"the world outside the organism. Both hearing and touch are types of mechanosensation. There are three main components of the human ear: the outer ear, the middle ear, and the inner ear. Smell, or olfaction, is a chemoreception that forms the sense of smell. Olfaction has many purposes, such as the detection of hazards, pheromones, and food. It integrates with other senses to form the sense of flavor. Olfaction occurs when odorants bind to specific sites on olfactory receptors located in the nasal cavity. Glomeruli aggregate signals from these receptors and transmit them to the olfactory bulb, where the sensory"
"Olfaction Olfaction is a chemoreception that forms the sense of smell. Olfaction has many purposes, such as the detection of hazards, pheromones, and food. It integrates with other senses to form the sense of flavor. Olfaction occurs when odorants bind to specific sites on olfactory receptors located in the nasal cavity. Glomeruli aggregate signals from these receptors and transmit them to the olfactory bulb, where the sensory input will start to interact with parts of the brain responsible for smell identification, memory, and emotion. Often, land organisms will have separate olfaction systems for smell and taste (orthonasal smell and retronasal"
"primary olfactory cortex. In contrast to vision and hearing, the olfactory bulbs are not cross-hemispheric; the right bulb connects to the right hemisphere and the left bulb connects to the left hemisphere. The gustatory cortex is the primary receptive area for taste. The word ""taste"" is used in a technical sense to refer specifically to sensations coming from taste buds on the tongue. The five qualities of taste detected by the tongue include sourness, bitterness, sweetness, saltiness, and the protein taste quality, called umami. In contrast, the term ""flavor"" refers to the experience generated through integration of taste with smell"
"of the amygdala, the periamygdaloid complex, and the rostral entorhinal cortex. A unique characteristic of olfaction is its independence from the thalamus. The odor signals are sent directly from the sensory receptor neuron to the primary cortex. However, communication between the primary and secondary olfactory cortex requires connections with the thalamus. Odor identity, quality, and familiarity are mainly deciphered by the piriform cortex. Consciousness of smell is achieved by projections from the piriform cortex to the medial dorsal nucleus of the thalamus and to the orbitofrontal cortex, which the secondary olfactory cortex is part of. There are approximately 1000 olfactory"
"olfactory receptors, each sensitive to a narrow range of odorants. These neurons send signals to the glomeruli within the olfactory bulb. Each glomerulus collects information from a specific olfactory receptor neuron. The olfactory signal is then conducted to piriform cortex and the amygdala, and then to the orbitalfrontal cortex, where higher level processing of the odor occurs. Olfactory memory is the recollection of a given smell. Research has found that odor memory is highly persistent and has a high resistance to interference, meaning these memories remain within an individual for long times despite possible interference of other olfactory memories. These"
"Olfactory reference syndrome Olfactory reference syndrome (ORS) is a psychiatric condition in which there is a persistent false belief and preoccupation with the idea of emitting abnormal body odors which the patient thinks that are foul and offensive to other individuals. People with this condition often misinterpret others' behaviors, e.g. sniffing, touching nose or opening a window, as being referential to an unpleasant body odor which in reality is non-existent and can not be detected by other people. This disorder is often accompanied by shame, embarrassment, significant distress, avoidance behavior, social phobia and social isolation. The term ""olfactory reference syndrome"""
"the amygdala via the piriform cortex of the primary olfactory cortex and directly projects from the main olfactory bulb to specific amygdala areas. The amygdala passes olfactory information on to the hippocampus. The orbitofrontal cortex, amygdala, hippocampus, thalamus, and olfactory bulb have many interconnections directly and indirectly through the cortices of the primary olfactory cortex. These connections are indicative of the association between the olfactory bulb and higher areas of processing, specifically those related to emotion and memory. Associative learning between odors and behavioral responses takes place in the amygdala. The odors serve as the reinforcers or the punishers during"
"for recognition are referred to now as odor objects. Experience therefore strengthens signal-to-noise ratio in that a previously sensed odor object can be more easily distinguished against greater background noise. The orbitofrontal cortex (OFC) is the final destination of the odor information and is where conscious smell perception arises. Smell information enters directly after passing through the olfactory cortex, which marks the distinction from other sensory information that first pass through the thalamus. The OFC is located dorsal to the prefrontal cortex, allowing smell information direct input to the prefrontal cortex, or the major decision-making area of the brain. There"
