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07 - Processing of visual motion

 

Topics addressed in the lecture:

  • motion as a fundamental perceptual dimension
  • motion as orientation in space-time
  • the anatomical localization of motion processing
  • the functional anatomy of area MT
  • the relationship between a stimulus, the neuronal response to it and the stimulus’ perception

Topics addressed in the seminar:

  • comparing psychometric and neurometric functions in a motion task
  • the relationship between the activity of single neurons in area MT and the perception of a moving stimulus
  • the effect of electrical microstimulation in area MT on perception

Questions you should be able to answer:

  • draw a space-time plot of a leftward motion
  • draw a polar plot of the tuning curve of a direction-selective cell, tuned to leftward motion
  • describe the topographic organization of area MT
  • what is meant by a neurometric curve and a psychometric curve (see Newsome et al. (1989))?
  • why is it interesting to compare these two curves?
  • describe the consequences of microstimulating area MT, as determined by Salzman et al. (1990)
  • what hypothesis is tested by this microstimulation experiment?

You should know the following terms and concepts after the lecture:

  • space-time plots for visual motion
  • tuning curve
  • Reichardt detector

You should know the following terms and concepts after the seminar:

  • psychometric and neurometric curves
  • relationship between the effects of microstimulation and cortical topography

Learning objectives (Lernziele) - Lecture:

  • Visual motion is a fundamental perceptual dimension.
  • Visual motion processing in primates is a high-performance system. It generates rich representations of the visual environment, even when only limited data are available (structure-from-motion, biological motion).
  • Simple visual motions are characterized by two parameters.
  • Motion can be thoght of as orientation in space-time.
  • In primates neurons that respond selectively to visual motion do not occur before cortex. They usually encode motion direction through bell-shaped tuning curves.
  • In visual cortex one of two processing pathways is specialized for visual motion information. Extrastriate area MT has been identified as an area particularly specialized for linear motion precessing. MT shows a topography for motion direction and binocular disparity.
  • A fundamental question in neuroscience is to elucidate the causal link between a sensory stimulus in the environment and an organism's perception of that stimulus. This has been particularly well investigated for area MT and visual motion perception.

Learning objectives (Lernziele) - Seminar:

  • A fundamental question in neuroscience is to elucidate the causal link between a sensory stimulus in the environment and an organism's perception of that stimulus. This has been particularly well investigated for area MT and visual motion perception.
  • Sudies in area MT have revealed a very strong quantitative similarity between psychometric and neurometric curves for motion stimuli in this area.
  • The strongest evidence for a causal link between the neural activity in area MT and an organism's perception comes from microstimulation experiments in MT.

Topics addressed in the lecture:

  • Stimulus-Sensation-Perception
  • Structure of eye and retina
  • Processing principles related to the structure of the retina
  • Cone and rod photoreceptor types 
  • Encoding of spatial information
  • Encoding of color information

Examples for questions you should be able to answer:

  • What is hierarchical coding?
  • What is retinotopy?

Important concepts:

  • Labeled-line coding
  • Hierarchical vs. parallel vs. horizontal processing
  • Receptive field
  • Retinotopy
  • Local coding
  • Coarse coding

 

Last update of this page: Jan 16, 2018