The relationship between sleep and memory has been postulated and studied since at least the beginning of the nineteenth century. Memory, the cognitive process in which experience, learning and recognition are remembered, is the product of brain plasticity, the structural changes in the synapses that create the association between stimuli. Stimuli are encoded in milliseconds; however, long-term care from memory can take an additional minute, day, or even year to fully consolidate and become a stable memory (more resistant to changes or disturbances). Therefore, the formation of certain memory occurs quickly, but the evolution of memory is often an ongoing process.
Memory processes have proven to be stable and enhanced (accelerated and/or integrated) and memory is more consolidated by night sleep and even naps. Certain sleep stages have been shown to be an increase in individual memory, although this is a special task. In general, declarative memories are believed to be enhanced by slow-wave sleep, while non-declarative memory is enhanced by rapid eye movement (REM) sleep, although there are some inconsistencies among experimental results. The effect of sleep on memory, especially those related to the human brain, is the field of active research in neurology, psychology, and related disciplines.
Video Sleep and memory
History
In 1801, David Hartley first postulated that dreaming alters the associative planetary link in the brain during the dreaming dream period. The idea that sleep has the effect of mental recovery, sorting and consolidating memories and ideas, intellectually acceptable at the end of the 19th century. In 'Peter and Wendy', JM Barrie writes 'It is the everyday habit of every good mother after her children fall asleep to search in their minds and put things straight the next morning, repackage to their places exactly a lot of articles that have been wandering around during the day.... When you wake up in the morning, the nasty anger and lust that you slept on has been folded small and placed at the base of your mind; and above, beautifully aired, scattered your more beautiful mind, ready for you to wear. The stories of Peter Pan occur in the mental world and contain many references to aspects of cognitive psychology, some of which precede their formal scientific investigations.
The first semi-multiple-systematic study of the relationship between sleep and memory was conducted in 1924 by Jenkins and Dallenbach, for the purpose of testing the theory of memory decay Hermann Ebbinghaus. Their results indicate that memory retention is much better after the sleep period compared to the same time interval spent waking hours. It was not until 1953, however, when sleep was described to be a rapid eye movement sleep and non-rapid eye movement sleep, studies that focused on the effects of certain stages of sleep on memory were performed. Because the behavioral characteristics of the sleep and memory effects become increasingly understood and supported, the researchers move to a fully understood sleep and memory base.
Maps Sleep and memory
Sleep cycle
Sleep lasts in cyclical mode through five stages. These four stages are collectively referred to as the non-rapid eye movement (NREM) sleep while the last cycle is a period of rapid eye movement. One cycle takes about 90-110 minutes to complete. Consciousness is found through EEG measurements that will be characterized by beta waves which are the highest and lowest frequencies in amplitude and tend to move inconsistently due to the large number of stimuli that a person encounters while awake.
- Pre-sleep is a period of perceptual degradation in which brain activity is characterized by a more rhythmic alpha wave , higher in amplitude and lower frequency than the beta wave.
- The first stage is characterized by light sleep and lasts about 10 minutes. Brain waves gradually transition into theta waves .
- The second stage also contains theta waves; However, a random burst of increasing frequency called sleep spindles is a defining characteristic of this stage.
- Stage three and four are very similar and together are considered "deep sleep." At this stage the activity of the brain transitions to the delta waves, which is the lowest and highest frequency in amplitude. These two combined stages are also called slow wave sleep (SWS).
- Stage five, REM sleep, is one of the most interesting stages because the brainwave pattern is similar to that seen in a relaxed consciousness. This is referred to as "active sleep" and is the period when most dreams occur. REM sleep is also considered to play a role in the cognitive development of infants and children as they spend more of their sleep time in the REM period as opposed to adults.
During the first half of the night, the largest portion of sleep is spent as SWS, but as night progresses, the SWS stage decreases in length while the REM stage rises.
Memory term
Stabilization vs. increase
Memory Stabilization is a memory retainer in place, where weak connections are formed. Procedural memory stabilization can even occur during waking hours, indicating that certain non-declarative tasks are enhanced by the absence of sleep. When the memory is said to be improved, however, the connection is reinforced by the exercise as well as connecting it with other related memories thus making the retrieval more efficient. While non-declarative memory stabilization can be seen to occur during awake states, the increase of most sensory and motor memory is found to occur during night sleep.
Processes that depend on usage vs. experience-dependent process
Brain activity that occurs during sleep is assessed in two ways: Dependency-use, and Dependency-Experience. Brain activity that depends on usage is the result of nerve use that occurs during the previous waking hours. Basically nerve regeneration, the activity that occurs whether you have learned something new or not.
Experimental brain activity is the result of new situations, environments, or tasks or facts learned that have occurred in the pre-bed period. This is a type of brain activity that demonstrates the consolidation/improvement of memory.
