with other molecules (drugs, water, oxygen) and injected into the subject 2. The tracers decay to form gamma rays which are recorded by detectors and fed to a computer 3. The data is reconstructed into images. |
Colours used for indicating brain region activity in PET | Red and yellow -> areas of high activity Green, blue and black -> areas of low activity |
Advantages of new PET machines over old PET machines | Able to take images of adjacent slices at the same time, allowing 3D reconstruction of brain activity |
Full name of SPECT | Single photon emission computed tomography |
Advantage and disadvantage of SPECT over PET | Cheaper but provides less visual detail |
Full name of MRI | Magnetic Resonance Imaging |
Raymond Damadian, Larry Minkoff, and Michael Goldsmith | Produced first MRI image in 1977 |
How does MRI work? | 1. Powerful magnets align hydrogen atoms within a magnetic field 2. RF pulses directed at desired part of body: atoms spin - resonate 3. RF pulse stops: Atoms relax, releasing pulses 4. Colour of voxels of tissue indicate level of pulse activity |
William James and Angelo Mosso | Measured and correlated blood flow with the patients' mental activity |
Full name of fMRI | Functional Magnetic Resonance Imaging |
Purpose of fMRI | Used to assess brain activity |
What fact concerning neurons does fMRI take advantage of? | Active neurons require more oxygen than less active neurons -> variations in blood flow to a particular area will reflect this |
BOLD effect | Blood Oxygenation Level Dependent effect: Oxygenated hemoglobin is diamagnetic (cannot be attracted) but deoxygenated hemoglobin is paramagnetic (can be attracted) |
How does fMRI take advantage of the BOLD effect? | Signals from a voxel will change depending on the oxygenation of the blood in that area |
Advantages of MRI over CT and PET? | It can provide images taken at any angel without any movement of the individual. It is alos superior in both spatial and temporal resolution to PET scans |
Full name of DTI | Diffusion tensor imaging. |
Purpose of DTI | Allows researchers to track the movement of water in the fiber pathways of the nervous system |
Types of Brain Output Recording | EEG, ERPS, MEG, Single-cell recordings |
Full name of EEG | Electroencephalogram |
How is brain activity measured in EEG? | Electrodes are placed on the scalp. Activity vaires during wakefulness, sleep, anesthesia and epilepsy |
Purpose of EEG | Computerised EEG brain tomograhy can be used to generate maps of activity, making it possible to pinpoint the source of abnormal activity |
Disorders detected by EEG | Schizophrenia, dementia, epilepsy, and ADHD |
Modern day EEG | Computerised analysis of EEG recordings can generate animations of activity and construct 3D maps of brain activity |
Full name of ERPs | Event-related Potentials |
Purpose of ERPs | Allows researchers to correlate the activity of cortical sensory neurons recorded through scalp electrodes with stimuli presented to the participant. These responses are then averaged. |
Uses of ERPs | Used in cases where a person's behaviour does not provide a clear indication of whether a stimulus has been percieved eg austistic people |
Full name of MEG | Magnetoencephalography |
Purpose of MEG | Allows researchers to record brain's magnetic activity |
How does MEG work? | 1. Active neurons put out tiny magnetic fields 2. Superconducting quantum interference devices (SQUIDS) convert this magnetic energy into electrical impulses 3. impulses are recorded and analysed 4. Recordings are imposed on 3D MRI images |
Why is recording magnetism (like in MEG) better than electrical activity (like in EEG)? | 1. Skull bones and tissues allow magnetism to pass through without any reduction 2. Recordings of magnetic fields can be taken much faster -> better temporal resolution 3. Is silent -> compare with hammering sound used by MRI magnets |
SQUID | Superconducting quantum interference devices |
Advantages of MEG | 1. Allows researcehr to localize cognitive functions 2. Provides precise localization of the source of the abnormal electrical activity in a SEIZURE |
How are single-cell recordings carried out? | Tiny microelectrodes are surgically implanted in the area of interest. |
Advantage of single-cell recordings | Electrodes can be permanently implanted -> allow animals free range of movement during stimulation. |
Vernon Mountcastle, David Hubel and Torstein Wiesel | Began using single-cell recordings |
What important discovery is single-cell recordings responsible for? | The discover of mirror neurons, or neurons that fire in response to an action. |
Why can the brain be stimulated during neurosurgery without pain? | The brain has no pain receptors |
Wilder Penfield | Investigated the brains of more than 1000 patients undergoing surgery for epilepsy |
Robert Heath | Implanted electrodes in patient suffering from narcolepsy |
Full name of rTMS | Repeated transcranial magnetic stimulation |
What is rTMS? | It is stimulating the brain through magnetic pulses delivered through a single coil of wire encased in plastic that is placed on the scalp. |
What does rTMS do? | Low frequency rTMS temporarily changes brain activity immediately below the stimulation site. |
Important effects of rTMS | 1. Can treat auditory hallucinations e.. schizo and depression 2. Can temporarily produce unusual calculation skills |
Optogenetics | Use of molecues genetically inserted in specific neurons in the brain -> allows neurons to be turned off and on by light |
Important discovery by optogenetics | Confirms a role for glutamate in reward and addiction pathways |
Lesion | Injury to neural tissue deliberate or natural |
Ablation | Removal of neural tissue |
Lesion analysis | Assess function of area by observing behaviour before and after lesion |
Discoveries with lesion analysis | 1. Identify role of ventromedial hypothalamus (VMH) in satiety 2. Treat cases of epilepsy |
How is lesioning carried out? | 1. Electrodes are inserted into area - Electrodes are insulated except at the tip. 2. Heat/Neurotoxins are applied, killing neurons. Area can also be chilled, producing temporary lesion. |
Heat vs neurotoxin | Both produce permanent damage, but neurotoxin can damage either the area of the brain or the fiber pathways passing through the area |
Microdialysis | Extracellular fluid is extracted from areas of the brain through implanted micropipettes. |
Monozygotic vs fraternal twins | 100 percent of genes shared vs 50 percents of genes shared |
Concordance rate | Probability that twin might share a disorder with a twin who has said disorder |
Heritability | Amount of a trait that varies in a population due to genetics |
Knockout genes | Genes that fail to produce the specific protein of the gene it is replacing. |
Matthes et al. 1996 | Bred mice without endorphin receptors which did not respond to morphine and were incapable of being addicted |
Adoption studies | Investigating influence of heredity by comparing similarity of an adopted individual to biological and adoptive parents. |
Ways of studying interaction of heredity and environment in producing traits | Twin studies, adoption studies, studies of genetically modified animals, and epigenetics |
Epigenetics | Development of traits by factors that influence the performance of genes without changing the underlying genes themselves e.g. baby rat licking |
How does epigenetics explain identical twins becoming different from each other in life? | Different choices in lifestyle and experience change the way genes behave |
Stem cell | Cell that can divide and differentiate into other types of cells. |
Embryonic stem cell vs adult stem cells | 1. Can differentiate into any sort of tissue (pluripotent) vs Can only differentiate into cells similar to their source 2. Immortal (can replicate indefinitely) vs on-immortal 3. Will provoke immune reaction in transplant vs less rejection chance |
Ethical practices for human participants | 1. Rewards should not be excessive or inappropiate 2. Participants must be informed that they can leave at any time without penalty 3. Participants must be told enough about the experiment to make a informed decision i.e. informed consent form |
Ethical practices for animal research | 1. Animal research must have a clear scientific purpose 2. Animals should be housed and cared for adequately 3. Experiments should cause as little pain and distress as possible |