Jeg har i flere af de senere indlæg været inde på det relativt nyopdagede "default network" i hjernen (på engelsk forkortet DMN som står for Default Mode Network).
Det er et neuralt netværk der er aktivt når hjerne og dermed bevidstheden ikke er optaget af udadvendt, aktiv og målrettet opgaveløsning.
Dette netværk er aktivt når sindet "vandrer": når man dagdrømmer, slapper af og "ikke tænker på noget særligt", når man "er fjern", "distræit", "uopmærksom", "langt væk".
Men dette netværk viser sig så også at være aktivt når man stilles over for bestemte typer mentale opgaver, som netop kræver at sindet i en eller anden forstand "ser indad", fx...
- når man prøver at fremkalde erindringer om tidligere oplevede erfaringer
- når man forestiller sig selv i en fremtidig situation
- når man forestiller sig hvad en anden person forestiller sig
- når man skal tage moralsk stilling til hvad man skal gøre i en tænkt situation.
Det kan man læse meget mere om på adressen:
Her dokumenterer forfatterne til artiklen fra 2008 blandt andet default-netværket i aktion - dvs. at de dele af hjernen "tænder" når de stilles over for snedigt udtænkt opgaver der vender sindet og opmærksomheden indad - mod selvet:
The default network is activated by diverse forms of tasks that require mental simulation of alternative perspectives or imagined scenes. Four such examples from the literature illustrate the generality. (A) Autobiographical memory: subjects recount a specific, past event from memory. (B) Envisioning the future: cued with an item (e.g., dress), subjects imagine a specific future event involving that item. (C) Theory of mind: subjects answer questions that require them to conceive of the perspective (belief) of another person. (D) Moral decision making: subjects decide upon a personal moral dilemma. Note that all the studies activate strongly PCC/Rsp and dMPFC. Active regions also include those close to IPL and LTC, although further research will be required to determine the exact degree of anatomic overlap. It seems likely that these maps represent multiple, interacting subsystems.
Her er et uddrag fra en anden ny artikel (2010) som findes på adressen:
Den når til stort set samme konkusion om default-netværkets (DMN) særlige funktion, men inddrager også muligheden for at det er aktivt ved "fictional narrative simulation":
The current set of analyses provides converging evidencethat 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). 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 thesedomains rely upon a pattern of brain activity operating within the DMN. The results provide the first direct evidence to support previous independent observation 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).(...)The present set of analyses provides converging evidence that the neuroanatomical correlates of autobiographical memory, prospection, and theory-of-mind 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 providea “long view” in decision-making, over and above stimulus–reward driven behavior, thereby facilitating theory-of-mind and promoting social cooperation (Boyer, 2008).
Jeg kan ikke se andet end at dette netværk er det der må være aktivt - det som hjernen trækker på - når der skal skrives litteratur. At skrive en roman er jo grundlæggende en form for kompliceret simulation, og indebærer netop: 1) at man må trække på egne erindringer, 2) at man må tænke sig ind i en anden (her fiktiv) persons synsvinkel, 3) at man må projicerer sider af sig selv ind i et (muligvis fremtidigt) imaginært univers.
