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Avoidance Learning
An avoidance response is a natural adaptive behavior performed in response to danger. Excessive avoidance has been suggested to contribute to anxiety disorders, leading psychologists and neuroscientists to study how avoidance behaviors are learned using rat or mouse models. Avoidance learning is a type of operant conditioning (also known as instrumental conditioning). Active avoidance, passive avoidance, and escape responses An escape response occurs when an aversive stimulus is presented and the subject makes a response to remove or escape the stimulus. In the laboratory, this is usually represented by a rat given a small shock to its feet through a grid floor and shuttling through a small opening in its chamber which stops the shock. Such a response is considered active avoidance when it occurs prior to the stimulus presentation and prevents the stimulus from occurring. In contrast, passive avoidance is the prevention of an aversive stimulus by withholding a behavior, which is us ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Operant Conditioning
Operant conditioning, also called instrumental conditioning, is a learning process where behaviors are modified through the association of stimuli with reinforcement or punishment. In it, operants—behaviors that affect one's environment—are conditioned to occur or not occur depending on the environmental consequences of the behavior. Operant conditioning originated in the work of Edward Thorndike, whose law of effect theorised that behaviors arise as a result of whether their consequences are satisfying or discomforting. In the 20th century, operant conditioning was studied by behaviorist psychologists, who believed that much, if not all, of mind and behaviour can be explained as a result of envirionmental conditioning. Reinforcements are environmental stimuli that increase behaviors, whereas punishments are stimuli that decrease behaviors. Both kinds of stimuli can be further categorised into positive and negative stimuli, which respectively involve the addition or removal o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Classical Conditioning
Classical conditioning (also known as Pavlovian or respondent conditioning) is a behavioral procedure in which a biologically potent stimulus (e.g. food) is paired with a previously neutral stimulus (e.g. a triangle). It also refers to the learning process that results from this pairing, through which the neutral stimulus comes to elicit a response (e.g. salivation) that is usually similar to the one elicited by the potent stimulus. Classical conditioning is distinct from operant conditioning (also called instrumental conditioning), through which the strength of a voluntary behavior is modified by reinforcement or punishment. However, classical conditioning can affect operant conditioning in various ways; notably, classically conditioned stimuli may serve to reinforce operant responses. Classical conditioning was first studied in detail by Ivan Pavlov, who conducted experiments with dogs and published his findings in 1897. During the Russian physiologist's study of digestion, Pav ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Extinction (psychology)
Extinction is a behavioral phenomenon observed in both operantly conditioned and classically conditioned behavior, which manifests itself by fading of non-reinforced conditioned response over time. When operant behavior that has been previously reinforced no longer produces reinforcing consequences the behavior gradually stops occurring.Miltenberger, R. (2012). ''Behavior modification, principles and procedures''. (5th ed., pp. 87-99). Wadsworth Publishing Company. In classical conditioning, when a conditioned stimulus is presented alone, so that it no longer predicts the coming of the unconditioned stimulus, conditioned responding gradually stops. For example, after Pavlov's dog was conditioned to salivate at the sound of a metronome, it eventually stopped salivating to the metronome after the metronome had been sounded repeatedly but no food came. Many anxiety disorders such as post traumatic stress disorder are believed to reflect, at least in part, a failure to extinguish c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amygdala
The amygdala (; plural: amygdalae or amygdalas; also '; Latin from Greek, , ', 'almond', 'tonsil') is one of two almond-shaped clusters of nuclei located deep and medially within the temporal lobes of the brain's cerebrum in complex vertebrates, including humans. Shown to perform a primary role in the processing of memory, decision making, and emotional responses (including fear, anxiety, and aggression), the amygdalae are considered part of the limbic system. The term "amygdala" was first introduced by Karl Friedrich Burdach in 1822. Structure The regions described as amygdala nuclei encompass several structures of the cerebrum with distinct connectional and functional characteristics in humans and other animals. Among these nuclei are the basolateral complex, the cortical nucleus, the medial nucleus, the central nucleus, and the intercalated cell clusters. The basolateral complex can be further subdivided into the lateral, the basal, and the accessory basal nucle ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Periaqueductal Gray
The periaqueductal gray (PAG, also known as the central gray) is a brain region that plays a critical role in autonomic function, motivated behavior and behavioural responses to threatening stimuli. PAG is also the primary control center for descending pain modulation. It has enkephalin-producing cells that suppress pain. The periaqueductal gray is the gray matter located around the cerebral aqueduct within the tegmentum of the midbrain. It projects to the nucleus raphe magnus, and also contains descending autonomic tracts. The ascending pain and temperature fibers of the spinothalamic tract send information to the PAG via the spinomesencephalic tract (so-named because the fibers originate in the spine and terminate in the PAG, in the mesencephalon or midbrain). This region has been used as the target for brain-stimulating implants in patients with chronic pain. Role in analgesia Stimulation of the periaqueductal gray matter of the midbrain activates enkephalin-releasing ne ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Infralimbic Cortex
The infralimbic cortex (IL) is a cortical region in the ventromedial prefrontal cortex which is important in tonic inhibition of subcortical structures and emotional responses, such as fear. Structure Connectivity Primates GABAergic neurons within the amygdala, known as intercalated (ITC) cells, receive a strong projection from the IL medial prefrontal cortex (mPFC) in primates. ITC cells are thought to play a role as the 'off switch' for the amygdala, inhibiting the amygdala's central nucleus output neurons and its basolateral nucleus neurons.Quirk, G.J. & Mueller, D. (2007). Neural mechanisms of extinction learning and retrieval. Neuropsychopharmacology Reviews, 1-17. Further, it has been shown that electrical stimulation of IL reduces conditioned fear and strengthens extinction memory, explaining cortical control over extinction processes, one of the simplest forms of emotional regulation. Rodents Amygdala ITC cells receive strong projection from the IL mPFC in rodents as w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prefrontal Cortex
In mammalian brain anatomy, the prefrontal cortex (PFC) covers the front part of the frontal lobe of the cerebral cortex. The PFC contains the Brodmann areas BA8, BA9, BA10, BA11, BA12, BA13, BA14, BA24, BA25, BA32, BA44, BA45, BA46, and BA47. 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, short-term memory, personality expression, moderating social behavior and controlling certain aspects of speech and language. Executive function relates to abilities to differentiate among conflicting thoughts, determine good and bad, better and best, same and different, future consequences of current activities, working toward a defined goal, prediction of outcomes, e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
