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Introduction to the Introduction to the nervous Systemnervous System

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Development of the Nervous Development of the Nervous SystemSystem

Formation of neurons – neurogenesis- largely Formation of neurons – neurogenesis- largely prenatalprenatal Majority of cells develop in first 3 months gestation - Majority of cells develop in first 3 months gestation -

up to 150,000 cells per minute easily disrupted by up to 150,000 cells per minute easily disrupted by chemicals and radiationchemicals and radiation

Migration pre and post natalMigration pre and post natal Cells move from where they were formed to their Cells move from where they were formed to their

target areatarget area They move either toward or away from chemicals They move either toward or away from chemicals

released by areas of the brainreleased by areas of the brainInterconnections develop – largely postnatalInterconnections develop – largely postnatalProgrammed cell deathProgrammed cell death

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Divisions of the nervous systemDivisions of the nervous system

Central nervous system - encased in boneCentral nervous system - encased in bone Spinal cordSpinal cord brainbrainPeripheral nervous system – everything elsePeripheral nervous system – everything else Somatic nervous system – voluntary controlSomatic nervous system – voluntary control

Sensory nervesSensory nervesMotor nervesMotor nerves

Autonomic nervous system – no conscious controlAutonomic nervous system – no conscious controlSympathetic nervous system – fight or flight responseSympathetic nervous system – fight or flight responseParasympathetic nervous system - Parasympathetic nervous system -

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The spinal cordThe spinal cord

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Function of the spinal cordFunction of the spinal cord

White matter – nerve White matter – nerve fibers running to and fibers running to and from the brainfrom the brainGray matter – Gray matter – neurons and neurons and synapses, mediates synapses, mediates reflexesreflexesDorsa horn – sensory Dorsa horn – sensory Ventral horn - motorVentral horn - motor

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The Non-Mammalian BrainThe Non-Mammalian Brain

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Mammal BrainsMammal Brains

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The Human BrainThe Human Brain

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HindbrainHindbrainMedulla – involved with Medulla – involved with autonomic system –regulating autonomic system –regulating breathing and vomiting, etc.breathing and vomiting, etc.Reticular activating and raphe Reticular activating and raphe system – activates the brain system – activates the brain maintaining arousal or reduces maintaining arousal or reduces arousal for sleeparousal for sleepLocus coeruleus – mood Locus coeruleus – mood control and alerting responsecontrol and alerting responseCerebellum – coordination of Cerebellum – coordination of voluntary movements, eye voluntary movements, eye saccades, and simple learningsaccades, and simple learning

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MidbrainMidbrain

Contains centres for the receipt and integration of Contains centres for the receipt and integration of several types of sensory informationseveral types of sensory informationThe The superior and inferior colliculisuperior and inferior colliculi are part of the visual are part of the visual and auditory systemsand auditory systemsThe The reticular formationreticular formation is the core of the brainstem is the core of the brainstem running through the mid-brain, pons and medullarunning through the mid-brain, pons and medulla Some researchers have speculated that the Some researchers have speculated that the reticular reticular formationformation controls approximately 25 specific behaviors, controls approximately 25 specific behaviors, including sleeping, walking, eating, urination, defecation, including sleeping, walking, eating, urination, defecation, and sexual activityand sexual activity

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Hindbrain and MidbrainHindbrain and Midbrain

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Limbic SystemLimbic SystemHypothalamusHypothalamus

Controls eating drinking, Controls eating drinking, sexual, etc. behaviorssexual, etc. behaviors

HippocampusHippocampus Formation of new Formation of new

memoriesmemories

SeptumSeptum Emotion and emotional Emotion and emotional

memoriesmemories

AmygdalaAmygdala Implements aggressive Implements aggressive

behavior behavior Active in fear conditioningActive in fear conditioning

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CerebrumCerebrum

Two hemispheresTwo hemispheresMajor coordinating centers for from which Major coordinating centers for from which sensory information and accompanying sensory information and accompanying motor actions originatemotor actions originateThe surface of the cerebrum is known as The surface of the cerebrum is known as the cerebral cortex the cerebral cortex

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CortexCortexComposed of grey matterComposed of grey matterHas many folds that increase surface area Has many folds that increase surface area (called fissures)(called fissures)Posterior and central areas primarily concerned Posterior and central areas primarily concerned with sensory and motor functionswith sensory and motor functionsFrontal lobe – inhibition of behaviors, Frontal lobe – inhibition of behaviors, expression of emotion, availability of rewardsexpression of emotion, availability of rewardsPrefrontal areasPrefrontal areas

Orbitofrontal – learning reward associationsOrbitofrontal – learning reward associations Prefrontal working memory and thinkingPrefrontal working memory and thinking Dorsolateral – maintenance of attentional demands Dorsolateral – maintenance of attentional demands

of a taskof a task Anterior cingulate – mediates attention, inhibition of Anterior cingulate – mediates attention, inhibition of

dominant behaviorsdominant behaviors

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The CortexThe Cortex

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Occipital LobeOccipital Lobe

Sensory areas associated with visionSensory areas associated with visionAssociation areas interpret visual Association areas interpret visual informationinformation

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Temporal LobeTemporal Lobe

Sensory areas associated with vision and Sensory areas associated with vision and hearinghearingAssociation areas have been linked to Association areas have been linked to memory and interpretation of sensory memory and interpretation of sensory informationinformation

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Parietal LobeParietal Lobe

Sensory areas associated with touch and Sensory areas associated with touch and temperature awarenesstemperature awarenessAssociation areas have been linked to Association areas have been linked to emotions and interpreting speechemotions and interpreting speech