Endocrine Factors And Their Interaction With Brain Systems
A small proportion of cases of obesity can be related to gene-related dysfunctions of the peptide systems in the hypothalamus; for example, 4% of obese individuals have deficient receptors for melanocyte-stimulating hormone . Cases of obesity that can be related to changes in the leptin hormone satiety system are very rare . Further, obese individuals generally have high levels of leptin, so leptin production is not the problem; instead, leptin resistance may be somewhat related to obesity, with the resistance perhaps related in part to smaller effects of leptin on arcuate nucleus neuropeptide Y/agouti-related protein neurons . However, although there are similarities in fatness within families, these similarities are as strong between spouses as they are between parents and children, so that these similarities cannot be attributed to genetic influences, but presumably reflect the effect of family attitudes to food and weight.
Five Prototypical Tastes Including Umami
In the primary and secondary taste cortex there are many neurons that respond best to each of the four classical prototypical tastes , but also there are many neurons that respond best to umami tastants such as glutamate and inosine monophosphate . This evidence, taken together with the identification of a glutamate taste receptor , leads to the view that there are five prototypical types of taste information channels, with umami contributing, often in combination with corresponding olfactory inputs , to the flavour of protein. In addition, other neurons respond to water and others to somatosensory stimuli including astringency, as exemplified by tannic acid and capsaicin .
New Map Shows Where Tastes Are Coded In The Brain
- Date:
- Howard Hughes Medical Institute
- Summary:
- Each taste, from sweet to salty, is sensed by a unique set of neurons in the brains of mice, new research reveals. The findings demonstrate that neurons that respond to specific tastes are arranged discretely in what the scientists call a ‘gustotopic map.’ This is the first map that shows how taste is represented in the mammalian brain.
Each taste, from sweet to salty, is sensed by a unique set of neurons in the brains of mice, new research reveals. The findings demonstrate that neurons that respond to specific tastes are arranged discretely in what the scientists call a “gustotopic map.” This is the first map that shows how taste is represented in the mammalian brain.
There’s no mistaking the sweetness of a ripe peach for the saltiness of a potato chip — in part due to highly specialized, selectively-tuned cells in the tongue that detect each unique taste. Now, Howard Hughes Medical Institute and NIH scientists have added to our understanding of how we perceive taste, showing that four of our basic tastes — sweet, bitter, salty, and “umami,” or savory — are also processed by distinct areas of the brain. The researchers published their work in the September 2, 2011, issue of the journal Science.
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The Nose And Nasal Cavity
Olfactory sensitivity is directly proportional to spatial area in the nosespecifically the olfactory epithelium, which is where odorant reception occurs. The area in the nasal cavity near the septum is reserved for the olfactory mucous membrane, where olfactory receptor cells are located. This area is a dime-sized region called the olfactory mucosa. In humans, there are about 10 million olfactory cells, each of which has 350 different receptor types composing the mucous membrane. Each of the 350 receptor types is characteristic of only one odorant type. Each functions using cilia, small hair-like projections that contain olfactory receptor proteins. These proteins carry out the transduction of odorants into electrical signals for neural processing.
The Olfactory System: A cross-section of the olfactory system that;labels all of the structures necessary to process odor information.
Olfactory transduction is a series of events in which odor molecules are detected by olfactory receptors. These chemical signals are transformed into electrical signals and sent to the brain, where they are perceived as smells.
Olfactory Nerve: The olfactory nerve connects the olfactory system to the central nervous system to allow processing of odor information.
What Are Taste Papillae
The taste papillae are a good number of wart-like bumps under the mucous membrane of the tongue. They increase the surface area of the tongue several times and make sure that individual tastes can be perceived more intensely. This is also called the magnifying effect of the tongue. The papillae contain several taste buds with sensory cells.
There are three types categorized by their shape:
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Olfactorytaste Convergence To Represent Flavour And The Influence Of Satiety
To investigate where in the human brain interactions between taste and odour stimuli may be realised to implement flavour, an event-related fMRI study has been performed with sucrose and monosodium glutamate taste, and strawberry and methional odours, delivered unimodally or in different combinations. The brain regions that were shown to be activated by both taste and smell include parts of the caudal orbitofrontal cortex, amygdala, insular cortex and adjoining areas, and anterior cingulate cortex. It was shown that a small part of the anterior insula responds to unimodal taste and to unimodal olfactory stimuli, and that a part of the anterior frontal operculum is a unimodal taste area not activated by olfactory stimuli. Activations to combined olfactory and taste stimuli where there is little or no activation to either alone were found in a lateral anterior part of the orbitofrontal cortex. Correlations with consonance ratings for the smell and taste combinations, and for their pleasantness, were found in a medial anterior part of the orbitofrontal cortex . Similarly, Small et al. have also found supradditive interactions between congruent taste and smell stimuli in areas including the caudal orbitofrontal cortex and anterior cingulate cortex . These results provide evidence on the neural substrate for the convergence of taste and olfactory stimuli to produce flavour in human subjects, and where the pleasantness of flavour is represented in the human brain.