It is often difficult to distinguish between them in an experimental setting because the setting itself is a new environment. This new environment will be seen in brain activity sleep along with newly learned tasks. To avoid this, most researchers insist participants spend one day in experimental conditions before testing begins so the setting is not new once the experiment begins. This ensures the data collected for brain activity that depends on the pure experience of the new task.
Consolidation
Memory consolidation is a process that takes an initially unstable representation and encodes it in a more robust, effective, and efficient way. In this new state, memory is less susceptible to interference. There are basically three phases of memory consolidation and all are considered facilitated by sleep or no sleep:
- Stabilization is a coding of memory that takes only 6 milliseconds.
- Improvement is a continuous consolidation process that can happen for a few minutes, 7 hours, days but not longer. Post-sleep behavioral activities can be seen to show significant improvement in the absence of exercise.
- Integration can also take hours or years and is the process of connecting recent encoded memory to an existing memory network.
Reconsolidate
Memory reconsolidation involves retrieving consolidated (explicit or implicit) memory, into short or working memory. Here it is brought to a volatile state where the next information can 'interfere' with what is currently in memory, thus altering the memory. This is known as a retroactivity disorder, and is a very significant problem for the court and eyewitness testimony.
Pre-training vs. post-training sleep deprivation
Researchers approached the study of sleep and memory from various angles. Several studies measured the effects of lack of sleep after new tasks were taught (subjects studied the task and sleep deprivation afterwards). This is referred to as lack of post-training sleep . Instead, other experiments have been conducted that measure the effects of lack of sleep before a task has been taught (subjects can not sleep and then learn the task). This is referred to as pre-training for lack of sleep .
offline memory processing
Neuroimaging can be classified into two categories, both used in various situations depending on what type of information is required. Structural imaging is related to brain structure (computed tomography) while functional imaging is more associated with metabolic processes in terms of anatomical function (positron emission tomography, functional magnetic resonance imaging). In recent years, the relationship between sleep and memory processes has been aided by the development of neuroimaging techniques.
Positron emission tomography (PET) is used in viewing the functional processes of the brain (or other body parts). Radionuclides that emit positrons are injected into the bloodstream and emit gamma rays detected by imaging. Computer analysis then enables 3-dimensional reconstruction of an area of ​​the brain or an attractive body part.
Functional magnetic resonance imaging (fMRI) is a type of brain imaging that measures the oxygen changes in the blood due to the activity of neurons. The resulting data can be visualized as a brain image with a colored representation of activation.
Molecular measurements
Although this may look similar to neuroimaging techniques, molecular measurements help increase the area of ​​activation that can not be solved with neuroimaging. One technique that helps both the temporal and visual fMRI resolution is the oxygen-level-dependent (BOLD) response. Changes in the BOLD response can be seen when there are different levels of activation in the areas that are suspected to work. Energy is supplied to the brain in the form of glucose and oxygen (which is transferred by hemoglobin). The blood supply is consistently regulated so that the activation area receives a higher amount of energy than the less-activated area. In positron emission tomography, the use of radionuclides (isotopes with a short half life) facilitates visual resolution. The radionuclides are attached to glucose, water and ammonia so that easy absorption into the activated brain area is achieved. Once these radioactive tracers are injected into the bloodstream, the efficiency and location of chemical processes can be observed using PET.
Sleep measuring method
Electrophysiological Measurement
The main method of measuring sleep in humans is polysomnography (PSG). For this method, participants often have to come to the lab where researchers can use PSG to measure things like total sleep time, sleep efficiency, waking after sleep, and sleep fragmentation. PSG can monitor various body functions including brain activity (electroencephalography), eye movement (electrooculography), muscle movement (electromyography), and heart rhythm (electrocardiography).
Electroencephalography (EEG) is a procedure that records electrical activity along the scalp. This procedure can not record the activity of individual neurons, but measures the overall average electrical activity in the brain.
Electrooculography (EOG) measures the difference in electrical potential between the front and the back of the eye. It does not measure responses to individual visual stimuli, but measures common eye movements.
Electromyography (EMG) is used to record the electrical activity of the skeletal muscle. A device called an electromyograph measures the electrical potential of muscle cells to monitor muscle movement.
Electrocardiography (ECG or ECG) measures electrical depolarization of the heart muscles using various electrodes placed near the chest and limbs. This depolarization measure can be used to monitor heart rhythm.
Measures of behavior
Actigraphy is a common and minimally invasive way to measure sleep architecture. Actigraphy has only one method of recording, movement. This movement can be analyzed using different actigraphic programs. Thus, aktigraf can often be worn the same as a watch, or around the waist as a belt. Because of the minimally invasive and relatively inexpensive, this method allows for recording beyond the lab setting and for several days at a time. However, aktigraphy often exceeds the estimated time of sleep (de Souza 2003 and Kanady 2011).
