Lec #1 Flashcards
Hippocrates
• Brain is the seat of intelligence
• Epilepsy disorder of the brain
• Recognized that paralysis occurs on side
of the body opposite of head injury
Galen
• Proposed that nerves convey fluid
secreted by brain and spinal cord to the
body’s periphery
• Dominate view until microscope revealed
true structure of cells in nervous tissue
Renee Descartes
• Distinguished body and mind = “dualism” (vs. monism debate) • Brain mediates everything that can be found in lower animals (motor, sensory perception, memory, motivation) • Mind mediates conscious experience; not by brain but by soul that communicates with brain via pineal gland
Luigi Galvani
• Discovered that muscle and nerve cells produce electricity • “animal electricity” (a.k.a. Galvanism) • Volta discovered battery
Johannes Müller
• Measured speed of conduction along nerve cell • Showed one nerves electricity affects another cells activity • Birth of modern electrophysiology
Franz Joseph Gall and Johann
Spurzheim
• Unified view of body and mind (monism) • The brain is not a homogeneous organ (localism vs holism debate) • Derived from experimental lesions in animals • Phrenology
Pierre Flourens
• Stimulated and ablated cortical regions in animals • Disputed phrenology • Aggregate theory = all brain regions participate in every mental operation
Paul Broca and Carl Wernike
• Challenged aggregate theory • “Behavior linked to postmortem studies of lesions in patients with focal epilepsy or stroke led to evidence of localization of function • “We speak with the left hemisphere!” Broca 1864
Gustov Fritsch and Eduard Hitzig
• Characteristic limb movements of dogs can be produced by electrical stimulation of a specific area of the cerebral cortex = motor cortex • Right controlled by left hemisphere
Korbinian Brodmann
• Classification of cortical
areas based on
cytoarchitecture
• Nissl stain method
Golgi’s Reticular theory
neurons connected by protoplasmic
links to form a reticulum (Latin “net”) for nerve cell
communication; pioneered staining with impregnation with
silver salts = Golgi technique
Ramon y Cajal’s Neuron Doctrine
nerve cells are discrete entities that communicate via specialized contacts
Charles Sherrington
• Worked on apparent transfer of electrical signals
via reflex pathways
• Termed them “synapses”, supported the neuron
doctrine
• Received the Nobel in 1932
Nerve cells = Neurons
Specialized for electrical signaling over long distances
Neurons communicate via synapses (predominately) or gap
junctions (rarely)
100 billion in brain
Projection neurons (afferent and efferent neurons) and
interneurons
Phenotypes vary with locale
Greater diversity in brain than in any other organ
Diverse subsets of neurons constitute ensembles of _________ = neural systems to process specific types of info
Diverse subsets of neurons constitute ensembles of neural
circuits = neural systems to process specific types of info
\_\_\_\_\_\_\_ = extension of cell body that may travel a few hundred μm \_\_\_\_\_\_\_ = targets for synaptic input from axons of other neurons
Axon = extension of cell body that may travel a few hundred μm Dendrites = targets for synaptic input from axons of other neurons
More _________ = more
innervation by other
neurons
More arborization of
dendrites = more
innervation by other
neurons
Convergence
Convergence = inputs to a
single neuron; a single human
neuron will receive 1-100,000
inputs
Divergence
Divergence = outputs to other
neurons by any one neuron
Action potential
carries signals over
long distances
Self-regenerating wave of electrical activity
All or nothing change in electrical potential
(voltage) across membrane
Propogates from axon hillock to axon
terminal synapses
Synaptic transmission
chemical and
electrical processes by which the info
encoded by action potentials is passed
at synapses
glia cells
Supporting cells; ratio glia to neurons is 3:1
Support system; do not participate in synaptic interactions
or electrical signaling
New evidence that glia cells retain characteristics of stem
cells = can enter mitosis and generate nervous tissue cells
Astrocytes
CNS
Blood-Brain Barrier
Maintain environment
Oligodendrocytes
CNS
myelin
Schwann cells
PNS
myelin
Microglia
Scavengers
Release cytokines
Similar to macrophages
Central Nervous System (CNS) consists of :
• __________
• __________
• __________
Central Nervous System (CNS)
• Sensory systems
• Motor systems
• Associational systems
• Nerve cells are arranged in 2
different ways: __________ and __________
• Nuclei = local accumulations of neurons with
similar functions; ie brainstem and