"Research with a variety of animals suggest the role of norepinephrine in olfactory learning, in which norepinephrine neurons in the locus coeruleus send projections to neurons in the main and accessory olfactory bulbs. This is significant in the formation of olfactory memory and learning. The main olfactory bulb is one of the neural structures that experiences profound change when exposed to offspring odors at the time of childbirth. Human neuroimaging studies suggest that activation of the medial prefrontal cortex (mPFC) occurs during tests of olfactory memory. The medial prefrontal cortex receives extensive olfactory projections, which are activated immediately after birth"
"are only three types of neurons that smell molecules pass before arriving at the OFC: the olfactory receptor cells in the olfactory epithelium, mitral cells, and olfactory pyramidal neurons. At the level of the OFC, associations with other brain areas are made, including input from the mouth (somatosensation), emotional input (amygdala), visual information, and evaluative information (prefrontal cortex). The OFC is responsible for selective odor tuning, fusing of sensory domains, and hedonic evaluations of smells. The experience of eating favored foods with a cold often disappoints. This is because congestion blocks nasal passageways through which air and flavor molecules enter"
"Olfactory fatigue Olfactory fatigue, also known as odor fatigue, olfactory adaptation, and noseblindness, is the temporary, normal inability to distinguish a particular odor after a prolonged exposure to that airborne compound. For example, when entering a restaurant initially the odor of food is often perceived as being very strong, but after time the awareness of the odor normally fades to the point where the smell is not perceptible or is much weaker. After leaving the area of high odor, the sensitivity is restored with time. Anosmia is the permanent loss of the sense of smell, and is different from olfactory"
"Neurogastronomy Neurogastronomy is the study of flavor perception and the ways it affects cognition and memory. This interdisciplinary field is influenced by the psychology and neuroscience of sensation, learning, satiety, and decision making. Areas of interest include how olfaction contributes to flavor, food addiction and obesity, taste preferences, and the linguistics of communicating and identifying flavor. The term neurogastronomy was coined by neuroscientist Gordon M. Shepherd. Out of all the sensory modalities, olfaction contributes most to the sensation and perception of flavor processing. Olfaction has two sensory modalities, orthonasal smell, the detection of odor molecules originating outside the body, and"
"Olfactory tubercle The olfactory tubercle (OT), also known as the tuberculum olfactorium, is a multi-sensory processing center that is contained within the olfactory cortex and ventral striatum and plays a role in reward cognition. OT has also been shown to play a role in locomotor and attentional behaviors, particularly in relation to social and sensory responsiveness, and it may be necessary for behavioral flexibility. The OT is interconnected with numerous brain regions, especially the sensory, arousal, and reward centers, thus making it a potentially critical interface between processing of sensory information and the subsequent behavioral responses. The OT is a"
"detected this way. Some deaf people are able to determine direction and location of vibrations picked up through the feet. Taste or gustation (adjectival form: gustatory) is one of the traditional five senses. It refers to the capability to detect the taste of substances such as food, certain minerals, and poisons, etc. The sense of taste is often confused with the ""sense"" of flavor, which is a combination of taste and smell perception. Flavor depends on odor, texture, and temperature as well as on taste. Humans receive tastes through sensory organs called taste buds, or gustatory calyculi, concentrated on the"
"cortex in the brain. Olfactory information is further processed and forwarded to the central nervous system (CNS), which controls emotions and behavior as well as basic thought processes. Odor sensation usually depends on the concentration (number of molecules) available to the olfactory receptors. A single odorant is usually recognized by many receptors. Different odorants are recognized by combinations of receptors. The patterns of neuron signals help to identify the smell. The olfactory system does not interpret a single compound, but instead the whole odorous mix. This does not correspond to the concentration or intensity of any single constituent. Most odors"
