Editing Classical conditioning (section)

==Applications==

===Neural basis of learning and memory===

Pavlov proposed that conditioning involved a connection between brain centers for conditioned and unconditioned stimuli. His physiological account of conditioning has been abandoned, but classical conditioning continues to be used to study the neural structures and functions that underlie learning and memory. Forms of classical conditioning that are used for this purpose include, among others, [[fear conditioning]], [[eyeblink conditioning]], and the foot contraction conditioning of ''[[Hermissenda crassicornis]]'', a sea-slug. Both fear and eyeblink conditioning involve a neutral stimulus, frequently a tone, becoming paired with an unconditioned stimulus. In the case of eyeblink conditioning, the US is an air-puff, while in fear conditioning the US is threatening or aversive such as a foot shock.

The American neuroscientist [[David A. McCormick]] performed experiments that demonstrated "...discrete regions of the [[cerebellum]] and associated [[brainstem]] areas contain neurons that alter their activity during conditioning – these regions are critical for the acquisition and performance of this simple learning task. It appears that other regions of the brain, including the [[hippocampus]], [[amygdala]], and [[prefrontal cortex]], contribute to the conditioning process, especially when the demands of the task get more complex."<ref>{{cite book |vauthors=Steinmetz JE |chapter-url=https://books.google.com/books?id=RMH8iUZdAFYC |chapter=Neural Basis of Classical Conditioning |title=Encyclopedia of Behavioral Neuroscience |publisher=Academic Press |date=2010 |pages=313–319 |isbn=9780080453965 |access-date=2018-10-01 |archive-date=2021-08-30 |archive-url=https://web.archive.org/web/20210830082457/https://books.google.com/books?id=RMH8iUZdAFYC |url-status=live }}</ref>

Fear and eyeblink conditioning involve generally non overlapping neural circuitry, but share molecular mechanisms. Fear conditioning occurs in the [[basolateral amygdala]], which receives [[Glutamine|glutaminergic]] input directly from thalamic afferents, as well as indirectly from prefrontal projections. The direct projections are sufficient for delay conditioning, but in the case of trace conditioning, where the CS needs to be internally represented despite a lack of external stimulus, indirect pathways are necessary. The [[Anterior cingulate cortex|anterior cingulate]] is one candidate for intermediate trace conditioning, but the hippocampus may also play a major role. Presynaptic activation of [[protein kinase A]] and postsynaptic activation of [[NMDA receptor]]s and its signal transduction pathway are necessary for conditioning related plasticity. [[CREB]] is also necessary for conditioning related [[Neuroplasticity|plasticity]], and it may induce downstream synthesis of proteins necessary for this to occur.<ref>{{cite journal |vauthors=Fanselow MS, Poulos AM |title=The neuroscience of mammalian associative learning |journal=Annual Review of Psychology |volume=56 |issue=1 |pages=207–34 |date=February 2005 |pmid=15709934 |doi=10.1146/annurev.psych.56.091103.070213}}</ref> As NMDA receptors are only activated after an increase in presynaptic [[calcium]](thereby releasing the [[Mg2+]] block), they are a potential coincidence detector that could mediate [[spike timing dependent plasticity]]. STDP constrains LTP to situations where the CS predicts the US, and LTD to the reverse.<ref>{{cite journal |vauthors=Markram H, Gerstner W, Sjöström PJ |title=A history of spike-timing-dependent plasticity |journal=Frontiers in Synaptic Neuroscience |volume=3 |pages=4 |date=2011 |pmid=22007168 |pmc=3187646 |doi=10.3389/fnsyn.2011.00004 |doi-access=free }}</ref>

===Behavioral therapies===
{{main|Behavior therapy}}
Some therapies associated with classical conditioning are [[aversion therapy]], [[systematic desensitization]] and [[flooding (psychology)|flooding]].

Aversion therapy is a type of behavior therapy designed to make patients cease an undesirable habit by associating the habit with a strong unpleasant unconditioned stimulus.<ref name="Kearney_2011" />{{rp|336}} For example, a medication might be used to associate the taste of alcohol with stomach upset. Systematic desensitization is a treatment for phobias in which the patient is trained to relax while being exposed to progressively more anxiety-provoking stimuli (e.g. angry words). This is an example of [[counterconditioning]], intended to associate the feared stimuli with a response (relaxation) that is incompatible with anxiety.<ref name="Kearney_2011">{{cite book |vauthors=Kearney CA |title=Abnormal Psychology and Life: A Dimensional Approach |date=January 2011}}</ref>{{rp|136}} Flooding is a form of [[Desensitization (psychology)|desensitization]] that attempts to eliminate phobias and anxieties by repeated exposure to highly distressing stimuli until the lack of reinforcement of the anxiety response causes its extinction.<ref name="Kearney_2011" />{{rp|133}} "Flooding" usually involves actual exposure to the stimuli, whereas the term "implosion" refers to imagined exposure, but the two terms are sometimes used synonymously.

