Sleep Disorders And Sleep
There are many sleep disorders that can influence sleep. They range from narcolepsy, which results in excessive fatigue, to insomnia, which makes it hard to get enough sleep. Sleep researchers are hard at work learning more about sleep and sleep disorders in order to help people get the sleep that they need. If you struggle with a sleep disorder, talk to your doctor or see a sleep specialist to help protect your brains health.
What Causes Shortage Of Sleep
Common causes of chronic insomnia include: Stress. Concerns about work, school, health, finances or family can keep your mind active at night, making it difficult to sleep. Stressful life events or trauma such as the death or illness of a loved one, divorce, or a job loss also may lead to insomnia.
Coupling Circadian Oscillators In The Scn
Individual SCN neurons exhibit autonomous circadian rhythms even when isolated in culture . The circadian period, phase, and amplitude differ from each other in dispersed cell culture, although their rhythms are synchronized in SCN slices and in vivo . Due to the involvement of heterogeneous oscillators in the SCN, individual SCN cells must couple to each other. Synchronized circadian rhythms in the SCN entrain lightdark cycles to adapt to environmental lightdark conditions. It is thought that GABA may be involved in mediating circadian rhythm coupling in individual SCN neurons.
B Rem Sleep Master Control Mechanisms
1. Location and neurotransmitter content of REM sleep controlling neurons in the brain stem
2. Mechanisms controlling NREM-REM transitions
One of the most consistent features of human sleep is the alternation between NREM and REM sleep during the night. Early sleep is characterized by a progression from light NREM to deeper stages of NREM sleep with the first REM episode occurring ~90 min into sleep. The 90-min cycles of NREM and REM sleep continue through the night with the proportion of REM sleep steadily increasing and the proportion of deep NREM declining over the course of a nightâs sleep. Lower mammals, including rats, mice, and cats, do not have such long consolidated periods of sleep as humans each of the behavioral states is much shorter and more transitions occur between states. However, the general sleep architecture is similar in that, with the exception of disease states , sleep following a period of prolonged wakefulness is initially NREM sleep. REM sleep follows a period of NREM and is not entered into directly from wakefulness.
A) Reciprocal Interaction Model (Cholinergic and Aminergic Mechanisms
IV) Evidence supporting the reciprocal interaction model: cholinergic excitation of aminergic neurons. Cholinergic neurons directly excite LC neurons . Cholinergic agonists acting on nicotinic receptors indirectly excite DRN serotonin neurons via a presynaptic facilitation of excitatory noradrenergic inputs .
B) Gabaergic Control of Rem Sleep
Which Part Of The Brain Controls Temperature
The hypothalamus controls temperature. The hypothalamus has a dual system of temperature regulation. Thus, the anterior or rostral portion, composed of parasympathetic centers, is responsible for dissipating heat, while in the posterior portion, with sympathetic centers, it preserves and maintains body temperature.
The perception n of temperature It is relative, since we do not have receptors to perceive the temperature in an absolute way. We are only capable of perceiving sudden changes in temperature for example, when moving our hand from a very cold water pot to a very hot one.
There are two types of receptors, some for cold and others for heat, heterogeneously distributed throughout the skin. Receptors for cold are closer to the epidermis, while receptors for heat are deeper. They are the same receptors they only differ on the level of situation.
The transduction in these receptors is produced by the deformation of the membrane or the cone of the receptor as a result of the dilation or contraction of the skin. This produces the opening of the membrane and the sodium channels.
If the receptors are densely packed together, the sensation of heat will be more intense. The nuclei associated with our having difficulty perceiving cold and heat from the thalamus are intralaminar and to a lesser extent ventricular.
