Biological Approach (copy)

Localization of function

Localization of function

Different parts of the brain have functions which play a role in human behavior.

MRI Scan

MRI scanners use a magnetic field and pulses of radio wave energy to make 3D pictures of organs and structures inside the body, including the brain.

Pros and Cons of MRI

Advantages

High sensitivity for detecting the presence or changes in a tumor.

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Useful to neuropsychologists studying brain-damaged individuals since they are more detailed and in 3D format (localization of damage is more precise)

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Only takes pictures of the static brain so we do not need to worry about ecological validity.

Limitations

People with heart pacemakers, metal plates, or screws in their bodies may not be scanned, this could mean a loss of potential participants in psychological studies.

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Some people suffering from claustrophobia, people with dementia, and children may find it difficult to tolerate the procedure.

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If people move during the scan, the images are unclear and difficult to interpret reliably.

Neurotransmitters

The body’s natural chemical messengers that transmit information from one neuron to another.

Excitatory Neurotransmitters

Increase the likelihood of a neuron firing, by depolarizing the neuron.

Inhibitory Neurotransmitters

Decrease the likelihood of a neuron firing, by hyperpolarizing the neuron.

Neurotransmission

• Information travels by stimulating the dendrites of a neuron

• The neuron is polarized, sending an electrical charge to the terminal buttons

• The terminal buttons release neurotransmitters across the synapse (gap between neurons)

• The neurotransmitters attach to the receptor sites of the dendrites of another neuron

Agonists

All neurotransmitters are agonists for receptor sites. They are referred to as endogenous (made within the body) agonists since they are biologically already a part of our nervous system.

Antagonist

Antagonists are drugs that block the receptor site, they do not allow the neurotransmitter to do its job, no action potential is sent down the neuron.

Neuroplasticity

The brain’s ability to alter its own structure following changes within the body or in the external environment.

Synaptic Plasticity

Synaptic plasticity works by the statement, use it or you lose it,

1. Synapses become stronger through repeated use, this is known as long term potentiation or LTP.

2. LTP leads to longer periods of depolarization on the postsynaptic membrane therefore a greater level of response,.

3. Over time, this leads to protein synthesis and gene expression that will be the building blocks used for dendritic branching (process called neuronal arborization). Dendritic branching allows for the formation of new synapses between neurons.

Neural Pruning

When a synapse is not used or is under-stimulated, it may go through synaptic pruning. This is the way for the brain to remove synapses that are no longer needed making the functioning of the neural networks more efficient.

Hormones

A class of chemicals that affect behavior, secreted by glands in the endocrine system.

• Hormones take longer to produce changes in behavior than neurotransmitters.

• They produce effects that last a lot longer than action potential.

Hormones only produce reactions in target cells which have an appropriate site for the hormone, when it binds to the cell it either increases or decreases its function.

Evolution

The result of genetic mutation. It is when the traits that are best for the gene pool survive (survival of the fittest).

Gene pool is the stock of different genes in an interbreeding population

Natural Selection

Those members of a species who have characteristics that are better suited to the environment and are more likely to breed, thus passing on these traits.

Intrasexual Selection

Type of sexual selection. Competition between one sex (usually males) for access to mates. Usually, the ‘strongest’ ends up being able to pass his or her genes.

Pheromones

A chemical substance produced and released into the environment by an animal, affecting the behavior or physiology of others of its own species.

Genetics

The study of genes, variation, and inheritance in living organisms.

Heritability

The extent to which a behavior is genetically inherited.