2017-02-15 08:37:08

Prelude

Today's Topics

  • Levels of analysis in the study of brain and behavior
    • Spatial
    • Temporal
  • Methods to the madness

Review of key concepts

What does the practice of trephining suggest about our human ancestors?

  • A. That they knew nothing about how to treat mental illness
  • B. That they knew a lot about how to treat mental illness
  • C. That they had some notion about the link between mental illness and the brain

What does the practice of trephining suggest about our human ancestors?

  • A. That they knew nothing about how to treat mental illness
  • B. That they knew a lot about how to treat mental illness
  • C. That they had some notion about the link between mental illness and the brain

Descartes thought that this brain structure played a central role in linking sensory information with the actions it triggers.

  • A. The cerebral ventricles
  • B. The pineal gland
  • C. Cerebro-spinal fluid

Descartes thought that this brain structure played a central role in linking sensory information with the actions it triggers.

  • A. The cerebral ventricles.
  • B. The pineal gland.
  • C. Cerebro-spinal fluid.

Which of the following statements about the Egyptians is false?

  • A. They employed a word meaning "brain".
  • B. They removed the brain in the process of mummification.
  • C. They created detailed drawings of human brain anatomy.

Levels of analysis

Spatial resolution

Spatial and Temporal Resolution

Spatial Resolution in Detail

  • Within an individual
    • molecular
      • genetic
      • receptor
    • chemical
      • neurotransmitter
    • cellular
      • neuronal firing

Spatial Resolution in Detail

  • Internal to individuals
    • network
      • lateral inhibition
    • area
    • region
    • system

Spatial Resolution in Detail

  • External to individuals
    • Social
      • Friends, family, teachers, others
    • Non-social
      • neighborhood, school, state/region, country
      • Physical environment

Temporal Resolution in Detail

  • Within one lifetime
    • Microseconds
      • detection position from acoustic stimulation
    • Milliseconds
      • action potential
    • Seconds
      • changes in EEG power
      • short-term memory

Temporal Resolution in Detail

  • Within one lifetime
    • Minutes
      • synaptic plasticity
    • Hours
      • memory consolidation
    • Days
    • Weeks
    • Months

Temporal Resolution in Detail

  • Within one lifetime
    • Years
      • education & training
      • disease processes
      • cultural change

Temporal Resolution in Detail

  • Across lifetimes
    • Centuries
      • cultural changes
    • Millenia

Why does this matter?

  • Different methods, different levels of analysis.
  • Challenge of interpretation.
  • Challenge of linking phenomena across levels.
    • How does the micro affect macro or vice versa?

Neuroscience methods

Methods to the madness

  • Tools in the neuroscientist’s toolkit
  • What they tell us, and what they don’t

Evaluating methods

  • What is the question?
  • What are we measuring?
    • Structure
    • Activity
  • Strengths & Weaknesses
    • Cost
    • Invasiveness
    • Spatial/temporal resolution

Spatial and Temporal Resolution

Types of methods

  • Structural
    • Mapping the circuitry
    • Anatomy
  • Functional (next time)
    • What does it do?
    • Physiology/Activity

Mapping structures

  • Cell/axon stains
    • Golgi stain – whole cells
    • Nissl stain – cell bodies only
    • Cellular distribution, concentration, microanatomy

Golgi stain

Nissl stain

Retrograde vs. anterograde histochemical tracers

  • Retrograde (from axon terminal to cell body); anterograde (from cell body to axon terminal)
  • What connects where

Retrograde vs. anterograde tracers

Brainbow

Brainbow

Eyewire.org

Clarity

Mapping structures

  • Computed axial tomography (CAT), CT
  • X-ray based

Tomography

Tomography

CT scan of stroke

Magnetic Resonance Imaging (MRI)

  • Magnetic resonance
  • Protons have spin (magnetic dipole)
  • Align with strong magnetic field
  • When perturbed, speed of realignment varies by tissue
  • Realignment gives off radio frequency signals

MRI

How MRI works

Structural MRI

  • Tissue density/type differences
  • Gray matter (neurons & dendrites & axons & glia) vs. white matter (mostly axons)
  • MR Spectroscopy
  • Region sizes/volumes

Structural MRI of the brain

Diffusion tensor imaging (DTI)

Diffusion tensor imaging (DTI)

  • Type of structural MRI
  • Reveals integrity/density of axon fibers
  • Measure of connectivity

Voxel-based morphometry (VBM)

Next time

  • Functional methods, including functional MRI (fMRI)

References

Lichtman, Jeff W., Jean Livet, and Joshua R. Sanes. 2008. “A Technicolour Approach to the Connectome.” Nature Reviews Neuroscience 9 (6): 417–22. doi:10.1038/nrn2391.

Sejnowski, Terrence J, Patricia S Churchland, and J Anthony Movshon. 2014. “Putting Big Data to Good Use in Neuroscience.” Nature Neuroscience 17 (11). Nature Publishing Group: 1440–1. doi:10.1038/nn.3839.