DEVELOPMENT

OF BRAIN STRUCTURES

NEUROGENESIS

Parallels:

- Elektric current

action potentials

- Cable network

neuronal network

weight: 1,3 kg

volume : 1,3 l

Number of neurons:

10 až 100 billion

Daily losts:

10000 neurons

(age ethanol)

BRAINHUMAN THINKING HARDWARE

The presence of extra material enormously increases the options.But only by removing the extra maerial the unique art is created.

Genes –environment

Body (Physiological) Needs such as air,

warmth, food, sleep, stimulation and activity.

This need concerns homeostasis. These

needs can be very strong because if

deprived over time, the person will die.

Security (Safety) Needs such as living in a

safe area away from threats. This level is

more likely to be found in children as they

have a greater need to feel safe

Social (Love and Belongingness) Needs

such as the love of family and friends.

Ego (Self esteem) Needs such as healthy

pride The Ego needs focus on our need for

self-respect, and respect from others.

Self Actualization (Fulfillment) Needs

such as purpose, personal growth and

realization of potentials. This is the point

where people become fully functional, acting

purely on their own volition and having a

healthy personality.

MASLOW´S HIERARCHY OF NEEDS

Production of cells that will become nervous tissue

ProliferationCell reproduction (mitosis)

MigrationLocation of cells in appropriate brain areas

DifferentiationDevelopment of neurons into particular type

SynaptogenesisFormation of appropriate synaptic connections

Selective cell deathElimination of mislocated cells and cells that failed

to form the proper synaptic connectionsFunctional validation

Strengthening of synapses in use, weakening of unused synapses

DEVELOPMENT OF HUMAN BRAIN

PROLIFERATION – governed by genes

- 3rd week i.u. 250 000 / minute- finished in the 5th month i.u. 1010-1011 neurons

Marginalzone

Ventricular zone

Embryonal brain

Daughter cell

Rostral Caudal

1. Stemm cell sends its process to pial surface

2. Nucleus migrates to pia, DNA copies

3. Nucleus moves back with copied genetic material

4. The process is retracted

5. The cell is divided, daughter cell migrates and stemm cell starts the new mitotic cycle

1) Some neurons migrate by following the long

fibers of cells called radial glia. These fibers

extend from the inner layers to the outer

layers of the brain. Neurons glide along the

fibers until they reach their destination.

2) Neurons also travel by using chemical

signals. Scientists have found special

molecules on the surface of neurons --

adhesion molecules -- that bind with similar

molecules on nearby glial cells or nerve

axons. These chemical signals guide the

neuron to its final location.

MIGRATION OF NEURONS

RADIAL GLIA

VENTRICULAR

ZONE

INTERMEDIATE

ZONE

MARGINAL

ZONE

ventral dorsal

MIGRATION OF NEURONS– GROWTH CONE

Lamellipodia FilopodiaGrowth cone is specialized to identifythe proper pathway for axonal growth

FasciculationChemoaffinity hypothesis (Sperry, 1981)

CAMs = cell-adhesion

molecules

molecules of lamininmolecules of integrins– support for growing

axons

MIGRATION

• Not all neurons are successful in their journey. Scientists think that only a third reach their destination. The rest either never differentiate, or die and disappear at some point during the two to three week phase of migration.

• Some neurons survive the trip, but end up where they shouldn’t be. Mutations in the genes that control migration create areas of misplaced or oddly formed neurons that can cause disorders such as childhood epilepsy or mental retardation. Some researchers suspect that schizophrenia and the learning disorder dyslexia are partly the result of misguided neurons.

