The olfactory cortex is a structurally distinct cortical region on the ventral surface of the forebrain, composed of several areas that receive input from the olfactory bulb (anterior olfactory nucleus, piriform cortex, olfactory tubercle, anterior cortical amygdaloid nucleus, periamygdaloid cortex, and entorhinal cortex
Entorhinal cortex
The entorhinal cortex is an area of the brain located in the medial temporal lobe and functioning as a hub in a widespread network for memory, navigation and the perception of time. The EC is the main interface between the hippocampus and neocortex. The EC-hippocampus system plays an important role in declarative memories and in particular spatial memories including memory formation, me…
What is the Order of olfactory?
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.
What is the meaning of olfactory?
pertaining to the sense of smell: those lobes of the deutocerebrum from which the nerves supplying the antennae arise. How to pronounce olfactory? How to say olfactory in sign language?
What does the name olfactory mean?
The definition of olfactory is related to the sense of smell. Nerves that help your sense of smell are examples of olfactory nerves. Relating to the sense of smell. Latin olfactorius, from olfactus, present participle of olfaciō (“I sniff"), from oleō + faciō.
How do olfactory nerves differ from other nerves?
Unlike many other nerves, the olfactory nerve has one job—making you able to smell things. When particles in the air enter your nasal cavity, they interact with the receptors on the olfactory nerve and a type of tissue called the olfactory epithelium, which is in several areas of the nasal cavity and contains millions of receptors.
Where is the olfactory cortex?
The primary olfactory cortex (POC) is a portion of the cerebral cortex. It is found in the inferior part of the temporal lobe of the brain. It receives input from the olfactory tract. It is involved in the sense of smell (olfaction).
How does the olfactory cortex process smell?
Our Sense of Smell When we sniff, chemicals in the air are dissolved in mucus. Odor receptor neurons in olfactory epithelium detect these odors and send the signals on to the olfactory bulbs. These signals are then sent along olfactory tracts to the olfactory cortex of the brain through sensory transduction.
What is the olfactory region responsible for?
olfactory system, the bodily structures that serve the sense of smell. The system consists of the nose and the nasal cavities, which in their upper parts support the olfactory mucous membrane for the perception of smell and in their lower parts act as respiratory passages.
What part of your brain controls smell and taste?
Parietal lobe It figures out the messages you receive from the five senses of sight, touch, smell, hearing and taste.
Which gland helps to detect a smell in your brain?
Your ability to smell comes from specialized sensory cells, called olfactory sensory neurons, which are found in a small patch of tissue high inside the nose. These cells connect directly to the brain. Each olfactory neuron has one odor receptor.
What happens when your olfactory nerve is damaged?
A damaged sense of olfaction is severely disrupting: the joy of eating and drinking may be lost, and depression may result. Furthermore, there are dangers associated with the loss of smell, including the inability to detect leaking gas or spoiled food.
What causes olfactory nerve damage?
The principal causes of olfactory dysfunction are sinonasal diseases, viral infections, head injuries, and neurodegenerative diseases.
Olfaction & Taste
Sensory gating takes several forms including modulation of sensation and perception due to changes in arousal, recent stimulus exposure, and selective attention. Olfactory cortex appears to play a major role in the first two sensory gating phenomena, and may be expected to also be involved in the latter.
Olfactory Higher Centers Anatomy
The olfactory cortex is a structurally distinct cortical region on the ventral surface of the forebrain, composed of several areas that receive input from the olfactory bulb (anterior olfactory nucleus, piriform cortex, olfactory tubercle, anterior cortical amygdaloid nucleus, periamygdaloid cortex, and entorhinal cortex) or the accessory olfactory bulb (medial and posterior cortical amygdaloid nuclei).
Olfaction
The olfactory cortex comprises (i) the anterior olfactory nucleus (AON), (ii) the olfactory tubercle (poorly developed in humans), (iii) the prepiriform cortex, (iv) the lateral entorhinal cortex, (v) the periamygdaloid cortex (a region contiguous with the underlying amygdala), and (vi) the cortical nucleus of the amygdala.
