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Anatomy of the nervous systemChapter 1 p7-9

Chapter 7 p168-176, p180-181 p192-199,

Box 7.2 and 7.3

Components of the CNS

Subdivisions of the nervous system

Anatomical planes of section

The central nervous system

The peripheral nervous system

Brain imaging techniques

MRI, PET

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Neuroscience

today

2

Cellular NeuroscienceHow molecules work

together to give neurons

specific properties

(action potential)

1

Molecular Neuroscience

The role of molecules(NTs, ions, proteins)

crucial for neuronal

communication

4

Behavioural NeuroscienceWhere in the brain is

specific behaviour

(dreams, emotions)

3

Systems NeuroscienceHow brain circuits analyze

sensory information

(movement, vision etc.)

5

Cognitive Neuroscience

how psychological/cognitivefunctions are produced

by the neural circuitry

(perception, intelligence)

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Formation of the nervous system

Inner cell massThe nervous system and the skin

The internal organs (viscera)

The bones and the muscles

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Neurulationthe process by which the neural plate becomes the

neural tube22 days after conception

The CNSThe PNS

notochord

plays a key role in understanding the development of the CNSFig 7.8

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Spina bifida

A developmental birth defect involving the neural tube:

incomplete closure of the embryonic neural tube results in anincompletely formed spinal cord

dysfunction of the spinal cord and associated nerves that controlthe muscles in the hip, leg, knee and foot

can be prevented with daily folic acid supplements taken priorto conception.

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Anatomical references

Lateral view

Posterior

Medial view

Anterior PosteriorAnterior

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Anatomical references

Dorsal

Ventral

PosteriorAnterior

Dorsal viewVentral view

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Anatomical planes of section

Fig. 7.3

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White matter and gray matter

Fig. 1.6

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Central Nervous System

Gray matter

Cell bodies

Dendrites Synapses

White matter

Axons (coated

with myelin)

C t f th NS

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Central nervous system (CNS)

Brain and

Spinal cord

The brain:

receives sensory input from the spinal cord

as well as from its own nerves

processing ofsensory inputs and

initiating appropriate motor outputs. The spinal cord:

conducts sensory information from the

peripheral nervous system to the brain

conducts motor information from the

brain to our various effectors

skeletal muscles

cardiac muscle smooth muscle

glands

Components of the NS

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Peripheral nervous

system (PNS)

Outside the CNS

Nerves extending frombrain and spinal cord

Cranial nerves

Spinal nerves

Link all regions of the

body to the CNS

Components of the NS

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Components of the CNS

(hypothalamus and thalamus)Forebrain

Major Divisions of the Brain

1. Spinal cord

2. Brainstem

3. Cerebellum

4. Forebrain Diencephalon

hypothalamus,

thalamus

Cerebral cortex

Spinal cord

BrainstemCerebellum

Medulla

Pons

Midbrain

DiencephalonCerebral cortex

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Components of the CNS

Brainstem consists of:

the medulla (an enlarged portionof the upper spinal cord),

pons and

midbrain

Controls the reflexes and automatic

functions (heart rate, bloodpressure),

limb movements and

visceral functions (digestion,urination).

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Components of the CNS

Cerebellum - "little brain" Control of movement & balance

Coordination of limb movements

C t f th CNS

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Components of the CNS

Hypothalamus - controls The viscera (internal organs)

Body temperature and Heart rate

Respiration

Fat metabolism

Thalamus receives all sensory messages from

the spinal cord (except for smell) prior

to being directed to the cerebrum'ssensory areas

b l t

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Cerebrum

consists of the cerebral cortex, large fiber tracts (corpus callosum links two hemisheres)

deeper structures (basal ganglia, amygdala, hippocampus)

cerebral cortex

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Corpus callosum and Primordial

Dwarfism

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Basal ganglia - caudatenucleus, putamen, globus

pallidus movement control

mood

memory and reasoning attention

Hippocampus

learning and memory Amygdala

fear aggression behaviour

Components of the CNS

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Cerebral lobes

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The cerebrum

Fig. 1.8

Centralsulcus

Sylvian fissure

(lateral sulcus)

Wrinkles and foldsof the brain:

-folds (gyri)

-grooves (sulci)

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PrefrontalcortexExecutive

functions,

Thinking, planning,

organizing &problem solving.