What Are The Parts Of The Nervous System
The nervous system is made up of the central nervous system and the peripheral nervous system:
- The brain and the spinal cord are the central nervous system.
- The nerves that go through the whole body make up the peripheral nervous system.
The human brain is incredibly compact, weighing just 3 pounds. It has many folds and grooves, though. These give it the added surface area needed for storing the body’s important information.
The spinal cord is a long bundle of nerve tissue about 18 inches long and 1/2-inch thick. It extends from the lower part of the brain down through spine. Along the way, nerves branch out to the entire body.
Both the brain and the spinal cord are protected by bone: the brain by the bones of the skull, and the spinal cord by a set of ring-shaped bones called vertebrae. They’re both cushioned by layers of membranes called meninges and a special fluid called cerebrospinal fluid. This fluid helps protect the nerve tissue, keep it healthy, and remove waste products.
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Show/hide Words To Know
Cerebral Cortex: the outer layers of the brain responsible for important brain functions, like thinking and feeling…;more
Cranial: relating to the skull or brain. The cranial nerves carry signals between the brain and body.
Gland: an organ that releases materials for use in certain places in the body or on the outside of the body…;more
Neurotransmitter: a chemical that acts as a messenger and communicates information throughout the brain and body. Nerve tissue uses neurotransmitters to communicate….more
Receptor: a molecule on the surface of a cell that responds to specific molecules and receives chemical signals sent by other cells.
Thalamus: is the part of the brain that works like a switching station. This part of the brain takes information coming from the body and sends it on to the cerebral cortex…;more
Taste Smell And Flavor
What is generally categorized as taste is basically a bundle of different sensations: it is not only the qualities of taste perceived by the tongue, but also the smell, texture and temperature of a meal that are important. The coloring of a taste happens through the nose. Only after taste is combined with smell is a foods flavor produced. If the sense of smell is impaired, by a stuffy nose for instance, perception of taste is usually dulled as well.
Like taste, our sense of smell is also closely linked to our emotions. This is because both senses are connected to the involuntary nervous system. That is why a bad taste or odor can bring about vomiting or nausea. And flavors that are appetizing increase the production of saliva and gastric juices, making them truly mouthwatering.;
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Role In The Taste Pathway
Like the olfactory system, the taste system is defined by its specialized peripheral receptors and central pathways that relay and process taste information. Peripheral taste receptors are found on the upper surface of the tongue, soft palate, pharynx, and the upper part of the esophagus. Taste cells synapse with primary sensory axons that run in the chorda tympani and greater superficial petrosal branches of the facial nerve , the lingual branch of the glossopharyngeal nerve , and the superior laryngeal branch of the vagus nerve to innervate the taste buds in the tongue, palate, epiglottis, and esophagus respectively. The central axons of these primary sensory neurons in the respective cranial nerve ganglia project to rostral and lateral regions of the nucleus of the solitary tract in the medulla, which is also known as the gustatory nucleus of the solitary tract complex. Axons from the rostral part of the solitary nucleus project to the ventral posterior complex of the thalamus, where they terminate in the medial half of the ventral posterior medial nucleus. This nucleus projects in turn to several regions of the neocortex which includes the gustatory cortex ” rel=”nofollow”>operculum and the insula), which becomes activated when the subject is consuming and experiencing taste.
V Meeting Science Educationstandards
The Benchmarks are listed by chapter, grade level, and item number; forinstance, 1A, 6-8, #1 indicates Chapter 1, section A, grades 6-8,benchmark 1.
The process of inquiry used in the sense of taste activities will help students reach the followingsummarized Benchmarks:
- 1A, 6-8, #1: When similar investigations give different results, thescientific challenge is to judge whether the differences are trivial orsignificant, and it often takes further studies to decide.
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Fixed Meal Times And The Availability Of Food
Another factor that could contribute to obesity is fixed meal times, in that the normal control of food intake by alterations in inter-meal interval is not readily available in human subjects, and food may be eaten at a meal time even if hunger is not present . Furthermore, because of the high and easy availability of food and stimulation by advertising, there is a tendency to start eating again when satiety signals after a previous meal have decreased only a little, and the consequence is that the system again becomes overloaded.
The Flavor Experience: Integration By The Brain
A message of taste moves from the taste buds in the tongue to the brain through cranial nerves. The signal is first received by areas in the brainstem, which connects the spinal cord with the rest of the brain. The signal then moves to the thalamus in the brain. Finally, the thalamus passes the signal onto a special area in the frontal lobe of the cerebral cortex, the gustatory cortex, where the taste signal is interpreted. The signal from the taste buds in the tongue to the brain moves between nerve cells through the release of special chemicals called neurotransmitters.
