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Psychology 127: Lecture 2 Principles of Neuroscience:

Psychology 127: Lecture 2 Principles of Neuroscience:. Announcements: 1. Sections are being held this week. Prepare Reader #1 2. Powerpoint slides are posted daily in advance. 3. Lectures are podcast.

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Psychology 127: Lecture 2 Principles of Neuroscience:

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  1. Psychology 127: Lecture 2 Principles of Neuroscience:

  2. Announcements: 1. Sections are being held this week. Prepare Reader #1 2. Powerpoint slides are posted daily in advance. 3. Lectures are podcast. http://webcast.berkeley.edu/course_details_new.php?seriesid=2008-D-16072|2008-D-74381&semesterid=2008-D 3. Adds via on-line system. QUESTIONS, QUESTIONS, QUESTIONS

  3. Neuron: Cell of the Nervous System Main Components Soma: Cell body Axon: Transmitting process Dendrite: Receiving process Synapse: Gap between neurons; Transmission occurs over synapse

  4. Physiology: Resting potential: -70 mV (millivolts) Due to negatively charged ions and blockage of positively charged sodium (NA). Gradual changes: depolarization: excitatory hyperpolarization: inhibitory Action potential: Massive inflow of sodium to +50 mV

  5. Synaptic Transmission Action potential: Calcium-gated channels open in axon terminal. Transmitter-containing vesicles bind to presynaptic membrane and release transmitter into synapse. Membrane potential of postsynaptic terminal is changed by binding of transmitter at receptors. Change can be excitatory (EPSP) or inhibitory (IPSP)

  6. Propagation of neural signaling: Postsynaptic changes from dendrites passively spread intracellularly. If sum of EPSPs reaches threshold, then action potential is generated, repeating process. Green dots: axon terminals Red processes: dendrites

  7. Neurotransmitters Over 100 different neurotransmitters. Neurons contain a single type of transmitter (chemical contained in presynaptic vesicles). Examples: glutumate, GABA, dopamine, serotonin Receptors vary in terms of transmitter affinity. Single neuron may have multiple receptor types. Midbrain and brainstem soma of two transmitters with wide distribution.

  8. Many other cells in the brain: blood vessels glia cells Involved in metabolic functions, repair and protection of neurons, improve conduction of signals. Oligodendrocytes form myelin around central axons Schwann cells form myelin around peripheral axons Astrocytes form blood brain barrier.

  9. Functional contribution of glia to neural signaling just beginning to be studied. Astrocytes, by creating blood-brain barrier can modulate neural activity. Two-photon calcium imaging in vivo in ferret occipital lobe. ∆F/F: Measure of increase in activity Astrocyte activity closely linked (with delay) to neural activity: Regulating delivery of oxygen, other substances over barrier.

  10. Functional contribution of glia to neural signaling just beginning to be studied. Astrocytes, by creating blood-brain barrier can modulate neural activity. Astrocyte activity closely linked (with delay) to neural activity: Regulating delivery of oxygen, other substances over barrier. Chemical applied to selectively shut down astrocyte (dose-dependent)

  11. Functional contribution of glia to neural signaling just beginning to be studied. Astrocytes, by creating blood-brain barrier can modulate neural activity. Astrocyte activity closely linked (with delay) to neural activity: Regulating delivery of oxygen, other substances over barrier. Chemical applied to selectively shut down astrocyte (dose-dependent) When astrocyte is shut down, neuron response is increased.

  12. General principles of neural organization • 1. Large number of neurons • >11 billion in cerebral cortex (neocortex) • Many more in subcortex • -- another 10 billion in cerebellum

  13. Many different types of neurons

  14. General principles of neural organization • 1. Large number of neurons • 2. Extensive interconnectivity • Cortical neurons make 1,000 – 5,000 synapses • No 1:1 connection • Each neuron is only few synapses away from other neurons. • Each neuron makes small contribution to overall function.

  15. General principles of neural organization • 1. Large number of neurons • 2. Extensive interconnectivity • Cortical neurons make 1,000 – 5,000 synapses • Subcortical neurons can make many more: • e.g., cerebellar Purkinje cells make • 200,000 synapses

  16. General principles of neural organization • 1. Large number of neurons • 2. Extensive interconnectivity • 3. Parallelism • Connections are many to many. • Observed at all levels: • molecular, cellular, system

  17. General principles of neural organization • 1. Large number of neurons • 2. Extensive interconnectivity • 3. Parallelism • Connections are many to many. • Observed at all levels: molecular, cellular, system • 4. Plasticity (learning) • Occurs in both “hardware” and “software”

  18. Visualizing development of new dendritic spines via injection of fluorescent dye A: Immediate B: 24 hours C: 48 hours

  19. Pruning and maturation of dendritic arbor in retina of the cat. Between-animal comparison of development.

  20. Visualizing changes in dendrite structure in monkey: Within-animal comparison in adult. Deletions and additions of spines over 1-week period. Label neurons and take high-powered photos of exposed cortex at different time points.

  21. Visualizing changes in dendrite structure in monkey: Within-animal comparison in adult. Deletions and additions of spines over 1-week period. Reader article this week! Label neurons and take high-powered photos of exposed cortex at different time points.

  22. Maturation via Pruning in Human Brain over 15 years Red: Relatively high amount of neurons (gray matter). Blue: Relatively low amount of neurons.

  23. Neurogenesis Classic View: No neurogenesis in mature mammalian brain. 1920’s (Cajal): Little evidence of mitotic division in mammalian brain and no transient (developing) forms of neurons found in histological analysis. 1960’s: New techniques developed to show dividing cells (stains absorbed into DNA). Evidence suggested that neurogenesis was absent in adult mammals.

  24. Neurogenesis Challenges to the Classic View Clear evidence of adult neurogenesis in many species including insects, fish, and birds. Seasonal changes in song birds.

  25. Neurogenesis Challenges to the Classic View Clear evidence of adult neurogenesis in many species including insects, fish, and birds. New labeling techniques show neurogenesis in some regions of mammalian brains. Hippocampus and olfactory bulb.

  26. Neurogenesis Rat hippocampal tissue labeled with retrovirus, GFP+ that expresses green fluorescent protein throughout newly dividing cell. • 2 days post-injection

  27. Neurogenesis Rat hippocampal tissue labeled with retrovirus, GFP+ that expresses green fluorescent protein throughout newly dividing cell. Interpretation issue?? • 2 days post-injection

  28. Neurogenesis Rat hippocampal tissue labeled with retrovirus, GFP+ that expresses green fluorescent protein throughout newly dividing cell. • 2 days post-injection 30 days post-injection

  29. Red: Neurons Green: BrdU Neurogenesis in human hippocampus Cancer patients given injection of DNA-active tracer, BrdU, to monitor tumor growth. BrdU will be visible only in the soma of new cells (green). Post-mortem analysis revealed that tracer was present in hippocampal neurons.

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