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CNS Peter Århem

Inst för neurovetenskap Karolinska institutet

Evolution of nervous systems

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The evolution of the vertebrate brain

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The evolution of the vertebrate brain –

three swellings

Forebrain Cortex

Basal gabnlia

Thalamus Hypothalamus

Midbrain

Hindbrain Cerebellum

Medulla oblongata

Mesencephalon

Human CNS and brain

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Central and peripheral nervous systems CNS and PNS

CNS = brain and spinal cord

Brain = Forebrain + midbrain + hindbrain

= Cerebrum + brainstem + cerebellum

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= midbrain + hindbrain – cerebellum

Brainstem = midbrain + pons + medulla oblongata

White and gray matter in forebrain

• Gray matter = nerve cell bodies

• White matter = axons

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The spinal cord

White and gray matter in spinal cord

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Spinal nerves – dorsal and ventral roots

Cranial nerves

N. olfactorius I

N. opticus II

N. oculomotorius III

N. trochlearis IV

N. trigeminus V

N. abducens VI

N. facialis VII

N. vestibulocochlearisVIII

N. glossopharyngeus IX

N. vagus X

N. accessorius XI

N. hypoglossus XII

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Fissura longitudinalis

Fissura transversalis

Fissura lateralis

Sulcus centralis

Important sulci and fissurae

Lobes of cerebrum

Lobus frontalis

(frontal lobe)

Lobus parietalis (parietal lobe)

Lobus occipitalis (occipiatl lobe)

Lobus temporalis (temporal lobe)

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Brodmann areas

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Frontal lobe

Functions • Motor areas • Personality • Working memory • Speech (Broca’s area)

Paul Broca

Parietal lobe

Functions • Somatosensory

areas • Association areas • Working memory

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Somatosensory areas: Somatotopic organization and”somatosensory homunculus”

Occipital lobe

Funktions

• Visual areas

• Association areas

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Vad?

Var?

Visual areas: Ventral and dorsal stream ”What?” and ”Where?”

Temporal lobe

Functions • Hearing • Speech (Wernicke’s area) • Memory (hippocampus)

Carl Wernicke

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Low frequent tones

High frequent tones

Basilar membrane

Auditory areas: tonotopic organization

Methods to study the human brain – functional and imaging methods

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Post-lesion studies

Phineas Gage

Post-lesion studies

• Localization of the lesion

• Correlation to behaviour

• Insights about higher functions

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Computed tomography (CT)

• X-ray images from different angles produce cross-sectional images

• Radiocontrast agents visualize blood vessels (angiography)

• Air visualizes ventricles

Electroencephalography (EEG)

Voltage differences between scalp electrodes

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Magnetic resonance imaging (MRI)

• A strong magnetic field is applied

• Hydrogen nuclei become aligned

• A transient magnetic pulse perturbs the nuclei

• A signal is created when nuclei return to initial state

Positron-emissionstomografi (PET)

• Radioactive isotope of e.g. glucose is injected

• Radioactivity is measured

• High glucose concentration – high neural activity

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Functional MRI (fMRI)

• Development of MRI

• Magnetic signal from hemoglobin

• Oxygene-rich and oxygene-depleted hemoglobin have different magnetic properties

• Oxygene saturation is used as a measure of neural activity