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NEUROPHYSIOLOGY Prof. MUDr. Daniela Ostatníková, PhD Institute of Physiology, Faculty of Medicine Comenius University

NEUROPHYSIOLOGY - uniba.sk · NEUROPHYSIOLOGY Prof. MUDr. Daniela Ostatníková, PhD Institute of Physiology, Faculty of Medicine Comenius University. PHYSIOLOGY – LOGIC OF LIFE

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Page 1: NEUROPHYSIOLOGY - uniba.sk · NEUROPHYSIOLOGY Prof. MUDr. Daniela Ostatníková, PhD Institute of Physiology, Faculty of Medicine Comenius University. PHYSIOLOGY – LOGIC OF LIFE

NEUROPHYSIOLOGYProf. MUDr. Daniela Ostatníková, PhD

Institute of Physiology, Faculty of Medicine

Comenius University

Page 2: NEUROPHYSIOLOGY - uniba.sk · NEUROPHYSIOLOGY Prof. MUDr. Daniela Ostatníková, PhD Institute of Physiology, Faculty of Medicine Comenius University. PHYSIOLOGY – LOGIC OF LIFE

PHYSIOLOGY –LOGIC OF LIFE

Page 3: NEUROPHYSIOLOGY - uniba.sk · NEUROPHYSIOLOGY Prof. MUDr. Daniela Ostatníková, PhD Institute of Physiology, Faculty of Medicine Comenius University. PHYSIOLOGY – LOGIC OF LIFE

Rembrandt van Rijn –

1606 – 1669

Anatomy lecture

MOTIVATION TO LEARN

Page 4: NEUROPHYSIOLOGY - uniba.sk · NEUROPHYSIOLOGY Prof. MUDr. Daniela Ostatníková, PhD Institute of Physiology, Faculty of Medicine Comenius University. PHYSIOLOGY – LOGIC OF LIFE

Maslow's Hierarchy

of Needs

Self Actualization Needs

(full potential)

Ego Needs (self respect,

personal worth,

autonomy)

Social Needs (love,

friendship, comradeship)

Security Needs

(protection from danger)

Physiological Needs

-Homeostasis

-(warmth, shelter, food)

Page 5: NEUROPHYSIOLOGY - uniba.sk · NEUROPHYSIOLOGY Prof. MUDr. Daniela Ostatníková, PhD Institute of Physiology, Faculty of Medicine Comenius University. PHYSIOLOGY – LOGIC OF LIFE

SIGNIFICANT

STIMULUSSELFREGULATORY PROCESSES

LIFE EXPERIENCES – ADEQUATE REACTIONS

a) Principle of hierarchy

b) Principle of excercise/usage

c) Principle of interconnections (feedback – feedforward)

Page 6: NEUROPHYSIOLOGY - uniba.sk · NEUROPHYSIOLOGY Prof. MUDr. Daniela Ostatníková, PhD Institute of Physiology, Faculty of Medicine Comenius University. PHYSIOLOGY – LOGIC OF LIFE

TRAIN YOUR BRAIN

Page 7: NEUROPHYSIOLOGY - uniba.sk · NEUROPHYSIOLOGY Prof. MUDr. Daniela Ostatníková, PhD Institute of Physiology, Faculty of Medicine Comenius University. PHYSIOLOGY – LOGIC OF LIFE

COGNITIVE BRAIN

(brain of Homo Sapiens) THINKING, MEMORY, LEARNING

EMOTIONAL BRAIN

(brain of a horse)

LIFE AND SPECIES PRESERVATION

REFLEXIVE BRAIN

(brain of a reptile)

PRIMARY PROTECTION

CENTRAL NERVOUS HIERARCHY

OUTLINE

Page 8: NEUROPHYSIOLOGY - uniba.sk · NEUROPHYSIOLOGY Prof. MUDr. Daniela Ostatníková, PhD Institute of Physiology, Faculty of Medicine Comenius University. PHYSIOLOGY – LOGIC OF LIFE

LIFE = ADAPTATION

Regulatory mechanisms for life preservation = regulatory

mechanisms for preservation of inner environment stability -

HOMEOSTASIS in spite of changes in external environment

IMMUNE SYSTEMPROTECTION, an ability to discriminate between self and non self, protection against

microorganisms´ reproduction

Systems of innate and adaptive immune reactions, fast and slow immune systems

ENDOCRINNE SYSTEMRegulation of metabolic and functional processes in human body, ensuring the

biorhythms, life stereotypes and responses to stress

Secretion of minimum doses of hormones (nanomoles, picomoles) to blood or to

extracellular space. Slow but very effective systems

NERVOUS SYSTEM Very fast regulation system, communication via nerve impulses – action potentials that

are spreading via nerve fibers to distant tissues (muscles, glands, brain tissue)

Page 9: NEUROPHYSIOLOGY - uniba.sk · NEUROPHYSIOLOGY Prof. MUDr. Daniela Ostatníková, PhD Institute of Physiology, Faculty of Medicine Comenius University. PHYSIOLOGY – LOGIC OF LIFE

HOMEOSTASIS & HOMEORHESISthe principles for life preservation

For a dynamical system,

homeostasis can be viewed

as sustaining internal

stability.

