Lecture 1 Philosophical antecedents Ramon y Cajal and the Neuron Doctrine Structure of the Neuron Structure and the functions of glial cells Plasma membrane o What Cajal said about the neuron still holds true he was genius The Neuron Doctrine 1 The Mind Body problem a How do physiological processes bring about human behavior and insoluble consciousness i Material basis matter energy etc of thought and will personal subjective ii Nervous system was machine for behavior but also for decision making motivation will desire etc 1 Nervous system is a decision making system and the neurons are not just structural entities but they are the machines that make the decisions Mind Body Dualism idea that the soul or mind was distinct from b Descarte s the body i Renee Descartes proposed that mind and body were separate and ii There is no evidence however that the pineal or any other structure acts interacts via the pineal body as the seat of the soul c Modern Interpretations i Psychophysical parallelism holds that physiological and mental events occur in parallel but do not cause on another ii Epiphenomenalism action of the brain 1 Binding problem but according to epiphenomenalism it is not a holds that consciousness is only a byproduct of the problem 2 Cajal and the Neuron Doctrine a The Spanish neurohistologist Santiago Ramo y Cajal sparked a revolution with his studies i He was able to identify important properties of neural circuits ii He showed that neurons were the structural and functional entities of the nervous system iii To know the brain the same thing as knowing the material course of thought and will the same thing as discovering the intimate history of life in its perpetual duel with eternal forces a history summarized and literally engraved in the defensive nervous coordination of the reflex the instinct and the association of ideas 1 Idea that natural selection made the brain 2 Reflex automatic simple 3 Instinct higher level and more coordinated 1 4 Association of ideas knowledge is essentially associating an idea ex it is a tiger because of features tigers have teeth can be dangerous if attack you etc b Neural Determinism i Neurons ii Behavior iii The organization of the nervous system reflects natural selection iv Implications are the structural and functional entities of the nervous system and consciousness result from the action of neurons 1 Selection favors behaviors which are adaptive fostering reproduction success 2 Adaptive behaviors result form species specific brain circuits which foster survival and reproduction a How do brain circuits help you survive and how do they enable you appropriately behave in an environment The Structure and Function of Neurons 1 The Neuron a Neurons are the principal cells of the nervous system i Nucleus 1 DNA is contained in the nucleus 1 Produces ribosomes iii Endoplasmic Reticulum 1 Protein synthesis an interesting shape 1 Neurites are the dendrites and axons extending from the soma or cell reason why soma cell body has occurs on the ER ii The nucleolus iv Neurites body 2 Dendrites a Branch close to the soma in a tree like fashion and typically receive inputs from other neurons 3 Axons a May branch sometimes extend long distances from the soma and convey messages to other neurons muscles or glands i Often terminate in the brain close to eh soma or dendrites of other neurons but make synapses with muscles and glands b Not all neurons have axons most cells in the retina do not have axons i But if you have an axon it doesn t branch in a tree like fashion c What makes it unique is the axon terminal bouton 2 Glial Cells support cells a Most of the cells of the nervous system are NOT neurons about 80 of the cells of the nervous system are the glial cells which play a supportive role in the nervous system 2 i A lot smaller than neurons so they do not take up a lot of space like neurons do i Astrocytes b Two kinds 1 Control the passage of substances from blood vessels to neurons and remove debris can stimulate divide and engulf dead tissue a Endothelial cells line the blood vessels ii Myelin Sheath 2 Make up blood brain barrier 1 Myelin sheath producing cells 2 Oligodendrocytes cells form a fatty sheath around axons which speeds message transmission system and Schwann cells do this in the peripheral nervous system a Oligodendrocytes CNS b Schwann cell PNS do this in the central nervous 3 One theory Myelination may vary somewhat and have something to do with general intelligence explain why not many people have remarkably high IQ s 3 The Plasma Membrane a The plasma membrane of the cell is a compartmentalizes each part of the cell phospholipids bilayer i The outer portions consist of phosphate groups 1 Pointing towards extracellular side of the membrane 2 Hydrophilic ii The inner portions consist of lipids fatty acid derived from glycerol 1 Hydrophobic 2 Pointing towards intracellular side of the membrane basis of bioelectricity b Ions i Can get through membrane but cannot go directly through plasma Na potassium K and Chloride Cl ions are most important membrane ii Ions are charged atoms iii Sodium for neural signaling 1 Sodium outside 2 Potassium inside 3 Chloride outside iv The flow of ions across the membrane is the basis for the coding of information by neurons 1 Not just neurons but also muscle fibers how the ions get through membranes v Ion Channels 3 1 Specialized proteins in the membrane acts as pores or channels for ions such as sodium highly specific can accept and reject ions 2 Selectivity of Ion Channels a Ions channels are selective for each type of ions based on the size b Positively charge and waters of hydration of the ions on the ion channel can attract or repel ions or negatively charged sites c Potassium ions are larger than sodium ions but sodium ions are surrounded by more water molecules Sodium Potassium Pump Lecture 2 The Resting Potential Nernst and Goldmann Equations Action Potentials c The Sodium Potassium Pump i A protein pump in the membrane concentrates Na outside the membrane and K inside 1 Produces a concentration gradient 2 Moves out more sodium then it moves potassium in ii Pump requires energy iii The action of this pump builds up concentration gradients for each ion 1 Leak Currents a Ions tend to flow back down these gradients i Sodium tends to leak into the cell and potassium tends to leak out 2 Cells way to build up an electrical charge Principles of Neurophysiology 1 Equilibrium potentials a An electrical