Neuroanatomy Presentation

8/6/2019 Neuroanatomy Presentation

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Neuroanatomy: Morphologyof the brain

Chapter 2

Majority of illustrations in this presentation are f rom Biological Psychology

4th edition (© Sinuer Publications)

Structure and Morphology

1. To understand behavior as it relates to many

processes in the brain, it is important to study

the structure or morphology of the brain.

Because many brain processes are based on

morphology of the brain.

2. We can study the structure of brain at the micro

level, looking at small units like neurons,

dendrites and receptors etc. or at the macro

level, looking at the regions, areas, and nucleiand/or study the brain

2

Micro-Level Morphology

1. To study the morphology of brain at the micro

level tools and techniques had to be developed.One such development was the optical

microscope(Leeuwenhoek, 17th century). More

recent developments include electron

microscopewith increased magnification.

2. Looking at he brain meant cutting the brain,

staining it, and make them worthy of the

microscope. Many different staining methods

have developed.3





Neurons

7

There are 100

billion neurons in

the human brain.Packed with 10

times more glial

cells. Each neuron

is divided into

three parts;

dendrites, cell

body and axon.

Histology

1. How do we know the parts of a neuron? Or

what are the shapes and sizes of different

neurons in the brain?

2. To answer these questions neuroanatomists use

histological methods to stain neurons and

assess their different shapes and sizes.

8

Immunocytochemistry

Staining processes have improved to include use of

labeled antibodies to stain targeted proteins in thebrain.

9

GAP-43 staining in the retina



Shapes of Neurons

10

There are at least

200 different

shapes of neuronsin the brain. Some

shapes are more

symmetrical than

others.

Sizes of Neurons

11

Neurons can be

small in length and

size. Length of

neurons can be a

few microns to

many meters long.

Similarly, small

neurons can be

10µm wide andlarge 100µm.

Large Pyramidal

Neuron

Small Granule

Neuron

Neuronal Processes

All neurons tend to grow branches or processes.

One kind of these process are called dendrites andthe other axons.

12



Functions of Neurons

Monopolar neurons serve as bridge between

neurons and other receptor-neuron cells. Bipolar

neurons carry messages from sense organs andmultipolar neurons to muscles and viscera.

13

How are neurons connected?

One neurons connects to another via processes,

however there is a gap between these processes

called synapse.

14

Electron Microscopy

Electron microscopes provide us with details of

morphological structure of the synapse, and releaseof neurotransmitters in the synaptic cleft.

15



Chemical Transport

Most chemicals in the neurons are synthesized and

recycled from and to the nucleus of the cell, they

need to be transported to the synaptic sites.

16

Glial Cells

Glial cells in the brain are non-communicative cells

and engage in other functions, some of which are

listed below:

17

1. Provide scaffolding to neurons

2. Provide nutrition to neurons

3. Myelinate (insulate) neurons

4. Guide neuronal development

5. Make blood-brain barrier (BBB)

6. Phagocytosis (eat microorganisms & deadneurons)

18

Provide support and Nutrition to

neurons in the and extracellularenvironment

m e m b e r s . t r i p o d . c o m

Astrocytes in the cortex

Arstrocytes



19

Oligodendrocytes & Schwann Cells

Myelinate neurons in the central and the

peripheral nervous system.

20

Radial Glia

Guiding neurons to their laminar

destinations.

21

Blood Brain Barrier (BBB)

Glial cells (endothelial cells) erect a

barrier between blood vessels and thebrain.



22

Microglia

Microglia eat away of microorganisms

that enter the brain and scavenging dead

neurons a process called phagocytosis.

w w w . m i c r o g l i a . n e t

Macro-Level Morphology

1. Understanding the brain as an organ of that

intimately controls behaviors neuroscientists

from 16th century onwards used ablation

methods in the brain.

2. Ablation of the brain involves removing or

destroying (lesions) areas of the brain as it

effects behavior.

3. This method is still used to localize behavioral

function with its advantages and disadvantages.

23

Brain Regions

Flourensconducted many

brain ablation experimentsand found that cerebellum

played an important role in

coordinated movements.

24

Pierre Flourens(1774-1867)

u p l o a d . w i k i m e d i a . o r g

Cerebellum

u p l o a d . w i k i m e d i a . o r g



25

Systems & Divisions

Nervous System

CentralNervous System

(CNS)

PeripheralNervous System

(PNS)

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Peripheral Nervous System

Peripheral Nervous System

Somatic Nervous System Autonomic Nervous System

Cranial Nerves Spinal Nerves

Sympathetic Nervous System

Parasympathetic Nervous System

Controls the viscera (organs)

Process sensory information and

controls the voluntary

muscle movements

27

Cranial Nerves

Mnemonic: On Old Olympic Towering Tops A Famous Vocal German Viewed Some Hops



28

Spinal Nerves

There are 31 pairs of spinal nerves connecting a

number of tissues and organs in the body.

