copyright © 2007 wolters kluwer health | lippincott williams & wilkins neuroscience: exploring...

Copyright © 2007 Wolters Kluwer Health | Lippincott Williams & Wilkins

Neuroscience: Exploring the Brain, 3e

Chapter 15: Neuroendocrine system: Chemical Control of the Brain and Behavior


IntroductionIntroduction• 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


The Secretory HypothalamusThe Secretory Hypothalamus

• Function

– Difference between hypothalamus and dorsal thalamus

• Hypothalamus defect

– Fatal disruption to body function

• Dorsal thalamus defect

– Blind spot, lack of feeling


• 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




• Structure of the Hypothalamus


• 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.The Secretory Hypothalamus: Neurosecretory neurons of the periventricular zone.


• Communication between kidneys and brain



• 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



• Stress Response

– Periventricular hypothalamus secretes CRH into portal circulation.

– ACTH released into circulation.

– ACTH stimulates cortisol release from adrenal cortex.



• 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

The Autonomic Nervous SystemThe Autonomic Nervous System


• ANS Circuits versus Somatic Motor System



The Autonomic Nervous SystemThe Autonomic Nervous System• Sympathetic and Parasympathetic Divisions


• 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



• 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



• 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



• 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



• 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

The Diffuse Modulatory Systems of the BrainThe 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



• Noradrenergic Locus Coeruleus



• 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




• The Serotonergic Raphe Nuclei


• 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



• Dopaminergic Substantia Nigra and Ventral Tegmental Area



• 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



• Cholinergic Systems



• 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



• 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



• Stimulants: Block reuptake

– Cocaine targets DA reuptake

– Amphetamine blocks NE and DA reuptake and stimulates DA release



Concluding RemarksConcluding 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


End of Presentation

copyright © 2007 wolters kluwer health | lippincott williams & wilkins neuroscience: exploring...

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