Taste and smell combine to make the flavor you taste when you eat food, like a cupcake. “Maya with Cupcake” painting by Maria Raquel Cochez. Click to enlarge.
Smell from odor receptors in the nose also have a direct connection to the brain. The odor signal travels to the primary olfactory cortex, or the smell center of the brain. The taste and odor signals meet, and produce the perception of flavor. Once our brains are aware of the flavor, a reaction is produced. We either accept or reject the food because we either enjoy it or not.
There are other reactions to food that dont involve processing by the brain. Has food every been so spicy it made you cry, or your nose drip? In addition to the nerves that carry signals from the taste receptors to the brain, there are other nerves that carry the signal from the taste receptor cells to the nasal cavity and to tear-producing glands near the eyes.
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It Starts At The Tongue: From Substance To Taste
But what is taste actually? What happens in our body that enables us to perceive flavor? The chemical substance responsible for the taste is freed in the mouth and comes into contact with a nerve cell. It activates the cell by changing specific proteins in the wall of the sensory cell. This change causes the sensory cell to transmit messenger substances, which in turn activate further nerve cells. These nerve cells then pass information for a particular perception of flavor on to the brain.
The numerous wart-like bumps on the mucous membrane of the tongue are where the substance producing the taste is transformed into a nerve signal. These bumps, which are called taste papillae, contain many sensory cells with a special structure: together with other cells they make up a bud that looks a bit like an orange with its sections arranged around a center.
In the middle of the top side is a small indentation filled with fluid. The chemical substances responsible for the taste are washed into this funnel-like hollow. This makes sure that the substances are detected and analyzed by as many sensory cells as possible before being swallowed.
Overview Of Smell And Taste Disorders
, MD, Montefiore Medical Center, The University Hospital of Albert Einstein College of Medicine
Because disorders of smell and taste are rarely life threatening, they may not receive close medical attention. Yet, these disorders can be frustrating because they can affect the ability to enjoy food and drink and to appreciate pleasant aromas. They can also interfere with the ability to notice potentially harmful chemicals and gases and thus may have serious consequences. Occasionally, impairment of smell and taste is due to a serious disorder, such as a tumor.
Smell and taste are closely linked. The taste buds of the tongue identify taste, and the nerves in the nose identify smell. Both sensations are communicated to the brain, which integrates the information so that flavors can be recognized and appreciated. Some tastessuch as salty, bitter, sweet, and sourcan be recognized without the sense of smell. However, more complex flavors require both taste and smell sensations to be recognized.
A partial loss of smell and complete loss of smell are the most common disorders of smell and taste. Because distinguishing one flavor from another is based largely on smell, people often first notice that their ability to smell is reduced when their food seems tasteless.
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How The Sense Of Taste Works
Taste, or gustatory perception, is one of our basic senses. It tells us from early childhood what is edible and what is not, what is good for our body and what can be potentially dangerous. Taking into account how important the sense of taste is for us, it is surprising how little we know about the underlying neurological mechanisms that produce the sensation of taste.
Taste relies on sensing certain molecules in food. Chemical recognition of these molecules on our tongue generates a signal which is sent to the brain and processed there. Processed signals give us certain ideas about the kind of food we are dealing with and allows us to take certain decisions and modify our behavior accordingly. For instance, sweetness is typically associated with highly caloric, attractive food, while bitterness might signal danger, since many toxins are associated with this taste.
The second part of the gustatory perception process, signal processing, is significantly less understood, and lots of research studies these days are aiming to figure out how our brain generates the huge variety and complexity of tastes using just a few basic taste receptors.
This, however, is only a part of the story: the taste we feel is not formed exclusively from the information received from the taste buds. The smell of food detected by the olfactory epithelium in the nose is another contributing factor which clearly works together with the taste perceived in the mouth.
Iiiplanning And Teaching Lab Activities
Provide background information
First, prepare students for lab activities by giving backgroundinformation according to your teaching practices . Because students have no way ofdiscovering sensory receptors or nerve pathways for themselves, they needsome basic anatomical and physiological information. Teachers may choosethe degree of detail and the methods of presenting the sense of taste,based on grade level and time available.
Offer students the chance to create their ownexperiments
While students do need direction and practice to become good laboratoryscientists, they also need to learn how to ask and investigate questionsthat they generate themselves. Science classrooms that offer only guidedactivities with a single “right” answer do not help students learn toformulate questions, think critically, and solve problems. Becausestudents are naturally curious, incorporating student investigations intothe classroom is a logical step after they have some experience with asystem.
The “Try Your Own Experiment” section of this unit offers students an opportunity to direct someof their own learning after a control system has been established in the”Class Experiment.” Because students are personally vested in this type ofexperience, they tend to remember both the science processes and conceptsfrom these laboratories.
Use “Explore Time”before experimenting
Explore before the Class Experiment
Explore before “Try Your Own Experiment”
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