A 8 Cervical Nerves

B 1 2 Th orac ic N erves

C 5 Lumbar Nerves

D 5 Sacral Nerves

E 1 Coccygeal Nerve

29

Autonomic Nervous System

1. Autonomic Nervous System (ANS) is a part of

PNS that controls automatic, involuntary

functions. It is divided into two divisions viz.,

sympathetic and parasympathetic.

2. Sympathetic division generally energizes bodily

functions when the individual experiences

arousal or stress. It therefore uses fight-or-flight

response to emergency situations etc.

3. Parasympathetic division counters sympatheticdivision’s to keep a balance. Rest and digest.

30

Autonomic Nervous System



31

Central Nervous System

Central Nervous System

Forebrain(Procencephalon)

Midbrain(Mesencephalon)

Hindbrain(Rhombencephalon)

Cerebrum

(Telencephalon)

Thalamus

(Diencephalon)

Reticular

Activation

System

CerebellumPonsMedulla

Superior

Colliculus

Inferior

ColliculusLimbic

System

Isocortex Basal

Ganglia

32

Orientation of Nervous System

To orient ourselves about the nervous system in

3D, we need to understand three planes in which

brain can be sectioned.

33

Development of Nervous System



34

Telencephalon (Cerebrum)

Telencephalon or cerebrum or the neo-cortex can

be divided into four lobes, with specific functions.

35

Frontal Lobe

The frontal lobe contains the motor strip, and

represents the body map (homunculus).

36

Parietal Lobe

The parietal lobe contains the somatosensory strip,

and represents the body map (homunculus).



37

Occipital Lobe

The occipital lobe houses visual areas in the brain.

It contains 30 some areas that process visual

information.

j o u r n a l o f c o s m o l o g y . c o m

38

Temporal Lobe

The temporal lobe houses sensory functions as

hearing, taste, and smell. Also in this area are

memory functions and nuclei for emotions.

e n . w i k i p e d i a . o r g

Temporal Lobe

39

Medial Cerebrum

If you cut the cerebral hemispheres in the middle, a

set of new structures come in view. Many of theseperform arrays of different functions.

http://upload.wikimedia.org/wikipedia/commons/0/0e/Lobes_of_the_brain_NL.svg



















40

Basal Ganglia

Contains four nuclei; caudate, globus pallidus,

amygdala, and substantia nigra. Involved with

motor control.

41

Limbic System

Contains four nuclei; Olfactory bulb (smell),hippocampus and fornix (memory), cingulate gyrus

(attention, emotion).

42

Diencephalon

Thalamus,a way station for all incoming and out

going nerves to and from the cortex.Hypothalamus,Regulates vital functions like

temperature, hunger, sex, and hormones.



43

Midbrain

Superior Colliculus, (#2, vision), Inferior Colliculus,

(#3, audition). Substantia Nigra (#5, Parkinson

disease, schizophrenia). Reticular Formation (Redarea, arousal, sleep, temperature).

w w w . m e d . u m i c h . e d u

44

Hindbrain

Pons, (#3, sensory and motor cranial nerves,

audition).Medulla Oblogata, (#4, cranial nerves XI

& XII, breathing and heart beat). Cerebellum (#2,

fine and coordinated motor movement).

w w w . m e d . u m i c h . e d u

45

Cerebellum

Cerebellum is a less convoluted structure with two

hemispheres. Composed of molecular, Purkinje celland granule cell layers. Granule cell layer forms

parallel fibers for coordinated movements.

e n . w i k i p e d i a . o r g

http://upload.wikimedia.org/wikipedia/commons/1/15/PurkinjeCell.jpg



















46

Layers of the Cerebrum

Cerebrum compared to cerebellum contain six

layers. Some layer receive inputs while others send

outputs.

47

Ventricles

Cerebrospinal Fluid (CSF) runs through the

ventricles, absorbing shock and providing important

minerals and electrolytes for the brain.

48

Meninges and BBB

Large volumes of blood

(20%) swaddle the brainand provide

nourishment. Meninges

consist of dura mater,

pia mater and arachnoid

space. Blood Brain

Barrier (BBB) keeps

bacteria and other toxic

agents outside the brain.





52

Positron Emission Tomography

Positron Emission Tomography (PET) involves the

acquisition of physiologic images (brain) based on

the detection of positrons. Positrons are particlesemitted from a radioactive substance administered

to the patient.

53

fMRI Scans

Functional Magnetic Resonance Imaging (fMRI)

visualizes brain function, by changes in chemical

composition of brain areas or changes in the flow of

fluids (blood) that occur over time.

54

Cognitive Neuroscience Expt.



55

Optical Imaging & TMS

Optical imaging uses near infrared light to measure

responses by the cortex. Transcranial Magnetic

Stimulation (TMS) stimulates the brain of an alertsubject mapped by optical imaging.

56

Event-related Potential

Event-related potentials

measures the brain's

electrical activity as it

responds to impinging

stimuli (events). Excellent

temporal resolution

(faster response)

compared to PET or

fMRI.

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Neuroanatomy Presentation