Chapter 15: Chemical Control of the Brain and Behavior
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Neuroscience: Exploring the Brain, 3e Chapter 15: Neuroendocrine system: Chemical Control of the Brain and Behavior
Copyright © 2007 Wolters Kluwer Health | Lippincott Williams & Wilkins
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 Copyright © 2007 Wolters Kluwer Health | Lippincott Williams & Wilkins
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
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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
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The Secretory Hypothalamus • Structure of the Hypothalamus
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The Secretory Hypothalamus: the periventricular zone.
Neurosecretory neurons of
• Pathways to the Pituitary – Two neurohormones
– Oxytocin • Lactation, suppress hypothalamic function – Vasopressin
• Regulate blood volume and salt concentration
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The Secretory Hypothalamus • Communication between kidneys and brain
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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
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The Secretory Hypothalamus • Stress Response – Periventricular hypothalamus secretes CRH into portal circulation. – ACTH released into circulation.
– ACTH stimulates cortisol release from adrenal cortex.
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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 Copyright © 2007 Wolters Kluwer Health | Lippincott Williams & Wilkins
The Autonomic Nervous System • ANS Circuits versus Somatic Motor System
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The Autonomic Nervous System • Sympathetic and Parasympathetic Divisions
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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
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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
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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 Copyright © 2007 Wolters Kluwer Health | Lippincott Williams & Wilkins
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
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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
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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
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The Diffuse Modulatory Systems of the Brain • Noradrenergic Locus Coeruleus
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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, sleepwake cycles, learning and memory, anxiety and pain, mood, brain metabolism
– Activation: New, unexpected, nonpainful sensory stimuli
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The Diffuse Modulatory Systems of the Brain • The Serotonergic Raphe Nuclei
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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
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The Diffuse Modulatory Systems of the Brain • Dopaminergic Substantia Nigra and Ventral Tegmental Area
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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
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The Diffuse Modulatory Systems of the Brain • Cholinergic Systems
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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 Copyright © 2007 Wolters Kluwer Health | Lippincott Williams & Wilkins
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
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The Diffuse Modulatory Systems of the Brain • Stimulants: Block reuptake – Cocaine targets DA reuptake – Amphetamine blocks NE and DA reuptake and stimulates DA release
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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 Copyright © 2007 Wolters Kluwer Health | Lippincott Williams & Wilkins
End of Presentation
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