Conditioning therapies usually take less time than [[humanistic psychology|humanistic]] therapies.<ref>{{cite web |last=McGee |first=Donald Loring |name-list-style=vanc |title=Behavior Modification |publisher=Wellness.com, Inc. |date=2006 |access-date=14 February 2012 |url=http://www.wellness.com/reference/health-and-wellness/behavior-modification |archive-date=24 March 2012 |archive-url=https://web.archive.org/web/20120324194345/http://www.wellness.com/reference/health-and-wellness/behavior-modification |url-status=live }}</ref>

===Conditioned drug response===
A stimulus that is present when a [[drug]] is administered or consumed may eventually evoke a conditioned physiological response that mimics the effect of the drug. This is sometimes the case with [[caffeine]]; habitual [[coffee]] drinkers may find that the smell of coffee gives them a feeling of alertness. In other cases, the conditioned response is a compensatory reaction that tends to offset the effects of the drug. For example, if a drug causes the body to become less sensitive to pain, the compensatory conditioned reaction may be one that makes the user more sensitive to pain. This compensatory reaction may contribute to [[drug tolerance]]. If so, a drug user may increase the amount of drug consumed in order to feel its effects, and end up taking very large amounts of the drug. In this case a dangerous overdose reaction may occur if the CS happens to be absent, so that the conditioned compensatory effect fails to occur. For example, if the drug has always been administered in the same room, the stimuli provided by that room may produce a conditioned compensatory effect; then an [[Drug overdose|overdose]] reaction may happen if the drug is administered in a different location where the conditioned stimuli are absent.<ref>{{cite book |last=Carlson |first=Neil R.|name-list-style=vanc |title=Psychology: The Science of Behaviour |year=2010 |publisher=Pearson Education Inc. |location=New Jersey, United States |isbn=978-0-205-64524-4 |pages=[https://archive.org/details/psychologyscienc0004unse/page/599 599–604] |url=https://archive.org/details/psychologyscienc0004unse/page/599}}</ref>

===Conditioned hunger{{anchor|Conditioned hunger}}===
Signals that consistently precede food intake can become conditioned stimuli for a set of bodily responses that prepares the body for food and [[digestion]]. These reflexive responses include the secretion of [[Gastric acid|digestive juices]] into the stomach and the secretion of certain hormones into the blood stream, and they induce a state of hunger. An example of conditioned hunger is the "appetizer effect." Any signal that consistently precedes a meal, such as a clock indicating that it is time for dinner, can cause people to feel hungrier than before the signal. The [[lateral hypothalamus]] (LH) is involved in the initiation of eating. The [[nigrostriatal pathway]], which includes the [[substantia nigra]], the [[lateral hypothalamus]], and the [[basal ganglia]] have been shown to be involved in hunger motivation.{{Citation needed|date=July 2021}}

===Conditioned emotional response{{anchor|Conditioned emotional response}}===
{{Further|Conditioned emotional response|Fear conditioning}}
The influence of classical conditioning can be seen in emotional responses such as [[phobia]], [[disgust]], [[nausea]], anger, and [[sexual arousal]]. A common example is conditioned nausea, in which the CS is the sight or smell of a particular food that in the past has resulted in an unconditioned stomach upset. Similarly, when the CS is the sight of a dog and the US is the pain of being bitten, the result may be a conditioned fear of dogs. An example of conditioned emotional response is [[#Conditioned suppression|conditioned suppression]].

As an adaptive mechanism, emotional conditioning helps shield an individual from harm or prepare it for important biological events such as sexual activity. Thus, a stimulus that has occurred before sexual interaction comes to cause sexual arousal, which prepares the individual for sexual contact. For example, sexual arousal has been conditioned in human subjects by pairing a stimulus like a picture of a jar of pennies with views of an erotic film clip. Similar experiments involving blue [[gourami]] fish and [[domesticated quail]] have shown that such conditioning can increase the number of offspring. These results suggest that conditioning techniques might help to increase fertility rates in [[Infertility|infertile]] individuals and [[endangered species]].<ref>{{cite book |last=Carlson |first=Neil R.|name-list-style=vanc |title=Psychology: The Science of Behaviour |year=2010 |publisher=Pearson Education Inc. |location=New Jersey, United States |isbn=978-0-205-64524-4 |pages=[https://archive.org/details/psychologyscienc0004unse/page/198 198–203] |url=https://archive.org/details/psychologyscienc0004unse/page/198}}</ref>