Competing theories
Most studies show a specific deficit in declarative memory that forms a pre or post REM sleep deficiency. Conversely, deficits in non-declarative memory occur before or after NREM lack of sleep. This is a special stage improvement theory. There is also a proposed dual-step hypothesis suggesting that optimal learning occurs when memory traces are initially processed in SWS and then REM sleep. Support for this is demonstrated in many experiments where greater memory enhancement with either SWS or REM sleep compared with sleep deprivation, but memory is even more accurate when the sleep period contains both SWS and REM sleep.
Declarative memory
Declarative memory is memory for conscious events. There are two types of declarative memory: episodic and semantic. The episodic memory to remember the experience while the semantic memory given the specific facts.
Temporary memory
The temporal memory consists of remembering when a certain memory has occurred. In the study participants were placed in 4 groups; two control groups were either given caffeine or placebo and two groups who were sleep deprived for 36 hours were either given caffeine or a placebo. The task used to measure temporal memory consists of differentiating between recent and less recent facial presentations. A set of twelve foreign faces is presented sequentially every 10 seconds. The self-directed assignment is used afterwards for 5 minutes to prevent the exercise and to remain tired of the occupied participants. This requires them to mark each new item viewed (either noun or abstract form) presented on 12 sheets. The second set is presented, followed by another self-appointed task, and then a random sequence of 48 good faces containing previously presented or new faces presented to the participants. They were asked if they recognized the face and whether they came from the first or second set. The results showed that sleep deprivation did not significantly affect facial recognition, but resulted in significant temporal memory disturbance (distinguishing which face was defined). Caffeine was found to have a greater effect on the sleep-deprived group than in the sleep-deprived placebo group but still performed poorer than the controls. Lack of sleep is also found to increase confidence to be true, especially if they are wrong. Their brain-deprived brain imaging studies found that the largest decrease in metabolic rate in the prefrontal cortex.
Verbal learning
The oxygen-dependent blood-level FMRI (BOLD) is used in research by Drummond et al. to measure the brain's response to verbal learning after sleep deprivation. An fMRI records brain activity during a verbal learning task from either participants who have a normal night's sleep or those who lose 34.7 (Ã, Â ± 1.2) hours of sleep. The task alternates between the basic conditions of determining whether a noun is uppercase or lowercase and the experimental conditions given the list of nouns. The results showed that performance was significantly worse on free withdrawal from the noun list when sleep deprivation (mean 2.8 Ã, Â ± 2 words) compared with a normal night's sleep (4.7 Ã, Â ± 4 words). In the case of brain regions activated, the left prefrontal cortex, the premotor cortex, and the temporal lobe are found to be activated during the duty in a resting state and the discrete regions of the prefrontal cortex are even more active during the task in a state of sleep deprivation. In addition, the bilateral parietal lobe, left frontal gyrus front, and front right frontal gyrus are found to be activated for those who are sleep deprived. The implication of these findings is that the brain can initially compensate for the effects of lack of sleep while maintaining partial intact performance, which decreases with increasing time-on-task. This initial compensation can be found in the bilateral frontal and parietal regions of the lobe and the activation of the prefrontal cortex is significantly correlated with drowsiness.
Cognitive performance
Cerebral activation during performance in three cognitive tasks (verbal learning, arithmetic, and divided attention) than after normal sleep and 35 hours of total sleep deprivation (TSD) in a study by Drummond and Brown. The use of fMRI measures these differences in the brain. In a verbal learning task, fMRI shows the areas involved in verbal learning and memorization. The results found that TSD and normal night sleep showed a significant response in the prefrontal cortex and after TSD showed additional area responses that included other prefrontal areas, bilateral inferior parietal lobes and superior parietal lobes. Increased sleepiness also correlates with the activation of two ventral prefrontal areas and a correlation between greater activation of the bilateral parietal lobe (which includes the language area) and lower rates of memory impairment were also found after TSD. In arithmetical tasks, normal sleep indicates expected activation in the bilateral prefrontal and parietal areas of work, but after TSD only shows activation in the left superior parietal lobe and left pretreatal cortex in response, with no new area to be compensated (as found in verbal learning). Increased sleepiness also correlates with activation in the ventral prefrontal area, but only one region. The shared attention task combines both verbal learning and arithmetic tasks. fMRI indicates that the cerebral response after TSD is similar to the verbal learning task (especially the right prefrontal cortex, bilateral parietal lobe, and cingulate gyrus showing the strongest response). The implication of these findings is that additional brain areas activated after verbal learning and attention duties that are shared after TSD represent the brain compensatory response to sleep deprivation. For example, there is a decrease in left temporal lobe response during the two tasks involved in different learning tasks during resting conditions but inferior parietal lobe involvement in short-term verbal memory storage after TSD suggests that this region may be offset. There is no new area for arithmetic tasks that may indicate that it relies heavily on working memory so compensation is not possible, compared to tasks such as verbal learning that are less dependent on working memory.
