Neuronal Imaging Flashcards
Golgi’s method
Silver staining technique
Stains a limited number of cells at random in their entirety
Impregnate aldehyde fixed nervous tissue with potassium dichromate and silver nitrate. Cells thus stained are filled by microcrystallization of silver chromate.
Soma
or cell body (30-50 μm in diameter) containing the nucleus and other intracellular organelles.
The control centre of the neuron
Axon
long (can be up to 2 metres long) and very thin (~1-2 μm) projection from the soma that ends in the axon terminal
(pre-synaptic structure).
Myelinated to speed AP propagation
The output of a neuron
Dendrite
thicker (~10 μm) multiple projections from the soma with a dense branching structure. Can be either smooth of covered in spines.
Communication between neurons take place at specialized sites known as synapses
The primary input to a neuron.
Confocal microscopy
Uses light from a laser through the objective of a standard light microscope to excite a fluorescent specimen within a narrow (pinhole) plane of focus. Any emission of light from out-of-focus planes is rejected by the pinhole, or confocal aperture
Laser
Emit temporally coherent light
Abbe Diffraction limit
determines the spot size to which a light beam can be focused
Super resolution microscopy
Allow images to have resolutions higher than those imposed by the diffraction limit
Predict where light scatters and refracts
Deterministic and Stochastic types
Deterministic super-resolution
Fluorophores show nonlinear response to excitation, and this nonlinear response can be exploited to enhance resolution
Stochastic super-resolution
The chemical complexity of many molecular light sources gives them a complex temporal behavior, which can be used to make several close-by fluorophores emit light at separate times and thereby become resolvable in time.
GFP
Green Fluorescent Protein
Fluoresces green light when exposed to UV light
Toxic - produces free radicals when excited
2 photon imaging
simultaneous absorption of two photons of identical or different frequencies in order to excite a molecule from one state (usually the ground state) to a higher energy
two photons with longer wavelength than the emitted light
non-linearity = spatial resolution produced
infrared light = less scattering
Brainbow
Randomly expressing different ratios of YFP, RFP, CFP
Flag each neuron with a distinctive color
Block-face imaging
Tissue sliced and imaged in panels and stitched together to form 3D image
Glycoprotein-Deleted Rabies virus
Rabies containing GFP and deleted glycoprotein = non-infectious
CRE w helper protein so it can jump synapses
Used to trace circuits