hypothalamus
• Cortex = sheet-like arrangement of nerve
cells; ie cerebral cortex and cerebellum
Axons are gathered into tracts, called
_________ when they cross the midline
(white matter)
Axons are gathered into tracts, called
commissures when they cross the midline
(white matter)
Peripheral Nervous System (PNS) consistis of :
Peripheral Nervous System (PNS) • Sensory neurons with cell bodies localized in ganglia • Axons bundled into nerves • Somatic motor division innervates skeletal muscle • Autonomic motor division innervates smooth muscle
Autonomic Nervous System (ANS)
Autonomic Nervous System (ANS)
• Sympathetic system
• Parasympathetic system
• Also organized in ganglia and nerves
• Representations of the information is processed at various levels : ____________ and ____________
• Representations of the information is processed at various levels
• Topographic maps = point-to-point correspondence between the
sensory periphery and CNS neurons (vision and somatosensation
• Computational maps = compare, assess and integrate stimulus
attributes to extract info (olfaction, gustation)
• Parallel pathways = ______________
• Parallel pathways = information from each submodality is
processed separately
what are the Hallmarks of nervous system and define each.
Unity of function: nterconnected ensemble of neurons with similar dedications
Representation of specific information: Representations of the information is processed at various levels: Topographic maps and Computational maps
Subdivision into subsystems : Division of the function of the system into submodalities (ie audition vs vision)
what is Tract-tracing and what are its types.
Tract-tracing provides “mapping” of neural connectivity
• Anterograde tract tracing = from cell body to axon terminal;
ie biotinylated dextranamine (BDA) and Phaseolus vulgaris
leucoagglutinin (PHA-L)
Retrograde tract tracing = from axon terminal to cell body;
ie fluorogold (FG), horseradish peroxidase (HRP)
what is Extracellular recordings and Intracellular recordings ?
Extracellular recordings = electrode placed near nerve
cell(s) of interest; detect temporal patterns of action
potential activity relating to other neural inputs, a stimulus
or a behavior
Intracellular recordings = electrode placed inside nerve
cell of interest; useful for detailed analysis of
communication between neurons; detect smaller graded
changes in electrical potentials that trigger action
potentials
Functional brain imaging records _______
Functional brain imaging records local metabolic activity
within small volumes of brain tissue
Neurons transmit and store info by _______
Neurons transmit and store info by generating electrical signals
Resting membrane potential is ______ and Action potential makes transmembrane potential ________
Resting membrane potential is negative and Action potential makes transmembrane potential positive
All-or-nothing principle
All-or-nothing principle = needs to reach threshold; intensity
of stimulus encoded as frequency
Receptor potential
- Electrical signals elicited in response to activation of sensory neurons by external stimuli
- Info about touch, light, sound, heat, etc. is encoded by receptor potentials
- Changes the resting potential proportional to stimulus intensity
Synaptic potential
• Activation of the synapse during communication between
neurons at the synapse allows transmission of info to
postsynaptic neuron
• Stimulation of presynaptic neuron changes postsynaptic resting
membrane potential
• Amplitude varies according to number of synapses activated
Ion movements produce electrical signals
• Electrical signals are generated based on the flow of ions (K+,
Cl-, Na+) across the neuron plasma membrane
• Membrane is selectively permeable to particular ions
• Ion concentration gradients depend on active transporters and
ion channels in the cell membrane
Describe the ionic basis for resting potential
• Diffusion from high to low concentration
• More K+ inside vs outside neuron (active transporters)
• Gradient causes K+ to diffuse out of cell taking its + charge with it
leaving the cell more negative relative to the outside
• Continual resting efflux of K+ holds neuron at negative resting
potential
Describe the ionic basis for action potential
• More K+ inside neuron, more Na \+ outside neuron at rest • Changes in ion channel permeability alter membrane potential • Membrane becomes temporarily more permeable to Na+ • Na+ channels open • Na+ flows into cell • Membrane depolarizes becoming more positive • Na+ channels close and K+ channels open • Repolarizes back to resting levels
