KANDEL PRINCIPLES OF NEUROSCIENCE CHAPTER 17 SENSORY CODING
The goal of sensory neuroscience is to follow the flow of sensory information from receptors toward
the cognitive centers of the brain.
Functional differences between sensory systems arise from two features:
1. The different stimulus energies that drive them
2. The discrete pathways that compose each system.
Our conscious sensations differ qualitatively from the physical properties of stimuli because the
nervous system extracts only certain features of each stimulus while ignoring others.
Sensory receptors are found in specialized epithelial structures sense organs (eye, ears, nose,
tongue, and skin).
Each receptor responds to a specific kind of energy at specific locations in the sense organ and
sometimes only to energy with a particular temporal or spatial pattern.
Receptor potential = the amplitude and duration of the electrical signal produced by the receptor.
Stimulus transduction = the process by which a specific stimulus energy is concerted into an
electrical signal.
Receptor specificity = most receptors are optimally selective for a single type of stimulus energy.
The neural representation of an object, sound, or scene is composed of a mosaic of individual
receptors that collectively signal its size, contours, texture, temporal frequency, color, and
temperature.
Mammalian sensory receptors are classified as:
- Mechanoreceptors
- Chemoreceptors
- Photoreceptors
- Thermoreceptors
Mechanoreceptors and chemoreceptors are most widespread and most varied in form and function.
Chemoreceptors are responsible for olfaction, gustation, itch, pain, and many visceral sensations.
Thermoreceptors
- In skin
- In hypothalamus monitors blood temp.
Photoreceptors
- Five kinds in the retina
Submodalities
- Some are mediated by discrete subclasses of receptors that respond to limited ranges of
stimulus energies of that modality
- Some are derived by combining information from different receptor types.
Receptor adaptation = if a stimulus persists unchanged for several minutes without a change in
position, or amplitude, the neural response and corresponding sensation diminishes.
Slowly adapting receptors = receptors that respond to prolonged and constant stimulation encode
stimulus duration by generating action potentials throughout the period of stimulation.
The goal of sensory neuroscience is to follow the flow of sensory information from receptors toward
the cognitive centers of the brain.
Functional differences between sensory systems arise from two features:
1. The different stimulus energies that drive them
2. The discrete pathways that compose each system.
Our conscious sensations differ qualitatively from the physical properties of stimuli because the
nervous system extracts only certain features of each stimulus while ignoring others.
Sensory receptors are found in specialized epithelial structures sense organs (eye, ears, nose,
tongue, and skin).
Each receptor responds to a specific kind of energy at specific locations in the sense organ and
sometimes only to energy with a particular temporal or spatial pattern.
Receptor potential = the amplitude and duration of the electrical signal produced by the receptor.
Stimulus transduction = the process by which a specific stimulus energy is concerted into an
electrical signal.
Receptor specificity = most receptors are optimally selective for a single type of stimulus energy.
The neural representation of an object, sound, or scene is composed of a mosaic of individual
receptors that collectively signal its size, contours, texture, temporal frequency, color, and
temperature.
Mammalian sensory receptors are classified as:
- Mechanoreceptors
- Chemoreceptors
- Photoreceptors
- Thermoreceptors
Mechanoreceptors and chemoreceptors are most widespread and most varied in form and function.
Chemoreceptors are responsible for olfaction, gustation, itch, pain, and many visceral sensations.
Thermoreceptors
- In skin
- In hypothalamus monitors blood temp.
Photoreceptors
- Five kinds in the retina
Submodalities
- Some are mediated by discrete subclasses of receptors that respond to limited ranges of
stimulus energies of that modality
- Some are derived by combining information from different receptor types.
Receptor adaptation = if a stimulus persists unchanged for several minutes without a change in
position, or amplitude, the neural response and corresponding sensation diminishes.
Slowly adapting receptors = receptors that respond to prolonged and constant stimulation encode
stimulus duration by generating action potentials throughout the period of stimulation.