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Process C And Process S
The two-process model provides a useful macroscopic perspective on the dynamic control of sleep and wakefulness. It is likely that a homeostatic factor accumulates during wakefulness and declines during sleep, and this factor interacts with a circadian process that helps regulate the timing of wakefulness and REM sleep. After a period of wakefulness, delta power in NREM sleep is thought to be a good indicator of Process S,, and somnogens such as adenosine may be the neurobiologic equivalent of Process S as disruption of adenosine signaling can blunt the usual increase in NREM sleep and the intense EEG delta power seen after sleep deprivation.
Neuroscientists Identify Cell Type In Brain That Controls Body Clock Circadian Rhythms
- UT Southwestern Medical Center
- Neuroscientists have identified key cells within the brain that are critical for determining circadian rhythms, the 24-hour processes that control sleep and wake cycles, as well as other important body functions such as hormone production, metabolism, and blood pressure.
UT Southwestern Medical Center neuroscientists have identified key cells within the brain that are critical for determining circadian rhythms, the 24-hour processes that control sleep and wake cycles, as well as other important body functions such as hormone production, metabolism, and blood pressure.
Circadian rhythms are generated by the suprachiasmatic nucleus located within the hypothalamus of the brain, but researchers had previously been unable to pinpoint which of the many thousands of neurons in the region were involved in controlling the bodys timekeeping mechanisms.
We have found that a group of SCN neurons that express a neuropeptide called neuromedin S is both necessary and sufficient for the control of circadian rhythms, said Dr. Joseph Takahashi, Chairman of Neuroscience and Howard Hughes Medical Institute Investigator at UT Southwestern, who holds the Loyd B. Sands Distinguished Chair in Neuroscience.
Key studies in the 1970s revealed that the SCN communicates and coordinates cells throughout the body to control circadian rhythms, but the SCN contains many neurons with different expression patterns of neuropeptides and neurotransmitters.
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The Cell Structure Of The Brain
The brain is made up of two types of cells: neurons and glial cells, also known as neuroglia or glia. The neuron is responsible for sending and receiving nerve impulses or signals. Glial cells are non-neuronal cells that provide support and nutrition, maintain homeostasis, form myelin and facilitate signal transmission in the nervous system. In the human brain, glial cells outnumber neurons by about 50 to one. Glial cells are the most common cells found in primary brain tumors.
When a person is diagnosed with a brain tumor, a biopsy may be done, in which tissue is removed from the tumor for identification purposes by a pathologist. Pathologists identify the type of cells that are present in this brain tissue, and brain tumors are named based on this association. The type of brain tumor and cells involved impact patient prognosis and treatment.
Intracellular Chloride Concentrations And Cellular Coupling
Long-day photoperiods also change the excitability , and levels of chloride transporter expression in SCN neurons. This determines the difference in circadian phase and period between the dorsal and ventral SCN . It was observed that under long-day conditions, the phase difference in Bmal1 promoter-driven luciferase reporter circadian rhythms between the dorsal and ventral SCN were increased, and the circadian period of the dorsal SCN was decreased compared with the ventral SCN. Myung et al. also measured intracellular chloride concentrations in the SCN, using N6-methoxyquinoliniumbromide fluorescence, and found that intracellular chloride concentrations were increased under long-day photoperiods. These results are due to a higher expression ratio of sodium/potassium/chloride cotransporter /potassium/chloride cotransporters , in the dorsal than the ventral SCN. Because NKCC1 is a chloride importer, a high ratio of NKCC1/KCC2 results in more GABA-induced excitation. KCC2 is expressed exclusively in VIP and GRP neurons, whereas NKCC1 is expressed in VIP, GRP, and AVP neurons within the SCN . Recently, Klett and Allen reported that intracellular chloride concentrations were higher during the day than at night in both AVP- and VIP-positive neurons . The prevalence of GABA excitation and inhibition is dependent on the level of chloride transporter expression and may affect the coupling of dorsal and ventral SCN circadian oscillations.
