Say to yourself and quickly what color you

Say to yourself (and quickly) what color you SEE in each word, NOT the word itself

This is called the Stroop Test. This test is used in neuropsychological evaluations to identify signs of developing Alzheimer's, dementia, and other cognitive impairments.

Numeric Memory Test • A. 3932

• B. 54923

• C. 439292

• D. 4812944

• E. 83231397

• F. 756391123

• G. 6732089420

• H. 43954973248

• I. 297562159364

Numeric Memory Test 1. What helped you or others remember larger numbers? 1. What does this tell you about how your memory works in your brain? 1. Is memory the same thing as learning?

How do we think and learn? The Nervous System (Topic 6. 5)

What is learning? • How does it occur in the brain? • Does your brain change when you learn? If so, how?

Neuroplasticity Video After the video be able to answer: • What is neuroplasticity? • https: //www. youtube. com/watch? v=i. Azmy. B 9 P Ft 4

Learning: Neuroplasticity • New experiences result in neurons (brain cells) connecting with each other • Repetition of the experience or information causes the pathway to strengthen • When pathways are not used, they are pruned (cut)

Neural Growth

Neural Pruning • What is neural pruning? • Between what ages does neural pruning occur? • Why do you think neurons are pruned during this period?

Parts of the Nervous System: 1) Central (CNS) 2) Peripheral (PNS) • Nervous System Composed of – Brain – Spinal Chord – Nerves Brain Spinal Chord Nerves

Spinal Cord – nerve pathways to and from brain

Nerves – pathways of neurons to and from brain

Label the Parts of Neuron Cell Structure

How do nerves send signals? • Nerves send signals through the individual neurons that make up each nerve. • Signal goes from the dendrite to the axon (label the direction with an arrow)

3 Functional Categories of Neurons: Interneuron (Relay or Bipolar), Motor, Sensory

Motor Neurons • Send information from the brain to a muscle to produce an action. • Also called efferent neurons

Sensory Neurons • Receive input from the “outside” → • To spinal cord → • To brain stem → • To area in brain which processes the information • “Sense” is perceived • Also called afferent neurons

Interneurons • Interneurons transmit information between sensory and motor neurons • Have two “poles” for receiving and sending signals

(interneurons)

Reflex Arc Animation • http: //www. sumanasinc. com/webcontent/ani mations/content/reflexarcs. html

Warm Up 11/30: 1) Draw a brief diagram of a neuron and label the following: axon, dendrite, Schwan cell, nodes of Ranvier, myelin sheath, axon terminal, cell/soma body, nucleus, cytoplasm. 1) In what direction does a signal travel through a neuron? 1) Draw a brief flow chart that shows the pathway of nerve communication when you accidentally touch something too hot (i. e. the reflex arc pathway). Make sure to include the following terms: relay neuron, spinal cord, motor nerve, sensory nerve, effector, interneuron. 1) Describe or draw the process of exocytosis.

• Hand touches fire → sensory input from heat of fire to sensory nerve → to spinal cord →to area in brain which processes info → sense is perceived → signal sent from brain → to spinal cord → to motor nerves → effector →muscles contract

How do neurons (and nerves) communicate? • A) Chemical signals → neurotransmitters & synaptic transmission • B) Electrical signals → action potential

How do neurons send signals to each other? The Synapse • Synapse = point of connection between two neurons • Molecules called neurotransmitters are used to send chemical signals between neurons • Neurotransmitters are released from synaptic vesicles • The synaptic cleft is a space between the axon of cell 1 and the dendrite of cell 2. CELL 1 CELL 2

What is synaptic transmission? • Signals are sent from the axon terminal of one neuron (presynaptic cell) to the dendrite of a neighboring neuron (postsynaptic cell) by sending neurotransmitters across the synapse • Neurotransmitters bind to receptor proteins on the postsynaptic cell, which initiates transmission of signal

• Neurotransmitters only fit into specific receptor proteins on a postsynaptic cell. • Once the signal is sent, neurotransmitters are reabsorbed by cell 1 to be used later.

Check in: • How does the axon send signals? • How does the synapse send signals?

