NPB163-MT1-Prep

Background:

Unit Name	Symbol	Relative to Meters
Nanometer
Micrometer (micron)
Millimeter
Centimeter
Decimeter
Meter		1

Week 1 - Intro & Techniques

Intro Techniques Local
NPB163-Problem-Set-1

Techniques:

• Levels of analysis for each question
  The key things to focus on:

1. What does it measure?
2. What is its spatial resolution? (single / multi unit, populational, etc. )
   • Single neuron, neuron in an area, whole brain, etc.
3. Temporal resolution? (Measuring a precise action potential, or more like a BOLD activity? )
4. Proper situation to employ activity?
   • Is invasiveness necessary?
     Spatial resolution vs Spatial coverage
     
     

Scratch Notes of each

Extracellular Recordings:

• Invasive technique, measures with a tiny metal sharp tip with an electrode. Needs to be placed directly on area of interest
• Has very limited coverage, only recording from one spot.
• Used for single-unit recordings, where the external voltage of a single neuron is recorded
• How strong recorded voltage is depends on distance from soma and size of neuron
• Frequently get data in the form of raster plots or peri-stimulus time histograms (PSTHs)
• Can also be used for Multi-unit activity (MUA) and for Local Field Potentials (LFP)
• Can also get wider coverage with multi electrode arrays (Utah arrays IE)
  Intracellular Recordings:
• Advantage is that they are able to track IPSPs and EPSPs through inner membrane voltage. However, they are difficult to perform, especially in vivo
  Electrocorticography (ECoG) / intracranial EEG (iEEG)
• An electrode grid is placed on cortical surface and provides LFP like signals from it
• High spatial coverage (covers a large amount of cortex) but low spatial resolution (records on the scale of LFPs and not direct neuron activity)
  Optical Imaging
• Part of the skull is removed to allow imaging of cortical surface with a CCD camera, which can be combined with the light absorption properties of oxy- and deoxyhemoglobin (HbO2 and HbR to provide metabolic information about neural activity
• An increase in neural activity is followed by a relatively fast and local reduction in hemogoblin oxygenation, followed by a slower and slightly more global increase in blood flow/volume and hemoglobin oxygenation
  • Optical imaging will pick up the first spike, will fMRI picks up the second
• Depending on wavelength of illumination chosen, changes in total hemoglobin and/or changes in hemoglobin oxygenation can be measured
  Voltage-sensitive dye (VSD) / Calcium Sensitive dye (CaSD) imaging
• VSC can be used to directly measure image electrical activity. VSDs bind across a neuro’s membrane and change their flourescence according to membrane ponetial.
• Calcium-sensitive dyes are instead sensitive to intracellular calcium concentration, and are sensitive to the calcium influx of a neuron firing.
• They provide a larger signal, but are more difficult to get into neurons.
  EEG
  MEG
  fMRI

Week 2 - Neural Codes

Information Primer Local
Neural Codes Local
NPB163-Problem-Set-2 - Information Theory

Weeks 3-5 - Sensory Systems

Sensory Systems 1 Local
NPB163-Problem-Set-3

Photoreceptors

• Located on the retina (back of the eye)
• 4 different types
  • 1 rod
  • 3 types of cones
    • L cones (red), M cones (green), S cones (blue)