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De Novo Protein Synthesis Theory Of Memory Formation
The de novo protein synthesis theory of memory formation is a hypothesis about the formation of the physical correlates of memory in the brain. It is widely accepted that the physiological correlates for memories are stored at the synapse between various neurons. The relative strength of various synapses in a network of neurons form the memory trace, or ‘ engram,’ though the processes that support this finding are less thoroughly understood. The de novo protein synthesis theory states that the production of proteins is required to initiate and potentially maintain these plastic changes within the brain. It has much support within the neuroscience community, but some critics claim that memories can be made independent of protein synthesis. History Originally, protein synthesis inhibitors (PSI) were only used as antibiotics. Through various mechanisms unique to each PSI, they would inhibit the synthesis of proteins, generally at the translational level. They achieved renown w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eukaryotic Cell
Eukaryotes () are organisms whose cells have a nucleus. All animals, plants, fungi, and many unicellular organisms, are Eukaryotes. They belong to the group of organisms Eukaryota or Eukarya, which is one of the three domains of life. Bacteria and Archaea (both prokaryotes) make up the other two domains. The eukaryotes are usually now regarded as having emerged in the Archaea or as a sister of the Asgard archaea. This implies that there are only two domains of life, Bacteria and Archaea, with eukaryotes incorporated among archaea. Eukaryotes represent a small minority of the number of organisms, but, due to their generally much larger size, their collective global biomass is estimated to be about equal to that of prokaryotes. Eukaryotes emerged approximately 2.3–1.8 billion years ago, during the Proterozoic eon, likely as flagellated phagotrophs. Their name comes from the Greek εὖ (''eu'', "well" or "good") and κάρυον (''karyon'', "nut" or "kernel"). Eu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Episodic Memories
Episodic memory is the memory of everyday events (such as times, location geography, associated emotions, and other contextual information) that can be explicitly stated or conjured. It is the collection of past personal experiences that occurred at particular times and places; for example, the party on one's 7th birthday. Along with semantic memory, it comprises the category of explicit memory, one of the two major divisions of long-term memory (the other being implicit memory). The term "episodic memory" was coined by Endel Tulving in 1972, referring to the distinction between knowing and remembering: ''knowing'' is factual recollection (semantic) whereas ''remembering'' is a feeling that is located in the past (episodic). One of the main components of episodic memory is the process of recollection, which elicits the retrieval of contextual information pertaining to a specific event or experience that has occurred. Tulving seminally defined three key properties of episodic memo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Semantic Memories
Semantic memory refers to general world knowledge that humans have accumulated throughout their lives. This general knowledge (word meanings, concepts, facts, and ideas) is intertwined in experience and dependent on culture. We can learn about new concepts by applying our knowledge learned from things in the past. Semantic memory is distinct from episodic memory, which is our memory of experiences and specific events that occur during our lives, from which we can recreate at any given point. For instance, semantic memory might contain information about what a cat is, whereas episodic memory might contain a specific memory of petting a particular cat. Semantic memory and episodic memory are both types of explicit memory (or declarative memory), that is, memory of facts or events that can be consciously recalled and "declared". The counterpart to declarative or explicit memory is nondeclarative memory or implicit memory. History The idea of semantic memory was first intro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Memory Deficit
Amnesia is a deficit in memory caused by brain damage or disease,Gazzaniga, M., Ivry, R., & Mangun, G. (2009) Cognitive Neuroscience: The biology of the mind. New York: W.W. Norton & Company. but it can also be caused temporarily by the use of various sedatives and hypnotic drugs. The memory can be either wholly or partially lost due to the extent of damage that was caused. There are two main types of amnesia: retrograde amnesia and anterograde amnesia. Retrograde amnesia is the inability to retrieve information that was acquired before a particular date, usually the date of an accident or operation. In some cases the memory loss can extend back decades, while in others the person may lose only a few months of memory. Anterograde amnesia is the inability to transfer new information from the short-term store into the long-term store. People with anterograde amnesia cannot remember things for long periods of time. These two types are not mutually exclusive; both can occur simul ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lidocaine
Lidocaine, also known as lignocaine and sold under the brand name Xylocaine among others, is a local anesthetic of the amino amide type. It is also used to treat ventricular tachycardia. When used for local anaesthesia or in nerve blocks, lidocaine typically begins working within several minutes and lasts for half an hour to three hours. Lidocaine mixtures may also be applied directly to the skin or mucous membranes to numb the area. It is often used mixed with a small amount of adrenaline (epinephrine) to prolong its local effects and to decrease bleeding. If injected intravenously, it may cause cerebral effects such as confusion, changes in vision, numbness, tingling, and vomiting. It can cause low blood pressure and an irregular heart rate. There are concerns that injecting it into a joint can cause problems with the cartilage. It appears to be generally safe for use in pregnancy. A lower dose may be required in those with liver problems. It is generally safe to use in those ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tetrodotoxin