DIFFERENTIATION

Cell differentiation – neuroblasts arrive at

its final place (guided by genes)

- electrical activity of the

neurons changes structure of the brain

(guided by the environment)

SYNAPTOGENESIS

Electric activity influences brain development – „USED IS DEVELOPED“

2 – 10. POSTNATAL YEARS – development of connections

– SYNAPTIC CAPACITY - up to 20 000 synapses per neuron

- SYNAPTIC PLASTICITY

SYNAPSE FORMATION

1) Growing motoneuron secretes protein AGRIN to basal ganglia

2) AGRIN interacts with specificreceptors in the cells of muscle membrane

3) The interaction leads to clustering of acetylcholine receptors in postsynaptic membrane

NEURONAL AND SYNAPTIC DEATH

Neurones compete with each other for trophic factors (NGF – nerve growth factor, Levi Montalcini, 1940) which

produce target neurons – selective nerve death

SYNAPTIC CAPACITY– NUMBER OF

SYNAPSES ON ONE NEURON – reduction to50% in adulthood

SYNAPTIC ELIMINATION depends on the

activity of neurons during development

„Use it or lose it” –Unused neurons areeliminated after critical

periodduring life span (in humans after the age of 10)situation in visual cortex)

a) Normal healthy cat b) After molecular deprivation

1 and 5 monocular activation, 2,3,4 binocular activation with eye preference in 2 a 4

SYNAPTIC COMPETITION

Plasticity on Hebb´s synapses(Hebb modification innucleus geniculatum laterale)

„Neurons that fire together, wire together”Synchronous connections are strengthened and asynchronous connectionsare eliminated

SYNAPTIC PLASTICITY

50 - 60 70 - 80 90 - 100 Alzheimerovavek v rokoch choroba

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Neurons of hippocampus in healthy humansof different age and in Alzheimer disease

PHYSIOLOGY OF

HIGHER NERVOUS

FUNCTIONS

PHYSIOLOGY OF THE CENTRAL NERVOUS SYSTEM

Sensory division of the CNS

Motor division of the CNS

Autonomic (vegetative) division of the CNS

PHYSIOLOGY OF THE HIGHER NERVOUS FUNCTIONS

SLEEP AND WAKEFULNESS

EMOTIONS

MEMORY AND LEARNING

SPEECH

BRAIN LATERALITY – FUNCTIONAL

SPECIALIZATION OF BRAIN

HEMISPHERES

LIFE = ADAPTATION

Regulatory mechanisms for life preservation = regulatory

mechanisms for preservation of inner environment stability -

Homeostasis in spite of changes in external environment

Homeorhesis – anticipation of changes due to rhythmic

oscilations

Transport and communication - blood - hormones

- nerves - el. impulses

Integration – central nervous system

Encefalisation – encephalon = brain

Multiplication of neurons between receptors and effectors during

phylogenesis and ontogenesis

Corticalisation – cortex = the youngest and the most complex structure in

the world

Centralisation of regulatory functions to brain cortex

Functional hierarchy – youngest structures regulate body

functions through older structures

CENTRAL NERVOUS SYSTEM

• Sensory system (senses, afferent fibres)

• Motor (effector) system (muscles and endocrine glands)

• Integration centre (brain)

• Feedback machanisms at different levels of the central nervous system check the outputs:

• Brain stem (breathing, blood pressure)

• Midbrain structures (eating and drinking, sleep and wakefulness)

• Brain cortex (conscious reactions, memory – the highest level of improvement on the base of the experience)

BRAIN –INFORMATION HIGHWAY

INFORMATIONS

COLLECTS ORGANISES SENDS

(SENSES) TRANSPORTS (MUSCLES,

STORES ENDOCRINE GLANDS)

sensory association motor

Neurons neurons neurons

INPUT DECISSION MAKING OUTPUT

ANALYSIS

3-level system:

reflexive

emotional

cognitive

REFLEXES

SPINAL CORD - reflexes,

BRAIN STEM - breathing

blood pressure)

very quick stereotypic reactions

“brain of the snake”

EMOTIONS

PALEOCORTEX

SUBCORTICAL NUCLEI - life and

species preservation, survival

“brain of the horse”

