Functional Disconnection
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Functional Disconnection
Functional disconnection is the disintegrated function in the brain in the absence of anatomical damage, in distinction to physical disconnection of the cerebral hemispheres by surgical resection, trauma or lesion. Applications have included alexia without agraphia dyslexia, persistent vegetative state and minimally conscious state as well as autistic spectrum disorders. Functional disconnection itself is not a medically recognized condition. It is a theoretical concept used to facilitate research into the causes and symptoms within recognized conditions. History In 1977, Witleson reported that developmental dyslexia may be associated with (i) bi-hemisphere representation of spatial functions, in contrast to the unitary right hemisphere control of these functions observed in normal individuals. The bilateral neural involvement in spatial processing may interfere with the left hemisphere's processing of its own specialized functions and result in deficient linguistic, seque ...
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Cerebral Hemispheres
The vertebrate cerebrum (brain) is formed by two cerebral hemispheres that are separated by a groove, the longitudinal fissure. The brain can thus be described as being divided into left and right cerebral hemispheres. Each of these hemispheres has an outer layer of grey matter, the cerebral cortex, that is supported by an inner layer of white matter. In eutherian (placental) mammals, the hemispheres are linked by the corpus callosum, a very large bundle of nerve fibers. Smaller commissures, including the anterior commissure, the posterior commissure and the fornix, also join the hemispheres and these are also present in other vertebrates. These commissures transfer information between the two hemispheres to coordinate localized functions. There are three known poles of the cerebral hemispheres: the '' occipital pole'', the '' frontal pole'', and the ''temporal pole''. The central sulcus is a prominent fissure which separates the parietal lobe from the frontal lobe and the pr ...
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Cerebrovascular Accident
Stroke is a medical condition in which poor blood flow to a part of the brain causes cell death. There are two main types of stroke: ischemic, due to lack of blood flow, and hemorrhagic, due to bleeding. Both cause parts of the brain to stop functioning properly. Signs and symptoms of stroke may include an inability to move or feel on one side of the body, problems understanding or speaking, dizziness, or loss of vision to one side. Signs and symptoms often appear soon after the stroke has occurred. If symptoms last less than 24 hours, the stroke is a transient ischemic attack (TIA), also called a mini-stroke. Hemorrhagic stroke may also be associated with a severe headache. The symptoms of stroke can be permanent. Long-term complications may include pneumonia and loss of bladder control. The most significant risk factor for stroke is high blood pressure. Other risk factors include high blood cholesterol, tobacco smoking, obesity, diabetes mellitus, a previous TIA, ...
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Working Memory
Working memory is a cognitive system with a limited capacity that can Memory, hold information temporarily. It is important for reasoning and the guidance of decision-making and behavior. Working memory is often used synonymously with short-term memory, but some theorists consider the two forms of memory distinct, assuming that working memory allows for the manipulation of stored information, whereas short-term memory only refers to the short-term storage of information. Working memory is a theoretical concept central to cognitive psychology, neuropsychology, and neuroscience. History The term "working memory" was coined by George Armitage Miller, Miller, Eugene Galanter, Galanter, and Karl H. Pribram, Pribram, and was used in the 1960s in the context of Computational theory of mind, theories that likened the mind to a computer. In 1968, Atkinson–Shiffrin memory model, Atkinson and Shiffrin used the term to describe their "short-term store". The term short-term store was the na ...
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Parietal Lobe
The parietal lobe is one of the four Lobes of the brain, major lobes of the cerebral cortex in the brain of mammals. The parietal lobe is positioned above the temporal lobe and behind the frontal lobe and central sulcus. The parietal lobe integrates sensory information among various sensory modality, modalities, including spatial sense and navigation (proprioception), the main sensory receptive area for the sense of touch in the somatosensory cortex which is just posterior to the central sulcus in the postcentral gyrus, and the two-streams hypothesis#Dorsal stream, dorsal stream of the visual system. The major sensory inputs from the skin (mechanoreceptor, touch, thermoreceptor, temperature, and nociceptor, pain receptors), relay through the thalamus to the parietal lobe. Several areas of the parietal lobe are important in language processing in the brain, language processing. The somatosensory cortex can be illustrated as a distorted figure – the cortical homunculus (Latin: "li ...
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Prefrontal Cortex
In mammalian brain anatomy, the prefrontal cortex (PFC) covers the front part of the frontal lobe of the cerebral cortex. It is the association cortex in the frontal lobe. The PFC contains the Brodmann areas BA8, BA9, BA10, BA11, BA12, BA13, BA14, BA24, BA25, BA32, BA44, BA45, BA46, and BA47. This brain region is involved in a wide range of higher-order cognitive functions, including speech formation (Broca's area), gaze ( frontal eye fields), working memory ( dorsolateral prefrontal cortex), and risk processing (e.g. ventromedial prefrontal cortex). The basic activity of this brain region is considered to be orchestration of thoughts and actions in accordance with internal goals. Many authors have indicated an integral link between a person's will to live, personality, and the functions of the prefrontal cortex. This brain region has been implicated in executive functions, such as planning, decision making, working memory, personality expression, moderating ...