Slow-wave sleep (SWS)
Slow wave sleep occurs during stages 3 and 4 of the sleep process. Slow wave activity increases by 25% after implicit learning and time spent in this sleep phase has been shown to improve the performance of tasks that are implicitly studied after sleep.
Macroscopic brain system
Correlation front brain front measurement
Researchers used mice to investigate the effects of new touch objects on the long-term evolution of major rodent forebrain loops important in species-specific behavior, including structures such as the hippocampus, putamen, neocortex and thalamus. The mice are monitored but uninterrupted for 48-96 hours, allowing normal sleep-wake cycles to occur. At some point four new touch objects are placed in the four corners of the mouse cage. They are all very different from each other and they are there for a total of one hour. Brain activity during this hour is used as a baseline or template to compare. The data analysis implies that the neural assembly during SWS correlates significantly with the template rather than during waking or REM sleep time. In addition, post-learning gossip, post-SWS lasts for 48 hours, longer than the duration of learning a new object (one hour), indicating long-term potential. Further analysis of neurons to the base of the neuron shows no part of the neuron (brain structure) responsible for the echo or anti-echo (the activity pattern is significantly different from the new stimulation template). Another notable difference is that the highest peak correlation in SWS is related to the lowest rate of neuronal firing in the forebrain, as opposed to REM sleep and wake up where the burn rate is the highest. It is hypothesized that this is due to interference from other incoming stimuli during the wake period. In SWS there is no incoming stimulus so the new experience can be played back, without interruption.
Hippocampal neural echo correlation
A study by Peigneux et al. , (2004) noted that the shooting sequences in the hippocampal ensemble during spatial learning were also active during sleep, indicating that post training sleep had a role in spatial memory processing. This study was conducted to prove that the same hippocampus area is activated in humans during route learning in virtual cities, and reactivated during subsequent slow wave sleep (SWS). To monitor this activation, the researchers used PET scans and fMRI to use cerebral blood flow as a marker of synaptic activity. The findings note that the amount of hippocampal activation during slow-wave sleep is positively correlated with an increase in the next day's virtual tour task, which indicates that hippocampal activity during sleep is correlated with improved memory performance. This finding proves that learning-dependent modulation in hippocampal activity during sleep suggests the previously studied episodic and spatial memory trace processing. This hippocampus modulation leads to plastic changes in the brain and ultimately performance improvements. The results of this study indicate that spatial memory traces are processed in humans when they are in NREM sleep. It shows the reaction of hippocampal formation during SWS, after decimalative spatial memory task. Experiments also found that in humans, there was modulation experience that depended on activity during NREM sleep in the hippocampal area, but not during REM sleep after learning. The evidence from this study is substantial for his hypothesis that information is learned upon awakening, alteration, and strengthening when humans are asleep.
Decrease of acetylcholine
In this study, two groups of participants took part in a two-night counterbalancing study. Two tasks are studied by all participants between 10: 00-10: 30pm. Declarative task is a list of coupled words-pair of 40 pair of related German semantic words. Non-declarative task is the task of copying the mirror. At 11:00 noon all participants were given a two hour infusion either physostigmine or placebo. Physostigmine is an acetylcholinesterase inhibitor; it is a drug that inhibits the breakdown of Acetylcholine's neurotransmitter inhibitor, allowing it to stay active longer in synapses. The sleeping group is put to sleep while the other groups stay awake. Testing of both tasks took place at 2:45 am, 30 minutes after sleep group awakened; sleep that has rich slow wave sleep (SWS). The results showed that the increase in ACh affects memory of negative memory (declarative task), in sleep state compared with participants who were given placebo. Specifically, recall after sleep for the placebo group showed an increase of 5.2 Ã, Â ± 0.8 words compared with an increase of only 2.1 Ã, Â ± 0.6 words when participants were given acetylcholinesterase inhibitors. In contrast, both speed and accuracy decreased in non-declarative mirror tasks when participants were given physostigmine, and task performance was also unaffected in the wake group when physotigmine was administered. This suggests that the goal of suppression of ACH during SWS allows for the consolidation of the hippocampus dependent declarative memory; a high ACh level during SWS blocks memory playback at hippocampal levels.
- Note: There is no correlation between SWS amount and withdrawal rate. Memory consolidation can be disrupted, however, if most of the SWs are lost.
Rising in the sleep spindle
Sleep spindles are short and intense bursts of synchronous spinning neurons, occurring in thalamo-cortical tissue. This peak is late at night and determines the characteristics of the second stage sleep. Sleep spindles are considered helpful in consolidating information during sleep and have been shown to increase after training on motor tasks.
