Lecture 1: Intro to perception Flashcards
N.C
What are the 5 classical sensory systems?
Sight, Taste, Smell, Hearing, Touch
Definition of sensation:
obtaining information from the environment through peripheral sensory systems
Definition of perception:
Using an interpreting the sensory informatino by means of (central) processes in the brain
What are the principles of sensory information processing, in order?
- Stimulus
- Transduction in sensory receptor cells
- Transmission from the sensory neurons to the brain (thalamus –> cortex)
What do sensory receptor cells do?
Monitor the environment for stimuli and convert (transduct) this ‘physical or chemical energy’ into electrochemical signals –> receptor potential
What do sensory neurons do?
Transmit the action potential to the brain and cortex for further processing
How can the ‘motion after effect’ be explained?
Adaptation in visual neurones that respond selectively to moving contours in image.
Exposure to a particular direction of motion alters this balance in favour of cells tuned to the opposite direction leading to the illusion.
General principle of sensory system
1.Stimulus
2. Sensory receptor
3. Transduction
4. Transmission - sensory nerve carries AP to CNS
5. Perception - processing sensation into perception in the brain
6. Action
Which characteristics of the stimulus should be encoded with APs?
modality, location, timing and intensity
What is modality and how are receptor cells connected to this?
Modality defines stimulus class (visual, auditory, smell or touch)
Receptor cells are specialized cells that can convert the physical energy of a particular stimulus into potentials (transduction)
Give an example of a sub modality.
Modality = light –> submodality = different wave lengths
How are receptor cells connected to location detection?
Receptor cells will generate a response when the stimulus is applied in their receptive field.
Receptors are topographically distributed in sense organs and a certain stimulus will only activate a certain set of receptor cells which gives info about where the stimulus is located.
What about timing should be encoded?
The onset and termination of the stimulus. Also the adjustment of fire frequency during the time of the stimulus (=adaptation)
How is intensity encoded?
Level of acitivity expressed in number of actions potentials per second
Is there a maximum firing frequency?
Yes, because of the opening and closing of the Na+ channels.
