Everything psychological is simultaneously…… biological .
Deals with the structure and function of neurons, nerves, and nervous tissue.
Especially focuses on their relationship to behavior and learning.
Fundamental questions we will be looking at in this module:
How does the brain work?
How does our brain organize itself?
How does our brain communicate within itself?
How does the brain process the information we need to:
Recognize our best friend.
Play a musical instrument.
Identify our first memory.
Shoot a basketball.
Write a paper.
How does brain chemistry factor in for things like: depression, aggression, multiple sclerosis, Parkinson’s disease, addictions, or sexual attraction?
Menu Overview of the Nervous System (Figure 2.1)
A nerve cell that makes up the nervous system and that receives and sends messages within that system.
The Neuron or soma
Menu LO 2.1 What are the nervous system, neurons and nerves
Bundles of axons coated in myelin that travel together through the body.
(Similar to a telephone cable made up of thousands of small wires.)
Grey fatty cells in the brain that…
provide support for the neurons to grow on and around
deliver nutrients to neurons
produce myelin to coat axons
clean up waste products and dead neurons, influence information processing
during prenatal development, influence the generation of new neurons.
Brain is made up off 10% neurons, 90% glial cells.
Action Potential: a brief electrical charge that travels down an axon.
How do neurons communicate?
The level of stimulation required to trigger a neural impulse.
The junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron. The tiny gap of this junction is call the synaptic gap .
Synaptic vesicle Synaptic knob
Chemical messengers that traverse the synaptic gaps between neurons.
When released by the sending neuron, neurotransmitters travel across the synaptic gap and bind to receptor sites on the receiving neuron, thereby influencing whether that neuron will generate a neural impulse.
Different neurons will produce only certain kinds of neurotransmitters as well as receive only certain kinds of neurotransmitters.
Outside chemicals introduced into the human system can substitute, mimic or block these neurotransmitters.
Cleaning up the Synapse
Reuptake - process by which neurotransmitters are taken back into the synaptic vesicles.
Enzyme - a complex protein that is manufactured by cells.
One type specifically breaks up acetylcholine because muscle activity needs to happen rapidly, so reuptake would be too slow.
How do neurotransmitters affect behavior?
All neural pathways use neurotransmitters, therefore neurotransmitters play a part in all behaviors and mental processes in some way.
Enables muscle action, learning, and memory.
The major neurotransmitter controlling muscles.
With Alzheimer’s disease, ACH-producing neurons deteriorate.
In Parkinson’s disease, ACH is overproduced, contributing to tremors and stiffness.
Influences movement, learning, attention, and emotion.
Associated with the pleasure system of the brain, providing feelings of enjoyment.
Drugs of abuse (alcohol, cocaine) alter the release of dopamine.
Amphetamines cause the over release of dopamine from the vesicles.
Other drugs mimic dopamine and cause rush of pleasure.
Dopamine and addiction…
The body adjusts to the higher level of dopamine by shutting down receptor sites.
Even when the chemicals causing the high dopamine levels are no longer in the system, the receptor sites for the dopamine have been reduced.
Now, normal levels of dopamine can’t fire the neurons effectively, because there aren’t sufficient numbers of dopamine receptors!
Symptoms of Dopamine deficiency
Reduced ability to feel pleasure
Flat, bored, apathetic and low enthusiasm
Low drive and motivation
Difficulty getting through a task even when interesting
Difficulty paying attention and concentrating
Slowed thinking and/or slow to learn new ideas
Low libido or impotence
Mentally fatigued easily and physically fatigued easily
Dopamine and addictions….
In order to feel better again, people return to their substance of choice (or another) which will increase coveted dopamine levels back to high levels again.
People may need increasing amounts of their drug just to feel normal!