Nervous system + plasticity

Nervous system + plasticity

Divisions of the nervous system

Learn these and their functions.

Study design - the roles of different divisions of the nervous system (central and peripheral nervous systems and their associated sub-divisions) in responding to, and integrating and coordinating with, sensory stimuli received by the body.

Central nervous system (CNS)

• is made up of the brain and the spinal cord.  

• enables the brain to communicate with the rest of the body by sending and receiving messages from the peripheral nervous system.

Brain

• directs psychological activity (memory, learning, thinking)

• processes information

• maintains life support

• plays a role in just about every major body system.

• Some of its main functions include:

  processing sensory information, regulating blood pressure and breathing, releasing hormones and initiating movement.

Spinal cord

• is responsible for carrying motor information from the brain to other neurons, muscles of glands.

• is responsible for carrying sensory information (from sensory receptors) to the brain.

Peripheral nervous system

• is made up of every neuron that is outside the CNS.

• is further divided into two parts - the autonomic and the somatic nervous systems.

• is responsible for carrying information to an from the CNS - two different pathways - sensory (afferent) pathway and motor (efferent) pathway.

Somatic nervous system

• contains sensory neurons that inform the central nervous system about our five senses; and motor neurons responsible for voluntary movements, such as walking or lifting an object.

• is responsible for a specific type of involuntary muscle responses known as spinal reflexes, controlled by a neural pathway known as the reflex arc.

Autonomic nervous system

• responsible for the communication of information between the CNS and the body’s non-skeletal muscles

  (e.g. heart & stomach), internal organs and glands.

• usually functions without voluntary conscious awareness; Note: can control some of these if we want.

• has two divisions sympathetic and parasympathetic nervous systems.

Summary

• The nervous system is a network of cells called neurons that coordinate ... It does this by extracting information from the environment using sensory receptors. ... cord and has various centers that integrate of all the information in the body.

• 6 quick questions

Multiple Choice

What would happen if your spinal cord was severed?

• You wouid not be able to move or pick up sensations in legs (and arms in some cases).

• You would not be able to breathe or digest food.

• You would become blind and unable to hear.

Multiple Choice

T or F: The main role of the somatic nervous system is to control the respiratory system, including breathing.

• True

• False

Multiple Choice

The part of the nervous system that consists of nerves that branch out from the central nervous system (CNS) and connect to other body parts is the _____________ nervous system.

• sympathetic

• parasympathetic

• autonomic

• peripheral

Multiple Choice

What are the main parts of the central nervous system?

• brain and chest

• spinal cord and spinal nerves

• brain and spinal cord

• heart and brain

Multiple Choice

The part of the nervous system that transmits impulses from the CNS to skeletal muscle is the

• somatic motor nervous system.

• autonomic nervous system.

• central nervous system.

• somatic sensory division.

Conscious vs unconscious responses

Study design - the distinction between conscious and unconscious responses by the nervous system to sensory stimuli, including the role of the spinal reflex.

Conscious responses

• Step 1 - sensory receptors register stimulus information - light, touch, temperature

• Step 2 - sensory neural messages are sent along sensory pathways of somatic NS, via the spinal cord to be integrated in the brain.

• Step 3 - brain coordinates and initiates a conscious motor response; motor neural message sent, via the spinal cord, along motor pathways of the somatic NS.

• Step 4 - the skeletal muscles receive the motor message and respond accordingly.

Unconscious responses

• Autonomic nervous system - responses like widening or constricting our pupils are not conscious; rather this is controlled by sympathetic and parasympathetic branches respectively.

• Somatic nervous system (reflexes)- responses like the shivering reflex and blinking reflex are not conscious; this unconscious response is controlled by the brain.

• Somatic nervous system (spinal reflexes)- the action of instantaneously pulling away from a hot object is not conscious and is an example of a spinal reflex which is unconscious response that does not involve the brain. See next slide for more information.

Write down 6 or more possible labels for this diagram

• write ideas one after the other with a comma in between ideas, DO NOT press enter!

Open Ended

Write down six or more possible labels for this diagram - separate ideas by a comma, DO NOT press enter until you are finished!