COGNITIVE

Neocortex – the highest level of

brain functions – learning and

memory

cognition – homo sapiens

“brain of a man”

ASSOCIATION AREAS OF THE BRAIN CORTEX

Association motor

cortex

Primary motor

cortex

Primary sensory cortex

Association sensory

cortex

Polymodal association

cortex

Primary auditory cortex

Association auditory cortex

Association visual cortexLimbic cortex

Prefrontal cortex

Three-neuronal afferent pathway from

sensory receptors to the brain cortex

I.order neuron

In the dorsal root ganglion

II. order neuron

In the spinal cord or

in the medulla

III. Order neuron

In the thalamus

The exception from

the three-neuronal rule is

the pathway of the smell

perception,

which transmits the sensory

signals directly from

olfactory area in the

nose to olfactory brain cortex

SENSORY DIVISION OF THE CNS

PRIMARY SENSORY CORTEX

(gyrus postcentralis

In parietal lobe)

MOTOR DIVISION OF THE CNS

PRIMARY MOTOR CORTEX

(gyrus praecentralis

In frontal lobe)

The case of Phineas Cage

The case of

„Pineas GAGE“, 1848"© Deakin University 2009"

prefrontal cortex damage – PREFRONTAL CORTICAL SYNDROMA

Behavioral disorder – impulsiveness, childish behavior, unsensitivity, bezohľadnosť,

nespôsobnosť (gatizmus), loss of social rules recklessness, uncontrolled emotions

Personality changes – capriciousness, unpoliteness, indecisiveness, moral insanity

The case of

„Pineas GAGE“, 1848

Frontal lobotomy 1930 - 1960

therapeutical cut

prefrontal areas with

Other brain

(Egaz Monitz, 1949)

Prefrontal lobes are site of

„COMMON SENSE“ and

human personality

TACTILE COGNITION – CORTICAL SYNDROMES

Dominance of the right hemisphere

Primary somatosensory cortex BA3

Secondary somatosensory cortex BA1, 2

People using Braille reading –

Enlargement of senzory-motor

cortical representation

TAKTILE AGNOSIA - inability to recognize objects by touch

ASTEREOGNOSIA –inability to recognize 3D objects by touch

APRAXIA – inability to do planned purposefull movements disorder of

eyes and movement integration

NEGLECT SYNDROMA

Ignoring of contralateral eye stimuli, half of the self,

(autopatognosia)

(disturbance of association somatosensory areas on the right,

or bilateraly)

NEGLECT SYNDROME

williamcalvin.org/bk7/bk7ch4.htm

Damage to nondominant hemisphere

Damage to nondominant hemisphere

NEGLECT SYNDROME

williamcalvin.org/bk7/bk7ch4.htm

Visual pathway

Fromnasal halfs of the retinas

Crossed (optic chiasm),

From temporal halfs of retinas uncrossed

To thalamus

And then to radiatio optica to

Primary visual area in

Occipital lobe BA 17

VISUAL COGNITION – CORTICAL SYNDROMES

Associative fibers from visual areas

OCCIPITOPARIETAL PATHWAY

(magnosystem) – WHERE IS IT ?

Disturbance of nerve fibers or

projection areas in parietal lobe –

lesion of visual - spatial perception

ALEXIA –DYSLEXIA (pure) inabilty to understand written speech, inability to couple

graphems to phonems (left hemispheric dominance)

Disturbance of left visual areas and disturbance of posterior part of corpus callosum

Ethiology: genetic – dyslectic locus on chromosome 6

obtained

(pre- a perinatal) disturbance of neuron migration (ektopic neurons),

mikrogyria (diminishing of gyri), glial scars, reduction of fibers through corpus callosum

Alexia is often associated with AGRAFIA – DYSGRAFIA with memory disturbances, visual

and auditory processing disturbances (left hemispheric dominance)

Association fibers from visual

areas

OCCIPITOTEMPORAL PATHWAYS

(parvosystem) – WHAT IS IT?

