Neurosciences – Neuron-glia plasticity
Nerve tissue
1. Neurons; vary in structure depending on their place in
nervous system. They have common characteristics
that enable them to communicate with each other and
the rest of their body in the same way
2. Neuroglia cells (glia cells); they are NO signal cells but
have supported functions and process information
(maintain physical structure of tissues, repair tissue
framework after injury, perform phagocytosis, provide
nutrients to neurons, regulate the composition of the interstitial fluid
surrounding neurons)
Types of glia cells in central nervous system
Oligodendrocytes; form myelin
Astrocytes; form support for central
nervous system, help from blood brain
barrier, secrete neurotropic factors,
take up K+ neurotransmitter
Microglia cells; modified immune cells;
act as scavengers (aaseters)
Ependymal cells; create barrier between
compartments
Types of glia cells in peripheral nervous system
Satellite cells; support cell bodies
Swann cells; form myelin and secrete neurotropic
factors
Neuron-glia plasticity; ability in humans to create new
structure and connections in the brain
1. Myelin plasticity
2. Synaptic plasticity
Myelin plasticity
Main function oligodendrocytes: insulation of axons exclusively in
central nervous system; can wrap around 50 axons
Main function Swann cells; insulation of axons exclusively in
peripheral nervous system; can wrap around 1 axon
Development of myelination;
1. Neurulation
2. Cell proliferation and migration
3. Myelination; in the beginning of life lot of
myelination this decreases when you get
older
a. Sensorimotor cortex; peak in the first
year; motor control, eye hand
coordination
, b. Parietal and temporal association cortex; peak around 4 years; being
conscious, having a long-term memory
c. Prefrontal cortex; continues into puberty; decision making
Learning increases myelination (white matter development). So piano practicing or
juggling (jongleren) has effect on white matter development, it increases.
When you use your brain a lot everything is more myelinated. But the volume
of your brain cannot get any more.
So, myelin integrates the signals. When a signal is further away myelin speeds
up the process. And the signals will arise at the same time, when the signals
arise at the same time they will get over the threshold value and cause an
action potential.
White matter defects (myelin defect) lead to CNS disorders and metal illness;
Psychiatric disorders;
Schizophrenia
Chronic depression
Bipolar disorder
Obsessive-compulsive disorder
Posttramatic stress disorder
Cognitive and emotional disorders
Autism
Dyslexia
ADHD
Alzheimer’s disease
Myelin regulate nerve conduction velocity;
Fine-tuning of velocity;
1. Thickness/compaction of myelin (changing electric
isolation)
2. Length between nodes (internodes). Only in node of
Ranvier are sodium channels.
Signals that regulate myelination;
Schwann cell precursor migrate along axons and
interact with thick (>1um) or small (<1um) axons
Committed Schwann cells. The small axons can
determine whether to myelinate the small or thick
axons.
This decision is made by the NRG1 type III.
Signal high; myelinate the thick ones; promyelination
Schwann cell – myelinating Schwann cell
Signal low; myelinate the small ones; non-myelination
Schwann cell – Remark bundle
Nerve tissue
1. Neurons; vary in structure depending on their place in
nervous system. They have common characteristics
that enable them to communicate with each other and
the rest of their body in the same way
2. Neuroglia cells (glia cells); they are NO signal cells but
have supported functions and process information
(maintain physical structure of tissues, repair tissue
framework after injury, perform phagocytosis, provide
nutrients to neurons, regulate the composition of the interstitial fluid
surrounding neurons)
Types of glia cells in central nervous system
Oligodendrocytes; form myelin
Astrocytes; form support for central
nervous system, help from blood brain
barrier, secrete neurotropic factors,
take up K+ neurotransmitter
Microglia cells; modified immune cells;
act as scavengers (aaseters)
Ependymal cells; create barrier between
compartments
Types of glia cells in peripheral nervous system
Satellite cells; support cell bodies
Swann cells; form myelin and secrete neurotropic
factors
Neuron-glia plasticity; ability in humans to create new
structure and connections in the brain
1. Myelin plasticity
2. Synaptic plasticity
Myelin plasticity
Main function oligodendrocytes: insulation of axons exclusively in
central nervous system; can wrap around 50 axons
Main function Swann cells; insulation of axons exclusively in
peripheral nervous system; can wrap around 1 axon
Development of myelination;
1. Neurulation
2. Cell proliferation and migration
3. Myelination; in the beginning of life lot of
myelination this decreases when you get
older
a. Sensorimotor cortex; peak in the first
year; motor control, eye hand
coordination
, b. Parietal and temporal association cortex; peak around 4 years; being
conscious, having a long-term memory
c. Prefrontal cortex; continues into puberty; decision making
Learning increases myelination (white matter development). So piano practicing or
juggling (jongleren) has effect on white matter development, it increases.
When you use your brain a lot everything is more myelinated. But the volume
of your brain cannot get any more.
So, myelin integrates the signals. When a signal is further away myelin speeds
up the process. And the signals will arise at the same time, when the signals
arise at the same time they will get over the threshold value and cause an
action potential.
White matter defects (myelin defect) lead to CNS disorders and metal illness;
Psychiatric disorders;
Schizophrenia
Chronic depression
Bipolar disorder
Obsessive-compulsive disorder
Posttramatic stress disorder
Cognitive and emotional disorders
Autism
Dyslexia
ADHD
Alzheimer’s disease
Myelin regulate nerve conduction velocity;
Fine-tuning of velocity;
1. Thickness/compaction of myelin (changing electric
isolation)
2. Length between nodes (internodes). Only in node of
Ranvier are sodium channels.
Signals that regulate myelination;
Schwann cell precursor migrate along axons and
interact with thick (>1um) or small (<1um) axons
Committed Schwann cells. The small axons can
determine whether to myelinate the small or thick
axons.
This decision is made by the NRG1 type III.
Signal high; myelinate the thick ones; promyelination
Schwann cell – myelinating Schwann cell
Signal low; myelinate the small ones; non-myelination
Schwann cell – Remark bundle
