Textbook Notes (363,452)
Canada (158,372)
Psychology (1,867)
PSY290H5 (64)
Chapter 4

Chapter 4 PSY290.docx

4 Pages
Unlock Document

University of Toronto Mississauga
Stuart Kamenetsky

Chapter Four: The Chemistry of Behaviour- Neurotransmitters and Neuropharmacology Many Chemical Neurotransmitters Have Been Identified -endogenous source (produced inside the body) called a neurotransmitter, that communicates with the postsynaptic cell -drugs affect behaviour by altering the chemical communication process at millions, or billions of synapses Classic Neurotransmitter: 1. The substance exists in presynaptic axon terminals 2. The presynaptic cell contains appropriate enzymes for synthesizing the substance 3. The substance is released in significant quantities when action potentials reach the terminals 4. Specific receptors that recognize the released substance exist on the postsynaptic membrane 5. Experimental application of the substance produces change in postsynaptic cells 6. Blocking release of the substance prevents presynaptic activity from affecting the postsynaptic cell Amine neurotransmitter: based on modifications of a single amino acid nucleus. Examples include acetylcholine, serotonin or dopamine Amino Acid neurotransmitter: that is itself an amino acid. Examples include GABA, glycine, or glutamate Peptide Neurotransmitter: consisting of a short chain of amino acids Gas neurotransmitter: a soluble gas such as nitric oxide or carbon monoxide that is produced and released by a neuron to alter the functioning of another neuron -neurotransmitters affect their targets by interacting with receptors, protein molecules embedded in the postsynaptic membrane that recognize the transmitter -transmitter molecule binds to receptor, changing shape to open ion channel (as with fast, ionotropic receptors) or altering chemical reactions within the target cell (a with slow, metabotropic receptors-doesn't contain ion channel but may when activated uses a G protein system to open a nearby ion channel) -these different receptor subtypes may trigger very diff responses in target cells, and are also distributed differently in the nervous system Any substance that binds to a receptor is termed a ligand and has one of several kinds of effects 1. A ligand that is classified as an agonist initiates the normal effects of the transmitter on that receptor 2. A receptor antagonist is a ligand that binds to a receptor and does not activate it, thereby blocking it from being activated by other ligands (including native neurotransmitter) 3. An inverse agonist is a less common type of ligand, binds to receptor and initiates an effect that is the reverse of the normal function of the receptor -drug with any of the 3 actions, are properly called competitive ligands b/c they bind to the same part of the receptor complex that the endogenous transmitter normally would -drug that does not normally bind with the transmitter for its binding site, we say that the drug is non-competitive ligand, binding to a modulatory site (when bound by compound, alters the receptors response to its transmitter) Neurotransmitter Systems Form a Complex Array in the Brain Acetylcholine was the first neurotransmitter to be identified -a neurotransmitter produced and released by parasynthetic postganglionic neurons by motoneurons, and by neurons throughout the brain -cholinergic: cells that use acetylcholine as their synaptic transmitter -widespread loss of cholinergic neurons is evident in Alzheimer's Disease; crucial for learning and memory -nicotinic: referring to cholinergic receptors that respond to nicotine as well as to achetylcholine -muscarinic ACh receptors are G protein- coupled (metabotropic) receptors, so they have slower responses when activated, can be excitatory or inhibitory Five monoamines act as neurotransmitters -catecholamine: neurotransmitters-- derived from the amino acid tyrosine (dopamine, epinehrine, and norepinephrine -indoleamines-- derived from the amino acid tryptophan-- are melatonin, serotonin Dopamine: -millions of neurons in the brain contain dopamine -several subtypes of DA receptors -mesostriatal pathway (a set of dopaminergic axons arising from the midbrain and innervating the basal ganglia, including those from the substantia nigra to the satriatum-major role in motor control) and the mesolimbocortical pathway (a set of dopaminergic axos arising in the midbrain and innervating the limbic system and cortex-important in reward and reinforcement) Norepinephrine: - two main clusters of neurons in the brainstem releasing norepinephrine are the locus coerculeus in the pons, and the laterla tegmental system of the midbrain. -NE producing cells are said to be noradrenergic -project broadly throughout the cerebrum, including the cerebral cortex, limbic system and thalamus -4 subtypes, all metabotropic receptors -noradrenergic contributions to diverse behavioural and physiological processes including
More Less

Related notes for PSY290H5

Log In


Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.