2022-01-20 07:53:20

Prelude 2:14

Prelude 1:22

Today’s topics

  • Warm-up
  • Wrap-up on structural measures
  • Functional measures

Warm-up

This cell-staining technique has what kind of spatial resolution?

This cell-staining technique has what kind of spatial resolution?

  • High/resolves fine details
  • Low/resolves crude details

This cell-staining technique has what kind of spatial resolution?

  • High/resolves fine details
  • Low/resolves crude details

This cell-staining technique has what kind of temporal resolution?

This cell-staining technique has what kind of temporal resolution?

  • High/resolves fine details or quickly changing phenomena
  • Low/resolves crude details or slowly changing phenomena

This cell-staining technique has what kind of temporal resolution?

  • High/resolves fine details or quickly changing phenomena
  • Low/resolves crude details or slowly changing phenomena

The cell-staining technique in question is…

  • A. Nissl stain
  • B. Golgi stain
  • C. Cartesian stain

The cell-staining technique in question is…

  • A. Nissl stain
  • B. Golgi stain
  • C. Cartesian stain

Wrap-up on structural measures

Link to prior class notes

Functional methods

Functional methods

  • Recording from the brain
  • Interfering with the brain
  • Stimulating the brain
  • Simulating the brain

Recording from the brain

  • Single/multi unit recording
    • Microelectrodes
    • Units -> Small numbers of nerve cells

Single/multi-unit Recording

Single/multi-unit recording

  • What does neuron X respond to?
  • High temporal (ms) & spatial resolution (um)
  • Invasive
  • Rarely suitable for humans, but…

Electrocorticography (ECoG)

ECoG and multimodal brain imaging

Positron Emission Tomography (PET)

Positron Emission Tomography (PET)

  • Radioactive tracers (glucose, oxygen)
  • Positron decay
  • Experimental condition - control
  • Average across individuals

Evaluating PET

  • Temporal (~ s) and spatial (mm-cm) resolution worse than fMRI
  • Radioactive exposures + mildly invasive
  • Dose < airline crew exposure in 1 yr

Functional Magnetic Resonance Imaging (fMRI)

  • Neural activity -> local \(O_2\) consumption increase
  • Blood Oxygen Level Dependent (BOLD) response
    • Oxygenated vs. deoxygenated hemoglobin creates magnetic contrast
    • Do regional blood \(O_2\) volumes (and flow) vary with behavior X?

fMRI

fMRI (Dougherty et al., 2003)

Evaluating fMRI

  • Non-invasive, but expensive
  • Moderate but improving (mm) spatial, temporal (~sec) resolution
  • Indirect measure of brain activity
  • Hemodynamic Response Function (HRF)
    • 1s delay plus 3-6 s ‘initial-dip’

Hemodynamic Response Function (HRF)

Electroencephalography (EEG)

  • How does it work?
    • Electrodes on scalp or brain surface
  • What do we measure?
    • Combined activity of huge # of neurons

EEG

EEG

  • High/fine temporal resolution but poor spatial resolution
  • Analyze frequency bands
    • LOW: deep sleep
    • MIDDLE: Quiet, alert state
    • HIGH:“Binding” information across senses

EEG Frequency

Event-related potentials (ERPs)

ERPs

Brain Computer Interface (BCI)

Magneto-encephalography (MEG)

  • Like EEG, but measuring magnetic fields
  • High temporal resolution, low spatial resolution
  • Magnetic field propagates w/o distortion

MEG

Manipulating the brain

  • Nature’s “experiments”
    • Stroke, head injury, tumor
    • Neuropsychology
  • If damage to X impairs performance on Y -> X critical for/controls Y
  • Poor spatial/temporal resolution, limited experimental control

Phineas Gage

Stimulating the brain

tDCS

TMS

Optogenetic stimulation

Evaluating stimulation methods

  • Spatial/temporal resolution?
    • Does stimulation mimic natural activity?
    • Optogenetic stimulation highly similar, others less so
  • Deep brain stimulation as therapy
    • Parkinson’s Disease
    • Depression
    • Epilepsy

Deep brain stimulation

Simulating the brain

  • Computer/mathematical models of brain function
  • Example: neural networks
  • Cheap, noninvasive, can be stimulated or “lesioned”

Application: AI

Spatial and Temporal Resolution

Bottom line…

  • Neuroscientists…
    • need to use many tools
    • seek converging evidence

Spatial and Temporal Resolution

Next time…

  • Brain anatomy (through song & dance)

References

Dayan, E., Censor, N., Buch, E. R., Sandrini, M., & Cohen, L. G. (2013). Noninvasive brain stimulation: From physiology to network dynamics and back. Nature Neuroscience, 16(7), 838–844. https://doi.org/10.1038/nn.3422

Dougherty, R. F., Koch, V. M., Brewer, A. A., Fischer, B., Modersitzki, J., & Wandell, B. A. (2003). Visual field representations and locations of visual areas V1/2/3 in human visual cortex. Journal of Vision, 3(10), 1–1. https://doi.org/10.1167/3.10.1

Han, W., Tellez, L. A., Rangel, M. J., Motta, S. C., Zhang, X., Perez, I. O., … Araujo, I. E. de. (2017). Integrated Control of Predatory Hunting by the Central Nucleus of the Amygdala. Cell, 168(1), 311–324.e18. https://doi.org/10.1016/j.cell.2016.12.027

Maren, S., & Quirk, G. J. (2004). Neuronal signalling of fear memory. Nature Reviews. Neuroscience, 5(11), 844–852. https://doi.org/10.1038/nrn1535

Redmon, J. (2018, March). YOLOv3. Youtube. Retrieved from https://www.youtube.com/watch?v=MPU2HistivI

Sejnowski, T. J., Churchland, P. S., & Movshon, J. A. (2014). Putting big data to good use in neuroscience. Nature Neuroscience, 17(11), 1440–1441. https://doi.org/10.1038/nn.3839