Reflex arc

• stimulus

• sensory receptors

• sensory neurons, sensory pathway

• inter-neurons

• spinal cord

• motor neuron, motor pathway

• effector - muscles; involuntary movement

Reflex arc

• Step 1 - Receptors detect a stimulus and creates an impulse. Sensory neurons conduct nerve impulses towards the spinal cord.

• Step 2 - Inter-neurons spinal cord connect sensory neurons to motor neurons; sensory pathway continues to take sensory information to the brain.

• Step 3 - Motor neurons conduct nerve impulses from the spinal cord to a muscle and respond to the impulses by contracting.

• 5 quick questions.

Multiple Choice

Reflex actions are important because

• they provide a quick, involuntary response.

• they prevent injury.

• they are adaptive responses, i.e. they help the organism to survive,

• All of the above.

Multiple Choice

In a spinal reflex action, the __________ initially bypasses the ___________.

• motor information;

  brain

• sensory information; brain

• sensory neuron;

  spinal cord

• motor neuron;

  spinal cord

Multiple Choice

An example of a spinal reflex action is

• touching a butterfly.

• brushing your hand against the side of your body.

• removing your hand very quickly after touching a hot stove.

• moving your legs as you walk.

Multiple Choice

Unconscious or involuntary activities are controlled by the _________ nervous system.

• somatic

• autonomic and somatic

• peripheral

• central

Multiple Choice

What sub division of the peripheral nervous system is involved with the conscious or voluntary activities of the body.

• somatic

• autonomic

• spinal cord

• central

Role of the neuron

-

Study design - the role of the neuron (dendrites, axon, myelin and axon terminals) as the primary cell involved in the reception and transmission of information across the synapse (excluding details related to signal transduction).

What is this an image of?

What is the name of the blue, yellow, green and red parts?

Multiple Choice

Blue represents __________; yellow represents __________; green represents _________ and red represents ____________. (parts must be in this order)

• myelin sheath, axon, dendrites, axon terminals

• axon, axon terminals, cell body, myelin sheath

• dendrites, axon, myelin sheath, axon terminals

• dendrites, myelin sheath, axon, axon terminals

Getting knowledge ready - how much do you know already

• 6 quick questions

Multiple Choice

The part of the neuron where action potentials travel down.

• Axon terminal button

• Myelin sheath

• Dendrite

• Axon

Multiple Choice

This part of the neuron stores, then releases, neurotransmitters into the synapse.

• axon

• dendrite

• myelin sheath

• axon terminal

Multiple Choice

The part of the neuron that insulates the axon and increases the speed of the neural message within the neuron.

• synapse

• dendrite

• myelin sheath

• axon terminal

Multiple Choice

This part of the neuron receives chemical messages from the neurotransmitters of other neurons.

• axon terminal

• dendrites

• myelin sheath

• cell body

Multiple Choice

Which is the following is represented by the letter B?

• cell body

• nucleus

• dendrites

• axon

Multiple Choice

The basic structural unit of the nervous system:

• nerve

• neuron

• brain

• spinal cord

Summary of role of parts of the neuron

• Dendrites - branch like extensions of the neuron that receive inputs from other cells; become bushier during LTP.neur

• Axon - long extension from the cell boy whose function is to transmit the neural impulse down the neuron.

• Myelin sheath - insulates axon from chemical or physical interference and increase speed of neural impulse.

• Axon terminals - at the end of the axon that send neurotransmitters to nearby cells (mostly the dendrites of other neurons) when triggered by the neural impulse that has traveled down the axon.

Role of neurotransmitters

Study design - the role of neurotransmitters in the transmission of neural information between neurons (lock-and-key process) to produce excitatory effects (as with glutamate) or inhibitory effects (as with gamma amino butyric acid [GABA])

Write down at least 5 extra words or phrases that could be used to annotate this diagram.

Think

Open Ended

Write down at least 5 extra words or phrases that could be used to annotate this diagram. Write one after the other with commas to separate - DO NOT press enter till the end!

Extra words!

• presynaptic neuron + postsynaptic

• inhibitory or excitatory neurotransmitters

• lock and key process

• neural transmission

• direction of neural impulse/action potential

• synaptic cleft/gap

• electrochemical energy

Key neurotransmitters

• Glutamate - the primary excitatory neurotransmitter found throughout the nervous system; particularly important role in learning.