For a dynamical system,

homeorhesis is viewed as

maintenance of order and

normalcy in the state

trajectory under internal

and external disturbances

by avoiding a potential

chaos.

Homeorhesis, derived from the Greek for "similar flow", is a concept

encompassing dynamical systems which return to a trajectory, as

opposed to systems which return to a particular state, which is termed

homeostasis

Page 10: NEUROPHYSIOLOGY - uniba.sk · NEUROPHYSIOLOGY Prof. MUDr. Daniela Ostatníková, PhD Institute of Physiology, Faculty of Medicine Comenius University. PHYSIOLOGY – LOGIC OF LIFE

OUTLINE OF THE LECTURES

• Physiology of the nerve cell

• Resting transmembrane potential, receptor

potential

• Depolarisation, hyperpolarisation, action

potential of the nerve cell

• Conduction of action potentials

• Physiology of senses (vision, hearing, pain

perception)

• Physiology of skeletal and smooth muscles

• Physiology of autonomous nervous system

Page 11: NEUROPHYSIOLOGY - uniba.sk · NEUROPHYSIOLOGY Prof. MUDr. Daniela Ostatníková, PhD Institute of Physiology, Faculty of Medicine Comenius University. PHYSIOLOGY – LOGIC OF LIFE

THE NERVOUS SYSTEM

Page 12: NEUROPHYSIOLOGY - uniba.sk · NEUROPHYSIOLOGY Prof. MUDr. Daniela Ostatníková, PhD Institute of Physiology, Faculty of Medicine Comenius University. PHYSIOLOGY – LOGIC OF LIFE

NERVOUS SYSTEM = INFORMATION HIGHWAY

INFORMATION

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

Page 13: NEUROPHYSIOLOGY - uniba.sk · NEUROPHYSIOLOGY Prof. MUDr. Daniela Ostatníková, PhD Institute of Physiology, Faculty of Medicine Comenius University. PHYSIOLOGY – LOGIC OF LIFE

THE NERVOUS SYSTEM

1) CENTRALa) BRAINb) SPINAL CORD

2) PERIPHERALNerve fibers - AXONS – connections tomuscles and glands

MOTOR NERVE FIBERS

AUTONOMIC (VEGETATIVE)NERVE FIBERS• Sympaticus• Parasympaticus

SENSORY NERVE FIBERS

Page 14: NEUROPHYSIOLOGY - uniba.sk · NEUROPHYSIOLOGY Prof. MUDr. Daniela Ostatníková, PhD Institute of Physiology, Faculty of Medicine Comenius University. PHYSIOLOGY – LOGIC OF LIFE

NEURON BASIC MORPHOLOGIC AND FUNCTIONAL UNIT

OF THE NERVOUS SYSTEM

NEURONS COMMUNICATE VIA ELECTRICAL (CHEMICAL) SIGNALS

Page 15: NEUROPHYSIOLOGY - uniba.sk · NEUROPHYSIOLOGY Prof. MUDr. Daniela Ostatníková, PhD Institute of Physiology, Faculty of Medicine Comenius University. PHYSIOLOGY – LOGIC OF LIFE

According to structure:

UNIPOLAR, BIPOLAR

PSEUDOUNIPOLAR

MULTIPOLAR

According to function:

SENSORY, AFFERENT CENTRIPETAL

MOTOR, EFFERENT, CENTRIFUGALA) Somatic – to skeletal muscles

B) Autonomic – to smooth muscles,

heart and glands

Ba) sympathetic

Bb) parasympathetic

ASOCIATION, INTERNEURONSIntegrative function in central nervous

system

CLASSIFICATION OF NERVES AND NEURONS

Page 16: NEUROPHYSIOLOGY - uniba.sk · NEUROPHYSIOLOGY Prof. MUDr. Daniela Ostatníková, PhD Institute of Physiology, Faculty of Medicine Comenius University. PHYSIOLOGY – LOGIC OF LIFE

Motor system

Sensory system

FUNCTIONAL CLASSIFICATION OF

NEURONSSENSORY, AFFERENT CENTRIPETAL

MOTOR, EFFERENT, CENTRIFUGAL

A)Somatic – to skeletal muscles

B)Autonomic – to smooth muscles,

heart and glands (sympathetic, parasympathetic)

