MSN 671 DB4

.docx

School

Northern Kentucky University *

*We aren’t endorsed by this school

Course

671

Subject

Psychology

Date

Apr 3, 2024

Type

docx

Pages

Uploaded by DeaconInternet9118

1. Compare and contrast the NMDA hypofunction hypothesis of schizophrenia with the dopamine hypothesis of schizophrenia. Include how the hypotheses account for positive and negative symptoms in schizophrenia. According to Wong (2021), historically, the most widely accepted cause of schizophrenia involves the neurotransmission of DA; however, more recent research has elucidated that different neurotransmitters could also be responsible for the typical schizophrenia symptomology. Stahl (2021) states that there are three main neurotransmitters involved in schizophrenia: N-methyl-D-aspartate (NMDA), serotonin, and dopamine (DA). The classic DA hypothesis theorizes that positive symptoms of schizophrenia and drug-induced highs occur due to hyperactivity of the mesolimbic pathway, while hypoactivity of the mesolimbic pathway results in negative symptoms of schizophrenia, anhedonia, and apathy; the mesolimbic pathway extends from the ventral tegmental area (VTA) in the brainstem to the nucleus accumbens in the ventral striatum (Stahl, 2021). The classic hypothesis suggests that the dorsal striatum (involved in the nigrostriatal DA pathway and stemming from the substantia nigra (SN)) affects movement, and the ventral striatum (involved in the mesolimbic pathway and stemming from the VTA), affects emotions (Stahl, 2021). However, recent research suggests a more complex explanation that involves an intermediate area between the ventral and dorsal striatum called the associative striatum; this portion of the striatum receives input from the SN rather than the VTA; therefore, research suggests that both nigrostriatal DA pathways and mesolimbic pathways are involved in hyperdopinergia/positive schizophrenia symptoms and would be better named the “Mesostriatal pathway” (Stahl, 2021). Essentially, the classic DA hypothesis posits that only the ventral striatum and VTA is involved in positive schizophrenia symptoms, while the newer hypothesis

posits that the ventral and intermediate striatum are involved, therefore, both the VTA and SN are linked to positive schizophrenia symptoms (Stahl, 2021). Alternatively, the NMDA glutamate hypofunction hypothesis could also explain the origins of positive vs negative symptoms of schizophrenia. This theory of psychosis suggests that psychosis may be caused by a dysfunction of glutamate synapses at GABA interneurons in the prefrontal cortex; glutamate is typically released and binds to NMDA receptors, but when these receptors are hypoactive it prevents glutamate from taking effect at the receptor and subsequently prevents GABA release from the interneuron (Stahl, 2021). When inhibitory GABA interneurons are not bound, the neuron is no longer inhibited and becomes hyperactive resulting in excessive glutamate release into the cortex (Stahl, 2021). Another possible explanation is that people with schizophrenia may have deficits in the enzyme that makes their own GABA, causing a compensatory increase of GABA receptors post-synaptically in an effort to more easily bind GABA and inhibit the release of glutamate (Stahl, 2021). According to Stahl (2021) the dysfunction of inhibitory GABA interneurons can be caused in three ways: neurodevelopmentally, drug-induced by both ketamine and phencyclidine (PCP), and neurodegeneratively. 2. Based on any required lecture material in Module 4, write two possible quiz/exam questions. You may write multiple choice questions or short essay questions. Please include the answer, a rationale, and the source. The questions should be

appropriately challenging and must be original (you may not use questions that are on the Osmosis website or located online)  Which of the 5 dopamine pathways extends from the substantia nigra (SN) to the striatum? (ANSWER= nigrostriatal dopamine pathway). According to Stahl (2021), the nigrostriatal DA pathway projects from the SN to the basal ganglia, or striatum, and is part of the extrapyramidal nervous system which controls motor function and movement. This pathway is also closely related to the mesolimbic pathway and is hypothesized to result in positive schizophrenia symptoms and hyperdopinergia similar to the mesolimbic pathway (Stahl, 2021).  Which of the 5 dopamine pathways extends from the VTA to the prefrontal cortex? (ANSWER: mesocortical dopamine pathway). According to Stahl (2021), the mesocortical pathway extends from the VTA to both the ventromedial prefrontal cortex (VMPFC) and the dorsolateral prefrontal cortex (DLPFC); the VMPFC is associated with emotions and affect while the DLPFC is associated with cognitive and executive functioning (Stahl, 2021). Hypoactivity of the VMPFC results in affective symptoms of schizophrenia, while hypoactivity of DLPFC results in cognitive symptoms of schizophrenia (Stahl, 2021). References Stahl, S. M. (2021). Essential psychopharmacology: Neuroscientific basis and practical application (5th ed.). Cambridge University Press.

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version

Access to all documents
Unlimited textbook solutions
24/7 expert homework help

Recommended textbooks for you

Ciccarelli: Psychology_5 (5th Edition)

Psychology

ISBN:9780134477961

Author:Saundra K. Ciccarelli, J. Noland White

Publisher:PEARSON

Cognitive Psychology

Psychology

ISBN:9781337408271

Author:Goldstein, E. Bruce.

Publisher:Cengage Learning,

Introduction to Psychology: Gateways to Mind and ...

Psychology

ISBN:9781337565691

Author:Dennis Coon, John O. Mitterer, Tanya S. Martini

Publisher:Cengage Learning

Psychology in Your Life (Second Edition)

Psychology

ISBN:9780393265156

Author:Sarah Grison, Michael Gazzaniga

Publisher:W. W. Norton & Company

Cognitive Psychology: Connecting Mind, Research a...

Psychology

ISBN:9781285763880

Author:E. Bruce Goldstein

Publisher:Cengage Learning

Theories of Personality (MindTap Course List)

Psychology

ISBN:9781305652958

Author:Duane P. Schultz, Sydney Ellen Schultz

Publisher:Cengage Learning

SEE MORE TEXTBOOKS

Recommended textbooks for you

Ciccarelli: Psychology_5 (5th Edition)
Psychology
ISBN:9780134477961
Author:Saundra K. Ciccarelli, J. Noland White
Publisher:PEARSON
Cognitive Psychology
Psychology
ISBN:9781337408271
Author:Goldstein, E. Bruce.
Publisher:Cengage Learning,
Introduction to Psychology: Gateways to Mind and ...
Psychology
ISBN:9781337565691
Author:Dennis Coon, John O. Mitterer, Tanya S. Martini
Publisher:Cengage Learning
Psychology in Your Life (Second Edition)
Psychology
ISBN:9780393265156
Author:Sarah Grison, Michael Gazzaniga
Publisher:W. W. Norton & Company
Cognitive Psychology: Connecting Mind, Research a...
Psychology
ISBN:9781285763880
Author:E. Bruce Goldstein
Publisher:Cengage Learning
Theories of Personality (MindTap Course List)
Psychology
ISBN:9781305652958
Author:Duane P. Schultz, Sydney Ellen Schultz
Publisher:Cengage Learning