Check in: • How is a signal sent down one neuron? An electrical action potential • How does one neuron send signals to another neuron? Chemical neurotransmitters

Animation: How and when does an signal stop? • http: //learn. genetics. utah. edu/content/neuroscien ce/crossingdivide/ • Some neurotransmitters are “stop signal” ; binding to receptors stops transmission to the next cell • The threshold for transmission is not reached because not enough neurotransmitters are crossing the synapse, and attaching to receptors.

What causes vesicles to release neurotransmitters? • The axon terminal also contains voltage-gated Ca 2+ channels. • “Voltage-gated” means that they respond to changes in voltage by changing shape.

Steps to Synaptic Transmission 7) Neurotransmitters are reabsorbed into the presynaptic cell

7. Neurotransmitters are released from receptors and get reabsorbed back into presynaptic cell.

Summary of Action Potential & Synaptic Transmission

How do psychoactive drugs act in the brain?

Caffeine

Look at the picture carefully. Serotonin is a neurotransmitter. The nerve pathways in your brain that it is found in are related to feeling good. Why might Prozac work to reduce depression?

• Dopamine is another neurotransmitter. It is in pathways that are responsible for euphoria. Using the diagram, explain why cocaine causes feelings of euphoria.

What is an action potential? How does this electrical signal travel from the dendrite to the axon terminal within a single neuron?

What is the role of ions in neuron communication? • Movement of a signal through a neuron depends on the movement of Na+ and K+ ions in and out of the cell • The movement of ions results in a difference in charge within the neuron

What is an action potential? • An action potential is the movement of an electrical signal through a neuron • The movement of an action potential down a neuron is caused by the moving exchange of sodium (Na+) and potassium (K+) ions moving in and out of the cell. • The movement of an action potential through a neuron consists of 2 main stages : depolarization and repolarization.

What is the state of a neuron when a signal is not being sent? Positive Outside, Negative Inside • This state is called Resting Potential

Depolarization happens over and over again until it the action potential reaches the end of the axon.

How does each segment of the neuron go back to “resting potential”? • Once the action potential passes, Na+ channels close, and K+ channels open. • K+ slowly moves out of the cell to restore the negative charge inside of the neuron. • Movement of Na+ out, and K+ in causes section of axon to revert back to resting potential (negative inside, positive outside).

Steps of Action Potential Moving Down a Neuron 1) The axon membrane is at a resting potential of 70 m. V, and then rises to the threshold potential of 50 m. V, either due to a stimulus, or the binding of a neurotransmitter at a synapse. 2) Them membrane depolarizes due to voltage-gated Na+ channels opening and Na+ rapidly moving in. 3) The membrane repolarizes due to voltage-gated K+ channels opening and K+ slowly moving out. 4) The membrane returns to the resting potential due to the eventual movement of Na+ back out, and K+ back into the cell.

Reference Site: • http: //webspace. ship. edu/cgboer/actionpot. h tml

Membrane Potential & 4 Stages of Moving Nerve Impulse

Nerve Impulse (Action Potential) Animation • http: //highered. mheducation. com/sites/0072 495855/student_view 0/chapter 14/animation __the_nerve_impulse. html

How does synaptic transmission propagate the action potential for the next neuron? • Binding of the neurotransmitters to receptors on the postsynaptic neuron causes Na+ gates to open, allowing Na+ to enter the cell and depolarize.

How does propagation differ between myelinated and non-myelinated neurons?

Myelinated vs Non-myelinated Neurons Giuliodori M J , and Di. Carlo S E Advan in Physiology Edu 2004; 28: 80 -81 © 2004 by American Physiological Society

How does a nerve impulse travel faster down myelinated vs. non-myelinated neurons? SALTATORY CONDUCTION

How fast is Saltatory Conduction? • The speed of nerve impulses varies enormously in different types of neuron. The fastest travel at about 250 mph, faster than a Formula 1 racing car. • For the impulse to travel quickly, the axon needs to be thick and well insulated. This uses a lot of space and energy, however, and is found only in neurons that need to transfer information urgently. For example, if you burn your fingers it is important that your brain gets the message to withdraw your hand very quickly.