ASOCIATION, INTERNEURONS

Integrative function in central

Nervous system

SOMATIC MOTOR

AUTONOMIC MOTOR

Page 17: NEUROPHYSIOLOGY - uniba.sk · NEUROPHYSIOLOGY Prof. MUDr. Daniela Ostatníková, PhD Institute of Physiology, Faculty of Medicine Comenius University. PHYSIOLOGY – LOGIC OF LIFE

Registering of inputs, coding, integration

and adequate response

Page 18: NEUROPHYSIOLOGY - uniba.sk · NEUROPHYSIOLOGY Prof. MUDr. Daniela Ostatníková, PhD Institute of Physiology, Faculty of Medicine Comenius University. PHYSIOLOGY – LOGIC OF LIFE

GLIAL CELLS – THE GIANTS OF THE

FUTURE

NEURON

GLIAL CELLS

THE NEURON: GLIAL CELLS

RATIO 1:10

Page 19: NEUROPHYSIOLOGY - uniba.sk · NEUROPHYSIOLOGY Prof. MUDr. Daniela Ostatníková, PhD Institute of Physiology, Faculty of Medicine Comenius University. PHYSIOLOGY – LOGIC OF LIFE

NEUROGLIA – GLIAL CELLSTheir serve as the functional support for neurons

NEUROGLIA – originated from glue (introduced by Rudolf Virchow v 1854)

ASTROCYTES (dark green)1) Involved in neuronal nutrition

2) Influence the EC environment

3) Influence the synaptic transmission by

neurotransmitter reuptake

OLIGODENDROCYTES

Myelination of axones

Influence the transmission speed

MICROGLIA

Immune cells in the brain

Have the capability of

phagocytosis

Page 20: NEUROPHYSIOLOGY - uniba.sk · NEUROPHYSIOLOGY Prof. MUDr. Daniela Ostatníková, PhD Institute of Physiology, Faculty of Medicine Comenius University. PHYSIOLOGY – LOGIC OF LIFE

SYNAPSE – FUNCTIONAL CONNECTION OF NEURONS

1. Action potential reaches presynaptic button

2. Mediator (neurotransmitter) is released to synaptic cleft

3. Mediator contacts receptors inpostsynaptic membrane

4. Action potential in postsynaptic neuron is transmitted (or not) -depends onthe transmitter (excitatory/inhibitory)

Page 21: NEUROPHYSIOLOGY - uniba.sk · NEUROPHYSIOLOGY Prof. MUDr. Daniela Ostatníková, PhD Institute of Physiology, Faculty of Medicine Comenius University. PHYSIOLOGY – LOGIC OF LIFE
Page 22: NEUROPHYSIOLOGY - uniba.sk · NEUROPHYSIOLOGY Prof. MUDr. Daniela Ostatníková, PhD Institute of Physiology, Faculty of Medicine Comenius University. PHYSIOLOGY – LOGIC OF LIFE

THE LIFE CYCLE OF

NEUROTRANSMITTER

• THE RELEASE (METABOLISM) OF NEUROTRANSMITTER

must be quick so as the new

signal could follow

Mechanisma/ Reuptake to presynapticneuron or to glial cell

b/ Degradation by specificenzymes

c/ Combination of both

Page 23: NEUROPHYSIOLOGY - uniba.sk · NEUROPHYSIOLOGY Prof. MUDr. Daniela Ostatníková, PhD Institute of Physiology, Faculty of Medicine Comenius University. PHYSIOLOGY – LOGIC OF LIFE

Autoreceptorsand their role

in synaptic transmission

receptors for its own and for other (different)

neurotransmitters on axon terminals. Receptors bind

the very same transmitter released by that neuron.

They function to decrease transmitter release in the

terminal.

Page 24: NEUROPHYSIOLOGY - uniba.sk · NEUROPHYSIOLOGY Prof. MUDr. Daniela Ostatníková, PhD Institute of Physiology, Faculty of Medicine Comenius University. PHYSIOLOGY – LOGIC OF LIFE

NEUTRANSMITTERS

NEUROMEDIATORS

Neurotransmitter characteristics:

END TO END CONNECTION

1. Is produced by neurons, is released to synaptic cleft from the presynaptic

membrane after the arrival of action potentials.