Olfactory Cortex Physiology
The olfactory cortex is defined as that cortical region of the mammalian brain that receives direct afferent input from the olfactory bulb. The olfactory cortex can be divided into multiple subregions based on anatomical characteristics, the largest of which is the piriform cortex (PCx, also known as the pyriform or prepyriform cortex).
Piriform Cortex and Amygdala
Fernando Martínez-García, ... Enrique Lanuza, in The Mouse Nervous System, 2012
Olfaction and Taste
K.L. Simpson, in Fundamental Neuroscience for Basic and Clinical Applications (Fifth Edition), 2018
The Olfactory System
Tim J. van Hartevelt, Morten L. Kringelbach, in The Human Nervous System (Third Edition), 2012
What is the olfactory cortex?
An understanding of the olfactory cortex requires a clear view of its place in the olfactory pathway. This pathway and its constituent neurons were first revealed by the use of the Golgi stain in the later part of the nineteenth century. The pathway consists of three main parts (see Figure 1). First is the olfactory sensory epithelium in the nose, containing the olfactory sensory neurons, which transduce the stimulating odor molecules into impulses that are sent over their axons in the olfactory nerve to the olfactory bulb, the second main structure of the olfactory pathway. Here the axons extend synapses onto the dendrites of relay neurons, the large mitral cells and smaller tufted cells. These cells interact with interneurons in the olfactory bulb and send the processed information by means of impulse discharges in their axons in the lateral olfactory tract (LOT) on the ventrolateral surface of the brain. The axons give rise to numerous collaterals, which terminate in the third main region, the olfactory cortex, to make synapses on the dendrites of cortical pyramidal neurons.
How is the olfactory cortex organized?
A traditional way to characterize the organization of the olfactory cortex is by its layers. The olfactory cortex is the prototypical three-layer cortex, consisting of an outer molecular layer of incoming fibers and apical dendrites; a middle layer of pyramidal cell bodies; and an inner plexiform or polymorphic layer of basal dendrites, fibers, and interneurons. It shares this three-layer organization with the hippocampus and contrasts with the six-layer construction of the neocortex.
What are the synaptic circuits of the olfactory cortex?
For the olfactory cortex, the main input elements are the fiber s from the LOT, which make excitatory synapses on the spines of the distal dendrites of the pyramidal neurons. The main output elements are the pyramidal neurons, each consisting of apical and basal dendrites, receiving excitatory synapses on their dendritic spines and inhibitory synapses on their dendritic shafts and cell bodies. The main intrinsic elements are two types of interneurons that make the inhibitory connections onto the pyramidal neurons. There are two main types of intrinsic circuits: a reexcitatory feedback circuit through long axon collaterals of the pyramidal neurons and inhibitory circuits for feedforward and feedback inhibition of the pyramidal neurons.
Where is the olfactory pathway?
As a result of the overgrowth of the forebrain in primates, the olfactory pathway is limited to the ventral surface of the brain. The olfactory bulbs give rise to a long LOT, which divides into three roots as it enters the brain. The lateral root goes to a cortical area at the junction of the frontal and temporal cortexes, which seems to be the homologue of the piriform cortex. From here there are connections to the prefrontal cortex, called the orbital cortex because it is on the surface of the brain facing the orbit of the eye. The medial root dives into a small area that, being pock-marked with many penetrating blood vessels, is called the perforated substance, a homologue of the olfactory tubercle. The medial root includes fibers that project toward or into the hypothalamus, from which there is a projection to the orbital cortex complementary to that from the piriform cortex. There are thus several routes over which information can be processed, through different olfactory cortical regions, to both cortical and subcortical regions.
Which circuit is used to correlate the olfactory cortex?
This basic circuit not only summarizes the main anatomical circuits within the piriform cortex but also, with minor variations, applies to the other olfactory cortical areas; moreover, it is similar to the other circuits: those of the hippocampus; the neocortex, particularly its superficial layers; and the "canonical circuit" proposed by some researchers for the neocortex. Thus, the basic circuit for the olfactory cortex is a useful model for correlating the general properties of all types of forebrain cortices.
What is the only part of the vertebrate forebrain that receives direct sensory input?
