1 Basics of Neuroscience & Neural Engineering

Welcome to Day One of the virtual YSP-REACH program! Today you will explore the basics of neuroscience and neural engineering.  We will start by describing the structure and function of the nervous system and follow with an overview of neural engineering.  There are readings, videos, quizzes, and a fun activity that should help you understand these topics.  During the Day One lecture, neuroscientist Dr. Eric Chudler (CNT Executive Director & Education Director; Research Associate Professor, UW Department of Bioengineering) will take you on a journey into the brain.

 

Part 1: The Nervous System

The is designed to receive information from our senses, process this information, and  send signals to muscles, glands, and organs to respond to the information.  This organization ensures the survival of an organism.  The nervous system is made up of the and (the ) and the nerves of the body (the ). You can think of the nervous system as the master control center that is responsible for perception, emotions, movement, thinking, and planning solving.  It is even responsible for functions that do not need conscious thought such as respiration and control of heart rate.

Cell of the Nervous System

There are two types of cells in the nervous system: (nerve cells) and (glial cells).  Neurons are specialized cells that send messages to other neurons, muscles and organs.  Glial cells, such as those that produce insulation, help support neurons. The human brain contains approximately 86 billion neurons and at least the same number of glial cells.  Although glial cells are essential for the proper function of neurons, we will concentrate our discussion on neurons.

A neuron has four basic parts:

  • Extensions that receive information from other neurons.
  • : Area that contains genetic material of the neuron , including the nucleus of the cell, and integrates signals received from dendrites.
  • :  Single extension that takes information away from the cell body.
  • : End of the axon where one neuron can communicate with another neuron or cell.

 

NeurotransmissionLabelled drawing of a synapse.

Communication of information between neurons is accomplished by movement of chemicals across a small gap called the . Chemicals, called , are released from one neuron at the axon terminal. Molecules of neurotransmitter then cross a small gap where they may attach to the next neuron at a specialized site called a receptor. The action that follows activation of a receptor site may be either a depolarization (an excitatory postsynaptic potential) or a hyperpolarization (an inhibitory postsynaptic potential). A depolarization makes it more likely that an action potential will fire; a hyperpolarization makes it less likely that an action potential will fire.

 

Reflect on What You Learned

Check your understanding with a quick quiz.

 

Watch This!

Watch how neurotransmission is modeled (using both electrical and chemical signals) in this video.

 

Action Potentials

When a neuron is not sending a signal, it is “at rest.” When a neuron is at rest, the inside of the neuron has a  negative electrical voltage relative to the outside of the neuron. The inside of a neuron is about -70 mV relative to the outside of the neuron. This potential difference is set up by different concentrations of sodium, potassium, and chloride ions and negatively charged protein molecules inside and outside of a neuron. An occurs when a neuron sends information down an axon, away from the cell body. Action potentials are electrical signals caused when different ions cross the neuron membrane. A depolarizing stimulus first causes sodium channels in the membrane of a neuron to open. Because there are many more sodium ions on the outside, and the inside of the neuron is negative relative to the outside, sodium ions rush into the neuron. Sodium has a positive charge, so the neuron becomes more positive (depolarized). It takes longer for potassium channels to open. When they do open, potassium rushes out of the cell, reversing the depolarization. Also at about this time, sodium channels start to close. This causes the action potential to go back toward -70 mV (a repolarization). The action potential actually goes past -70 mV (a hyperpolarization) because the potassium channels stay open a bit too long. Gradually, the ion concentrations go back to resting levels and the cell returns to -70 mV.

The action potential will travel all the way to the axon terminal where neurotransmitters will be released and the message can continue to the next neuron.

 

Try It!

Build a model neuron with things you can find around the house.  The examples below show neurons made from playdough, pipe cleaners, and candy. Get creative!

Then, take a photo of your model neuron and post it to this Neuron Model Padlet. See what other VRP participants have posted as well. You can “favorite” the ones you really like.