2. It must have an effect on postsynaptic neuron

2. After trensmitting the signal it must be quickly degraded - deactivated

4. It has to have the same effect on postsynaptic neuron during experimental use as

in vivo

Page 25: NEUROPHYSIOLOGY - uniba.sk · NEUROPHYSIOLOGY Prof. MUDr. Daniela Ostatníková, PhD Institute of Physiology, Faculty of Medicine Comenius University. PHYSIOLOGY – LOGIC OF LIFE

NEUROMODULATORS

DIFUSE MODULATORY SYSTEMS

CENTRES ARE SMALL SUBCORTICAL NUCLEI

Localised in brain stemm

One neuron releases its modulator

to the ECF and could influence

Up to 100 000 neurons in the CNS

Characteristics of the neuromodulators:

1. They do not transmitt the neuronal impulses

2. They influence synthesis, degradation a reabsorption of the

neurotransmitters

3. They have regulatory effects upon synaptic transmission adnd

moreover on the extrasynaptic neuronal receptors

Page 26: NEUROPHYSIOLOGY - uniba.sk · NEUROPHYSIOLOGY Prof. MUDr. Daniela Ostatníková, PhD Institute of Physiology, Faculty of Medicine Comenius University. PHYSIOLOGY – LOGIC OF LIFE

NEUROTRANSMITTERS- NEUROMODULATORSMore than 50 chemical substances

1. Small molecules with rapid effects

Stored in axonal vesicules

Effect on postsynaptic membrane approx. 1 ms, - opening of ion channels,

Brief inactivation, recycled, fromed in the body of neurons

Class I. ACH

Class II. Amines : NA, A, Dopamin, serotonin, histamin

Class III. Aminoacids: GABA, Glycin, Glutamate, Aspartate

Class IV. NO

2. NEUROPEPTIDES, prolonged effects, are integral part of protein molecules

In neuronal bodies, are fromed in the bodies and compose the vesicules inside of them,

then they are brought to the axonal terminals with longlasting effect (hours - days)

Modulates the expression of genes

A. Hypothalamic releasing hormones

B. Pituitary peptides: beta-endorfin, MSH, Prolactin, GH, vasopresin, oxytocin,

ACTH, LH, TSH

C. Peptides operating in GIT and brain: Leucin, enkefalin, methionin

substance P, gastrin, cholecystokinin, VIP, neurotensin, insulin, glucagon

D. From other tissues: angiotensin II, Bradykinin, Carnosin, calcitonin, sleep peptides

Page 27: NEUROPHYSIOLOGY - uniba.sk · NEUROPHYSIOLOGY Prof. MUDr. Daniela Ostatníková, PhD Institute of Physiology, Faculty of Medicine Comenius University. PHYSIOLOGY – LOGIC OF LIFE

Many synapses are activated on one neuron (up to 5000)

The voltage of each is about 1-4 mV (local, graded potentials)

The sum of local potentials which are either

EXCITATORY POSTSYNAPTIC POTENTIALS – EPSP or

INHIBITORY POSTSYNAPTIC POTENTIALS - IPSP

enables to reach threshold value for action potential on axon

(axon depolarization)

or can even decrease transmembrane potential

(axon hyperpolarization).

axodendritic, axosomatic,

axoaxonal

SYNAPSE – FUNCTIONAL CONNECTION OF CELLS –AT LEAST ONE IS NEURONAL

Page 28: NEUROPHYSIOLOGY - uniba.sk · NEUROPHYSIOLOGY Prof. MUDr. Daniela Ostatníková, PhD Institute of Physiology, Faculty of Medicine Comenius University. PHYSIOLOGY – LOGIC OF LIFE

SUMMATION OF THE EXCITATORY AND

INHIBITORY LOCAL POSTSYNAPTIC POTENTIALS

ON THE BODY AND DENDRITES -

ANALOG/AMPLITUDE CODE

ACTIVE SYNAPSE

Page 29: NEUROPHYSIOLOGY - uniba.sk · NEUROPHYSIOLOGY Prof. MUDr. Daniela Ostatníková, PhD Institute of Physiology, Faculty of Medicine Comenius University. PHYSIOLOGY – LOGIC OF LIFE

ACTIVE SYNAPSE

SUMMATION OF THE EXCITATORY AND

INHIBITORY LOCAL POSTSYNAPTIC POTENTIALS

ON THE BODY AND DENDRITES -

ANALOG/AMPLITUDE CODE

Page 30: NEUROPHYSIOLOGY - uniba.sk · NEUROPHYSIOLOGY Prof. MUDr. Daniela Ostatníková, PhD Institute of Physiology, Faculty of Medicine Comenius University. PHYSIOLOGY – LOGIC OF LIFE

SPATIAL SUMMATION

OF EXCITATORY PSP

(A+B)

ACTIVE SYNAPSES

SUMMATION OF THE EXCITATORY AND

INHIBITORY LOCAL POSTSYNAPTIC POTENTIALS

ON THE BODY AND DENDRITES -

ANALOG/AMPLITUDE CODE

Page 31: NEUROPHYSIOLOGY - uniba.sk · NEUROPHYSIOLOGY Prof. MUDr. Daniela Ostatníková, PhD Institute of Physiology, Faculty of Medicine Comenius University. PHYSIOLOGY – LOGIC OF LIFE

