[U-13C]Glutamate metabolism was studied in primary brain cell cultures. Cell extracts as well as redissolved lyophilized media were subjected to nuclear magnetic resonance spectroscopy in order to identify 13C labeled metabolites. Both neurons and astrocytes metabolized glutamate extensively with 13C label appearing in aspartate in all cultures. Additionally, GABA is synthesized in the GABAergic cortical neurons. Labeling of lactate and glutamine was prominent in medium from astrocytes, but not detectable in cerebral cortical neurons. Cerebellar granule neurons showed some labeling of lactate. Glutamate derived from the first turn of the tricarboxylic acid cycle (1,2,3-13C3-isotopomer) is present in all cell types analyzed. However, glutamate derived from the second turn of the cycle was only detected in granule neurons. In astrocytes, the transaminase inhibitor aminooxyacetic acid not only abolished the appearance of aspartate, but also of the 1,2,3-13C3-isotopomer of glutamate, thus showing that transamination is necessary for the conversion of 2-oxoglutarate to glutamate. The entry of glutamate into the tricarboxylic acid cycle was, however, not seriously impaired. 3-nitropropionic acid abolished the appearance of aspartate, the 1,2,3-13C3-isotopomer of glutamate and lactate in cerebellar granule neurons.

SammendragKunnskap om tilrettelegging for kritisk tenkning er vesentlig i barnehage og skoler, i laererutdanning og i veilederutdanning. Artikkelen presenterer og døfter eksempler på hvordan veiledningssamtaler mellom nyutdannede og deres veiledere å pner for kritisk tenkning ved å vise til data fra to doktorgradsavhandlinger (Bjerkholt, 2013a;Ødegå rd, 2011). Denne å pningen kommer til uttrykk ved at deltakerne tydeliggjør og gransker beslutningsgrunnlaget for pedagogiske valg. Analysene viser at spor av kritisk tenkning er tydeligere i noen samtaler enn i andre. Sporene varierer i form og omfang, og de arter seg forskjellig. Forhold som barnehage-og skolekontekst, veiledningskontekst og relasjoner mellom de nyutdannede og veilederne samt veiledernes kompetanse har betydning for hvordan og i hvilken grad veiledningssamtaler å pner for kritisk tenkning.Nøkkelord: Kontekstualisering, relasjoner, antakelser, begrunnelser, perspektiver, autonom, funksjonaer, demokrati Abstract Knowledge of how to facilitate critical thinking is essential in kindergartens and schools, in teacher education and in the education of mentors. This article presents and debates examples of how mentoring sessions between the new teachers and their mentors create room for critical thinking, by referring to data from two doctoral dissertations. The analyses of the mentoring sessions show how the sessions, to a certain extent, provide room for critical thinking. This opening for critical thinking is reflected in the way the participants clarify and examine the basis for pedagogical choices. The analyses also show that traces of critical thinking are more apparent in some sessions than in others. These traces vary in form and magnitude, and they appear in different ways. Various factors have important influence on how and to what degree the mentoring sessions open up for critical thinking; for example, the conditions in kindergartens-and school contexts, mentoring context, and relations between the new teachers and their mentors, as well as the mentors' abilities and competences.