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Adaptive Behavior
Adaptive behavior is behavior that enables a person (usually used in the context of children) to cope in their environment with greatest success and least conflict with others. This is a term used in the areas of psychology and special education. Adaptive behavior relates to everyday skills or tasks that the "average" person is able to complete, similar to the term life skills. Nonconstructive or disruptive social or personal behaviors can sometimes be used to achieve a constructive outcome. For example, a constant repetitive action could be re-focused on something that creates or builds something. In other words, the behavior can be adapted to something else. In contrast, maladaptive behavior is a type of behavior that is often used to reduce one's anxiety, but the result is dysfunctional and non-productive coping. For example, avoiding situations because you have unrealistic fears may initially reduce your anxiety, but it is non-productive in alleviating the actual problem ...
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Learning
Learning is the process of acquiring new understanding, knowledge, behaviors, skills, value (personal and cultural), values, Attitude (psychology), attitudes, and preferences. The ability to learn is possessed by humans, non-human animals, and some machine learning, machines; there is also evidence for some kind of learning in certain plants. Some learning is immediate, induced by a single event (e.g. being burned by a Heat, hot stove), but much skill and knowledge accumulate from repeated experiences. The changes induced by learning often last a lifetime, and it is hard to distinguish learned material that seems to be "lost" from that which cannot be retrieved. Human learning starts at birth (it might even start before) and continues until death as a consequence of ongoing interactions between people and their environment. The nature and processes involved in learning are studied in many established fields (including educational psychology, neuropsychology, experimental psycho ...
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Emotional Memory
Emotion can have a powerful effect on humans and animals. Numerous studies have shown that the most vivid autobiographical memories tend to be of emotional events, which are likely to be recalled more often and with more clarity and detail than neutral events. The activity of emotionally enhanced memory retention can be linked to human evolution; during early development, responsive behavior to environmental events would have progressed as a process of trial and error. Survival depended on behavioral patterns that were repeated or reinforced through life and death situations. Through evolution, this process of learning became genetically embedded in humans and all animal species in what is known as flight or fight instinct. Artificially inducing this instinct through traumatic physical or emotional stimuli essentially creates the same physiological condition that heightens memory retention by exciting neuro-chemical activity affecting areas of the brain responsible for encodi ...
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Schizophrenia
Schizophrenia () is a mental disorder characterized variously by hallucinations (typically, Auditory hallucination#Schizophrenia, hearing voices), delusions, thought disorder, disorganized thinking and behavior, and Reduced affect display, flat or inappropriate affect. Symptoms Prodrome, develop gradually and typically begin during young adulthood and rarely resolve. There is no objective diagnostic test; diagnosis is based on observed behavior, a psychiatric history that includes the person's reported experiences, and reports of others familiar with the person. For a diagnosis of schizophrenia, the described symptoms need to have been present for at least six months (according to the DSM-5) or one month (according to the ICD-11). Many people with schizophrenia have other mental disorders, especially mood disorder, mood, anxiety disorder, anxiety, and substance use disorders, substance use disorders, as well as obsessive–compulsive disorder (OCD). About 0.3% to 0.7% of peo ...
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Synaptic Plasticity
In neuroscience, synaptic plasticity is the ability of synapses to Chemical synapse#Synaptic strength, strengthen or weaken over time, in response to increases or decreases in their activity. Since memory, memories are postulated to be represented by vastly interconnected neural circuits in the brain, synaptic plasticity is one of the important neurochemical foundations of learning and memory (''see Hebbian theory''). Plastic change often results from the alteration of the number of neurotransmitter receptors located on a synapse. There are several underlying mechanisms that cooperate to achieve synaptic plasticity, including changes in the quantity of neurotransmitters released into a synapse and changes in how effectively cells respond to those neurotransmitters. Synaptic plasticity in both Excitatory synapse, excitatory and Inhibitory synapse, inhibitory synapses has been found to be dependent upon postsynaptic calcium release. Historical discoveries In 1973, Terje Lømo and ...
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Visual System
The visual system is the physiological basis of visual perception (the ability to perception, detect and process light). The system detects, phototransduction, transduces and interprets information concerning light within the visible range to construct an imaging, image and build a mental model of the surrounding environment. The visual system is associated with the eye and functionally divided into the optics, optical system (including cornea and crystalline lens, lens) and the nervous system, neural system (including the retina and visual cortex). The visual system performs a number of complex tasks based on the ''image forming'' functionality of the eye, including the formation of monocular images, the neural mechanisms underlying stereopsis and assessment of distances to (depth perception) and between objects, motion perception, pattern recognition, accurate motor coordination under visual guidance, and colour vision. Together, these facilitate higher order tasks, such as ...
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