Transcript Chapter 15: Chemical Control of the Brain and Behavior

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