Textbook Wolfe Chapter 14 Flashcards
1
Q
Cribriform Plate
A
- A bony structure riddled with tiny holes - Separates nose from brain at the level of eyebrows - Axons from OSNs pass through the tiny holes to enter the brain
2
Q
Entorhinal Cortex
A
- Phylogentically old cortical region - Provides major sensory association input to the hippocampus - Receives direct projections from Olfactory Regions
3
Q
G protein-coupled Receptor (GPCR)
A
- Any receptor that is on the surface of OSNs
- Characterised by seven membrane-spanning helices
4
Q
Olfactory Cilia
A
- Hairlike protrusions on the dendrites of olfactory sensory neurons
- Contain receptor sites where odorant molecules bind
- The first structures involved in olfactory signal transduction.
5
Q
Supporting Cells
A
- Supporting cells and basal cells
- Serve to nourish and support the hard-working olfactory sensory neurons (OSNs).
6
Q
Tufted Cells
A
- Tufted cells form the next layer of cells in the olfactory bulb
- After the juxtaglomerular neurons,
- These cells respond to more odorants than juxtaglomerular neurons but fewer than mitral cells
7
Q
Granule Cells
A
- Granule cells are located in the deepest layer of the olfactory bulb
- Form a network of inhibitory neurons that help to integrate input from other cells in order to better distinguish specific odorants.
8
Q
Olfactory Anatomy - Microstructures (10)
A
- Olfactory Epithelium
- Supporting Cells
- Olfactory Cilia
- Ofactory Sensory Neurons
- Cribriform Plate
- Glomerulus
- Granule Cells
- Mitral Cells
- Tufted Cells
- Olfactory Bulb
9
Q
Odour Adaptation
A
- When we first perceive an odour it is quite strong
- Within a short time we no longer smell the stimulus
eg: Smell coffee when it is first brewed but do not smell it after sitting in the kitchen for a while
- Once odorants have been activating the receptor proteins in your nasal cavity for a few minutes the receptor proteins react by burying themselves inside their cell bodies
- Odourants can no longer make contact with receptors
- Receptors will no longer begin action potentials to the bran
10
Q
Odour Habituation
A
- Decreased behavioral response to odors is created by repeated exposure
eg: after working in a bakery for a while you will no longer smell the baking smell - Receptors become exhausted from receding in the adaptation process
- They now begin to stay inside the cell bodies permanently and the Transduction Process does not happen
- This fatigue is not permanent but you are adapted to the bakery odours
- It takes weeks to de-habituate to a stimulus
11
Q
Normal Olfactory Sequence
A
- Odorant molecules connect with receptors in the cilia at the bottom of OSNs
- Odorant molecule fits into a receptor and sends an action potential up the length of the OSN’s axon.
- Synapses with mitral cells in a glomerulus of the olfactory bulb.
- The mitral cell in turn sends a neural signal back to the amygdala or to the entorhinal cortex.
- Once the signal reaches the brain, the smell is registered and elicits a cognitive reaction.
12
Q
Olfactory Lateralisation
A
- Olfaction differs from other senses because its OSN connections to the brain are ipsilateral
- Significant because it is beleived that the cerebral hemispheres are specialised for different functions.
- Interestingly Olfaction and Emotion are lateralised to the right hempisphere
- as such we tend to find odours smelt with right nostril more pleaseant and odours on the left nostril will be easier to name
13
Q
Verbal Olfactory Interactions
A
- We are verbal creatures and we tend to tag verbal codes to each stimulus experience
- This is not the case with smell
- We often experience odors wholly and completely without assigning any verbal codes to them
- when words come along with an odor, our perception of smells gets re-routed into our verbal circuits and to some extent ceases to be completely olfactory
