Psychology 2221A/B Midterm: Midterm #2 notes 2221A
23 Jun 2018
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Bio Psychology Midterm #2
Chapter 5
Goals of Research in Behavioural Neuroscience:
- Assess how different brain areas control behaviour
- Determine which cells and chemicals are involved in behaviour
- Measure activity of neurons in conjunction with behaviour
Making Neurons Visible
Histology to prepare nervous tissue for examination under the microscope
1. Perfusion: flush blood from animals body using saline- put saline into heart to pump
blood out of brain
2. Fixation: chemicals (formalin) stabilize tissue to prevent disintegration after death,
makes the brain hard (most common)
Embedding and Slicing
- Embed brain in wax or other supporting medium (freeze)
- Slice very thin and mount each slice on a microscope slide
- BUT sectioned brain tissue is nearly transparent- visualizing requires stain
Staining to See Structure
- Different dyes adhere to different cells or parts of nervous system
- Nissl Staining
In the late 1800’s Franz Nissl discovered that methylene blue would stain cell
bodies
Nissl Staining is one of the most common structural stains
Dyes have changed though
Cresyl violet and thionin stain
Staining wherever there is grey matter
- Myelin Stains
Colours the sheath that surrounds the neurons so fibre bundles are observed
Attaches where there is myelin
Doesn’t tell the direction of the pathway
E.g. Weigert
- Golgi Staining
Extremely important staining method
Developed in the late 1800’s by Camillo Golgi
Chemical reaction results in some neurons stained
Allows morphology of whole neuron to be seen
Selectively stains only 2-5% of neurons
Allows researchers to see initial shape of neuron
find more resources at oneclass.com
find more resources at oneclass.com
Neuroanatomical Tracing Techniques
- Anterograde (forward)
Tracing where axons project away from an area (efferent connections)
PHA-L
- Retrograde (backward)
Tracing where axons are projecting into an area (afferent pathways)
Flourogold
Methods of Visualizing the Living Human Brain
Contrast X-Rays
- Beam of x-rays passed through an object onto a photographic plate
- E.g. Pneumoencephalogram
Involves temporarily replacing some of CSF with air
Ventricles & fissures visible
What can it tell us? Shows us where there is air in ventricles and subarachnoid
space. If it is pushed out of space- possible tumor?
- E.g. Cerebral Angiogram
Visualizes cerebral circulatory system
Infuse radio-opaque dye through a cerebral artery
What can it tell us? If you’re getting a stroke. If blood vessel is not in the right
location, then it could determine location of tumor
Computerized Tomography (CT Scans)
- X-ray beam and detector rotate around individual
- Computer integrates info into a 2D image
- Usually 8 horizontal pictures
- Series of 2D images can be combined to create 3D image
- Allows researchers to see inside of the brain
- Pictures usually limited to horizontal plane
- Can also see tumor
Magnetic Resonance Imaging (MRI)
- Measures waves emitted by hydrogen atoms when they are placed into magnetic field
- Neural structures different densities of H atoms (e.g. water, iron , fat, etc) white and
grey matter, CSF
- Not exposed to X-rays
- Disadvantages:
Cannot have any metal in body
Tight space, cant move
Sedate children
Extremely loud
Cost
Wait a long time
Only structure, not function
find more resources at oneclass.com
find more resources at oneclass.com
Positron Emission Tomography (PET)
- Highlights active areas of brain
- Patient injected with radiolabelled glucose (2-DG)
- Active brain areas use more glucose
- PET localizes glucose using decay
- Big lag of time- get injected, do a task, then come back for scan
Functional Magnetic Resonance Imaging
- Main tool used by cognitive neuroscience
- Images increase in oxygen (blood) flow to active brain areas
- Blood oxygenated level dependent signal (bold)
- Advantages:
Nothing injected
Provides structural and functional info
Spatial resolution better
Changes can be measured in real time
- Disadvantages:
Expensive
Correlational- assuming increased areas of blood flow are analogous
Paired-Image Subtraction Technique
- Compares images during different cognitive tasks differing in only one constituent
cognitive process
- Averaging helps reduce ‘noise’
- Diffusion Tensor Imaging—maps the white matter in a living brain
Recording Human Psychophysiological Activity
1. Brain activity scalp EEG
2. Somatic Nervous System Activity muscle tension (EMG) OR eye movements (EOG)
3. Autonomic Nervous System Activity skin conductance OR cardiovascular activity
EEG- measuring brain waves
- A measure of the average electrical activity of the brain
- Some EEG wave forms associated with: Specific states of consciousness, cerebral
pathology
- Event-related potentials: measuring electrical patterns in response to external stimuli
Transcranial Magnetic Stimulation
- NOT a measure of activity- actually alters neural activity
- Applies a brief, strong magnetic field that alters neural activity
- Either activates or deactivates brain structures depending on stimulation parameters
Invasive Physiological Research Methods in Animals
Typically fall into 3 categories:
1. Lesioning
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Determine which cells and chemicals are involved in behaviour. Measure activity of neurons in conjunction with behaviour. Embed brain in wax or other supporting medium (freeze) Slice very thin and mount each slice on a microscope slide. But sectioned brain tissue is nearly transparent- visualizing requires stain. Different dyes adhere to different cells or parts of nervous system. In the late 1800"s franz nissl discovered that methylene blue would stain cell bodies. Nissl staining is one of the most common structural stains. Colours the sheath that surrounds the neurons so fibre bundles are observed. Doesn"t tell the direction of the pathway. Developed in the late 1800"s by camillo golgi. Allows morphology of whole neuron to be seen. Allows researchers to see initial shape of neuron. Tracing where axons project away from an area (efferent connections) Tracing where axons are projecting into an area (afferent pathways) Beam of x-rays passed through an object onto a photographic plate.