A study, using 49 mice showed increased sleep coils during slow-wave sleep after learning. This provides evidence for an increase in spindle frequency during non-REM sleep after pairing of motor skills learning association duties. Using EEG, a sleep spindle is detected and shown to be present only during slow wave sleep. Beginning with a preliminary study, rats underwent six hours of observed sleep, after a period of study. The results showed that during the first hour after study, there was the most noticeable effect on sleep-modulated spindle density. However, increased spindle density does not depend on training conditions. In other words, there is an increase in spindles regardless of how the rats are trained. The EEG pattern showed a significant difference in sleep spindle density compared to the density of the rat control group, who did not undergo any training before their measured sleep spindles. This increased spindle density effect lasts only for the first hour until sleep after training, and then disappears within the second hour to fall asleep.
Appreciate learning and memory
In a study by Fischer and Born, 2009, prior knowledge of prize money and post-training sleep proved to be a significant predictor of the overall finger tapping performance. Subjects are presented with two different finger order tasks that must be replicated at a later time. The subject was informed that there would be a reward offered for improvement on the task of tapping a specific finger sequence. The control group was not given any knowledge of the prize. The subjects were further separated by allowing a sleep period between initial training and final testing for one group while the other group faced a wake-up retention interval. It was concluded that groups receiving information about rewards and sleep also displayed the highest performance improvements in both finger tapping sequences. Knowledge of gifts without sleep and sleep without knowledge of reward is a significant contributor to improving performance. In all cases sleep was determined to have a beneficial effect on overall performance when compared to the group undergoing a 12 hour retention period.
Non-declarative memory
Non-declarative memory is memory gained from previous experiences that are unconsciously applied to everyday scenarios. Non-declarative memory is essential for performance of learned skills and habits, for example, running or cooking favorite foods. There are three types of non-declarative memory: implicit memory (unconscious memory, priming), instrumental memory (classical conditioning), and procedural memory (automatic memory capability).
Lack of sleep
ERK phosphorylation
Kinases associated with extracellular signals, also known as classic MAP kinases, are a group of protein kinases located in neurons. This protein is activated or disabled by phosphorylation (addition of phosphate groups using ATP), in response to neurotransmitters and growth factors. It can produce subsequent proteins for protein interactions and signal transduction (neurotransmitters or sending hormones to cells), which ultimately control all cellular processes including gene transcription and cell cycle (important in learning and memory). A study tested four groups of rats in the Morris Water Maze, the two groups in the task of spatial (hidden platform) and two groups in the task of non-spatial (platform invisible.) The effects of six hours of total sleep sleep deprivation (TSD) is rated for the experimental group ( one spatial group, one non-spatial group) in both tasks. Six hours after the TSD period (or sleep period for control), the mice group was trained on one of the tasks then tested 24 hours later. In addition, the total level of phosphorylation of ERK (ERK 1 and ERK 2), a protein phosphate 1 (PP1), and MAPK phosphatase 2 (the latter two are both involved in the dephosphorylation) rated by beheading four groups of other mice, (two beds was reduced and two non -the bed is unplugged), and remove their hippocampus after six hours of TSD, or two hours after TSD (total of eight hours). The results show that TSD does not interfere with learning spatial tasks, but it destroys memory. With regard to non-spatial tasks, learning again does not differ in TSD; However, the memory in the TSD group is actually slightly better, though not significant enough. Analysis shows that TSD hippocampus significantly lower levels of total ERK phosphorylation by about 30%. TSD does not affect proteins in the cortex which indicates that the decrease in ERK levels is due to signal transduction interruption in the hippocampus. In addition, either PP1 or MAPK phosphatase 2 levels increased indicating that ERK decrease was not due to deposforilasi but as a result of TSD. Therefore, it is proposed that the TSD have aversive effects on cellular processes (ERK: gene transcription, etc.), Which underlies the flexibility of memory depends on the bed.
REM sleep
REM sleep is known for its apparent creation and resemblance to the bioelectric output of the awake person. This sleep stage is characterized by muscle atony, rapid EEG and low voltage and, as the name implies, rapid eye movement. It is difficult to attach memory gain to a single stage of sleep when it may be the entire sleep cycle that is responsible for memory consolidation. Recent research conducted by Datta et al. using evasion duties followed by a post-training REM sleeping period to examine changes in the P waves that affect the process of recurrence of recently acquired stimuli. It was found that not only the P waves increased during post sleep training but also the wave density. This finding may imply that P waves during REM sleep can help to activate the critical frontal brain and cortical structures associated with memory consolidation. In Hennevin et al. study, 1989, reticular mesencephalic formation (MRF) is given mild electrical stimulation, during REM sleep, which is known to have beneficial effects for learning when applied after training. Rats in trials are trained to run the maze in search of food rewards. One group of mice was given unstained MRF electrical stimulation after each of their labyrinth experiments compared to a control group that did not receive electrical stimulation. It appears that mice that are stimulated are significantly better in terms of error reduction. This finding implies that dynamic memory processes occur both during training and during post-training sleep. Another study by Hennevin et al. (1998) rats are conditioned to fear the sound associated with the next leg shock. An interesting part of this experiment is that fear that responds to noise (measured in the amygdala) is observed when noise is expressed during REM sleep. This is compared to a group of pseudo-conditioned rats that do not show the same amygdalar activation during post-training sleep. This will indicate that the nerves responding to stimuli previously prevalent are maintained even during REM sleep. There is no shortage of research done on the effects of REM sleep on the brain that works but consistency in findings is what struck recent research. There is no guarantee as to what REM sleep functions for our body and brain but modern research always extends and assimilates new ideas to advance our understanding of the process.
