Ch15

Slide 1Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams

& Wilkins

Bear: Neuroscience: Exploring the Brain 3e

Chapter 15: Chemical Control of the Brain and Behavior


& Wilkins

Introduction

Synaptic ConnectionsPoint-to-point

Mechanism to restrict synaptic communicationBrief transmissionPresynaptic “autoreceptors”

Three nervous system componentsSecretory hypothalamusAutonomic nervous system (ANS)Diffuse modulatory systems


& Wilkins

The Secretory Hypothalamus

FunctionDifferent for hypothalamus and dorsal thalamus

Hypothalamus defectFatal disruption to body function

Dorsal thalamus defectBlind spot, lack of feeling


& Wilkins

HomeostasisRegulatory process: Regulates body temperature and blood composition levels

Hypothalamus commands in cold weather

Shiver, goosebumps, turn blueHypothalamus commands in hot weather

Turn red, sweat



& Wilkins

Structure and Connections of the Hypothalamus



& Wilkins

Pathways to the Pituitary

Two neurohormonesOxytocin

Lactation, suppress hypothalamic function

VasopressinRegulate blood volume and salt concentration



& Wilkins

Hypothalamic Control of the Posterior Pituitary



& Wilkins

Hypothalamic Control of the Anterior Pituitary

Anterior lobeControlled by parvocellular neurosecretory cells

Secrete hypophysiotropic hormoneBind to specific receptors on pituitary cellsReceptor activation: Pituitary cells secrete or stop secreting hormones

Adrenal glands: Adrenal cortex and adrenal medulla



& Wilkins

Divisions of autonomic nervous system (ANS)Sympathetic division

Increased heart rate and blood pressureDepressed digestive functionMobilized glucose reserves

Parasympathetic divisionSlower heart rate, fall in pressureIncreased digestive functionsStop sweating

The Autonomic Nervous System


& Wilkins

ANS Circuits versus Somatic Motor System

ANSActions multiple, widespread, slowWide coordinated and graded controlCommands all tissue and organ except skeletal muscleOutside CNSDisynaptic pathway



& Wilkins


ANS Circuits versus Somatic Motor System (Cont’d)

SomaticRapid and accurateOnly peripheral targetsCommands only skeletal muscleWithin CNSMonosynaptic pathway


& Wilkins


Sympathetic and Parasympathetic Divisions


& Wilkins

The Enteric DivisionLocation: 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 foodInputs: From brain via axons of the sympathetic and parasympathetic divisions



& Wilkins

Central Control of the ANSConnections for autonomic control

Periventricular zone connections to brain stem and spinal cord nucleiNucleus of solitary tract

Function of solitary nucleusIntegrates sensory information from internal organs and coordinates output



& Wilkins

Neurotransmitters and the Pharmacology of Autonomic Function

ANS: Better understanding of drug mechanisms influencing synaptic transmission (vs. CNS)

Preganglionic NeurotransmittersPrimary transmitter: AChACh: Binds to nAChR, evokes fast EPSPGanglionic ACh: Activates mAChR, slow EPSPs and IPSPsPreganglionic terminals: Small EPSPs



& Wilkins

Postganglionic NeurotransmittersParasympathetic: Release Ach

Local effectSympathetic: Release NE

Far-reaching effectsParasympathomimetic: Mimic or promote muscarinic actions of ACh or inhibit actions of NESympathomimetic: Mimic or promote NE actions or inhibit muscarinic actions of ACh



& Wilkins

Anatomy and FunctionsDifferent structure and function, common principles

Small set of neurons at coreArise from central core of brainOne neuron influences othersSynapses release transmitter molecules into extracellular fluid

The Diffuse Modulatory Systems of the Brain


& Wilkins

The Nonadrenergic Locus CoeruleusPath: Axons innervate cerebral cortex, thalamus, hypothalamus, olfactory bulb, cerebellum, midbrain, spinal cordFunction: Regulation of attention, arousal, sleep-wake cycles, learning and memory, anxiety and pain, mood, brain metabolismActivation: New, unexpected, nonpainful sensory stimuli



& Wilkins

The Serotonergic Raphe Nuclei



& Wilkins

Dopaminergic CellsSubstantia Nigra

Projects axons to the striatumFacilitates the initiation of voluntary movements

Ventral tegmental areaInnervates circumscribed region of telecephalon

Mesocorticolimbic dopamine system: Dopaminergic projection from midbrain



& Wilkins

Cholinergic SystemsBasal forebrain complex

Core of telencephalon, medial and ventral to basal gangliaFunction: Unknown, participates in learning and memory

Pontomesencephalotegmental complexReleases AChFunction: Regulates excitability of thalamic sensory relay nuclei



& Wilkins

Drugs and the Diffuse Modulatory Systems

Psychoactive drugs: Act on CNSMany drugs of abuse act on modulatory systems

NoradrenergicDopaminergicSerotonergic



& Wilkins

HallucinogensLSD discovery: Accidentally by Swiss chemist Albert HofmannLSD chemical structure: Close to serotonin, potent agonistEffect: Dreamlike state, mixing of perceptions – cortical areas



& Wilkins

Stimulants



& Wilkins

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 levelAll work to maintain brain homeostasis


& Wilkins

End of Presentation

Date post:	25-Oct-2014
Category:	Documents
Upload:	encem-boy-man
View:	46 times
Download:	0 times

Ch15

Documents