Olfaction + Gustation Lecture Slides Oct 11 2024 (PDF)

Olfaction and Gustation: Liza Pain, OT Reg. (Ont.), PhD Debbie Hebert, OT Reg. (Ont.) 2024©  Muscle Spindles Golgi Tendon Organs Joint Receptors Olfac...

Olfaction and Gustation: Liza Pain, OT Reg. (Ont.), PhD Debbie Hebert, OT Reg. (Ont.) 2024©  Muscle Spindles Golgi Tendon Organs Joint Receptors Olfaction + Vision Temperature Touch, Pain Gustation Vibration, Pressure Figure 3.6 - Types of peripheral receptors. (From Module #12)  Olfaction (Sense of Smell) Why do we need the Sense of Olfaction? Different Scents have different meanings for different people Practical Experience: 1) Identify an odour 2) Identify if it is “Good” or “Bad” 3) Does it make you feel happy, unhappy, or indifferent 4) Does it trigger a memory? Experience – Neurological Structures Experience Neurological Structures Involved Experience/perceive odour Chemoreceptors Olfactory nerve (CN1) Primary olfactory area Identify/name odour Temporal Lobe/Association area Make a decision about odour Frontal Lobe/Association area (what is it? Good? Bad?) Emotional experience Limbic System; Amygdala (Does it make you happy? Concerned? Indifferent?) Connection to a memory? Hippocampus (Does it illicit a previous memory? Result in a new memory?) Trigger a physiological/bodily Hypothalamus – plays a key role in response (Thirst, hunger, change in regulating the autonomic system heart rate/blood pressure, body temp/perspiration, etc.) (From Module #9) (From Module #9)  Diencephalon: Thalamus (From Module #3) IMAGE IS FOR INTEREST ONLY Parts of thalamus Anterior part Parts separated by internal medullary lamina Medial part Each part consists of groups of nuclei A) Anterior part B) Medial part C) Lateral part (VPM) VP Nuclei of thalamus (need to know these nuclei) 1. Ventral anterior nucleus (VA) (somatic motor) (VPL) 2. Ventral lateral nucleus (VL) (somatic motor) Lateral part 3. Ventral posterior nucleus (VP) (somatic sensory) Ventral posterolateral nucleus (VPL) (ST+DCML tracts) Ventral posteromedial nucleus (VPM) (trigeminothalamic tract and gustation) Posterolateral view of left thalamus 4. Lateral geniculate nucleus (LGN) (vision) KWA2 Fig.14.2 5. Medial geniculate nucleus (MGN) (auditory) 6. Dorsomedial nucleus (DM) (from olfactory cortex to orbitofrontal cortex)  Diencephalon (From Module #3) Hypothalamus: Maintains homeostasis (hunger, thirst, temperature, heart rate) Anterior regions activate parasympathetic NS; posterior regions activate sympathetic NS Receives input from limbic system (hippocampus + amygdala) Epithalamus Subthalamus Functions as part of the basal ganglia Plays a significant role in motor control and coordination Subthalamus Epithalamus Includes the pineal gland (involved in KWA2 Fig. 14.1 hormone regulation)  Functional Components: ANS (From Module #1) Visceral Sub-System (Involuntary and non-conscious) The motor efferent system includes the Autonomic Nervous System (ANS). The ANS has 2 subcomponents: 1) Sympathetic Nervous System (SNS): Prepares the body for “fight or flight” responses during stressful situations by dilating pupils, increasing heart rate, increased muscle tension/activity and inhibits digestion. 2) Parasympathetic Nervous System (PNS): Promotes “rest and digest” activities by constricting pupils, slowing heart rate, enabling muscle relaxation and stimulating digestion. Chronic/long term activation of SNS is referred to as chronic stress. This can lead to hypertension, altered sleep patterns, immune system suppression, digestive issues, and metabolic changes resulting in weight changes. Healthcare And Medical Photos and Images | Shutterstock Different Scents have different meanings for different people Different Scents have different meanings for different people Different Scents have different meanings for different people  Function of Smell [Olfaction] Alerts us to danger Helps us to identify objects – type and quality Possibly helps to identify people in our environment Stimulates memories – Proust Effect ▪ [Chu and Downes, 2000] “If odour is associated with an experience, then that odour can recall the memory and emotions of smell better than any other senses.” ▪ “The Proust effect refers to the vivid reliving of events from the past through sensory stimuli.”  Function of Smell [Olfaction] Stimulates our own emotions Allows us to read other’s emotions Main contributor to taste Other functions explored in the literature (more research required): ▪ Pheromones and sexual attraction? ▪ Mother-infant and sibling bonding? ▪ Influences charitability?  Olfactory System: Important Structures  Olfactory System: Important Structures CN1: Olfactory Nerve Dr. Anne Agur. (From Module #5)  Olfactory System: Important Structures  Olfactory System: Important Structures Axons from the mitral and tufted cells [secondary olfactory neurons] continue as the olfactory tract and project to the olfactory cortex. Periglomerular cells and granule cells can inhibit signal transmission, resulting in enhanced perception of certain odours and habituation to other odours.  