What is Olfaction?
The ability to detect, identify and distinguish between different Odours
(smells)
Odour (smell)
Odorant (the chemical compound responsible for causing said smell)
What is meant by the phrase: "Olfaction is Synthetic"
Olfaction, unlike vision/audtitory system, is not perceived exactly
according to it's input. for example: when you see an image, you are
seeing exactly according to the input the brain recieves - if you see a
chair, you see it's legs because of light from the legs reaching your
retina etc.
However in Olfaction this isnt the case. When you smell an odour - e.g.
A perfume - you do not percieve the 100 different odorants within the
odour - you percieve it as 1 complete smell - the perfume. In this way
your experience of this odour is 'synthetic' it is manufactured by your
brain. Thus Olfaction is known as "high-dimensional"
Brainpower
Read More
What is 'Dimensionality' in the context of sensory processing?
Tldr: how many dimensions are required to "code" the sensory input. For
example:
touch is 2 dimensional: As you can only perceive touch on the outside of
, your body, each point on your skin could be coded along a 2
dimensional axis. You could stretch your skin out to form a complex 2D
shape, where every point could be put on an X-Y grid.
Likewise Vision is 2 dimensional (at least monochromatically): Each
point in your visual space can be put on a 2-dimensional grid. -
remember depth perception is a function of processing, your "true" vision
is flat.
What is the 'lowest-level' neuron in olfaction? i.e. which neurons are
responsible for actually detecting the odorants?
Olfactory Sensory Neurons (OSN's). Their number and distribution is
highly variable among species.
vertebrates OSNs, somewhat akin to all sensory neurons, are a bipolar
neuron (as some other sensory neurons are pseudo-bipolar) which an
axon running to the CNS and a sensory dendrite, forming a globular
dendritic knob (lol) with tiny cillia-like processes coming off of it. It is not
exposed directly to the air and is instead covered in mucus
Insect OSN's are very similar in structure. The difference between the
two is the medium surrounding the OSN (mucus in vertebrates, lymph in
insects)
What is the purpose of Odour Binding Proteins?
They help soubilise odorant compounds. As OSN's are covered in a
water-based (aqueous) medium (e.g. mucus) and a lot of odorants are
hydrophobic (e.g. essential oils) proteins are needed to associate these
molecules in water so they can be detected by OSN's.
Thus, OBP's will bind with the odorant to form a complex, which will then
bind to Odorant Receptor proteins on the surface of the cilia of OSN's
The ability to detect, identify and distinguish between different Odours
(smells)
Odour (smell)
Odorant (the chemical compound responsible for causing said smell)
What is meant by the phrase: "Olfaction is Synthetic"
Olfaction, unlike vision/audtitory system, is not perceived exactly
according to it's input. for example: when you see an image, you are
seeing exactly according to the input the brain recieves - if you see a
chair, you see it's legs because of light from the legs reaching your
retina etc.
However in Olfaction this isnt the case. When you smell an odour - e.g.
A perfume - you do not percieve the 100 different odorants within the
odour - you percieve it as 1 complete smell - the perfume. In this way
your experience of this odour is 'synthetic' it is manufactured by your
brain. Thus Olfaction is known as "high-dimensional"
Brainpower
Read More
What is 'Dimensionality' in the context of sensory processing?
Tldr: how many dimensions are required to "code" the sensory input. For
example:
touch is 2 dimensional: As you can only perceive touch on the outside of
, your body, each point on your skin could be coded along a 2
dimensional axis. You could stretch your skin out to form a complex 2D
shape, where every point could be put on an X-Y grid.
Likewise Vision is 2 dimensional (at least monochromatically): Each
point in your visual space can be put on a 2-dimensional grid. -
remember depth perception is a function of processing, your "true" vision
is flat.
What is the 'lowest-level' neuron in olfaction? i.e. which neurons are
responsible for actually detecting the odorants?
Olfactory Sensory Neurons (OSN's). Their number and distribution is
highly variable among species.
vertebrates OSNs, somewhat akin to all sensory neurons, are a bipolar
neuron (as some other sensory neurons are pseudo-bipolar) which an
axon running to the CNS and a sensory dendrite, forming a globular
dendritic knob (lol) with tiny cillia-like processes coming off of it. It is not
exposed directly to the air and is instead covered in mucus
Insect OSN's are very similar in structure. The difference between the
two is the medium surrounding the OSN (mucus in vertebrates, lymph in
insects)
What is the purpose of Odour Binding Proteins?
They help soubilise odorant compounds. As OSN's are covered in a
water-based (aqueous) medium (e.g. mucus) and a lot of odorants are
hydrophobic (e.g. essential oils) proteins are needed to associate these
molecules in water so they can be detected by OSN's.
Thus, OBP's will bind with the odorant to form a complex, which will then
bind to Odorant Receptor proteins on the surface of the cilia of OSN's