Emotions &

behavioural control,

personality

Temporal lobeMemory,

understanding &

language

Occipital lobe

Vision

CerebellumBalance

Spinal cordCarrying messages

Auditorycortex

Motor cortexFine Movement

Somatosensory

cortexSensation

Parietal lobePerception

Making sense of the world,arithmetic, spelling

Frontal lobe

Th ti t

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The somatic sensory system

CNS components of thesomatic sensory system spinal cord,

brain stem,

thalamus, and

cerebral cortex

Somatosensoryinformation from the bodysurface is mapped intodorsal root ganglion DRG

Information from the headand neck is relayed to the

CNS via the trigeminalganglion

Trigeminalganglion

Dorsal root ganglion

The somatic sensory system

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The somatic sensory systemParallel pathways

Fig 7.14

Thalamus

Sensory relay station to the cerebralcortex (except for smell)

Thalamus Thalamus

Th

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The somatosensory system

The dorsal root ganglia (DRG)

contain the cell bodies of sensory

neurons located outside the brain

Dorsal root

ganglion

D l t li

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Dorsal root ganglion

Afferent information to CNS

Efferent information from CNSto muscles and glands

White matter

Gray matter

Simplified Design of the Nervous System

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Simplified Design of the Nervous System

Cerebral cortex

Cerebrum

Brain stem

Thalamus

Sensory input

Interneuronbringing sensory

Information tothe cerebral cortex

Motor output

Nervous system: basic function

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Nervous system: basic function

Cerebrum, hypothalamus, thalamus,

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The four ventricles consist of the two lateral ventricles,

the third ventricle and the fourth ventricle

We have water in our brainand spinal cord. Why?

Firstly, to support and cushion

them from trauma.

Secondly, "to clean" waste

products of metabolism, drugs

and other substances that

diffuse into the brain from the

blood.

Brain Ventricles

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Brain Ventricles

Ventricles - the cavities in the

brain that contain CSF

(cerebrospinal fluid), which

acts as a buffer against

damage caused by blows to

the head.

contains small amounts of

protein, glucose, andpotassium and relative large

amounts of sodium chloride

formed by choroid plexuses

located in the walls and roofsof the ventricles

Brain Imaging Techniques

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Brain Imaging Techniques (Box 7.3)

Magnetic resonance imagining (MRI). Brain anatomy (X-rays)

Functional magnetic resonance imagining (fMRI). Brain function based on local metabolism

Position emission tomography (PET).

Activity-dependent changes in blood flow, tissue metabolism, orbiochemical activity (Gamma rays)

Injection of precursor molecules of specific neurotransmitters, orglucose radiolabeled

Single-photon emission computerized tomography(SPECT). Injection or inhalation of radiolabeled compound (e.g. 123I-

labeled iodoamphetamine)

MRI and disease diagnosis

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MRI and disease diagnosis

(i.e. Multiple sclerosis)

Magnetic resonance imaging (MRI) of thebrain and spine

shows areas of demyelinationasbrightlesions.

can reveal lesions prior toclinical

symptoms

MRI MS Diagnosis

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Typical MRI characteristics

white matter abnormalities 95% ofpatients

White lesions indicate areas of freshinflammation and open BBB.

Brain atrophy with widened lateral

ventriclesandcortical sulci.Sospedra2005

MRI- MS Diagnosis

PET (P it E i i T h )

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PET (Positron Emission Tomography)

The PET scan allows one to see howthe brain uses glucose

Glucose provides energy to each

neuron so it can perform work Brain metabolic activity

Thered color shows the highestlevel of glucose utilization

yellow represents lessutilization and blueshows the least)

The reduction in the neurons' abilityto use glucose (energy) results indisruption of many brain functions.

PET and MRI in Alzheimers

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Mark Mattson "Pathways towards and away from Alzheimer's Disease" Nature v. 430 August 5, 2004.

Brain Atrophy

PET and MRI in Alzheimer s

Loss of energy metabolism

PET and MRI in Schizophrenia

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PET and MRI in Schizophrenia

PET scan

show frontal lobe

hypometabolism(toolittle)

MRI :

1. Increasedlateral ventricularvolume.

2. Decreasedvolume ofhippocampus, prefrontal cortex,thalamus.

Next Class

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Next Class

Chapter 2, Box 2.5

Neurons and glia

Neuronal cell and types of neurons

Types of glial cells