Disturbance of nerve fibers or

projection areas – medial parts of

parietal and temporal lobes

Consequences:

a) VISUAL AGNOSIA

„SEE BUT NOT RECOGNIZE“

–cortical blidness

Inability to recognize and name

Visually presented objects

Disturbances of recognition

Of complex shapes in connection

right hemispheric lesion

b) CEREBRAL ACHROMATOPSIA

Inability of color perception

In undisturbed vision

c) PROSOPAGNOSIA

Inability to recognize common faces,

And his/her own

Inferior areas of the right hemisphere

VISUAL COGNITION – CORTICAL SYNDROMES

AUDITORY PATHWAY

From receptors (hair cells) in organ

of Corti through vestibulocochlear nerve

(VIII.) to thalamus and primary auditory

cortex in temporal lobe

AUDITORY COGNITION – CORTICAL SYNDROMES

Primary auditory cortex – BA 41

Secondary auditory cortex – BA 42

Wernicke area for speech perception-

BA 22 – WERNICKE APHASIA (LEFT

HEMISPHERIC DOMONANCE)

WORD DEAFNESS

„hear but does not understand“ also non-speech sounds

WORD AGNOSIA

„hear but does not understand“ but understands non-speech sounds

(left hemispheric dominance)

AMUSIA

Disturbance of recognition and reproduction of music (right hemispheric dominance)

MUSIC AGNOSIA

Inability to recognize musical instruments and human voice, inability to sing and

To remember melodies (right hemispheric dominance)

PHYSIOLOGY OF THE

MOTOR DIVISION OF THE

CENTRAL NERVOUS SYSTEM

Motor homunculusis the unproportionate “man” drawn

over the surface of the brain – over

The primary motor cortex in precentral

gyrus (gyrus praecentralis)

Motor movements are governed from

that part of the brain through

pyramidal and extrapyramidal tracts

MOTOR

PATHWAYS

A

Pyramidal tractDirect connection

from motor cortex to

skeletal muscles

through motor end plate

Tractus corticospinalis

B

Extrapyramidal

tractsIndirect connections

Throug basal ganglia

thalamus, cerebellum,

brain stem

Tractus reticulospinalis

Tractus rubrospinalis

Epineurium

Endoneurium

Axon

Peripheral nerve

Is composed of number of axons of efferent and afferent neurons, myelin sheets and connective tissuesTypes of fibres: A alfa – thick, quick to 120 m/s,

movement

A beta – thinner, to 70 m/s,

touch, pressure

A gama – thinner, do 30 m/s,

muscle tone

A delta – thinner, do 30 m/s,

pain, warmth

B – thin and slow, 2 m/s,

autonomic fibres

C – thin and slow,

autonomic fibres, pain

Perineurium

vessels

PROTECTED BY BACKBONE

Gray matter – neurons – butterfly shaped White matter – nerve fibers

Anterior horns – motor spinal nerve exitFrom motor neuronsAlfa- motor neuronsGama-motor neurons

Posterior horns – sensory spinal nerve entrance

SPINAL CORD

Cross section of the spinal cord

Schwann cells – glial cells in PNS - the sheath of peripheral nerve fibres –

made of Schwann cells . Multiple wrappings around axon of neuron form

myelin sheath.

Nodes of Ranvier separate apart the Schwann cells and give rise to - saltatory

transmission of action potentials

Myelin sheath serves for regeneration of cut nerves – the tube for growth of the

proximal part of the axon.