• GABA - the primary inhibitory neurotransmitter; particularly important in regulating anxiety. (LINK to biological treatment of specific phobia as the class of drugs called benzodiazepine is an agonist that binds with GABA receptors and reduces anxiety)

Neural transmission (lock & key) process

• Step 1 - neurotransmitters (acting like keys) are released from the axon terminals of the presynaptic neuron into the synaptic cleft.

• Step 2 - the neurotransmitters (keys) bind to the complimentary shaped receptors (acting like a locks).

• Step 3 - if the neurotransmitter is an excitatory one (like Glutamate) the post synaptic neuron is more likely to fire and the neural impulse continues; if the neurotransmitter is an inhibitory one (like GABA) the post synaptic neuron is less likely to fire and the neural impulse may not be transmitted.

Lock and key

The lock and key model of synaptic posits that neurotransmitters only affect postsynaptic receptor sites that have the correct shape for that particular molecule, in the same way that a key has to have the shape to fit the lock.

• 6 quick questions

Multiple Choice

A chemical produced by neurons that carries messages to other neurons

• myelin sheath
• neurotransmitter
• axon
• axon terminal

Multiple Choice

Example of a neurotransmitter which is inhibitory so decreases the chance of the next neuron firing.

• nor-adrenaline

• GABA

• melatonin

• adrenaline

Multiple Choice

Type of synapse which decreases the chance of the next neuron firing.

• Inhibitory

• Excitatory

• Neurotransmitters

• Neuron

Multiple Choice

Type of synapse which increases the chance of the next neuron firing.

• Inhibitory

• Excitatory

• Neurotransmitters

• Neuron

Multiple Choice

The process by which neighbouring neurons communicate with each other.

• neurotransmitters

• synaptic transmission

• endocrine system

• nervous system

Multiple Choice

T or F: During synaptic transmission, neurotransmitters are released from syntactic ventricles.

• True

• False

Interference to neurotransmitter function

Study design - the effects of chronic changes to the functioning of the nervous system due to interference to neurotransmitter function, illustrated by the role of dopamine in Parkinson’s disease.

Interference to neurotransmitter levels and function

• can have serious consequences for nervous system functioning

• includes - neuronal loss and degeneration, structure or substance build up in the synapses between or within neurons; competition by other substances at the neurons receptor sites and neurotransmitters depleted before they get to their receptors.

• is demonstrated by Parkinson's disease.

Example - Parkinson's disease

• is a progressive neurological condition caused by interference to the neurotransmitter dopamine.

• symptoms are caused by the degeneration of dopamine releasing neurons in the substantia nigra so insufficient dopamine, required for the coordination of movement, is produced.

Symptoms

• Motor - muscle rigidity, slowness of movement, involuntary movement (resting tremors) of the hands, arms, feet, legs, head or head, difficulty balancing, and stooped posture.

• Non-motor - tiredness (fatigue), decreased sense of smell, depression, memory loss, and difficulty sleeping.

Dopamine

• is a neurotransmitter whose main role is the coordination of voluntary body movement and experience of pain and pleasure.

• is needed to control messages as they pass between neurons in the substantia nigra and striatum (responsible for balance and control of movement).

• in insufficient amounts means the neurons of the striatum fire uncontrollably which prevents a Parkinson's disease sufferer from adequately controlling their movements.

• 6 quick questions

Multiple Choice

Which of the following is not a motor symptom of Parkinson's disease?

• loss of balance

• tremor

• depression

• muscle rigidity

Multiple Choice

What interference with the nervous system leads to Parkinson's disease?

• Sensory neuron death

• Motor neurons apathy

• Decreased acetylcholine

• Loss of dopamine producing neurons

Multiple Choice

Parkinson's disease results largely from the interference to the neurotransmitter dopamine. In terms of the lock and key process, there is a/an

• reduction of required locks.

• reduction in required keys.

• over-production of required locks.

• over-production of required keys.

Multiple Choice

One cause of Parkinson's disease is the over stimulation or under stimulation of certain neurons in the brain. In terms of neurotransmitter functioning, this means that there is

• inadequate inhibition and excitation.

• too much neural reception.

• too much neural transmission.

• not enough locks for the keys.

Multiple Choice

A major motor symptom of Parkinson's disease is the lack of control of voluntary movements. In terms of nervous system functioning, this means that there is difficulty sending messages from the CNS to the

• sympathetic nervous system.