Olfactory Pathway Odorants enter the upper nasal cavity and upper nasal septum > dissolve in the mucus produced by mucous cells Odorants stimulate the chemoreceptors on the cilia, which are attached to the olfactory knobs When chemoreceptors are stimulated, it causes depolarization of the cell, and results in the firing of an action potential. The action potential travels up the axon of the primary olfactory neuron [first order neuron]. Axons of primary olfactory neurons (also called receptor cells/neurons) group together and pass through the cribiform plate to become olfactory nerves olfactory nerves (CN1) enter the olfactory bulb and synapse with tufted cells and mitral cells [second order neurons]. The synapse occurs within the glomeruli. The axons from the tufted cells and mitral cells become the olfactory tract, and travel to the olfactory cortex.  Primary Olfactory Cortex: Orbitofrontal Part of Amygdala cortex + Piriform Area (inferomedial part of temporal lobe) Olfactory tract separates into: Piriform Area: Medial olfactory striate Uncus (connects to contralateral Entorhinal area olfactory tract – shares Limen Insulae information between tracts) Lateral olfactory striate Oribofrontal Cortex: (connects to primary Conscious awareness olfactory cortex – enables of odour conscious perception Cognitive of odour) decision-making re: olfaction  Olfactory System: Important Structures  Olfactory System: Important Structures  Olfactory Pathway Continued: Projections from the Tract Olfactory tract projections: Via medial olfactory stria to contralateral olfactory bulb Via lateral olfactory stria to the primary olfactory cortex > perception of odour Connections from the primary olfactory areas go to: Orbitofrontal cortex: ▪ Functions include odor perception, discrimination, learning, and attention. ▪ Information about the identity, the reward value, and response planning towards odours is represented. ▪ Note: One pathway travels via dorsal medial (dorsomedial) nucleus of thalamus for conscious appreciation. There is also a non-thalamic route that bypasses the thalamus and goes right to the orbitofrontal cortex. Hypothalmus: ▪ Odours may trigger autonomic and endocrine functions like hunger/ nausea to food, thirst, body temperature, blood pressure, heart rate, and sexual activity. Limbic System Structures: Hippocampus and amygdala ▪ Odours may impact motivation, emotion and memory  How Does One Aquire Anosmia (loss of smell)? Head injury creating sheering of the nerves Fractures of nasal cavity Tumors/Cortex Damage Congenital anosmia Aging Colds and sinus infections Alzheimer’s Disease ** What problems would this create?  Functional Impact of Anosmia Affects safety [i.e., ability to detect smoke/fire] Affects taste/desire to eat Difficulty with personal hygiene Affects mental health [can't smell things you enjoy]  Screening for Olfaction Materials: 5-6 different scents e.g. coffee, cinnamon, chocolate, lemon, mint. Consider making an “olfaction testing kit”. Procedure: Test each nostril separately by having the client occlude one nostril at a time. Present substance to the client with vision occluded. Have the client take two sniffs and indicate if they smell anything at all, and if so, can they identify what they are smelling. Scoring method: 2 - if they can detect and correctly identify, 1 - if they can detect but cannot identify 0 - if they experience no detection. Download Ask Reply Question Mark Royalty-Free Stock Illustration Image - Pixabay  Gustation OCT1172Y Liza Pain, OT Reg. (Ont.), PhD Debbie Hebert, OT Reg. (Ont.) 2024©  What happens when our taste is impaired? ⚫ Impaired ability to identify food entering body – protective mechanism ⚫ Decreases the stimulation of salivation- required for chewing, swallowing, and taste – saliva is required to distribute tastants ⚫ Decreased hunger/cravings – extreme forms lead to malnutrition ⚫ Decreased enjoyment of food - increased salt/sugar/flavourant intake can have health risks ⚫ Experience losses related to memories of tastes and altered mood – due to hippocampus and limbic connections  Muscle Spindles Golgi Tendon Organs Joint Receptors Olfaction + Vision Temperature Touch, Pain Gustation Vibration, Pressure Figure 3.6 - Types of peripheral receptors. (From Module #12)  The Taste Receptors Taste cell receptors group together to form taste buds (1 bud = 50 – 150 cells ); there are 2,000-5,000 buds in the oral cavity Papillae are groups of taste buds Taste cell receptors found on tongue; also on soft palate, pharynx, glottis and epiglottis Chemically stimulated when liquidated food comes in contact with cells by entering pore of bud Effect of Olfaction and Salivation on Gustation Practical Experience: 1) Identify: - What is the tasted food? - “Good” or “Bad”? - Does it trigger any emotions? - Does it trigger any memories? 