TEMPORAL SUMMATION

OF EXCITATORY PSP

ON „A“ SYNAPSE

Aktívna synapsa

SUMMATION OF THE EXCITATORY AND

INHIBITORY LOCAL POSTSYNAPTIC POTENTIALS

ON THE BODY AND DENDRITES -

ANALOG/AMPLITUDE CODE

Page 32: NEUROPHYSIOLOGY - uniba.sk · NEUROPHYSIOLOGY Prof. MUDr. Daniela Ostatníková, PhD Institute of Physiology, Faculty of Medicine Comenius University. PHYSIOLOGY – LOGIC OF LIFE

SUMMATION OF EPSP A IPSP FOR

GENERATING ACTION POTENTIAL

Page 33: NEUROPHYSIOLOGY - uniba.sk · NEUROPHYSIOLOGY Prof. MUDr. Daniela Ostatníková, PhD Institute of Physiology, Faculty of Medicine Comenius University. PHYSIOLOGY – LOGIC OF LIFE

Every synapse excites or

depresses

the membrane of the neuron

body or neuron dendrites only

LOCALLY –the changed

permeability of the membrane

is conducted to a nearby place

to a limited distance with

deceasing amlitude – local

depolarization or local

hyperpolarization

The sum of local potentials

enables to reach threshold

value for action potential on

axon in case that overall

stimulation is higher than

overall depression and the

stimulation reaches the

thereshold value

= action potential of an axon

NEURON

dendrites

Glial cells

Axon of postsynaptic neuron

Axons of

presynaptic neurons

Page 34: NEUROPHYSIOLOGY - uniba.sk · NEUROPHYSIOLOGY Prof. MUDr. Daniela Ostatníková, PhD Institute of Physiology, Faculty of Medicine Comenius University. PHYSIOLOGY – LOGIC OF LIFE

Excitatory and inhibitory potential

EPSP is caused by opening of Na

channels in the postsynaptic membrane

IPSP is caused by the opening of Cl

channels in the postsynaptic membrane

Page 35: NEUROPHYSIOLOGY - uniba.sk · NEUROPHYSIOLOGY Prof. MUDr. Daniela Ostatníková, PhD Institute of Physiology, Faculty of Medicine Comenius University. PHYSIOLOGY – LOGIC OF LIFE

Each neuron get thousands of inputs

It integrates it to a single output – synaptic integrationThe output dependes on:

1. Strenght of presynaptic stimulation

2. Amount of released neurotransmitter

3. Amount of active PS receptors

EPSP – excitatory postsynaptic potentiál

IPSP – inhibitory postsynaptic potential

IPSP -Cl ions involved

EPSP - Na ions involved

Page 36: NEUROPHYSIOLOGY - uniba.sk · NEUROPHYSIOLOGY Prof. MUDr. Daniela Ostatníková, PhD Institute of Physiology, Faculty of Medicine Comenius University. PHYSIOLOGY – LOGIC OF LIFE

RESTING MEMBRANE

POTENTIAL

Page 37: NEUROPHYSIOLOGY - uniba.sk · NEUROPHYSIOLOGY Prof. MUDr. Daniela Ostatníková, PhD Institute of Physiology, Faculty of Medicine Comenius University. PHYSIOLOGY – LOGIC OF LIFE

RESTING MEMBRANE POTENTIAL

There is unequal distribution of ions outside and inside the cell membrane (valid for all

cells in the body) POLARITY OF THE MEMBRANE

Na is more concentrated in ECF

K is in higher concentration in ICF

Thanks to intracellular proteins (big

negatively charged molecules) the inside

of the cell membrane is negativelly

charged in relation to the inner side

of the cell membrane

Calculation of equlibrium potential of an ion

R- gas constant, T – temperature

Z – valence of an ion, F – Faraday constant

Co – concentration outside

Ci – concentration inside

Page 38: NEUROPHYSIOLOGY - uniba.sk · NEUROPHYSIOLOGY Prof. MUDr. Daniela Ostatníková, PhD Institute of Physiology, Faculty of Medicine Comenius University. PHYSIOLOGY – LOGIC OF LIFE

TRANSMEMBRANE POTENTIAL

ION CONCENTRATIONS

OUTSIDE AND INSIDE

THE MEMBRANE

Page 39: NEUROPHYSIOLOGY - uniba.sk · NEUROPHYSIOLOGY Prof. MUDr. Daniela Ostatníková, PhD Institute of Physiology, Faculty of Medicine Comenius University. PHYSIOLOGY – LOGIC OF LIFE

