Brain anatomy tutorial

Dr. Michal Ben-Shachar

The human brain

http://www.brainmuseum.org/

Left

hemisphere

Right

hemisphere

Zoom out

Zoom in

Types of Brain Tissue

• Gray Matter: Cell bodies (+ short

connections)

• White Matter: Axons which form

pathways for conducting information

between brain cells.Gray matter

White matter

Gray matter, White matter

Gray matter (stained purple): folded sheet containing

cell bodies, dendrites, local axons collaterals.

White matter: axons, long range connections.

Cerebrospinal Fluid (CSF)

• Located between the menings and in the ventricles of the brain

• Functions– mechanical buffer

– fluid for metabolic functions

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The hemispheres: Two brains for

the price of one?

Fiber tracts

(White matter)

The hemispheres: Two brains for

the price of one?

The Virtual Hospital

• The hemispheres

are connected

through the corpus

callosum

Cortex

(Gray matter)Fiber tracts

(White matter)

Defining the lobes

Frontal

Parietal

Occipital

Temporal Sylvian Fissure

Central Sulcus

Separates temporal lobe from parietal

and frontal lobes

Sylvian Fissure

Sylvian Fissure (or lateral sulcus)

Gross functional map

Find the differences

Nichols and Newsome, 1999

Localization is not the final goal

“The recent avalanche of PET and fMRI papers has produced many

insights concerning localization of mental functions (Fig. 2b). Although they

are substantially more informative than previous findings based on brain

damage, distillations of data like the one in Fig. 2b are disconcertingly

similar to the one-function-one-brain-area maps of the phrenologists.

Will we ‘understand’ the brain when the map in Fig. 2b is completely filled

with blobs? Obviously not; localization data provide little insight into the

exact nature of the signals encoded in a given structure, the computations

being performed and the interactions between different structures.”

Nichols and Newsome, 1999

Middle Cerebral Artery

MCA stroke

Radiopedia.org; contributed by Dr. Frank Gaillard, July 2010

Gyri of the cerebral cortex

• Much of cortex referred to by combination of coordinate+lobe+gyrus: Superior Temporal Gyrus(STG), Middle Temporal Gyrus(MTG), Inferior Frontal Gyrus (IFG)

Duvernoy 1991

Sulci of the cerebral cortex

• Major sulci: Central Sulcus, Sylvian fissure

• Other important sulci: Superior Temporal Sulcus (STS), Intraparietal sulcus (IPS)

Duvernoy 1991

Brain slices

Sagittal Axial Coronal

Sagittal and Midsagittal

• A Sagittal slice down the

midline is called the

‘midsagittal’ view.

midsagittal sagittal

Describing cortical locations:

Brodman’s areas

Cytoarchitectonically defined brain regions – i.e., areas with the same

physiological characteristics are grouped under a given number.

Methods for structural brain imaging

• CT – Computerized Tomography

• MRI – Magnetic Resonance Imaging

CT

• X-ray based method

• Involves collecting

multiple x-ray images

• Cheaper than MRI

therefore commonly

used in clinical setup

Brain CT

MRI

• Relies on a fixed strong magnetic field

• Applies radio frequency in order to excite

hydrogen atoms, and measures they

energy they release when they return to

low energy state

• No ionizing radiation

• Can’t be used with

cardiac pacemakers,

cochlear implants etc.

Brain MRI

Basic principles of MRI

http://sites.sinauer.com/neuroscience5e/animations01.01.html

For more in depth videos:

https://sites.google.com/site/mritutorial/mri-physics-tutorials

MR images can be

sensitized to many different

tissues

• Blood vessels:

• Gray-white

matter contrast:

• White matter

structure:

• Blood

oxygenation:

Find the differences – MRI or

CT?

Jeffries and Lambon-Ralph, 2006

Methods for measuring brain

function “In Vivo”• ERP – Event related potentials, measures

electrical signals from the scalp

• MEG – Magnetic encephalography, similar

to ERP but measures magnetic signals

• TMS – Transcortical Magnetic Stimulation

• PET – Positron Emission Tomography

• NIRS – Near Infrared Spectroscopy

• fMRI – functional Magnetic Resonance

Imaging, measures blood oxygenation

EEG

ERP

MEG

TMS

NIRS

fMRI

Imaging based box models of word

recognition

Price 2000

Updated models: Hickok and

Poeppel 2004 and on