1 Psychology 304: Brain and Behaviour Lecture 15

2 Announcement I will hold additional office hours in preparation for the midterm exam: Friday, October 15: 3:30 - 4:30 PM Monday, October 18: 11:30 AM - 1:00 PM Tuesday, October 19: 10:00 AM - 12:00 PM

3 Last class, some students suggested that smooth muscle tissue is subject to voluntary control. Researchers unequivocally describe smooth muscle tissue (found in blood vessels, the iris, the gastrointestinal tract, the respiratory tract, etc.) as subject to involuntary control. From last class.... Smooth Muscle Tissue

4 Smooth muscle tissue is innervated by the autonomic nervous system. If you are interested in obtaining a reference regarding this point, please see me after class.

5 Transmission of Electrochemical Neural Signals and Neuropharmacology 3. What neurotransmitters have been identified? 1. How do neurotransmitters generate electrochemical signals in postsynaptic neurons? 2. What mechanisms terminate synaptic transmission?

6 By the end of today’s class, you should be able to: 1. distinguish between ionotropic and metabotropic receptors. 2. describe the processes of reuptake and enzymatic degradation. 3. distinguish between classes of neurotransmitters in terms of function and location.

7 How do neurotransmitters generate electrochemical signals in postsynaptic neurons? (continued) Metabotropic receptors (MRs): (continued)

8 Metabotropic Receptor Activity Figure AFigure B

9 What mechanisms terminate synaptic transmission? Two mechanisms terminate synaptic transmission: 1. Reuptake. Neurotransmitters are repackaged into vesicles in the cystoplasm (i.e., pinocytosis). 2. Enzymatic degradation. Example: Acetylcholinestrase.

10 Mechanisms of Neurotransmitter Deactivation

11 What neurotransmitters have been identified? Four classes of small-molecule neurotransmitters have been identified: 1. Acetylcholine (ACh)  Found at neuromuscular synapses, synapses in the autonomic nervous system, and synapses in parts of the central nervous system.  One of the most widespread neurotransmitters.

12  Associated with movement, autonomic function, learning, and memory. 2. Monoamine neurotransmitters  Found in neurons whose cell bodies are largely located in the brain stem. These neurons give rise to an enormous number of terminal buttons distributed throughout many brain regions.  Deficiency associated with Alzheimer’s disease.

13  Subdivided into two groups: (a)Catecholamines: Dopamine: associated with movement, attention, reinforcement/reward, verbal learning, and planning. Deficiency associated with Parkinson’s disease and ADHD. Excessive levels associated with schizophrenia.

14 Production of the Catecholamines

15 Epinephrine (adrenalin): associated with attention and arousal. Norepinephrine (noradrenaline): associated with attention, arousal, mood, feeding, and sexual behaviour. Deficiency associated with depression.

16. Melatonin: associated with sleep. Serotonin: associated with mood, sleep, feeding, sexual behaviour, and pain. (b) Indoleamines: Deficiency associated with depression.

Amino acid neurotransmitters  Found in fast-acting neurons in the central nervous system.  Include glutamate, gamma-aminobutyric acid (GABA), glycine, and aspartate. Of these, glutamate and GABA are most important:

18 Glutamate: the principle excitatory neurotransmitter in the brain and spinal cord; associated with learning and memory. Deficiency associated with impaired performance on learning tasks

19 GABA: the principle inhibitory neurotransmitter in the brain and spinal cord; associated with mood and the “seizure threshold.” Deficiency associated with anxiety disorders and seizures.

20 4. Soluble gas neurotransmitters  Include nitric oxide (NO) and carbon monoxide (CO).  Unconventional neurotransmitters. After production in the cytoplasm, they immediately diffuse through the presynaptic cell membrane. Thereafter, the diffuse through the postsynaptic cell membrane and stimulate the production of a second messenger.

21  Function as retrograde transmitters: Diffuse back to the presynaptic neuron and regulate its activity.  Little is known about the functions of CO. NO is associated with autonomic activity, learning, and memory.

22  Found largely in neurons of the CNS. Large-molecule neurotransmitters are neuropeptides:  Include five categories: pituitary peptides, hypothalamic peptides, brain-gut peptides, opioid peptides, and miscellaneous peptides.

23 Transmission of Electrochemical Neural Signals and Neuropharmacology 3. What neurotransmitters have been identified? 1. How do neurotransmitters generate electrochemical signals in postsynaptic neurons? 2. What mechanisms terminate synaptic transmission?