Behavioral Neuroscience, Lecture on November 12th
General principles of sensory processing
There are many different types of energy all around us.
-sound, odors, vision and heat.
This energy can effect us, so we must be able to detect it so that we can respond
How do we detect these energies?
Through our sensory systems, starting with the receptor cells in our sensory
Sensory receptor organs are specialized body parts particularly sensitive to some
forms of energy.
- the retina has receptor cells.
These organs act as filters:
- they detect some information and ignore other information.
Not all species have the same hearing capabilities. Similarly, not all species see
the same things. Humans are very visual, but some species can see things that we
Sensory processing begins at receptor cells:
- these receptors are whole cells, not like the receptor proteins we have been
talking about so far.
- their job is to convert (we usually say "transduce" outside energy into a language
that the brain can understand: action potentials.
-- this is what we mean by "signal transduction" conversion of one type into
Auditory signal transduction: hair cells are the receptor cells in the inner ear.
-hair cells sit in a membrane (basilar membrane) in the inner ear. Sound makes
that membrane vibrate.
- sound waves move into the cochlea where transductions occur.
- the ear contains the three smallest bones in the body.
Displacement of hairs leads to action potentials.
-the "hairs" are embedded in another membrane and the vibration displaces the
- the hair displacement opens ion channels in the hair cell which allows positive
ions to pass through
-- stereocilia vibrate and move against the tectorial membrane which opens the
The first step in sensory processing is to change the electrical potential of the
- this can lead to an action potential and release of neurotransmitters.
- some receptor cells have axons and some do not. Then, somatosensory information enters CNS via the dorsal roots.
- dorsal root ganglia get information from the periphery, like the skin, and bring
it into the spinal cord and up into the brain.
-- sensory information around the head and neck; that enters the CNS via cranial
Different receptors in skin detect different types of stimuli.