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