Tetrodotoxin (TTX) is a potent neurotoxin. Its name derives from Tetraodontiformes, an order that includes pufferfish, porcupinefish, ocean sunfish, and triggerfish; several of these species carry the toxin. Although tetrodotoxin was discovered in these fish and found in several other animals (e.g., in blue-ringed octopuses, rough-skinned newts, and moon snails), it is actually produced by certain infecting or symbiotic bacteria like ''Pseudoalteromonas'', ''Pseudomonas'', and ''Vibrio'' as well as other species found in animals. Tetrodotoxin is a sodium channel blocker. It inhibits the firing of action potentials in neurons by binding to the voltage-gated sodium channels in nerve cell membranes and blocking the passage of sodium ions (responsible for the rising phase of an action potential) into the neuron. This prevents the nervous system from carrying messages and thus muscles from contracting in response to nervous stimulation. Its mechanism of action, selective blocking o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Postsynaptic Terminal
Axon terminals (also called synaptic boutons, terminal boutons, or end-feet) are distal terminations of the telodendria (branches) of an axon. An axon, also called a nerve fiber, is a long, slender projection of a nerve cell, or neuron, that conducts electrical impulses called action potentials away from the neuron's cell body, or soma, in order to transmit those impulses to other neurons, muscle cells or glands. Neurons are interconnected in complex arrangements, and use electrochemical signals and neurotransmitter chemicals to transmit impulses from one neuron to the next; axon terminals are separated from neighboring neurons by a small gap called a synapse, across which impulses are sent. The axon terminal, and the neuron from which it comes, is sometimes referred to as the "presynaptic" neuron. Nerve impulse release Neurotransmitters are packaged into synaptic vesicles that cluster beneath the axon terminal membrane on the presynaptic side of a synapse. The axonal terminals ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CAMP Response Binding Element Protein
CREB-TF (CREB, cAMP response element-binding protein) is a cellular transcription factor. It binds to certain DNA sequences called cAMP response elements (CRE), thereby increasing or decreasing the transcription of the genes. CREB was first described in 1987 as a cAMP-responsive transcription factor regulating the somatostatin gene. Genes whose transcription is regulated by CREB include: '' c-fos'', BDNF, tyrosine hydroxylase, numerous neuropeptides (such as somatostatin, enkephalin, VGF, corticotropin-releasing hormone), and genes involved in the mammalian circadian clock (PER1, PER2). CREB is closely related in structure and function to CREM (cAMP response element modulator) and ATF-1 (activating transcription factor-1) proteins. CREB proteins are expressed in many animals, including humans. CREB has a well-documented role in neuronal plasticity and long-term memory formation in the brain and has been shown to be integral in the formation of spatial memory. CREB downregu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NMDA Glutamate Receptor
The ''N''-methyl-D-aspartate receptor (also known as the NMDA receptor or NMDAR), is a glutamate receptor and ion channel found in neurons. The NMDA receptor is one of three types of ionotropic glutamate receptors, the other two being AMPA and kainate receptors. Depending on its subunit composition, its ligands are glutamate and glycine (or D-serine). However, the binding of the ligands is typically not sufficient to open the channel as it may be blocked by Mg2+ ions which are only removed when the neuron is sufficiently depolarized. Thus, the channel acts as a “coincidence detector” and only once both of these conditions are met, the channel opens and it allows positively charged ions (cations) to flow through the cell membrane. The NMDA receptor is thought to be very important for controlling synaptic plasticity and mediating learning and memory functions. The NMDA receptor is ionotropic, meaning it is a protein which allows the passage of ions through the cell membrane ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tetanus
Tetanus, also known as lockjaw, is a bacterial infection caused by ''Clostridium tetani'', and is characterized by muscle spasms. In the most common type, the spasms begin in the jaw and then progress to the rest of the body. Each spasm usually lasts a few minutes. Spasms occur frequently for three to four weeks. Some spasms may be severe enough to fracture bones. Other symptoms of tetanus may include fever, sweating, headache, trouble swallowing, high blood pressure, and a fast heart rate. Onset of symptoms is typically three to twenty-one days following infection. Recovery may take months. About ten percent of cases prove to be fatal. ''C. tetani'' is commonly found in soil, saliva, dust, and manure. The bacteria generally enter through a break in the skin such as a cut or puncture wound by a contaminated object. They produce toxins that interfere with normal muscle contractions. Diagnosis is based on the presenting signs and symptoms. The disease does not spread between pe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Long Term Potentiation
In neuroscience, long-term potentiation (LTP) is a persistent strengthening of synapses based on recent patterns of activity. These are patterns of synaptic activity that produce a long-lasting increase in signal transmission between two neurons. The opposite of LTP is long-term depression, which produces a long-lasting decrease in synaptic strength. It is one of several phenomena underlying synaptic plasticity, the ability of chemical synapses to change their strength. As memories are thought to be encoded by modification of synaptic strength, LTP is widely considered one of the major cellular mechanisms that underlies learning and memory. LTP was discovered in the rabbit hippocampus by Terje Lømo in 1966 and has remained a popular subject of research since. Many modern LTP studies seek to better understand its basic biology, while others aim to draw a causal link between LTP and behavioral learning. Still, others try to develop methods, pharmacologic or otherwise, of enha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
