Neural communication, addiction and neuroplasticity Biopsychology day 2

Action potential Fluid outside the axon membrane has mostly positively charged ions (+) At rest, the fluid interior of an axon has negatively charged particles This state is called the resting potential The surface of the axon is selectively permeable

Action Potential: Electrical & Chemical Communication A brief electro/chemical signal that travels down the axon to the terminal buttons.

A Closer Look at a Neuron Neural impulse - hyperlink Details of an action potential - hyperlink

Not in isolation but in connection

Someone touched a… _ _ _ _ _ In the peripheral nervous system a bundle of axons is called a nerve. In the CNS a bundle of axons is called a tract. Nerves can be categorized into two groups based on where they connect to the central nervous system: spinal cranial  (parts of the head and connect directly to the brain).

A Closer Look at a Terminal Button Neurotransmitter endogenous chemical messengers that cross the synaptic gaps between neurons synapse - hyperlink

Keys in the lock Neurotransmitter – the key fits in nicely Agonist – (excites) mimics the neurotransmitter and stimulates the receptor Antagonist – (inhibits) blocks and does not stimulate the receptor

Neurotransmitters Serotonin Dopamine Acetylcholine Norepinephrine GABA Substance P Endorphins Hyperlink

A Closer Look at Reuptake the process by which the sending neurons collect the excess neurotransmitter hyperlink

Pathways 40 billion neurons each connect to approx. 10 000 other neurons, thus we end up with possibly 400 trillion synapses Neurons cluster into neural networks Neurotransmitter pathways – may use only one or two neurotransmitters and neurotransmitters may affect specific behaviours and emotions Learning occurs as experience strengthens connections

Two key pathways

Plasticity This is the brain’s ability to change, especially during childhood Reorganizing after damage or building new pathways based on new experiences or neurogenesis (new brain cells produced) Not all damage can be remediated – neurons that are severed usually do not regenerate Neurons that fire together, wire together We have synaptic pruning but we also have creation of synapses

Teenage Brain To what extent do you see a mismatch between the teenage brain and how society is set up? If you could change, if you could have a revolution, how would you change society to fit you? Can we, or should we, try to save you from yourselves?