Prelude
Today's Topics
- Sensory systems
Sensation/Cognition/Action
From sensation to action
Systems/information processing view
- Input
- Processing
- Memory
- Output
You vs. Your Smartphone
Multisensory processing in a smartphone
- Accelerometer
- Gyroscope
- Magnetometer
- Proximity sensor
- Ambient light sensor
- Barometer
Multisensory processing in a smartphone
- Thermometer
- Mic
- Camera
- Radios (Bluetooth, wifi, cellular, GPS)
Dimensions of sensory processing
- Interoceptive
- How am I?
- Exteroceptive
- What's in the world, where is it?
Questions for interoception
- Tired or rested?
- Well or ill?
- Hungry or thirsty or sated?
- Stressed vs. coping?
- Emotional state?
Questions for exteroception
- Who/What is out there?
- Where is it?
Who/what
- Animate/inanimate?
- Conspecific (same species)/non?
- Threat/non?
- Familiar/un?
- Mate/non? or Friend/not?
- Food source/non?
Where
- Distance
- Elevation, azimuth
- Coordinate frames
- Self/ego (left of me)
- Object (top of object)
- Allo/world (North of College)
- Where moving?
How
- What kind of response?
- External
- Internal
- Approach/avoid/freeze
- Signal/remain silent
- Manipulate
More than 5 senses
How sensory channels differ
- What is the energy/chemical source
- How does the channel inform
- What is out there
- Where it's located
Features of sensory signals
- Tonic (sustained) vs. phasic (transient) responses
- Adaptation
- Decline in sensitivity with sustained stimulation
- Most sensory systems attuned to change
- Information propagates at different speeds
Common principles
- Sensors detect repeating signals
- In space (textures)
- In time
Spatial frequency/contrast sensitivity
Frequencies in sound
Common principles
- Compare (>1) sensor for each channel
- Eyes
- Ears
- Nostrils
- Skin surface
Why is the snake's tongue forked?
Common principles
- Sensory neurons have "receptive fields"
- Area on sensory surface that when stimulated changes neuron's firing
Tactile receptive field
Visual receptive field
Common Principles
- Topographic maps
Tonotopic (frequency) maps in auditory cortex
Retinotopic maps in visual cortex
Common principles
- Non-uniform sensitivity
Two-point touch thresholds
Acuity variations across visual field
Hearing threshold varies across frequency
Hierarchical processing
Parallel processing
Parallel processing
Next time…
- Somatosensation