The olfactory cortex is the only part of the vertebrate forebrain to receive a direct sensory input. Present in even the most primitive fish, it retains its place and form throughout the vertebrate series, suggesting that it is a core element in the basic plan of the vertebrate forebrain. Since olfaction is the dominant sensory modality in most vertebrate species, an understanding of olfactory cortical mechanisms can yield insight into basic behavioral patterns underlying much of mammalian and primate behavior. The olfactory system is also one of the first sensory systems to differentiate and become functional during fetal life.
Where is the olfactory cortex located?
The olfactory cortex is a structurally distinct cortical region on the ventral surface of the forebrain, composed of several areas that receive input from the olfactory bulb (anterior olfactory nucleus, piriform cortex, olfactory tubercle, anterior cortical amygdaloid nucleus, periamygdaloid cortex, and entorhinal cortex) or the accessory olfactory bulb (medial and posterior cortical amygdaloid nuclei). The olfactory bulb fibers run through the lateral olfactory tract and end in layer Ia. Intracortical association fibers have a complementary termination mainly in layers Ib and III. There are extrinsic axonal projections from the olfactory cortex to the orbital cortex, mediodorsal thalamic nucleus, hypothalamus, amygdala, and hippocampus.
What are the two parts of the olfactory cortex?
The olfactory cortex comprises (i) the anterior olfactory nucleus (AON), (ii) the olfactory tubercle (poorly developed in humans), (iii) the prepiriform cortex, (iv) the lateral entorhinal cortex, (v) the periamygdaloid cortex (a region contiguous with the underlying amygdala), and (vi) the cortical nucleus of the amygdala. Major connections between the primary olfactory cortex and the secondary olfactory cortex in the orbitofrontal region occur via the mediodorsal nucleus of the thalamus, as well as via direct corticocortical projections from prorhinal cortex to the posterolateral orbitofrontal region.
Which part of the brain receives direct afferent input from the olfactory bulb?
The olfactory cortex is defined as that cortical region of the mammalian brain that receives direct afferent input from the olfactory bulb. The olfactory cortex can be divided into multiple subregions based on anatomical characteristics, the largest of which is the piriform cortex (PCx, also known as the pyriform or prepyriform cortex). The PCx has received the greatest attention of any olfactory cortical region, and thus PCx physiology is the focus of this description.
What is sensory gating?
Sensory gating takes several forms including modulation of sensation and perception due to changes in arousal, recent stimulus exposure, and selective attention . Olfactory cortex appears to play a major role in the first two sensory gating phenomena, and may be expected to also be involved in the latter. Spontaneous alternation between fast-wave and slow-wave cortical states, roughly comparable to alert and sleep states respectively, produces corresponding shifts in the state of piriform cortical membrane depolarization. Fast-wave cortical states are associated with depolarized piriform cortical neurons and robust responsiveness to odorant stimulation, while slow-wave states are associated with membrane hyperpolarization and reduced sensory responsiveness (Murakami, M. et al., 2005 ). In this way, the piriform cortex can gate sensory throughput to higher cortical areas based on arousal level. Similarly, the piriform cortex is a critical component of odor habituation. Activity-dependent presynaptic depression of cortical afferents can account for both cortical and simple behavioral adaptation to odors ( Best, A. R. and Wilson, D. A., 2004; Best, A. R. et al., 2005 ). Prevention of cortical short-term adaptation prevents adaptation of simple behavioral responses, demonstrating that adaptation of receptors in the nose cannot account for short-term behavioral habituation.
Which part of the brain is responsible for the sense of smell?
The portion of the cerebral cortex concerned with the sense of smell. It includes the piriform lobe and the hippocampal formation.
Which part of the uncus receives its major afferents from the olfactory bulb?
the olfactory cortex, corresponding to the rostral half of the uncus; receiving its major afferents from the olfactory bulb, it is classified as allocortex.
Where is the sense of smell housed?
The researchers used functional MRI techniques and cutting-edge, pattern-based analysis to identify the existence of predictive coding in the olfactory cortex of the brain, where the sense of smell is housed.
What is the primary olfactory cortex?