"association cortical areas, these brain regions synthesize sensory information into our perceptions of the world. The olfactory bulb, responsible for the sense of smell, takes up a large area of the cerebrum in most vertebrates. However, in humans, this part of the brain is much smaller and lies underneath the frontal lobe. The olfactory sensory system is unique since the neurons in the olfactory bulb send their axons directly to the olfactory cortex, rather than to the thalamus first. Damage to the olfactory bulb results in a loss of olfaction (the sense of smell). Speech and language are mainly attributed"
"Olfactory memory Olfactory memory refers to the recollection of odors. Studies have found various characteristics of common memories of odor memory including persistence and high resistance to interference. Explicit memory is typically the form focused on in the studies of olfactory memory, though implicit forms of memory certainly supply distinct contributions to the understanding of odors and memories of them. Research has demonstrated that the changes to the olfactory bulb and main olfactory system following birth are extremely important and influential for maternal behavior. Mammalian olfactory cues play an important role in the coordination of the mother infant bond, and"
"OR2L13 Olfactory receptor 2L13 is a protein that in humans is encoded by the ""OR2L13"" gene. Olfactory receptors interact with odorant molecules in the nose, to initiate a neuronal response that triggers the perception of a smell. The olfactory receptor proteins are members of a large family of G-protein-coupled receptors (GPCR) arising from single coding-exon genes. Olfactory receptors share a 7-transmembrane domain structure with many neurotransmitter and hormone receptors and are responsible for the recognition and G protein-mediated transduction of odorant signals. The olfactory receptor gene family is the largest in the genome. The nomenclature assigned to the olfactory receptor"
"fatigue. It is a term commonly used in wine tasting, where one loses the ability to smell and distinguish wine bouquet after sniffing at wine(s) continuously for an extended period of time. The term is also used in the study of indoor air quality, for example, in the perception of odors from people, tobacco, and cleaning agents. Olfactory fatigue is an example of neural adaptation or sensory adaptation. The body becomes desensitized to stimuli to prevent the overloading of the nervous system, thus allowing it to respond to new stimuli that are 'out of the ordinary'. After olfactory neurons depolarize"
"of 6 layers: olfactory nerve layer, glomerular layer, external plexiform layer, mitral cell layer, internal plexiform layer, and granule layer. The terminals of the receptor axons synapse with the dendrites of mitral and tufts cells within the glomeruli of the olfactory bulb. The axons of the mitral and tufts cells send signals to the olfactory cortex. Signals from odor sensation are sent from the olfactory bulb through mitral and tufts cell axons via the lateral olfactory tract and synapse at the primary olfactory cortex. The primary olfactory cortex includes the anterior olfactory nucleus, the piriform cortex, the anterior cortical nucleus"
"it is widely assumed that olfaction and taste are senses that are not specialized for conveying spatial information. Multiple case studies and investigations have been conducted on unilateral neglect within the visual, auditory, and tactile sensory modalities, but only three case studies have been reported on neglect within the olfactory sensory modality. It is still unclear whether humans can localize at all the source of the olfactory stimulation by distinguishing between odors that are processed through the right versus the left nostril. This is particularly true when the stimulus is a pure odorant rather than trigeminal, that is when the"
"flavor occurs, in contrast to that of proper smell, which occurs during the inhalation phase of breathing. The olfactory system is the only human sense that bypasses the thalamus and connects directly to the forebrain. Olfaction and sound information has been shown to converge in the olfactory tubercles of rodents. This neural convergence is proposed to give rise to a perception termed smound. Whereas a flavor results from interactions between smell and taste, a smound may result from interactions between smell and sound. The following are disorders associated with olfaction: Scientists have devised methods for quantifying the intensity of odors,"
"or via the BNST). The hippocampus forms new and reinforces existing memories. Similarly, the parahippocampus encodes, recognizes and contextualizes scenes. The parahippocampal gyrus houses the topographical map for olfaction. The orbitofrontal cortex (OFC) is heavily correlated with the cingulate gyrus and septal area to act out positive/negative reinforcement. The OFC is the expectation of reward/punishment in response to stimuli. The OFC represents the emotion and reward in decision making. The anterior olfactory nucleus distributes reciprocal signals between the olfactory bulb and piriform cortex. The anterior olfactory nucleus is the memory hub for smell. Loss of smell is known as anosmia."