2) Restrict contribution of olfaction to taste 3) Restrict contribution of salivation to taste Experience – Neurological Structures Experience Neurological Structures Involved Experience/perceive taste Chemoreceptors Cranial nerves (CNVII, CNIX, CNX) Primary gustatory area Identify/name the taste Temporal Lobe/Association area Make a decision about the taste Frontal Lobe/Association area (what is it? Good? Bad?) Emotional experience Limbic System; Amygdala (Does it make you happy? Concerned? Indifferent?) Connection to a memory Hippocampus (Does it illicit a previous memory? Result in a new memory?) Trigger a physiological/bodily response Hypothalamus – plays a key role in (Thirst, hunger, change in heart regulating the autonomic system rate/blood pressure, body temp/perspiration, etc.) Primary Gustatory Cortex  Gustatory System: Important Structures  Basic Tastes and Flavor What are the 5 basic tastes? Sweet Sour Salty Bitter Savoury [Umami]  Hanig’s Taste Map (now considered obsolete)  Gustatory Pathway: Cranial Nerves Facial Nerve - CNVII innervate taste buds in anterior 2/3 tongue and palate believed to be involved in food selection Glossopharyngeal Nerve - CNIX innervates taste buds on posterior 1/3tongue believed to play a role in reflexes and swallowing Vagus Nerve - CNX Innervates the pharynx, epiglottis and glottis believed to initiate reflexes that protect the airway CNVI1: Facial Nerve Dr. Anne Agur. (From Module #5) CN1X: Glossopharyngeal Nerve Dr. Anne Agur. (From Module #5) CNX: Vagus Nerve Dr. Anne Agur. (From Module #5)  Gustatory System: Important Structures  Diencephalon: Thalamus (From Module #3) IMAGE IS FOR INTEREST ONLY Parts of thalamus Anterior part Parts separated by internal medullary lamina Medial part Each part consists of groups of nuclei A) Anterior part B) Medial part C) Lateral part (VPM) VP Nuclei of thalamus (need to know these nuclei) 1. Ventral anterior nucleus (VA) (somatic motor) (VPL) 2. Ventral lateral nucleus (VL) (somatic motor) Lateral part 3. Ventral posterior nucleus (VP) (somatic sensory) Ventral posterolateral nucleus (VPL) (ST+DCML tracts) Ventral posteromedial nucleus (VPM) (trigeminothalamic tract and gustation) Posterolateral view of left thalamus 4. Lateral geniculate nucleus (LGN) (vision) KWA2 Fig.14.2 5. Medial geniculate nucleus (MGN) (auditory) 6. Dorsomedial nucleus (DM) (from olfactory cortex to orbitofrontal cortex) From Bear, M. F., Connors, P. W. & Paradiso, M. A. (2001) Neuroscience: Exploring the Brain, Baltimore:Lippincott, Williams and Wilkins pg. 264  Pathways Conscious Appreciation Taste Receptors > Cranial Nerves VII, IX and X > Gustatory Nucleus >Ventral Posterior Medial (VPM) Nucleus of Thalamus > Primary Gustatory Cortex Swallowing, Salivation, Gagging ,Vomiting, Digestion and Respiration. Taste Receptors > Cranial Nerves VII, IX and X > Gustatory Nucleus > Brainstem Desire to Eat & Control of Eating Taste Receptors > Cranial Nerves VII, IX and X > Gustatory Nucleus > Hypothalamus Integration with Smell Taste Receptors > Cranial Nerves VII, IX and X > Gustatory Nucleus > Orbitofrontal Cortex  Basic Tastes and Flavor What are the 5 basic tastes? Sweet, sour, salty and bitter + Savoury [Umami] What actually constitutes flavor? Smell Temperature Texture Levels of acidity Others  Flavour is also influenced by: Visual appearance of the meal – Visual System Socialization – Limbic System Maturity of taste buds/perception of various tastes and textures Degree of hunger - Hypothalamus Personal experience with flavours: Frontal Lobe cultural experiences possible genetic contributions Adaptation effect  Who Develops Ageusia/ Hypoageusia? Fark et al, 2013 Older adults > 60 years of age Damage to a cranial nerve (surgery, radiation therapy) Head injury, MS, Parkinson’s or stroke affecting any part of the primary gustatory pathway, ventral posterior medial nucleus of thalamus or primary gustatory cortex Smokers; GERD; poor oral hygiene; dry mouth Medications might create loss or hypersensitivity in taste Parageusia and Phantogeusia Cold + Flu with sinusitis/increased mucous production  Test for Gustation Materials: Test with 4 solutions: ▪ Sour (vinegar) ,sweet (sugar) ,bitter (Quinine) and salt (salt) ▪ Cotton swabs/Q-Tips to apply to tongue ▪ Glass of water Procedure: Client protrudes tongue. ▪ Each flavour can be applied separately to the anterior 2/3 of tongue (CNVII) and posterior 1/3 of tongue (CNIX); CNX is difficult to assess. ▪ Water should be given to rinse out mouth between each flavour ▪ Items are recorded as correct or incorrect FOR INTEREST ONLY Download Ask Reply Question Mark Royalty-Free Stock Illustration Image - Pixabay