The primary olfactory cortex has been defined as cortical brain regions which receive the mitral and tufted cell axon projections. This includes the anterior olfactory nucleus, the pyriform cortex, regions of the amygdala and periamygdaloid complex, and the rostral entorhinal cortex (Fig. 3). The axonal projections from the bulb are primarily ipsilateral. Unlike other sensory systems, the output neurons project directly to cortex, albeit a simpler three-layered allocortex, without first synapsing in the thalamus. It has been suggested that this may help to explain strong associations between odors and memory, emotion, and endocrine function. The secondary olfactory cortex is defined as cortical regions receiving projections from the primary olfactory cortex. The structure most commonly termed secondary olfactory cortex in humans is the orbitofrontal cortex.
What is the most commonly termed secondary olfactory cortex in humans?
The structure most commonly termed secondary olfactory cortex in humans is the orbitofrontal cortex. Figure 3. The anatomy of the human basal forebrain and medial temporal lobes, including the olfactory bulb, tract, and surrounding nonolfactory structures.
What is the anterior olfactory nucleus?
In humans, the anterior olfactory nucleus is a predominantly two-layered cortical-like structure with connections to the olfactory tract. It has an anterior segment located posterior to the olfactory bulb and a posterior segment within the anterior temporal lobe. Its functions are multiple, including reciprocal transfer of information from the bulb to the piriform cortex and the relay of information between the left and right olfactory bulbs, as well as the left and right piriform cortices, largely via the anterior commissure.
What is the function of the piriform cortex?
Its functions are multiple, including reciprocal transfer of information from the bulb to the piriform cortex and the relay of information between the left and right olfactory bulbs, as well as the left and right piriform cortices, largely via the anterior commissure.
Where is the orbital cortex located?
The orbitofrontal cortex is located in the posterior ventral region of the frontal cortex. This five-layered agranular neocortex receives projections from, and sends projections to, all primary olfactory regions, including the amydala, piriform cortex, and entorhinal cortex.
Which lobe of the brain receives axonal projections from the olfactory bulb?
Recent neuroimaging studies suggest that the amygdala responds to the intensity of emotionally significant, that is, pleasant or unpleasant, odors. The most caudal temporal lobe region that receives axonal projections from the olfactory bulb is the lateral entorhinal cortex.
Which part of the brain is responsible for processing basic olfactory information?
The large three-layered piriform cortex, named for its pear-like shape, has frontal (‘prepiriform’) and posterior (temporal) components. This cortex reciprocally connects with a number of brain regions involved with behavior and emotion and is critical for processing basic olfactory information.
Where is the olfactory cortex located?
The olfactory cortex is vital for the processing and perception of odor. It is located in the temporal lobe of the brain , which is involved in organizing sensory input. The olfactory cortex is also a component of the limbic system.
What is the olfactory system?
This sense, also known as olfaction, is one of our five main senses and involves the detection and identification of molecules in the air. Once detected by sensory organs, nerve signals are sent to the brain where the signals are processed.
Why is the sense of smell and emotion different?
The connection between our sense of smell and emotions is unlike that of the other senses because olfactory system nerves connect directly to brain structures of the limbic system. Odors can trigger both positive and negative emotions as aromas are associated with specific memories.
What part of the brain is responsible for odor?
This is due to activity of an area of the brain known as the piriform cortex which is activated prior to odor sensation.
How does the sense of smell work?
Our sense of smell works by the detection of odors. Olfactory epithelium located in the nose contains millions of chemical receptors that detect odors. When we sniff, chemicals in the air are dissolved in mucus. Odor receptor neurons in olfactory epithelium detect these odors and send the signals on to the olfactory bulbs.
Why is smell important?
Our sense of smell is closely linked our sense of taste as both rely on the perception of molecules. It is our sense of smell that allows us to detect the flavors in the foods we eat. Olfaction is one of our most powerful senses. Our sense of smell can ignite memories as well as influence our mood and behavior.
Where do olfactory nerves end?
Olfactory nerve fibers extend from the mucous membrane, through the cribriform plate, to the olfactory bulbs. Olfactory bulbs: bulb-shaped structures in the forebrain where olfactory nerves end and the olfactory tract begins. Olfactory tract: band of nerve fibers that extend from each olfactory bulb to the olfactory cortex of the brain.