"easily inhibited by neighboring cells, while tufted have high rates of firing and are more difficult to inhibit. The uncus houses the olfactory cortex which includes the piriform cortex (posterior orbitofrontal cortex), amygdala, olfactory tubercle, and parahippocampal gyrus. The olfactory tubercle connects to numerous areas of the amygdala, thalamus, hypothalamus, hippocampus, brain stem, retina, auditory cortex, and olfactory system. *In total it has 27 inputs and 20 outputs. An oversimplification of its role is to state that it: checks to ensure odor signals arose from actual odors rather than villi irritation, regulates motor behavior (primarily social and stereotypical) brought on"
"Olfactory receptor neuron An olfactory receptor neuron (ORN), also called an olfactory sensory neuron (OSN), is a transduction cell within the olfactory system. Humans have about 10 million olfactory receptor neurons. In vertebrates, ORNs are bipolar neurons with dendrites facing the external surface of the cribriform plate with axons that pass through the cribriform foramina with terminal end at olfactory bulbs. The ORNs are located in the olfactory epithelium in the nasal cavity. The cell bodies of the ORNs are distributed among all three of the stratified layers of the olfactory epithelium. Many tiny hair-like cilia protrude from the olfactory"
"and amygdala affect odor perception. During certain physiological states such as hunger a food odor may seem more pleasant and rewarding due to the associations in the amygdala and hippocampus of the food odor stimulus with the reward of eating. Olfactory information is sent to the primary olfactory cortex, where projections are sent to the orbitofrontal cortex. The OFC contributes to this odor-reward association as well as it assesses the value of a reward, i.e. the nutritional value of a food. The OFC receives projections from the piriform cortex, amygdala, and parahippocampal cortices. Neurons in the OFC that encode food"
"recent works, Nalls has advanced concepts of aesthetics to consider the olfactory sense over the historically privileged sense of vision. While the visual remains dominant, artists have and are now increasingly working with the sense of smell to produce emotionally and phenomenologically resonant works in the emergent genre of Olfactory Art. Nalls “like many other olfactory artists, uses only natural fragrances and essential oils. “I call it ‘rewilding the mind,’” she says. For Nalls, the connection between olfaction and social or participatory art is rooted in the evolutionary biology of the sense of smell. As the oldest sense, olfaction has"
"actually having to see it. It also controls eating, writing, and using utensils. This sense enables a person to understand the amount of pressure used to carry out routine tasks, such as eating and writing. Bodily pressure is part of this as well; for example, a child may enjoy being held tighter by someone or leaning into things such as walls, desks, and potentially other people. The olfactory system is considered the sense of smell. People with Sensory Dysfunction Disorder could have difficulty with certain fragrances or odors. Conversely, they may find certain smells to be soothing, and use them"
"primary visual cortex. The absolute threshold for vision is the minimum amount of sensation needed to elicit a response from photoreceptors in the eye. This amount of sensation has a definable value and is often considered to be the amount of light present from someone holding up a single candle 30 miles away, if one's eyes were adjusted to the dark. Smell allows the body to recognize chemical molecules in the air through inhalation. Olfactory organs located on either side of the nasal septum consist of olfactory epithelium and lamina propria. The olfactory epithelium, which contains olfactory receptor cells, covers"
"OR51B4 Olfactory receptor 51B4 is a protein that in humans is encoded by the ""OR51B4"" gene. Olfactory receptors interact with odorant molecules in the nose, to initiate a neuronal response that triggers the perception of a smell. The olfactory receptor proteins are members of a large family of G-protein-coupled receptors (GPCR) arising from single coding-exon genes. Olfactory receptors share a 7-transmembrane domain structure with many neurotransmitter and hormone receptors and are responsible for the recognition and G protein-mediated transduction of odorant signals. The olfactory receptor gene family is the largest in the genome. The nomenclature assigned to the olfactory receptor"
"Rhinencephalon In animal anatomy, the rhinencephalon (from the Greek, ῥίς, ""rhis"" = ""nose"", and ἐγκέφαλος, ""enkephalos"" = ""brain"") also called the smell-brain or olfactory brain is a part of the brain involved with smell (i.e. olfaction). It forms the paleocortex and is rudimentary in the human brain. The term ""rhinencephalon"" has been used to describe different structures at different points in time. One definition includes the olfactory bulb, olfactory tract, anterior olfactory nucleus, anterior perforated substance, medial olfactory stria, lateral olfactory stria, parts of the amygdala and prepyriform area. Some references classify other areas of the brain related to perception"
"Olfactory tract The olfactory tract is a bundle of afferent nerve fibers from the mitral and tufted cells of the olfactory bulb that connects to several target regions in the brain, including the piriform cortex, amygdala, and entorhinal cortex. It is a narrow white band, triangular on coronal section, the apex being directed upward. It lies in the olfactory sulcus on the inferior surface of the frontal lobe, and divides posteriorly into two striae, a medial olfactory stria and a lateral olfactory stria. Fibers of the olfactory tract appear to end in the antero-lateral part of the olfactory tubercle, the"
"OR7D4 Olfactory receptor 7D4 is a protein that in humans is encoded by the ""OR7D4"" gene. Olfactory receptors interact with odorant molecules in the nose, to initiate a neuronal response that triggers the perception of a smell. The olfactory receptor proteins are members of a large family of G protein-coupled receptors (GPCR) arising from single coding-exon genes. Olfactory receptors share a 7-transmembrane domain structure with many neurotransmitter and hormone receptors and are responsible for the recognition and G protein-mediated transduction of odorant signals. The olfactory receptor gene family is the largest in the genome. The nomenclature assigned to the olfactory"