• somatic nervous system.

• autonomic nervous system.

• parasympathetic nervous system.

Multiple Choice

The two characteristic changes to neurons in Alzheimer's disease are

• Lewy bodies and neurofibrillary tangles.

• amyloid plaques and neurofibrillary tangles.

• agglutinated inclusions and amyloid plaques.

• amyloid plaques and Lewy bodies.

Multiple Choice

Alzheimer’s disease is the result of damage to the brain that affects the activity of the neurotransmitter ___________.

• dopamine

• serotonin

• adrenaline

• acetylcholine

Neural plasticity - LTP + LTD

Study design - neural plasticity and changes to connections between neurons (including long-term potentiation and long-term depression) as the fundamental mechanisms of memory formation that leads to learning.

Neural plasticity

• refers to the ability of the brain to physically change in response to experience (LINKS to learning and memory)

• involves changes to individual synapses and/or an entire neural network that serve as the basis of specific functions or memories.

• includes synaptic plasticity that refers to the ability of synaptic connections to form, strengthen (LTP involved) or weaken (LTD involved) in response to experience.

Summary

• neural plasticity is very important to memory formation and learning.

• specifically synaptic plasticity, through the process of long term potentiation (LTP) and long term depression and (LTD), helps the brain to learn and form new memories.

• 5 quick questions. Note - with the 3rd question you have to select two correct responses.

Multiple Choice

Which is most important for learning and memory?

• LTP

• LTD

• LIT

• Both LTP and LTD

Multiple Choice

Which statement about LTP is not true?

• LTP leads to increased efficiency of communication

• LTP occurs due to high frequency use

• LTP involves 2 or more neurons

• LTP removes any unused synaptic connections

Multiple Select

Which changes occur on the post-synaptic neuron when learning has taken place? Select two answers.

• Greater number of neurotransmitters produced and released

• Bushier dendrites

• Additional neurons become involved in sending neurotransmitters across the synapse

• Increased sensitivity of receptor sites on dendrites

Multiple Choice

When neural connections are repeatedly used and co-activated then it is likely they will

• strengthen.

• weaken.

• be pruned.

• disappear.

Multiple Choice

Your brain has the ability to change in response to

experience. This ability is known as

• neural flexibility.

• plasticity.

• responsiveness.

• reactivity.

Neurotransmitters and neurohormones

Study design - the role of neurotransmitters and neurohormones in the neural basis of memory and learning (including the role of glutamate in synaptic plasticity and the role of adrenaline in the consolidation of emotionally arousing experiences).

Summary

• Neurotransmitter - chemical substance that carries information between neurons. e.g. Glutamate as an excitatory neurotransmitter plays an essential role in LTP during learning and consolidation of memories.

• Neurohorme - chemical substance sent from neurons into the bloodstream. e.g. Adrenaline as a neurohormone is released in times of emotional arousal and stress and heightens the physiological reactions and consolidating associated memories.

• 5 quick questions (Last ones)

Multiple Choice

Adrenaline can induce the release of ____________ in the ________ during heightened emotional arousal which may signal to the ______________ the details are important and long term memory storage should be strengthened.

• noradrenaline; amygdala; hippocampus

• noradrenaline; hippocampus; amygdala

• glutamate; amygdala; hippocampus

• dopamine; hippocampus; amygdala

Multiple Choice

Which part of the brain has a critical role in consolidation of most of our memories?

• hippocampus

• cerebral cortex

• spinal cord

• cerebellum

Multiple Choice

During chemical communication within the brain, neurohormones and neurotransmitters are both secreted from

• the hypothalamus.

• the pituitary gland.

• synapses.

• axon terminals.

Multiple Choice

Neurohormones

• are manufactured during synaptic plasticity.

• are manufactured by the endocrine system.

• communicate messages to dendrites.

• communicate messages slower than neurotransmitters.

Multiple Choice

What is a neurotransmitter?

• fatty covering of the axon

• chemical messenger sent from neurons into the blood stream

• chemical messenger that carriers information between neurons

• gap between neurons that chemicals are released into

Well done.

Use this information to revise and study this area and fill in the A3 summary sheets for Unit 3 AOS 1 and some of Unit 3 AOS 2.