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Rediscovering Biology: Molecular to Global Perspectives
Neurobiology
A neuron’s electrical activity results in the release of neurotransmitters that account for everything from survival to addiction to learning and memory. This unit explains the basic electrical workings of the neuron and touches on each of these functions, and explores the recent technological advances that allow scientists to study them.
ONLINE TEXTBOOK
The online textbook chapters support and extend the content of each video. The Web version can be viewed as a full chapter or as individual sub-sections, and includes links to glossary terms and other related material.
ANIMATIONS & IMAGES
Explore the archive of animations, images and figures from the videos and online textbook. All of the images can be viewed online or downloaded as jpg files.
EXPERT INTERVIEW TRANSCRIPTS
Read profiles of the expert scientists featured in the video and find the complete transcripts of the interviews conducted for this unit.
Wolfhard Almers, Ph.D.
Fred Gage, Ph.D.
Richard Huganir, Ph.D.
John Williams, Ph.D.
Chapter Contents
Introduction
The Neuron as a Battery
Voltage-Gated Channels
The Action Potential
Myelin Speeds up Thought
Across the Synapse
Neurotransmitters and Receptors
Neurotransmitters, Psychoactive Drugs, and the Reward Pathway
The Molecular Basis of Learning and Memory
Memory and Hippocampus
Neuronal Stem Cells
Unit Glossary
Action potential
A nerve impulse; a traveling wave of positive voltage that is propagated along a neuron.
Depolarization
An excitatory state that occurs when the voltage difference across the mebrane in part of a neuron becomes less negative; required to begin an action potential.
Exocytosis
The release of neurotransmitters from their vesicles into the synapse.
Hippocampus
A region of the brain associated with both short-term and long-term memory formation. Also the site of long-term potentiation (LTP).
Hyperpolarization
A state that occurs at the end of an action potential in which the neuron has a more negative voltage than the resting potential.
A state that occurs at the end of an action potential in which the neuron has a more negative voltage than the resting potential.
Ionotropic receptors
Receptors in which activation of the neuron is directly coupled with the neurotransmitter binding to the receptor.
Long-term potentiation
The phenomenon in which a neuron becomes more sensitive to stimuli after receiving synchronized stimuli.
The phenomenon in which a neuron becomes more sensitive to stimuli after receiving synchronized stimuli.
Membrane potential
The difference in voltage between that inside the cell and its surroundings.
Neurogenesis
The formation of New neurons from precursor stem cells.
The formation of New neurons from precursor stem cells.
Neurotransmitter
A molecule that travels across the synapse and, by binding to the receptor on the postsynaptic neuron, influences its probability of firing.
A molecule that travels across the synapse and, by binding to the receptor on the postsynaptic neuron, influences its probability of firing.
Postsynaptic neuron
The receiving neuron in a synapse; formed by a neuron’s dendrite.
The receiving neuron in a synapse; formed by a neuron’s dendrite.
Presynaptic neuron
The transmitting neuron. Its synaptic terminals extend into synapses.
The transmitting neuron. Its synaptic terminals extend into synapses.
Resting potential
The membrane potential of a neuron when it is not firing.
The membrane potential of a neuron when it is not firing.
Reuptake
The recapture of neurotransmitters in the synapse by the presynaptic neuron.
The recapture of neurotransmitters in the synapse by the presynaptic neuron.
Reward pathway
A region of the brain that is stimulated when an animal is engaged in pleasurable activities.
A region of the brain that is stimulated when an animal is engaged in pleasurable activities.
Synapse
A functional connection between two neurons where information can be exchanged.
Voltage-gated channels
Ion channels on the cell membrane that will open or close depending upon the voltage.
Ion channels on the cell membrane that will open or close depending upon the voltage.
Unit Animations
- Increased Receptor Sensitivity
In LTP, it is now known that the postsynaptic neuron becomes more sensitive to neurotransmitter in a variety of ways. One way is that phophorylation of the glutamate receptor causes it to pass more excitatory ions upon subsequent stimulation.
View Quicktime Movie
- Long-Term Potentiation
In LTP, neurons continue to fire at an elevated rate, even though the stimulus has returned to normal.
View Quicktime Movie
- LTP Mechanisms
The two main hypotheses to explain LTP are presynaptic, in which increased neurotransmitter is released; and postsynaptic, in which sensitivity to neurotransmitter is somehow increased.
View Quicktime Movie
- Neuronal Stem Cells
Fred Gage has found that new neurons are formed in two areas of the brain: the hippocampus (shown in yellow) and in the subventricular zone (in light blue).
View Animation Still - Reward Pathway
The main structures that make up the reward pathway are the ventral tegmental area, the nucleus accumbens (both shown in purple), the amygdala (in green), and the prefrontal cortex (in grey).
View Animation Still - Synapse
Neurons have two ends — dendrites and an axon — which they use to communicate with one another via neurotransmitters.
View Quicktime Movie
- Synaptic Vesicles
Synaptic vesicles fuse with the presynaptic membrane, freeing neurotransmitter molecules into the synaptic space.
View Quicktime Movie
Related Resources
Books
Calvin, W. H. and G. A. Ojemann. 1994. Conversations with Neil’s brain: The neural nature of thought and language. Perseus Publishing.
Building from case examples, a neurobiologist and a neurosurgeon describe the workings of the brain.
Drickamer, L. C., S. H. Vessy, and E. M. Jakob. 2002. Animal behavior: Mechanisms, ecology, and evolution. 5th ed. McGraw Hill.
A university-level textbook on animal behavior that has an excellent section on the neurobiology of behavior.
Timmons, C. R. and L. W. Hamilton. Drugs, brains & behavior. www.rci.rutgers.edu/~lwh/drugs/.
A short e-book detailing the neuropharmalogical effects of drugs.
Article
Sullivan, J. M., 2002. Cannabinoid receptors. Curr. Biol. 12:R681.
A short guide to recent research on cannabinoids and their receptors.