RELATIVE CONCENTRATIONS OF SOME IMPORTANT IONS INSIDE AND

OUTSIDE THE NEURON AND THE FORCES ACTING ON THEM

HENDERSON EQUATION

R – gass constant

T – temperature

F – Faraday constant

Co – concentration outside

Ci – concentration inside

Page 40: NEUROPHYSIOLOGY - uniba.sk · NEUROPHYSIOLOGY Prof. MUDr. Daniela Ostatníková, PhD Institute of Physiology, Faculty of Medicine Comenius University. PHYSIOLOGY – LOGIC OF LIFE

TRANSMEMBRANE POTENTIAL

Transmembrane potential is dependant on the permeability of the membrane

for every important ion and the balanced potential for every difuisible

ion. All cells have the membrane potential, but not all have the same value.

Most of the cells have transmembrane potential in the range of

–65 mV to –90 m V

Only nerve and muscle cells could change the potential and elicit action

Potential – voltage gated channels

Na/K pumps remain the equilibrium

Page 41: NEUROPHYSIOLOGY - uniba.sk · NEUROPHYSIOLOGY Prof. MUDr. Daniela Ostatníková, PhD Institute of Physiology, Faculty of Medicine Comenius University. PHYSIOLOGY – LOGIC OF LIFE

Measuring of transmembrane cell

potential

Explorative electrode

Is insetred inside the cell,

Therefore the value is negative.

(the inside is negative in

comparison with the outside) !!!!!!

Page 42: NEUROPHYSIOLOGY - uniba.sk · NEUROPHYSIOLOGY Prof. MUDr. Daniela Ostatníková, PhD Institute of Physiology, Faculty of Medicine Comenius University. PHYSIOLOGY – LOGIC OF LIFE

ALTERATIONS OF AXON

MEMBRANE

POTENTIAL

ACTION POTENTIAL

Page 43: NEUROPHYSIOLOGY - uniba.sk · NEUROPHYSIOLOGY Prof. MUDr. Daniela Ostatníková, PhD Institute of Physiology, Faculty of Medicine Comenius University. PHYSIOLOGY – LOGIC OF LIFE

Registering of inputs, coding, integration

and adequate response

Page 44: NEUROPHYSIOLOGY - uniba.sk · NEUROPHYSIOLOGY Prof. MUDr. Daniela Ostatníková, PhD Institute of Physiology, Faculty of Medicine Comenius University. PHYSIOLOGY – LOGIC OF LIFE

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

Page 45: NEUROPHYSIOLOGY - uniba.sk · NEUROPHYSIOLOGY Prof. MUDr. Daniela Ostatníková, PhD Institute of Physiology, Faculty of Medicine Comenius University. PHYSIOLOGY – LOGIC OF LIFE

Only a few types of cells can alter their membrane potential by varying the

membrane permeability to specific ions in response to stimulation

Ability to change the membrane potential have nervous and muscle cells

thanks to EXCITABILITY of their membranes

the membrane can

be excited by the stimulus,

the increase of premeability

to a certain ion occurs,

the response to the stimulus is limited

and causes either depolarization or

hyperpolarization of the membrane,

the response can be graded and is

conducted with decrement

there is no refractory phase

there is time and place summation

ALTERATIONS IN MEMBRANE POTENTIAL

AMPLITUDE

ANALOG

CODE

Page 46: NEUROPHYSIOLOGY - uniba.sk · NEUROPHYSIOLOGY Prof. MUDr. Daniela Ostatníková, PhD Institute of Physiology, Faculty of Medicine Comenius University. PHYSIOLOGY – LOGIC OF LIFE

Only a few types of cells can alter their membrane potential by varying the

membrane permeability to specific ions in response to stimulation

Ability to change the membrane potential have nervous and muscle cells

thanks to IRRITABILITY OR EXCITABILITY of their membranes

EXCITABILITY – the membrane

is excited by the stimulus and

when the axon membrane is

depolarized to a threshold level

the Na gates open and the

membrane becomes permeable

to Na (transpolarization)

valid for the axon

1) all or none law

2) refractory periods

3) intensity is coded by frequency

ALTERATIONS IN MEMBRANE POTENTIAL

Page 47: NEUROPHYSIOLOGY - uniba.sk · NEUROPHYSIOLOGY Prof. MUDr. Daniela Ostatníková, PhD Institute of Physiology, Faculty of Medicine Comenius University. PHYSIOLOGY – LOGIC OF LIFE

GENERATION OF ACTION

POTENTIAL

Excitable membrane

ANALOG

Conductive membrane

DIGITAL

Page 48: NEUROPHYSIOLOGY - uniba.sk · NEUROPHYSIOLOGY Prof. MUDr. Daniela Ostatníková, PhD Institute of Physiology, Faculty of Medicine Comenius University. PHYSIOLOGY – LOGIC OF LIFE

receptor membrane is the real heart of the sensory system. It is a part of the plasma membrane of the sensory cell, which is in some way constructed so that a stimulus will cause a change in the membrane's permeability to some ion.