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B Control Of Sleep Timing And Intensity
The timing, depth, and duration of sleep are controlled by the interaction of time of day and by the duration of prior wakefulness as proposed in the two-process model of Borbely . The cellular mechanisms in the suprachiasmatic nucleus which generate circadian rhythms are not covered herein, since they have been reviewed extensively elsewhere . The output pathways from the SCN that control the circadian timing of NREM and REM sleep are covered in sections III and IV. Homeostatic control of sleep is also covered in these sections.
What Youll Learn To Do: Describe What Happens To The Brain And Body During Sleep
We devote a very large portion of time to sleep, and our brains have complex systems that control various aspects of sleep. Several hormones important for physical growth and maturation are secreted during sleep. While the reason we sleep remains something of a mystery, there is some evidence to suggest that sleep is very important to learning and memory.
You may not feel particularly busy while you sleep, but youll learn in this section that your brain and body are quite active. You pass through four different stages of sleep. In this section, youll learn more about these sleep stages, dreaming, and sleep disorders.
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What Is A Synapse
The synapse, rather, is that small pocket of space between two cells, where they can pass messages to communicate. A single neuron may contain thousands of synapses. In fact, one type of neuron called the Purkinje cell, found in the brains cerebellum, may have as many as one hundred thousand synapses.
Components Of The Brainstem
The three components of the brainstem are the medulla oblongata, midbrain, and pons.
Brainstem Anatomy: Structures of the brainstem are depicted on these diagrams, including the midbrain, pons, medulla, basilar artery, and vertebral arteries.
The medulla oblongata is the lower half of the brainstem continuous with the spinal cord. Its upper part is continuous with the pons. The medulla contains the cardiac, respiratory, vomiting, and vasomotor centers regulating heart rate, breathing, and blood pressure.
The midbrain is associated with vision, hearing, motor control, sleep and wake cycles, alertness, and temperature regulation.
The pons lies between the medulla oblongata and the midbrain. It contains tracts that carry signals from the cerebrum to the medulla and to the cerebellum. It also has tracts that carry sensory signals to the thalamus.
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Why Does Caffeine Wake You Up
Melatonin is not the only chemical that determines our sleep schedule. Adenosine also plays an important role: it slows down the activity of neurons.It gradually builds up in our bodies when we are awake and makes us feel sleepy by the end of the day. Then, when we sleep, adenosine molecules break down, so the cycle can start all over again. Our neurons, or nerve cells, are embedded with adenosine receptors. When adenosine binds to these receptors, a variety of proteins that inhibit neurons are released. This suppression of nerve cell activity is what causes the feeling of drowsiness.
Caffeine has a chemical structure similar to that of adenosine . Both molecules have a double-ring structure, which allows caffeine to bind to adenosine receptors. Unlike adenosine, however, caffeine does not activate these receptors or suppress neuron activity. By reducing the concentration of available adenosine receptors, caffeine slows the rate of reaction: Less-bound adenosine means we feel less sleepy.
Cortical And Thalamic Activity Across Sleep And Wakefulness
All the arousal systems we have discussed thus far are located in the BF, hypothalamus, or brainstem and exert diffuse effects on the cortex and many other target regions. These subcortical systems are essential for the generation of sleep/wake states and for the regulation of the transitions between these states. However, patterns of EEG activity and consciousness itself arise from interactions between these subcortical systems, the thalamus, and the cortex.
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Information Systems And Functional Genomics Of Arousal State Control
The ability to create in real time a complete, digital, anesthesia record offers a powerful tool for translational research. The large amount of human physiologic information that can be synthesized by digital information systems has the potential to provide anesthesiology with unique patient data for phenotyping comorbidities. These information systems also give anesthesiology a special opportunity for developing a functional genomics that can link genetic factors to anesthesia outcome.
