Transcript The effect of stimulus intensity and duration

Ch. 10: Sensory Physiology
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Types of sensory information
Receptive field
Threshold
Receptor potential
Labeled line coding
Location of stimulus
Lateral inhibition
Intensity and duration of stimulus
Tonic and phasic receptors
Types of conscious stimuli
• Special senses: vision, hearing, taste,
smell, equilibrium
• Somatic senses: touch-pressure,
temperature, pain, proprioception (make
us aware of body position)
Receptor cells
• Sensory systems contain receptor cells
that respond to stimuli
• The receptor cells transduce stimulation to
a cellular response
• Receptor cells can be neurons
(somatosensory) or non-neural cells
(hearing)
•Receptor cells can be neurons (somatosensory) or non-neural cells (hearing)
Sensory pathways carry
information to the CNS.
• Relays: primary sensory neurons 
secondary neurons  tertiary neurons
Receptive fields
• Each receptor picks
up information from a
specific area
• Sensory neurons
converge on second
order neurons, etc.
You can recognize two points:
Transduction:
• Convert stimulus energy to change in
membrane potential (ions moving through
channels)
• Need an adequate stimulus for
transduction (sensitivity)
• Change in membrane potential is receptor
potential (special senses) and generator
potential (somatic senses)
If the receptor potential exceeds threshold in the trigger
zone, an action potential Is formed and conducted for long
range signaling to the axon terminal.
The effect of stimulus intensity and duration:
Labeled line coding
• When a sensory neuron is activated,
signals follow a specific pathway and elicit
a specific sensation
Lateral inhibition (I have more, you can’t tell you neighbor that you have some)