This causes depolarization ofreceptor membrane –

RECEPTOR POTENTIALamplitude of the receptor potential depends of the strength of the stimulus

= AMPLITUDE CODE

SENSORY (RECEPTOR)

MEMBRANE

Occures on the border between receptor

Membrane and axon membrane

If the amplitude of the receptor potential in

this place reaches threshold level

ACTION POTENTIAL IS INITIATED

= FREQUENCY CODE

Page 49: NEUROPHYSIOLOGY - uniba.sk · NEUROPHYSIOLOGY Prof. MUDr. Daniela Ostatníková, PhD Institute of Physiology, Faculty of Medicine Comenius University. PHYSIOLOGY – LOGIC OF LIFE

1. Stimulation of the membrane by subthreshold stimulus elicits local graded

excitation with decreasing of potential difference on the membrane

(depolarization) or with decreasing potential difference (hyperpolarization)

2. Stimulation with threshold stimulus iniciates nerve impulse – action

potential (on axon hillock) and its conduction on the axon po axóne spikes

- transpolarization

RESTING STATE depolarization

hyperpolarization

Threshold

Local response

Page 50: NEUROPHYSIOLOGY - uniba.sk · NEUROPHYSIOLOGY Prof. MUDr. Daniela Ostatníková, PhD Institute of Physiology, Faculty of Medicine Comenius University. PHYSIOLOGY – LOGIC OF LIFE

ACTION POTENTIAL

– CHANGES IN MEMBRANE PERMEABILITY TO IONS

AP time duration 4ms

Page 52: NEUROPHYSIOLOGY - uniba.sk · NEUROPHYSIOLOGY Prof. MUDr. Daniela Ostatníková, PhD Institute of Physiology, Faculty of Medicine Comenius University. PHYSIOLOGY – LOGIC OF LIFE

AP is caused by opening of Na channels

after the threshold stimulus

Page 53: NEUROPHYSIOLOGY - uniba.sk · NEUROPHYSIOLOGY Prof. MUDr. Daniela Ostatníková, PhD Institute of Physiology, Faculty of Medicine Comenius University. PHYSIOLOGY – LOGIC OF LIFE

NA/K pump

Na/K ATPase

Page 54: NEUROPHYSIOLOGY - uniba.sk · NEUROPHYSIOLOGY Prof. MUDr. Daniela Ostatníková, PhD Institute of Physiology, Faculty of Medicine Comenius University. PHYSIOLOGY – LOGIC OF LIFE

SELECTIVE Na ION CHANNEL

Ions diffuse down their electrochemical gradient, usually through pores called ion

channels.

Ion channels can be highly selective for the chemical species they let through.

Sodium's diffusion across the membrane is facilitated by an ion channel. It is

selective for Na+ by the size of the pore in the channel and the charges on

amino acids inside the pore. K+ is too big to pass through; Cl− is repeld

because the charges inside are negative as well as the Cl ion itself.

Page 55: NEUROPHYSIOLOGY - uniba.sk · NEUROPHYSIOLOGY Prof. MUDr. Daniela Ostatníková, PhD Institute of Physiology, Faculty of Medicine Comenius University. PHYSIOLOGY – LOGIC OF LIFE

Action potential is produced by

an increase in sodium diffusion

followed by an increase of

potassium diffusion

Both depolarization and repolarization

are produced by the diffusion of ions

down their concentration gradients

The Na/K pumps then rebuild the

concentration gradients of both ions

(sodium and potassium)

ACTION POTENTIAL, NERVE IMPULSE

treshold

Once a region of the axon membrane has been

depolarized to a threshold, the duration and the

amplitude of the AP is independent of the strenght

of the stimulus – ALL OR NONE LAW

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ALL OR NONE LAW

CONSTATNT REGENERATION OF DEPOLARIZATION OF THE MEMBRANE

CONDUCTION OF ACTION POTENTIALS WITHOUT DECREMENT

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ACTION POTENTIAL AND ITS REFRACTORY PERIODS

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CONDUCTION OF

ACTION POTENTIALS

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CONDUCTION OF THE NERVE IMPULSES – ACTION POTENTIALS

osciloscop

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CONDUCTION OF THE NERVE IMPULSES – ACTION POTENTIALS

Conduction on unmyelinated fibers

= without myelin sheath around the axon

Action potential is regenerated on the adjacent

region of the excitable membrane of an axon

Conduction on myelinated fibers

= with myelin sheath wrapped around the axon

made of Schwann cells

Action potential is propagated by

SALTATORY CONDUCTION

(“jumps” from one Ranvier node to another)

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CONDUCTION OF THE NERVE IMPULSES

ON UNMYELINATED FIBERS

Each AP injects positive charges (sodium

ions)

Into the axon

These are conducted by the cable

properties

of the axon to an adjacent region that still

has

a membrane potential of –65 mV.

