Neuroscience: Exploring the Brain, 3e

1. Neuroscience: Exploring the Brain, 3e Chapter 15: Neuroendocrine system: Chemical Control of the Brain and Behavior

2. Introduction • Synaptic Connections • Point-to-point • Restricts synaptic communication • Brain areas with expanded influence over space and time • Secretory hypothalamus • Autonomic nervous system (ANS) • Diffuse modulatory systems

3. The Secretory Hypothalamus • Function • Difference between hypothalamus and dorsal thalamus • Hypothalamus defect • Fatal disruption to body function • Dorsal thalamus defect • Blind spot, lack of feeling

4. The Secretory Hypothalamus • Homeostasis • Regulatory process: Regulates body temperature and blood composition • Hypothalamus commands in cold weather • Shiver, goosebumps, turn blue • Hypothalamus commands in hot weather • Turn red, sweat

5. The Secretory Hypothalamus • Structure of the Hypothalamus

6. Pathways to the Pituitary Two neurohormones Oxytocin Lactation, suppress hypothalamic function Vasopressin Regulate blood volume and salt concentration The Secretory Hypothalamus: Neurosecretory neurons of the periventricular zone.

7. The Secretory Hypothalamus • Communication between kidneys and brain

8. The Secretory Hypothalamus • Hypothalamic Control of the Anterior Pituitary • Controlled by parvocellular neurosecretory cells • Secrete hypophysiotropic (‘releasing’) hormones • Hypothalamiopituitary portal circulation • Pituitary cells secrete or stop secreting hormones

9. The Secretory Hypothalamus • Stress Response • Periventricular hypothalamus secretes CRH into portal circulation. • ACTH released into circulation. • ACTH stimulates cortisol release from adrenal cortex.

10. The Autonomic Nervous System • Divisions of autonomic nervous system (ANS) • Sympathetic division • Increased heart rate and blood pressure • Depressed digestive function • Mobilized glucose reserves • Parasympathetic division • Slower heart rate, fall in pressure • Increased digestive functions • Stop sweating

11. The Autonomic Nervous System • ANS Circuits versus Somatic Motor System

12. The Autonomic Nervous System • Sympathetic and Parasympathetic Divisions

13. The Autonomic Nervous System • The Enteric Division • Location: Lining of esophagus, stomach, intestines, pancreas, and gallbladder • Composition: Two complicated networks- myenteric (Auerbach's) plexus and submucous (Meissner's) plexus • Function: Control physiological processes involved in transport, digestion of food • Inputs: From brain via axons of the sympathetic and parasympathetic divisions

14. The Autonomic Nervous System • Central Control of the ANS • Connections for autonomic control • Periventricular zone connections to brain stem and spinal cord nuclei • Nucleus of solitary tract • Function of solitary nucleus • Integrates sensory information from internal organs and coordinates output

15. The Autonomic Nervous System • Neurotransmitters and the Pharmacology of Autonomic Function • ANS: Better understanding of drug mechanisms influencing synaptic transmission (vs. CNS) • Preganglionic Neurotransmitters • ACh: Binds to nAChR, evokes fast EPSP • Ganglionic ACh: Also activates mAChR, slow EPSPs and IPSPs • Preganglionic terminals: Small EPSPs

16. The Autonomic Nervous System • Postganglionic Neurotransmitters • Parasympathetic: Release Ach • Local effect • Sympathetic: Release NE • Far-reaching effects • Parasympathomimetic: Mimic or promote muscarinic actions of ACh or inhibit actions of NE • Sympathomimetic: Mimic or promote NE actions or inhibit muscarinic actions of ACh

17. The Diffuse Modulatory Systems of the Brain • Anatomy and Functions • Four systems with common principles: • Small set of neurons at core • Arise from brain stem • One neuron influences many others • Synapses release transmitter molecules into extracellular fluid

18. The Diffuse Modulatory Systems of the Brain • Anatomy and Functions • Four systems with common principles: • Noradrenergic Locus Coeruleus • Serotonergic Raphe Nuclei • Dopaminergic Substantia Nigra and Ventral tegmental Area • Cholinergic Basal Forebrain and Brain Stem Complexes

19. The Diffuse Modulatory Systems of the Brain • Noradrenergic Locus Coeruleus

20. The Diffuse Modulatory Systems of the Brain • The Nonadrenergic Locus Coeruleus • Path: Axons innervate cerebral cortex, thalamus, hypothalamus, olfactory bulb, cerebellum, midbrain, spinal cord • Function: Regulation of attention, arousal, sleep-wake cycles, learning and memory, anxiety and pain, mood, brain metabolism • Activation: New, unexpected, nonpainful sensory stimuli

21. The Diffuse Modulatory Systems of the Brain • The Serotonergic Raphe Nuclei

22. The Diffuse Modulatory Systems of the Brain • The Serotonergic Raphe Nuclei • Path: Innervate many of the same areas as noradrenergic system • Function: Together with noradrenergic system, comprise the ascending reticular activating system. Raphe system particularly involved in sleep/wake cycles. Also mood • Activation: New, unexpected, nonpainful sensory stimuli

23. The Diffuse Modulatory Systems of the Brain • Dopaminergic Substantia Nigra and Ventral Tegmental Area

24. The Diffuse Modulatory Systems of the Brain • Dopaminergic Substantia Nigra and Ventral Tegmental Area • Substantia Nigra • Projects to the striatum • Facilitates the initiation of voluntary movements(Parkinson’s Disease) • Ventral tegmental area • Innervates circumscribed region of telecephalon • Mesocorticolimbic dopamine system: Dopaminergic projection from midbrain

25. The Diffuse Modulatory Systems of the Brain • Cholinergic Systems

26. The Diffuse Modulatory Systems of the Brain • Cholinergic Systems • Basal forebrain complex • Core of telencephalon, medial and ventral to basal ganglia • Function: Unknown, participates in learning and memory • Pontomesencephalotegmental complex • Releases ACh • Function: Regulates excitability of thalamic sensory relay nuclei

27. The Diffuse Modulatory Systems of the Brain • Drugs and the Diffuse Modulatory Systems • Psychoactive drugs: Act on CNS • Many drugs of abuse act on modulatory systems • LSD, Psilocybe mushrooms, and peyote close to structure of serotonin • Cocaine and amphetamine affect dopaminergic and noradrenergic systems - sympathomimetic

28. The Diffuse Modulatory Systems of the Brain • Stimulants: Block reuptake • Cocaine targets DA reuptake • Amphetamine blocks NE and DA reuptake and stimulates DA release

29. Concluding Remarks • Three Components of the Nervous System That Have Great Reach of Their Influences • Secretory hypothalamus (all over the body) • Autonomic nervous system (all over the body) • Diffuse modulatory systems (all over the brain) • Detailed level • Each system performs different functions • General level • All work to maintain brain homeostasis

30. End of Presentation