PGO wave
In animals, the emergence of ponto-geniculo-occipital waves (PGO waves) is related to the bioelectric output of rapid eye movement. This wave is most clearly seen during the transition from non-REM to REM sleep. Although phasic waves are observed in many parts of the animal's brain, they are most visible in pons, lateral geniculate bodies, and occipital cortex. Peigneux et al., 2006, reported that the lateral geniculate nuclei and the occipital cortex showed higher activity levels during REM sleep than when awake. This will add to the theory that activation in these areas is similar to the activation of PGO waves in animals. Waves of pontoons are commonly seen in animals as a mechanism to help facilitate learning and memory consolidation. Improved task performance is seen as a result of an increase in P wave between REM sleep sessions. In a study using post-learning REM sleep deprivation, the stimulatory effect of P wave generator (located in pentine tegmentum) of a mouse was observed. Two groups of mice undergo evacuation learning tasks and then let sleep periods while other groups of mice do not sleep. When comparing the two groups, sleep-deprived mice showed a significant deficit in learning because they did not experience REM sleep. In another group of mice, the P-wave generator was stimulated using carbachol injection and the rats then underwent a sleep-deprivation stage. When these mice were reexamined in their learning, it was shown that activation of P wave generator during sleep deprivation resulted in normal learning achieved. This will show the fact that P wave activation, even without REM sleep, is enough to improve the memory process that would not normally occur.
Implicit facial memory
Face is an important part of one's social life. To be able to recognize, respond, and act against someone requires an accidental encoding and memory retrieval process. Facial stimulation is processed in the fusiform gyrus (occipito-temporal brain area) and this process is an implicit function that represents a typical form of implicit memory. REM sleep has been seen to be more beneficial for implicit visuospatial memory processes, rather than slow wave sleep which is essential for explicit memory consolidation. REM sleep is known for its visual experience, which may often include detailed depictions of the human face. The recognition task is used to measure familiarity with the previously displayed face sequence after the next REM sleep period. It appears that the fusiform gyrus is active during training, the REM sleep period, and the introduction task as well. It has been hypothesized that brain mechanisms during REM sleep, as well as purely repetitive priming, may explain the implicit recognition of previously demonstrated faces.
Macroscopic brain system
Previous research has shown REM sleep to reactivate cortical nerve post training during serial reaction time (SRT) tasks, in other words REM sleep replay processing that occurs when a person learns an implicit task in the previous wake-up hours. However, the control subjects did not complete the SRT task, so the researcher could not assume the reactivation of certain tissues as a result of the sequence/grammar that was implicitly studied because it could be due to basic visuomotor processing obtained in both groups. To answer this question, the experiment was repeated and another group was added which also took part in the SRT task. They did not experience a sequence to the SRT task (random group), whereas the experimental group did not experience a sequence (probabilistic group), albeit without consciousness. The PET scan results show that bilateral cuneus is significantly more active during SRT exercises as well as post-training REM sleep in the Probabilistic group than in the Randomized group. In addition, this activation increased significantly during REM sleep versus SRT task. This suggests that certain brain regions are specifically involved in sequential sequential information processing. This is further supported by the fact that regional CBF (RCBF) during post-training REM sleep is modulated by high-order levels, but not low-level learning obtained before bedtime. Therefore, the area of ​​the brain that takes part in the learning process is modulated by the sequential structure of the learned material (increased activation in cuneus), and the amount of high-level learning (rCBF).
REM sleep deprivation and neurotrophic factors
The effects of REM sleep deprivation (RSD) on neurotropic factors, particularly neuronal growth factors (NGF) and brain-derived neurotrophic factors (BDNF), were assessed in 2000 by Sie et el. Neurotrophins are proteins found in the brain and periphery that help the survival, function and formation of neurons; this is an important element in the process of synaptic plasticity, the underlying neurochemical basis in shaping memories. Sei et al., Incorporating the electrodes into the skulls of seven pairs of mice to measure the Electroencephalogram (EEG), and inserting the wire into the rat neck muscles to measure the Electromyogram (EMG), a technique used to measure the amount of muscle activity. Half of the mice had a six-hour REM sleeping period, while the other half had a six-hour sleep period, which contained all sleep cycles. The results showed that in mice in the sleep-deprived group showed decreased levels of brain-derived neurotrophic factors in the cerebellum (coordination, motor learning) and brainstem (sensory and motorcycles on track), on the other hand the hippocampus (long-term, spatial memory). navigation), indicating decreased levels of nerve growth factor. BDNF protein has been shown to be necessary for procedural learning (non-declarative memory form). Because procedural learning has also shown consolidation and improvement under REM sleep, it is proposed that the impairment of procedural learning tasks is due to the lack of BDNF protein in the cerebellum and brain stem during RSD. In association with NGF, the basal frontal brain (the production and distribution of acH in the brain), more specifically the medial septal region, sends cholinergic (stimulant in the hippocampus) and GABAinergic neurotransmitters (inhibitors) through fiber to target hippocampus cells. This target cell then removes the NGF which plays a key role in the physiological state of the hippocampus and its function. It has been noted that REM sleep enhances the secretion of NGF, it has therefore been suggested that as long as RSD cholinergic activity decreases causing decreased NGF and impairment in procedural learning.