When this adjacent region of the

membrane

reaches threshold level of depolarization

It too produces an AP as its voltage

regulated

gates open

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DIAGRAM OF TIME DURATION

NEEDED FOR ELICITING

THE ACTION POTENTIAL

DEPENDING ON STIMULUS

INTENSITY IN THE SAME

NERVE

FREQUENCY CODING OF

THE STIMULUS INTENSITY

THE STONGER THE INTENSITY

OF THE STIMULUS, THE MORE

ACTION POTENTIALS ARE

TRANSMITTED VIA AXON TO

CNS IN CERTAIN PERIOD

OF TIME

= HIGHER FREQUENCY

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PERIPHERAL NERVOUS

SYSTEM

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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

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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

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LATENCY

STIMULATION POINT

FIBERS OF DIFFERENT CONDUCTION VELOCITY

WITHIN ON PERIPHERAL NERVE

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Schwann cells – glia cells in

PNS form the sheath around the

peripheral nerve fibres

Multiple wrappings around axon

of neuron form myelin sheath.

Nodes of Ranvier

separate the internodia of the

Schwann cells and give rise to –

saltatory transmission of action

potentials

MYELIN SHEATH

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Myelin sheath serves for regeneration of cut nerves

– the tube for growth of the proximal part of the axon e.g. after

injury.

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Protected in spinal cordGray matter – neurons –butterffly shapeWhite matter – nerve fibers

Ventral horn – lower motor neuronsMotor output to spinal nerveMotor input from upper motor neuros

Alpha motor neuronsGamma motor neurons

Dorsal horn – sensory inputFrom muscle spindlesFrom spinal innterneuorns

SPINAL CORD

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Hematomyelia –SPINALCORD MAEMORRHAGE

LESIONS OF THE SPINAL CORD AND PERIPHERAL NERVES

1) PERIPHERAL PALSYa) Lesion of peripheral motor neurons in ventral hornb) Lesion of spinal rootsc) Lesion of peripheral nerves

2) CENTRAL PALSYa) Lesion of pyramidal tractb) Intracranial lesion

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RESTING MEMBRANE POTENTIAL FOR POTASSIUM IONS

CHEMICAL GRADIENT OF K IONS

moves the ions outward

(higher concentration of K ions inside

the cell)

ELECTRICAL GRADIENT OF K IONS

moves the ions inward

(positive charge outside the cell)

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The Nobel Prize in Physiology or Medicine 1932"for their discoveries regarding the functions of neurons"

SYNAPTIC TRANSMISSION

In experiments with dogs, Sherrington noted

reflexes are slower than simple conduction along an axon would

suggest.

Sherrington reasoned that the delay in neural transmission in a reflex

occurred because it took time for the signal to cross the synapses. It

takes about 0.05 s for a signal to cross.

weak stimuli presented at different times or in different locations elicit a

stronger response than a single strong stimulus does.

(TEMPORAL AND SPATIAL SUMMATION)

excitation of one muscle set leads to relaxation in its opposing muscle

set.

From these observations, Sherrington concluded

some of the most important qualities about synapses

and transmission of messages within the nervous

system.

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Many synapses are activated on one neuron (up to 5000)

The voltage of each is about 1-4 mV (local, graded potentials)

The sum of local potentials which are either

EXCITATORY POSTSYNAPTIC POTENTIALS – EPSP or

INHIBITORY POSTSYNAPTIC POTENTIALS - IPSP

enables to reach threshold value for action potential on axon (depolarization) or

to get away from the threshold value for eliciting action potential (hyperpolarization).

SYNAPTIC INTEGRATION

PLACE (SPATIAL) AND TIME (TEMPORAL)

SUMMATION

(simultaneous (repeated stimulation

activation of the synapse causes

of high new PSP before the

number of former one is over)

synapses) one PSP lasts 15 ms axodendritic, axosomatic, axoaxonal

SYNAPSE – FUNCTIONAL CONNECTION OF NEURONS

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Temporal summation: repeated stimuli within a relatively short period of time can

have a cumulative effect

Spatial summation: stimuli occurring at different locations can have a cumulative effect.

Sir John Eccles (1903-

1997) showed temporal

summation in single cells.

Won the Nobel Prize in

1963 for his work on how

inhibitory and excitatory

processes occur at the

synapse.