Option E.4 Neurotransmitters & Synapses Page 360

Synaptic Transmission Neurons communicate with each other chemically across a space called a synapse Presynaptic membrane Sending Postsynaptic membrane Receiving The molecule moving across the space (synaptic cleft) is called a neurotransmitter

Neurotransmitters Some NTs are excitatory Some NTs are inhibitory Stimulate the next neuron to forward the message Increase the permeability to positive ions (positive ions move in) Some NTs are inhibitory They cause positive ions to move out of the postsynaptic cell Movement of positive ions back into the synaptic cleft chemically depresses the postsynaptic cell (harder to excite)

Question When two neurons communicate with each other, the presynaptic neuron sends a message across the synapse to the postsynaptic neuron. 1. What type of molecule carries the message across the synapse and what type of molecule receives the message? 2. Explain the two ways that presynaptic neurons can act on postsynaptic neurons.

Decisions, decisions What interaction occurs between excitatory and inhibitory presynaptic neurons acting at the synapse? Open your book to page 361. Read pages 361-362. Then answer the following questions: In your own words, outline the steps of decision making in the central nervous system. Identify an excitatory neurotransmitter. Outline how an excitatory neurotransmitter works. Identify an inhibitory neurotransmitter. Outline how an inhibitory neurotransmitter works.

Psychoactive drugs Before we talk about how drugs affect the brain & personality, we need to have a fundamental understanding of two neurotransmitters: Acetylcholine Noradrenaline

Cholinergic vs. Adrenergic Synapses Synapses using acetylcholine are called cholinergic synapses Nicotine, for example, stimulates transmission in cholinergic synapses  calming effect “C” Synapses using noradrenaline are called adrenergic synapses Cocaine & amphetamines stimulate adrenergic synapses  increased alertness, energy & euphoria “A”

What’s amphetamine? Adderall (ADHD/cognitive control) Sometimes prescribed “off label” for depression, obesity & nasal congestion

Effect of drugs on the brain Drugs can alter your mood & emotional state Excitatory drugs like nicotine, cocaine and amphetamine increase nerve transmission Inhibitory drugs like benzodiazepines, alcohol and tetrahydrocannabinol (THC) decrease likelihood of nerve transmission

How can drugs change synaptic transmission? Block a receptor for a neurotransmitter Block release of a neurotransmitter Enhance release of a neurotransmitter Enhance neurotransmission by mimicking a neurotransmitter Block removal of a neurotransmitter from the synapse and prolong the effects of the NT

EXCITATORY!!!! DRUGS Turn to page 365. Explain the effects of nicotine, cocaine and amphetamine in terms of their actions at the synapses in the brain.

Inhibitory Drugs Turn to page 366. Explain the effects of GABA, alcohol and THC in terms of their actions at the synapses in the brain.