Steps of regeneration

of proximal part of

an axon after injury

http://epistemic-forms.com/Limbic-system.html

Nucleus caudatusSTRIATUM

BASAL

GANGLIA

Putamen

Globus

Pallidus

Thalamus

Substantia nigra

Cerebellum

Nucleus subthalamicus

MOZOČEK - CEREBELLUM

ENSURES :A) UPRIGHT POSITION AND BALANCEB) FINE REGULATION OF MOVEMENTS AND

POSITION, TIME MANAGEMENT OF MOVEMENTS

C) COORDINATION OF MUSCLE UNITS IN COMPLEX MOVEMENTS INCLUDING SPEECH MOVEMENTS MECHANISM (cerebelárna dysartria a dysfónia)

D) MOTOR LEARNING

SLEEP AND

WAKEFULLNESS

EVOKED POTENTIALS reach the brain by ascending pathways from receptors

1. Primary EP – projection neurons (sensatio) 15´´-20´´2. Secondary EP – asociation neurons (via Reticular Formaion) 40´´-60´´ (perceptio)

BRAIN – electrical oscilator system

Electrocorticography ECGSummation action potentials from the surface of the brain

Electroencephalography EEGSummation action potentials from the skull

It provides:1. Monitoring of the depth of the narcosis2. Haematoma diagnostics

( amplitúdy)3. Epileptic seissures - dg4. Death criterion5. Sleep stage differentiation

Elektroencephalografy (EEG)

Asynchronic EEG

Synchronized EEG

- Simultaneous activity of thousands of neurons

- Is not analysing WHAT we think, but IF we think

- AMPLITUDE depend on synchronization

- FREQUENCY: depends of neuronal activity

8-13 Hz, calm, awake > 14 Hz, aktivita

Delta: < 4 Hz, deep sleep

Theta: 4-7 Hz, sleep

SLEEP AND WAKEFULLNESS

Why do we do sleep?

Cirkadiann theory

Passive theory

Active theory

BRAIN STEM

MEDULLA

Nuclei releasing

acetylcholin

Nuclei releasing

serotonín

CIRCADIAN RHYTHM - REGULATIONHYPOTHALAMUSNUCLEUS PARAVENTRICULARIS, NUCLEUS SUPRACHIASMATICUS

Nerve fibers from retina – light inhibits melatonin release, darkness promotes melatonin release from pineal gland (glandula pinealis)

SLEEP STAGES

REM - rapid eye movement

Paradox sleep

Active brain

In paralysed body

Bizzar dreams

Increased metabolism

NonREM

SWS - slow wave sleep

Orthodox sleep

Idling brain

In moving body

Decreased metabolism

Somnambulism

somnilokvia

SLEEP – reversible state of decreased reaction to stimuli and decreased interaction with

the environment

SLEEP CYCLE AND EEG

These brain waves, taken by

electroencephalogram, are

used by sleep experts to

identify the stages of sleep.

Close your eyes and your brain

waves will look like the first

band above, "relaxed

wakefulness."

Theta waves indicate Stage 1

sleep. Stage 2 sleep shows

brief bursts of activity as sleep

spindles and K-complex

waves. Deep sleep is

represented by large, slow

delta waves (Stages 3 and 4).

REM sleep = reverse learning, and originally attributed it only one

purpose: forgetting the unnecessary memory ballast. (Crick, Nature,1983)

• converting poorly associative memories into highly associative memories (the origin of the ancient phrase: let me consult my pillow)

• eliminating knowledge interference; a REM bout should help you avoid confusing two similar concepts

• extracting common properties of objects and building models (pictorially: instead of holding 100 pictures of someone's face and searching on each encounter, recognize all common model characteristics are execute recognition in milliseconds)

• optimizing procedural reflexes transferring memories from overloaded circuits (e.g. the hippocampus) to spacious areas of the neocortex

SLEEP DEPRIVATION

The image above

reflects deactivation

in specific brain

regions, including the

prefrontal cortex

following 24 hours of

sleep deprivation.

DURATION OF REM AND NONREM SLEEP IN DIFFERENT PHASES

OF ONTOGENY

EOG

EMG

PULSE

BREATHING

SLEEP AND BIORHYTHMS

REM SLEEP DURING LIFE SPAN

SLEEP TOTAL DURING LIFE SPAN