Back to Unit Page Unit Textbook Chapter Animations & Images Expert Interview Transcripts Unit Glossary Related Resources View Text Only List 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 Ê dendrites and an axon Ê 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 Images Action potential movement through an axon A cross-section of an axon, with an action potential (AP) moving from left to right. The AP has not yet reached point 4; the membrane there is still at rest. At point 3, positive sodium ions are moving in from the adjacent region, depolarizing the region; the sodium channels are about to open. Point 2 is at the peak of the AP; the sodium channels are open and ions are flowing into the axon. The AP has passed by point 1; the sodium channels are inactivated, and the membrane is hyperpolarized. AMPA receptor figure Pictured are many of the molecules that are known to interact with AMPA receptors and play some role in long-term potentiation. Arcuate nucleus neurons Neurons of the arcuate nucleus Chemical structures of dopamine-like drugs The chemical structures of dopamine, Ritalin, and cocaine are structurally similar: they all bind at the dopamine transporter, affecting reuptake of dopamine. Cocaine PET scan PET scans of a cocaine user's brain Confocal neuron A reconstruction of a neuron in a brain slice using confocal microscopy Cortex neurons Cortical neurons stained in a slice Docked 1 vesicle Docked vesicles at axons, showing "post-synaptic density" Dopamine transporter Left: Dopamine in the synaptic space binds to dopamine receptors on the post-synaptic cell. Dopamine transporters in the presynaptic membrane take up the dopamine molecules from the synaptic cleft and return them to the presynaptic cell. Cocaine blocks the reuptake of dopamine, leading to molecular changes that contribute to addiction. Dorsal ganglia cells Sensory neurons of the dorsal root ganglia Hippocampal neuron Double-labeled hippocampal neuron stained with yellow and red fluorescence Hippocampal neurons Two hippocampal neurons labeled with green fluorescent protein, viewed with confocal microscopy. Such neurons release and sense glutamate, and engage in long-term potentiation (LTP). Note the synaptic connections between the lateral processes of the two neurons. Light field of neurons and under fluorescence Neurons under light field and fluorescence microscopy Locu Ceruleus neuron Green fluorescent protein labeled neurons in a brain slice of the Locu Ceruleus MAP2NF neuron photo Light microscopy image of branching neurons with many processes Methamphetamine PET scan PET brain scans of a methamphetamine user and a control subject Molecules of LTP 2 A schematic figure of the many molecules thought to be involved in long-term potentiation (LTP) MRI of brain A colored magnetic resonance image (MRI) of a human adult brain MRI of brain, side profile Multiple labeled neurons Multiple labeled neurons in confocal microscopy Neuron Green fluorescent protein stains a hippocampal neuron. Neuron A neuron branching to many processes Neuron The parts of the neuron: information is received by dendrites, and action potentials are sent out from the cell body down the axon to the synaptic terminals. Neuron AMPA receptor AMPA receptors stained with green fluorescent protein Neuron CamKII Calcium-calmodulin kinase II (CamKII), an enzyme involved in long-term potentiation, is stained with green fluorescent protein on this hippocampal neuron. Neuron labeled in vivo Confocal microscopy of a multiple fluorescent-labeled neuron Neurons Neurons with multiple labeling Neurons in culture Many neurons growing on a grid surface in culture New adult neuron formed in brain Confocal microscopy reconstruction shows a newly formed adult neuron. Pons neurons Neurons of the pons Synapse Synaptic vesicles fuse with the presynaptic membrane to release neurotransmitter into the synaptic space. Here, they bind with neurotransmitter receptors in the postsynaptic membrane.

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