Then, hit the “back” arrow on your web browser to return to this chapter and keep reading.

Sample Neuron Models
playdough neuron
Playdough Neuron
Candy neuron
Candy Neuron

 

Pipe Cleaner Neuron
Pipe Cleaner Neuron

 

 

 

 

 

 

The Brain

The adult human brain weighs about three pounds (1.4 kg) and contains about 86 billion neurons and trillions of synapses. The brain can be divided down the middle into two halves called the . Each cerebral hemisphere is divided into four lobes by (fissures) and (bumps) that can be seen on the surface of the brain.

 

  • : Concerned with reasoning, planning, speech production, movement (motor cortex), emotions, and problem-solving.
  • : Concerned with perception of stimuli such as touch, pressure, temperature and pain.
  • : Concerned with perception and recognition of auditory stimuli (hearing), memory (hippocampus) and language comprehension.
  • : Concerned with vision.
Middle view of brain

 

Located below the temporal and occipital lobes is the . The cerebellum helps with movement, balance and posture. The connects the brain to the spinal cord and is responsible for the control of breathing, heart rate, and blood pressure. The brain stem contains structures including the medulla, pons, tectum, reticular formation, and tegmentum. Near the center of the brain is the . The thalamus help direct sensory and motor information to and from the spinal cord and . As the name implies, the is located below the thalamus and is responsible for regulating many bodily functions such as  body temperature,  hunger, thirst, and biological rhythms.

Optional Resources for Further Learning

Resources:

 

Part 2: Neural Engineering

Hetling et al. (J. Neural Eng., 5:360-361, 2008) provide a good definition of neural engineering:

“The  discipline  of  neural  engineering  uses  engineering approaches to understand, repair, replace, enhance, or exploit the  properties  of  neural  systems,   often  accompanied  by scientific  research  directed  at  the  interface  between  living neural systems and non-living components.”

 

(or neuroengineering) brings together the expertise of people in the fields of engineering, neuroscience and medicine to study the nervous system. Neural engineering has the potential to discover treatments, therapies, and cures for neurological disorders such as stroke, spinal cord injury, Parkinson’s disease, and epilepsy. Some neural engineers are interested in enhancing neural function by improving memory, attention, or sensory abilities. The Center for ElectrodeNeurotechnology (CNT) is interested in developing neural devices and methods to direct engineered in the brain and spinal cord. Engineered neuroplasticity uses devices to restore lost or injured connections in the brain, spinal cord, and other areas of the nervous system. The CNT hopes that the research performed by its students, faculty, and staff will improve sensory and motor function for people with spinal cord injury, stroke, and other neurological disorders. Neural engineering research also raises many ethical issues about new technologies that interact with the nervous system. are a system of moral principles, rules, or standards that govern thinking, decision making, and behavior, in particular for how humans think and act in regards to others. These issues are part of the field of include questions of privacy, security, moral, and legal responsibility, changes in our understanding of agency (the capacity of individuals to act independently and make their own free choices), shifts in personal identity, and social justice.

 

Preview of the Week

As we move through this week, we will explore several neural engineering topics including:

  • Brain-Computer Interfaces (BCI)
  • Brain and Spinal Cord Stimulation
  • Neuroethics
  • Neural Engineering/Science College and Career Pathways

 

Be sure to join tomorrow’s virtual presentation featuring Dr. Rajesh Rao, who will be sharing his research about brain-computer interfaces.

Optional Resources for Further Learning

Resources

Citations:

  • Synapse image:  National Institute of Mental Health, National Institutes of Health
  • Action potential image; neuron model images:  Neuroscience for Kids
  • Lobes of the brain image:  University of Wisconsin
  • Electrode image:  Kassegne Lab/San Diego State University

License

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Virtual REACH Program 2020 by Center for Neurotechnology, University of Washington is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License, except where otherwise noted.

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