===Pavlovian-instrumental transfer===
{{Main|Pavlovian-instrumental transfer}}
{{expand section|date=May 2017}}
Pavlovian-instrumental transfer is a phenomenon that occurs when a conditioned stimulus (CS, also known as a "cue") that has been associated with [[reward system|rewarding]] or [[aversives|aversive]] [[stimulus (psychology)|stimuli]] via classical conditioning alters [[motivational salience]] and [[operant behavior]].<ref name="Pavlovian-instrumental transfer review">{{cite journal |vauthors=Cartoni E, Puglisi-Allegra S, Baldassarre G |title=The three principles of action: a Pavlovian-instrumental transfer hypothesis |journal=Frontiers in Behavioral Neuroscience |volume=7 |pages=153 |date=November 2013 |pmid=24312025 |pmc=3832805 |doi=10.3389/fnbeh.2013.00153 |doi-access=free }}</ref><ref name="Aversive PIT in humans - review">{{cite journal |vauthors=Geurts DE, Huys QJ, den Ouden HE, Cools R |title=Aversive Pavlovian control of instrumental behavior in humans |journal=Journal of Cognitive Neuroscience |volume=25 |issue=9 |pages=1428–41 |date=September 2013 |pmid=23691985 |doi=10.1162/jocn_a_00425 |s2cid=6453291 |url=https://www.zora.uzh.ch/id/eprint/90321/1/Geurts_et_al_Aversive_Pavlovian-control.pdf |access-date=2019-01-06 |archive-date=2019-05-01 |archive-url=https://web.archive.org/web/20190501131424/https://www.zora.uzh.ch/id/eprint/90321/1/Geurts_et_al_Aversive_Pavlovian-control.pdf |url-status=live }}</ref><ref name="Pavlovian-instrumental transfer of reward - review">{{cite journal |vauthors=Cartoni E, Balleine B, Baldassarre G |title=Appetitive Pavlovian-instrumental Transfer: A review |journal=Neuroscience and Biobehavioral Reviews |volume=71 |pages=829–848 |date=December 2016 |pmid=27693227 |doi=10.1016/j.neubiorev.2016.09.020 |quote=This paper reviews one of the experimental paradigms used to study the effects of cues, the Pavlovian to Instrumental Transfer paradigm. In this paradigm, cues associated with rewards through Pavlovian conditioning alter motivation and choice of instrumental actions.&nbsp;... Predictive cues are an important part of our life that continuously influence and guide our actions. Hearing the sound of a horn makes us stop before we attempt to cross the street. Seeing an advertisement for fast food might make us hungry and lead us to seek out a specific type and source of food. In general, cues can both prompt us towards or stop us from engaging in a certain course of action. They can be adaptive (saving our life in crossing the street) or maladaptive, leading to suboptimal choices, e.g. making us eat when we are not really hungry (Colagiuri and Lovibond, 2015). In extreme cases they can even play a part in pathologies such as in addiction, where drug associated cues produce craving and provoke relapse (Belin et al., 2009). |doi-access=free|hdl=11573/932246 |hdl-access=free }}</ref><ref name="Mesolimbic computation of reward motivation review">{{cite journal |vauthors=Berridge KC |title=From prediction error to incentive salience: mesolimbic computation of reward motivation |journal=The European Journal of Neuroscience |volume=35 |issue=7 |pages=1124–43 |date=April 2012 |pmid=22487042 |pmc=3325516 |doi=10.1111/j.1460-9568.2012.07990.x |quote=Incentive salience or 'wanting' is a specific form of Pavlovian-related motivation for rewards mediated by mesocorticolimbic brain systems&nbsp;...Incentive salience integrates two separate input factors: (1) current physiological neurobiological state; (2) previously learned associations about the reward cue, or Pavlovian CS&nbsp;...<br />Cue-triggered 'wanting' for the UCS<br />A brief CS encounter (or brief UCS encounter) often primes a pulse of elevated motivation to obtain and consume more reward UCS. This is a signature feature of incentive salience. In daily life, the smell of food may make you suddenly feel hungry, when you hadn't felt that way a minute before. In animal neuroscience experiments, a CS for reward may trigger a more frenzied pulse of increased instrumental efforts to obtain that associated UCS reward in situations that purify the measurement of incentive salience, such as in Pavlovian-Instrumental Transfer (PIT) experiments&nbsp;... Similarly, including a CS can often spur increased consumption of a reward UCS by rats or people, compared to consumption of the same UCS when CSs are absent&nbsp;... Thus Pavlovian cues can elicit pulses of increased motivation to consume their UCS reward, whetting and intensifying the appetite. However, the motivation power is never simply in the cues themselves or their associations, since cue-triggered motivation can be easily modulated and reversed by drugs, hungers, satieties, etc., as discussed below.}}</ref> In a typical experiment, a rat is presented with sound-food pairings (classical conditioning). Separately, the rat learns to press a lever to get food (operant conditioning). Test sessions now show that the rat presses the lever faster in the presence of the sound than in silence, although the sound has never been associated with lever pressing.

Pavlovian-instrumental transfer is suggested to play a role in the [[differential outcomes effect]], a procedure which enhances operant discrimination by pairing stimuli with specific outcomes.{{Citation needed|date=July 2021}}