Neuroscience Analysis of Occupational Performance (OCTH 455)
and
Neuroscience (PTRS 850)
Sensory Review: Question #2

The Question

The Answers

1. Within the same sensory domain, adjacent receptive fields determine contrast boundaries of a stimulus. If a stimulus activates one receptive field (+) but not surrounding receptive fields (-), information about the size (small) and nature (a stationary point) is provided:
   - - - - - -
   - - + - - -
   - - - - - -
   
2. If a band of receptive fields are stimulated together, the stimulus is perceived as a line or bar:
   - - + - - -
   - - + - - -
   - - + - - -
   

3. Perception of motion takes place when a series of adjacent receptive fields are stimulated successively:
   left.............................right
   First..... - + - - - - -
   then...... - - + - - - -
   then...... - - - + - - -
   and....... - - - - + - -
   result = left to right motion
   

4. A stimulus often has different sensory qualities. When the higher levels of the cortex (secondary sensory and sensory association areas) integrate information from receptive fields from different sensory modalities, a better picture of the stimulus emerges. A pin prick, for instance, may activate not only pain receptors but touch receptors and pressure receptors. Furthermore, because the receptive fields collectively form a map of the sensory world, these areas of the cortex can identify where the stimulus has occurred.

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