Axons – transmit information one neuron to the next (analogous to a telephone wire) o Myelin sheath – covers the axon to insulate it and make impulses travel along the axon faster and more efficiently o Axon terminal or synaptic terminal – sends information across a synapse using neurotransmitters or electrical impulses o Synapse – the gap between two neurons 2. Describe a synapse and the effects of synaptic transmission o Synapse: is the conjunction of a terminal button of one neuron and the membrane of another. The terminal button is on the neuron sending the message, or the presynaptic neuron, and the postsynaptic neuron receives the message. The space between the two is called the synaptic cleft, or gap. Neurotransmitters act like bridges or ferry boats to carry messages across the cleft from one neuron to the next. The effects of these synapses on the postsynaptic neuron are sometimes referred to as excitatory postsynaptic potential and inhibitory postsynaptic potential. These postsynaptic electrical potentials, whether excitatory or inhibitory, are graded potentials. 3. Describe the action potential. o The action potential is an “all-or-none” event. If a neuron is sufficiently depolarized (i.e., if it reaches the threshold of activation), it will generate an action potential. There are no large or small action potentials. If it does not reach the threshold of activation, the impulse will decay rapidly and will not reach the end of the axon. Ex. flushing of a toilet: If you push the lever on a toilet a little bit, a bit of water flows out, but it is not enough to get rid of the waste. Once you push it far enough, the toilet flushes and you cannot stop the process 4. Describe the ways in which drugs can alter synaptic transmission Any substance that affects behavior does so by changing the nature of neurotransmitter activity at the synapse, generally in one of three ways. The substances can: o Block or enhance neurotransmitter synthesis and release in the presynaptic neuron. o Block or enhance binding at the postsynaptic receptors. o Block or enhance neurotransmitter reuptake, the processes that chemically transform neurotransmitters so that they are no longer active.
6. Describe the neurotransmitters (amines, amino acids and peptides, and members of these families) and their functional roles. Neurotransmitters can be classified into three “families” based on their chemical structure: o the amines: includes dopamine, epinephrine, norepinephrine, serotonin, and acetylcholine o the amino acids: includes glutamate and GABA o the peptides: regulate emotions, pain perceptions, and stress responses. The members of each of these three groups have similar properties and functions. WEEK 6: Discuss the evidence supporting localization of function versus equipotential: Early in brain studies was the question of whether the brain consisted of discrete areas with specialized functions or was a single general processor. Proponents of the latter theory suggested that the brain was
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- Winter '08