Sider

tirsdag den 21. februar 2012

Hvad er de kognitive funktioner som default netværket varetager?

Jeg fandt en "kladde" her på min blog som udelukkende bestod af et langt citat fra en videnskabelig artikel om "the default network" og hvad det er for nogle mentale og kognitive processer det tager sig af.
   Jeg kører den lige igennem og "oversætter" lidt undervejs:
The current set of analyses provides converging evidence that DMN regions are engaged with specific cognitive behaviors. These behaviors may not be limited to those observed here, but may also include related processes such as moral decision-making (Greene, Sommerville, Nystrom, Darley, & Cohen, 2001), fictional narrative simulation (Mar & Oatley, 2008; Mar, 2004), or mind-wandering (Christoff, Gordon,Smallwood, Smith, & Schooler, 2009; Mason et al., 2007). 
Altså her nævnes tre specifikke kognitive funktioner som DMN tager sig af:
  • moralsk vurderinger og beslutninger: "Hvad ville være det rigtige at gøre hvis...."
  • simulation af fiktionshistorier: "Vi leger at vi er på vej til månen, du er kaptajn på rumskibet..."
  • dagdrømme og tankeflugt: "Hvad var det egentlig jeg lavede i går, men måske skulle jeg heller tag til stranden, hvem mon kommer med til mødet i aften..."
Men hvad tager Default Mode Nework sig ellers af?
In order to determine the neural (in)dependence of these processes, however, neuropsychological investigations into co-occurring autobiographical and interpersonal deficits with compromised functional integrity of the midline, and lateral parietal and lateral temporal cortex are also necessary. Our analyses were designed to investigate the neural mechanisms underlying autobiographical memory, prospection, and theory-of-mind, and to determine if these domains rely upon a pattern of brain activity operating within the DMN. The results provide the first direct evidence to support previous independent observations that projection of the self into the past, the future, or the minds of others engages a common set of brain regions largely overlapping with the DMN (Spreng et al.,2009; Buckner & Carroll, 2007). 
Altså: deres undersøgelser viser at mental projektion af selvet ind i fortiden, inde i fremtiden eller ind i andres sind, engagere et fælles sæt af hjerneområder som falder sammen med Default Netværket.
Her refereres også til den sevlbiografiske hukommelse, og "theory of mind" og "prospection".
   "Theory of mind" er det mentale fænomen at man har en forestilling om at andre har et sind der er indrettet ligesom ens eget, hvilket betyder at man antager at hvis man selv vil føle og tænke noget i en bestemt situation, så vil en anden i samme situation nok tænke og føle det samme.
    "Prospection" går på det mentale fænomen at man kan forestille sig egne mentale, emotionelle og kognitive processer i en forventet fremtid:
....to have prospection abilities, which permit anticipating future mental processes and motivational and emotional states. For instance, we can evaluate future outcomes in light of the motivational state we expect to have when the outcome is collected, not (only) when we make a decision. Consequently, we can plan for the future and choose to store food to be consumed when we expect to be hungry, not immediately. Furthermore, similarly to any expected outcome, we can assign a value to our anticipated mental processes and emotions.
Pointen er at vi ikke blot kan forestille os hvordan vil f'øle i en given fremtidig situation, men også tillægge de forstillede følelser positiv eller negativ værdi.
Task-related functional connectivity analysis revealed reliable correlations within the core regions of the DMN, and only two nodes in the task-positive network, suggesting that the DMN was engaged during our experimental conditions, but not the task-positive network. The present study does not directly compare the experimental tasks with “rest.” Although preand postscan questionnaires have helped clarify resting state cognition (e.g., Andrews-Hanna, Huang, Reidler, &amp Spreng and Grady 1121Buckner, 2008; Mason et al., 2007), we remain unsure what people do while resting. 
    In order to circumvent this issue, novel techniques and analyses are needed to assess default cognition and its neural associations. For example, one study assessed the overlap between episodic memory and theory-of-mind tasks, and then determined peak activity!s relationship with the DMN using resting state functional connectivity analysis (Andrews-Hanna, Saxe, Poulin, & Buckner, 2007). 
     The present set of analyses provides converging evidence that the neuroanatomical correlates  of autobiographical memory, prospection, and theory-ofmind are shared and that the DMN is involved in the processing necessary to carry out these specific cognitive behaviors. This sharing of neural resources may allow remembering the past and imagining the future to provide a “long view” in decision-making, over and above stimulus–reward driven behavior, thereby facilitating theory-of-mind and promoting social cooperation (Boyer, 2008).
Her har de altså fundet ud af at de tre processer: den selvbiografiske hukommelse, even til at forestille sig selv mentalt i fremtiden, og evnen til at forestille sig andres mentale setup som ens eget, alle udspringer af og er aktive i default-netværket

Ingen kommentarer:

Send en kommentar