Editing Psychosis (section)

=== Negative symptoms ===
{{Technical|section|date=November 2019}}<!-- Probably need further explanations on: 1) implicit/explicit contingencies 2) reward prediction + positive/negative reward prediction errors. -->
Psychosis is associated with [[Ventral striatum|ventral striatum]] (VS), which is the part of the brain that is involved with the desire to naturally satisfy the body's needs.<ref name=":02">{{cite journal | vauthors = Jensen J, McIntosh AR, Crawley AP, Mikulis DJ, Remington G, Kapur S | title = Direct activation of the ventral striatum in anticipation of aversive stimuli | journal = Neuron | volume = 40 | issue = 6 | pages = 1251–1257 | date = December 2003 | pmid = 14687557 | doi = 10.1016/S0896-6273(03)00724-4 | s2cid = 14691522 | doi-access = free }}</ref> When high reports of [[Symptom#Negative symptoms|negative symptoms]] were recorded, there were significant irregularities in the left VS. Anhedonia, the inability to feel pleasure, is a commonly reported symptom in psychosis; experiences are present in most people with schizophrenia.<ref name=":12">{{Cite journal| vauthors = Germans MK, Kring AM |date=April 2000|title=Hedonic deficit in anhedonia: support for the role of approach motivation|url=https://linkinghub.elsevier.com/retrieve/pii/S0191886999001294|journal=Personality and Individual Differences|language=en|volume=28|issue=4|pages=659–672|doi=10.1016/S0191-8869(99)00129-4|access-date=2021-10-16|archive-date=2018-07-01|archive-url=https://web.archive.org/web/20180701042319/https://linkinghub.elsevier.com/retrieve/pii/S0191886999001294|url-status=live}}</ref> Anhedonia arises as a result of the inability to feel motivation and drive towards both the desire to engage in as well as to complete tasks and goals. Previous research has indicated that a deficiency in the [[neural representation]] in regards to goals and the motivation to achieve them, has demonstrated that when a reward is not present, a strong reaction is noted in the ventral striatum; reinforcement learning is intact when contingencies about stimulus-reward are implicit, but not when they require explicit neural processing; reward prediction errors are what the actual reward is versus what the reward was predicted to be.<ref name=":22">{{cite journal | vauthors = Schultz W | title = Reward prediction error | journal = Current Biology | volume = 27 | issue = 10 | pages = R369–R371 | date = May 2017 | pmid = 28535383 | doi = 10.1016/j.cub.2017.02.064 | s2cid = 29170534 | doi-access = free | bibcode = 2017CBio...27.R369S }}</ref> In most cases positive prediction errors are considered an abnormal occurrence. A positive prediction error response occurs when there is an increased activation in a brain region, typically the [[striatum]], in response to unexpected rewards. A negative prediction error response occurs when there is a decreased activation in a region when predicted rewards do not occur. [[Anterior Cingulate Cortex (ACC)]] response, taken as an indicator of effort allocation, does not increase with reward or reward probability increase, and is associated with negative symptoms; deficits in [[Dorsolateral prefrontal cortex|Dorsolateral Prefrontal Cortex (dlPFC)]] activity and failure to improve performance on cognitive tasks when offered monetary incentives are present; and dopamine mediated functions are abnormal.