Reorganize macro brain system
Walker and Stickgold hypothesize that after the initial memory acquisition, sleep resets memory representation at the macro-brain level system. Their experiments consist of two groups; night-bed group is taught block motor sequence intercepts duty at night, put to sleep and then retested 12 hours later. The day-wake group is taught the same task in the morning and tested 12 hours later without mixed sleep. FMRI is used to measure brain activity during retest. The results showed significantly fewer errors/sequences in the night-bed group compared with the wake-up group during the day. FMRI outputs for night-bed groups show increased activation in the right primary motor cortex/M1/​​Preurgal Gyrus (counter-handsal hand they block tapping with), right frontal medial prefrontal lobe, right hippocampus (long-term memory, spatial memory), right ventral striatum (olfactory tubercle, nucleus accumbens), and cerebellar regions (lobulus V1, V11). In the day-wake group, fMRI shows "decreased" bilateral activation of signals in the parietal cortex (integrating multiple modalities), in addition to the left insular cortex (homeostatic regulation), the temporal left pole (most anterior of the temporal cortex), and the fronto-polar cortex inferior left. Previous investigations have shown that increased signal indicates brain plasticity. Increased signal activity seen in M1 after sleep in accordance with increased activity in this area seen during exercise; however, one should practice longer than they should sleep to get the same M1 level increase. Therefore, it is suggested that sleep enhances the cortical representation of motor tasks with the expansion of the brain system, as seen by increased signal activity.
Working memory
Considered a mental workspace that allows temporary storage and retrieval of information, working memory is essential for problem solving and analysis of different situations. Work memory capacity is a measure of a number of mental processing functions that can be performed sequentially. Increasing one's working memory capacity can be achieved by a strategy known as chunking. Aritake et al. experimenting on knocking the order of fingers where subjects are shown colored dots in sequence on the monitor corresponding to the keys on their keyboard. When a color is shown, the subject must react by pressing the right color on the keyboard. Subjects are separated into three groups. Group one continues to be trained without sleep. The two groups were trained and retested for over ten hours followed by eight hours of sleep and a final test. The third group was trained at ten o'clock, followed by eight hours of sleep. The group is then tested the next day and then on the same day. The results shown that waking up are significant predictors of performance improvements, unless followed by a sleep period. Groups allowed to undergo post-training sleeping period, regardless of time in reference to training, are useful for improvements in finger-tapping sequences. The initial working memory capacity of the group averaged three to four units. In groups of two and three the working memory capacity increased to an average of 5-6 units. It is proposed that sleep-dependent improvements may contribute to an overall increase in the working memory capacity leading to increased fluid intelligence.
Lack of sleep
Lack of sleep, whether it is total sleep deprivation or lack of partial sleep, may interfere with memory work in memory size, cognitive processing speed, attention and task shifting. Casement et al. found that when subjects were asked to recognize the digits displayed on the screen by typing them on the keypad, the working memory speed of the sleeping subject was limited to four hours a night (about 50% of their normal sleep) was 58% slower than the control group allowed to sleep their full eight hours.
Synaptic plasticity
The brain is a model of information sharing and processing that is constantly changing, plastic. In order for the brain to combine new experiences into an enhanced scheme, it must undergo a special modification to consolidate and assimilate all new information. Synaptic plasticity can be described as a power change between two related neurons. Neuroplasticity is most clearly seen in cases of REM sleep deprivation during brain maturation. Regional brain measurements in neo-natal REM sleeping mice showed significant reduction in size in areas such as the cerebral cortex and brainstem. The rats were robbed during critical periods after birth and thus reduction of anatomical size was observed. Using pursuit tasks (used to test visuomotor abilities) in combination with fMRI, Maquet et al., 2003, found that increased activation was seen in additional and right dentate core plane subjects that were allowed to sleep compared with people who were sleep deprived. The right superior temporal sulcus is also considered to have a higher activation rate. When functional connectivity is analyzed, it is found that the dentate core is more closely involved with superior temporal sulcus function. The results show that performance on the chase task depends on the subject's ability to understand the proper motion pattern for recreation of optimal movement. Lack of sleep is found to interfere with the slow process that leads to learning these procedural skills and alters the connectivity changes that would normally look after a night's rest. Neuroplasticity has been thoroughly researched over the last few decades and the results have shown that significant changes occurring in our cortical processing area have the power to modulate nerve shootings for new and experienced stimuli.