A Electrographic Signs Of Nrem Sleep
In humans, the different stages of NREM sleep are classified according to the criteria established by Rechtschaffen and Kales . Stage 1 NREM sleep exhibits theta activity at frontal sites and alpha activity posteriorally, similar to drowsy waking . Stage 2 NREM sleep is characterized by the appearance of sleep spindles and K-complexes in the EEG. Stages 3 and 4 of NREM sleep exhibit prominent, high-amplitude slow, delta waves . The cortical slow oscillation discovered by Steriade and colleagues synchronizes the activity of cortical and thalamic neurons that generate spindle and delta waves throughout NREM sleep . In animals, NREM sleep is not usually subdivided into these four stages, but deep sleep may be distinguished from light NREM sleep. NREM sleep is also characterized by low skeletal muscle tone and slow, rolling eye movements. Here we first describe phasic events occurring during NREM sleep in the thalamocortical system and hippocampal formation and then discuss the delta and slow oscillations typical of deep NREM sleep.
1. Thalamocortical spindles
A) Cellular Mechanisms Underlying Spindles
B) Inhibition of Spindles During Wakefulness and Rem
2. Hippocampal sharp waves and high-frequency ripples
3. Delta and slow oscillations
A) Role of Low-Threshold Calcium Channels in Delta Waves
B) The Neocortical Slow Oscillation
C) Cellular Mechanism Causing up and Down States
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The Arousal Network: Interactions Among Wake
Each of the arousal systems presented above is independently capable of promoting wakefulness, yet these systems work together to generate behavioral arousal. Anatomically, there are many interconnections between the systems. For instance, ACh and 5-HT fibers innervate and excite LC neurons, and nearly all wake-promoting neurons respond to HA, NE, and orexin. In addition, these neurotransmitters often produce similar effects on their targets. For example, all the arousal systems excite thalamic and cortical neurons. These interconnections and parallel effects may explain why injury to any one of the arousal systems often produces little lasting effect on wakefulness. Functionally, this is adaptive, as it helps ensure that wakefulness will still occur after injury to any one of the arousal systems. In fact, there are only a few brain regions in which lesions produce lasting reductions in arousal. One is the rostral reticular formation in the midbrain and posterior hypothalamus in which lesions from strokes or tumors can produce severe hypersomnolence or even coma, probably from damage to many of the ascending monoaminergic and cholinergic pathways.
Dropping Into Quiet Sleep
To an extent, the idea of dropping into sleep parallels changes in brain-wave patterns at the onset of non-REM sleep. When you are awake, billions of brain cells receive and analyze sensory information and coordinate behavior by sending electrical impulses to one another. If youre fully awake, an EEG records a messy, irregular scribble of activity. Once your eyes are closed and your brain no longer receives visual input, brain waves settle into a steady and rhythmic pattern of about 10 cycles per second. This is the alpha-wave pattern, characteristic of calm, relaxed wakefulness .
The transition to quiet sleep is a quick one that might be likened to flipping a switchthat is, you are either awake or asleep , according to research.
Unless something disturbs the process, you will proceed smoothly through the three stages of quiet sleep.
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Multiple Traits Define Arousal States
The success of sleep neurobiology has been derived, in part, from deconstructing states into their component traits and then characterizing the mechanisms regulating those traits. Those data, and the lack of support for a unitary hypothesis of anesthesia,, make clear that characterizing the mechanisms generating anesthetic traits provides a powerful paradigm for gaining insight into the regulation of anesthetic states. The desirable anesthetic state is a constellation of reversible traits that include analgesia, amnesia, unconsciousness, blunted sensory and autonomic reflexes, and skeletal muscle relaxation. In addition to the characteristic of reversibility, another goal of anesthesia is the temporal coordination of the foregoing five traits. Ideally, the onset of these drug-induced traits occurs at approximately the same time. Undesirable anesthetic complications often are characterized by temporal dissociations in the offset of drug-induced traits, such as failure of a seemingly awake, postanesthetic patient to maintain upper airway patency. As with successful anesthesia, normal sleep also requires the temporal coordination of multiple traits. In fact, the nosology of many sleep disorders is characterized by the intrusion of sleep traits into the state of wakefulness or the expression of waking traits during sleep .
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.
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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