An Introduction to the Field of Neuroscience

 Devise a metaphor/imagery exercise for neural communication.

 Sketch and briefly explain the steps involved in a neural impulse.

 Write an open-ended (How/Why) question relating to the brain/nervous system.  This should be the number one thing that you want to learn during this unit.

Imagery of the Nervous System

 Takes many small parts and puts them together to make one big part, not a complete product.  Appears to be the main body part of the Neuron.  Takes in and processes bits of information from other neurons.  Waits for information from our nerves, which operate according to our senses, etc.

 Each delivers a necessary part from an outside source into the factory.  Grow outward from the cell body.  Small parts (bits of data) travel.  The more we think, the more plentiful dendrites become; the more successful our company, the more supply routes and supplies are needed.

 Axons are exit-only highways, much larger than dendrites.  After the Neuron has processed the information it has taken in, it sends out the processed information to another Neuron to help ‘complete the puzzle’.

 Factories rely on other roads, just as Neurons rely on other Neurons’ dendrites.  The dendrites of other Neurons wait for information on the other side of the synapse, just as small roads branch out on the other side of the river from the Axon, but they never actually touch.  The synapse is simply the gap between Axon and Dendrites.

 The ferries carry the parts across the river to the waiting roads that will take them to other factories;  Neurotransmitters carry the informative signals across the synapse "from the Axon to the next dendrites, which will rush the information to the other waiting Neurons.

Neurotransmission

 You're taking Prozac, and you've heard it described as an SSRI. Maybe you know that SSRI stands for selective serotonin reuptake inhibitor. But that's quite a mouthful -- what does it mean?

 I will give a brief, simplified description of how the brain's message carriers (neurotransmitters) operate, and then try to clarify the process by telling the illustrated story, "GABAs in the 'Hood." *

 The monoamines - serotonin, norepinephrine and dopamine  GABA (gamma amino butyric acid)  Glutamate.

 When a message comes in at one end of a nerve cell, an electrical impulse travels down the "tail" of the cell, called the axon, and causes the release of the appropriate neurotransmitter.  Molecules of the neurotransmitter are sent into the tiny space between nerve cells, called the synaptic gap.

 There, one or more of the following can occur for each molecule: 1. It may bind (attach) to the receptors in the adjacent nerve cell, send the message on, leave the receptor, then repeat this process or go on to one of the other steps.

2. It may hang around in the synapse until a receptor becomes available, bind to it, release, and continue with steps 1 to 3 until its activity is ended by steps 4, 5 or 6.

3. It may bind to the first cell's autoreceptors, which tell that cell not to release any more of the neurotransmitter molecules, then leave the autoreceptor and continue trying to bind again somewhere until its activity is ended by step 4, 5 or 6.

4. It may be rendered inactive by an enzyme.

5. It may be reabsorbed by the first cell in the "reuptake" process, and recycled for later use or deactivated.

6. It may diffuse out of the synapse and be deactivated elsewhere.

 Now, so many things can go wrong with this process that it's not surprising mood disorders are fairly common.

 The nerve cells (neurons) might not be manufacturing enough of a neurotransmitter.  Too many molecules of the neurotransmitter may be dissolved or deactivated by enzymes.  Too much of a neurotransmitter may be released.

 The molecules may be reabsorbed too quickly by the reuptake transporters.  The autoreceptors may be activated too soon, shutting down the release of neurotransmitter molecules prematurely.