Neurotransmitter settings
The change in the quantity of certain neurotransmitters and how the post-synaptic terminal responds to these changes is the mechanism underlying brain plasticity. During sleep there is a remarkable change in modulatory neurotransmitters throughout the brain. Acetylcholine is an excitatory neurotransmitter that is seen rising to near levels of awake during REM sleep while compared to lower levels during slow-wave sleep. Evidence has shown that the function of the hippocampus-dependent memory system (episodic memory and autobiographical memory) is directly influenced by cholinergic changes throughout the sleep-wake cycle. A high ACh level will improve the information obtained during wakefulness to be stored in the hippocampus. This is done by pressing the previous excitation connection while facilitating the encoding without interruption of the previously stored information. During NREM sleep, and especially slow-wave sleep, a low Ach level will lead to the release of this suppression and allow for the recovery of spontaneous hippocampal neurons that result in the facilitation of memory consolidation.
Gene expression
Recently, about a hundred genes whose brain expression increased during the sleep period have been found. A number of similar genes are found to promote gene expression during waking. This set of genes is associated with different functional groups that can improve different cellular processes. Genes expressed during awake can perform many tasks including energy allocation, synaptic excitatory neurotransmission, high transcription activity and synaptic potential in learning new information. There is an increase in sleep-related processes that involve synthesis and maintenance of synapses. Such processes include membrane trade, recycling of synaptic vesicles, formation of myelin structural proteins, and cholesterol and protein synthesis. In a different study it was found that there was an increase in sleep-related kinodulin-dependent protein kinases that had been specifically involved in synaptic depression and in long-term memory consolidation. These findings encourage the relationship between sleep and various aspects of neural plasticity.
Alternate sleep schedule
Motor skills learning
The impact of a nap was seen by Walker and Stickgold (2005). The experimental group was given 60-90 minutes (one full cycle) afternoon sleep, after the morning motor skills job, while the control group did not receive a nap. The napping group increased 16% when tested after their nap, while the group without a nap did not make significant improvements. However, it seems that all even come out after sleeping the same night; groups without a nap increased 24% and the napping group increased by only 7% more for a total of 23%, almost identical. With regard to learning motor skills, napping seems to only accelerate skills upgrading, rather than increasing the number of improvements.
Visual learning skills
Just like learning motor skills, learning verbal skills increases after a period of daytime sleep. Mednick researchers and colleagues have shown that if the task of visual skills is taught in the morning and repeatedly tested throughout the day, the individual will actually get worse in his task. Individuals who are allowed to nap 30-60 minutes seem to get skill stabilization because no damage occurs. If left to nap 60-90 minutes (REM sleep and slow wave sleep), the individual is shown an increase. Unlike motor tasks, improvement is not suppressed during sleep at night if the individual has slept early. In learning situations of visual skills, napping has been shown to prevent deterioration that is awakened and even enhance learning above and beyond the increase that occurs in nocturnal sleep.
Shift worker
The shift of workers working all night is known to have more accidents than day workers. This can be attributed to several factors, including fewer staff and fatigue; However, part of the problem may be workers with poor working memory and poor performance skills due to poor memory consolidation. Both tasks are studied implicitly and the tasks explicitly studied increase by about 20% after a full night's sleep. Without a sufficient night's sleep between learning new tasks and task performance, performance fails to increase. The shift of workers who are not given sufficient numbers of sleep, especially at the NREM stage, between learning and task performance will not work as well as workers who maintain a standard sleep routine.
Sleeping and aging
Sleep is often a deregulation in the elderly and can cause or worsen a pre-existing memory decline.
Healthier adult adults
The positive correlation between sleep and memory is broken with aging. In general, older adults suffer from decreased sleep efficiency. The amount of time and density of REM and SWS sleep decreases with age. Consequently, it is common that the elderly do not receive an increase in memory after a period of rest.
To combat this, donepezil has been tested in healthy elderly patients where it is shown to increase the time spent in REM sleep and improve memory memory the next day.
Alzheimer's Disease
Patients with Alzheimer's disease experience more sleep disorders than healthy parents. Studies have shown that in patients with Alzheimer's disease, there is a rapid decline in spindles. It has also been reported that the spindle density of the night before the memory test is positively correlated with accuracy on direct recall tasks. A positive correlation between time spent in SWS and future autobiographic memory memories has also been reported in Alzheimer's patients.
See also
- Sleep lessons
- Effect of exercise on memory
- Emotions and memory
- Memory and aging
- Memory and social interactions
References
Source of the article : Wikipedia
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