Cog & Bio Olfaction Flashcards
In the last 5 years, what % had food related incidents (hazard detection)
32.2%
In the last 5 years, what % had more than 1 gas incident?
14.8%
In the last 5 years, what % had at least 1 gas scare?
34.5%
In the last 5 years, what % had one or more work incidents?
18.5%
What does smell promote in young infants?
Learnt the smell of their parents in the environment, encourages associative learning and positive emotional experiences which promotes bonding
At what age to infants have a preference towards the smell of their mother?
2 days old
What do infants orientate their head towards?
The olfaction stimulus from their mother
What is found when people are exposed to their partners odour?
Sleep quality increases
What is the Proust effect?
Smell has the ability to evoke memories
What was found about emotionality and evocativeness?
Significantly higher for the odour evoked memories compared to verbal, visual & auditory evoked memories
What was found with odours and wellbeing?
Inhaling lavender led to participants feeling more relaxed compared to non-odourous condition
What has been found about lemon?
Has positive effects on cognition, increased performance in memory task
What was found with smell and eating / drinking functions?
Sense of smell can regulate eating behaviour - smell of food increases appetite for that specific food group - smelling savoury foods increased appetite for savoury foods and decreases it for sweet foods
What is olfactory epithelium?
Nasal cavities
Where are peripheral olfactory areas?
Within the nose
Where are central olfactory areas?
In the brain
What happens when an individual sniffs?
Air & odour molecules being transported through the nasal passages to the olfactory receptors in the epithelium - axons of these receptors in the epithelium synapse with neurons from central olfactory nervous system
How is odour perceived?
Made up of many different odour molecules, which attach onto different receptor neurons which allows for identification of the odour, based on this specific pattern
Each odour receptor can receive information from…
An array of different odour molecules - even a slight change in the odour receptor pattern can have a dramatic impact on the overall odour that is perceived
What happens in the central olfactory network?
Olfactory signals are transferred from the olfactory bulb to the primary olfactory cortices before being transferred to secondary olfactory regions
What are secondary olfactory regions?
Regions that receive signals from the olfactory bulb - has connections with hippocampus which is the strongest with olfactory than other senses which could be why this provokes the most vivid memories
What activates the trigeminal system?
Most odours - activates it through the trigeminal nerves in the nasal cavity
What happens when the trigeminal system is activated?
This leads to somatosensory sensations such as pain or temperature - e.g some odours result in burning, itching
What is the piriform cortex involved in?
Involved in processing both the initial chemical structure of the odour and its perceptual dimensions such as pleasantness or quality
In the anterior piriform cortex, increased signal change was due to what?
Due to molecular changes
In the posterior piriform cortex, increased signal change was more dependent on?
Odour quality
What other function does the piriform cortex play a role in?
The semantic processing of four related information - lower levels of smell
What was found in reading odour labels and the piriform cortex?
Reading odour labels can activate the piriform cortex - odour not presented but people could smell the scent of whatever was on the label
What was found when imagining pleasant and unpleasant odours?
Caused activation patterns in the piriform cortex that mirror that of olfactory perception
Subregions of the entorhinal cortex form what?
Part of the primary olfactory network
The entorhinal cortex acts as what?
A gateway to the hippocampus
In neurodegenerative diseases such as Alzheimer’s, the entorhinal cortex is what?
One of the first regions to be impacted by the disease - it is theorised that this contributes to the reduction of both memory and olfactory functioning during the disease
The medical amygdala, cortical amygdala and the periamygdaloid complex form what?
Part of the primary olfactory cortex
What does the amygdala process?
Emotion - therefore its role in the olfactory network may explain the highly emotional quality of olfactory evoked memories
What else is also suggested that the amygdala plays a role in?
Odour pleasantness & intensity processing, olfactory associated motor responses, cross-modal processing
What does the hippocampus show the strongest connectivity to?
Primary olfactory regions
What does the hippocampus maintain?
Both odour associated episodic memories as well as semantic knowledge of olfactory concepts
What is olfaction?
Signals directly sent to regions
When is there activation in the hippocampus?
When remembering old items
What does the thalamus play a key role in?
Sending the olfactory signals to higher order regions such as the orbitofrontal cortex
Why is olfaction unique?
The thalamus is a secondary processing region rather than a first
Subregions of insula play a key role in?
Evaluating the valence of the olfactory stimuli - study found ability to detect odours in the environment was unaffected but pleasant odours were perceived as unpleasant
What does the orbitofrontal cortex play a key role in?
Conscious and unconscious olfactory processing, valence processing and multisensory integration
What is multisensory integration?
Integrating olfactory information with information from other sensory modalities
What is cross-modal interaction?
When the sense of smell interacts with another sense - e.g vision
What 4 things shape cross-modal association?
Repeated exposure to objects
Physiological similarities
Semantic similarities
Emotion
Electrophysical olfactory tests have the aim of what?
Measuring the electrical activity in the brain when individuals smell odours
In individuals with no sense of smell often olfactory event related potentials are…
Not present whereas among those with a reduced sense of smell the results vary
When can both structural and functional imaging be used?
When investigating individuals with smell loss
MRI techniques are used to…
Measure the volume of olfactory structures, which give indications regarding the nature of olfactory loss
What has research found about smaller olfactory bulb volume?
Participants with olfactory dysfunction had smaller olfactory bulb volume than those without olfactory dysfunction, with OB volume as baseline predicting olfactory test scores as follow up
What do psychological methods measure?
Cognitive response - aim of testing what individuals can consciously perceive
What is the debate surrounding psychological methods?
Whether they are subjective or not - not measuring brain activity directly
Psychological olfactory tests are screening tests designed to…
Classify normal olfactory functioning from abnormal olfactory functioning
What 3 things can affect results of psychological measures?
Culture, learning effects and semantic memory
Psychological methods can measure olfactory threshold which relies on…?
Peripheral olfactory processing, discrimination, and identification
What test measures threshold, discrimination and identification?
The sniffin sticks olfactory test battery
Example of self-rated olfactory functioning questionnaire is?
English olfactory disorders questionnaire
Hyposmia is often seen as?
The invisible disease
What have smell loss patients report?
Both increased and decreased eating, anxiety about hazards and hygiene, frustration about lack of treatment options, difficulty within intimate relationships, trouble binding with children
What did patients with smell loss report in terms of hazards and hygiene?
Feelings of anxiety about hazards and personal hygiene
What does olfactory dysfunction impact?
Strength of odour perception, quality of perceived odours, and smelling odours which are not present
What is anosmia?
Complete loss of smell
Why is hyposmia?
Reduction in smell
What is parosmia?
Change in smell
What is phantosmia?
Smell things that aren’t actually there
What is olfactory intolerance?
Feeling like you cannot deal / are intolerant to a smell but smell tests come back as normal
Cognitive effect of olfactory dysfunction?
Impacts memory for both events and facts
Poorer olfactory imagery quality
