Deck 3: D: Biological Psychology

Question 1

Describe neuronal communication,beginning with the stimulation of a presynaptic cell and ending with the initial stimulation of the postsynaptic cell.

Answer 1

When a neuron is positively stimulated,there is a surge of positive ions into the cell that changes the potential of the neuron (e.g. ,changing from -70 mV to -68 mV).These charges flow down the dendrites and cross the cell body to the axon hillock,where the cell body meets the axon.If enough positively charged ions reach the axon hillock to push its charge past that cell's firing threshold (e.g. ,-55 mV),the neuron will then initiate an action potential,a wave of electrical activity that originates at the base of the axon and rapidly travels down its length.When an action potential occurs,the charge of that part of the axon changes from approximately -70 mV to approximately +35 mV;in other words,the cell changes from being negatively to positively charged.When the action potential reaches the axon terminal,it triggers the release of that cell's neurotransmitters into the synapses,the microscopically small spaces that separate individual nerve cells.The cell that releases these chemicals is known as the presynaptic cell ("before the synapse")whereas the cell that receives this input is known as the postsynaptic cell (or "after the synapse").The dendrites of the postsynaptic cell contain specialized receptors that are designed to hold specific molecules,including neurotransmitters.Then,this process of neural communication will begin again.

Question 2

Select three neuroimaging techniques outlined in the textbook.Describe each technique and provide one benefit and one drawback of each.

Answer 2

Student could select any three from the list below.
Computerized tomography (CT)scan: 3D image created using multiple X-rays.Benefit: Cheap,no issues with metal in the body.Drawback: Lower resolution than other techniques (e.g. ,MRI).
Magnetic resonance imaging (MRI): 3D image created by measuring how different areas of the brain absorb and release energy while in a magnetic field.Benefit: High-resolution.Drawback: Use of magnetics means individuals with metal embedded or surgically inserted into their bodies may not be able to be scanned or are at risk for injury.
Diffusion tensor imaging (DTI): measures white matter pathways in the brain.Benefit: White matter tends to be implicated in many diseases and disorders.Drawback: Doesn't image gray matter (cortex).
Electroencephalogram (EEG): Measures patterns of brain activity.Benefit: High temporal resolution-can indicate when brain activity is occurring.Drawback: Low spatial resolution-not very precise in determining where activity is originating.
Magnetoencephalography (MEG): Measures electrical activity associated with active neurons.Benefit: Better spatial resolution than EEGs and good temporal resolution (speed).Drawback: Although better than EEGs,still not very high spatial resolution (hard to pinpoint specific brain area).
Positron emission tomography (PET)scan: Measures activity in the brain by measuring levels of radioactive isotope (often glucose).Benefit: Allows researchers to see metabolic activity in the brain and measure involvement of specific receptors.Drawback: PET scans are very slow which means it is difficult to measure quick changes in brain activity.
Functional magnetic resonance imaging (fMRI): measures brain activity by detecting oxygen consumption in brain areas.Benefit: Allows for accurate measurements of specific active brain areas,easy to use,does not involve radioactivity.Drawback: Correlational,meaning causation cannot be derived from the results.