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Samuelsson, Andrew R. (2011) DISSECTING THE REGISTRATION AND PROCESSING OF OLFACTORY EVENTS DURING GENERAL ANESTHESIA. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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It is commonly accepted that general anesthesia produces unconsciousness and amnesia. However, the extent to which the anesthetized brain receives and retains information is not well understood. Memory of a given event relies upon initial consolidation and subsequent retrieval. In order to test the effects of anesthesia on these separate memory components, we compared what rats reported behaviorally with what their brains 'reported' histologically. In chapter 2, we fully anesthetized rats with ketamine/xylazine anesthesia and exposed the animals to a novel odorant mixture. The following day the rats were presented with the same odorant mixture while awake in order to assess behavioral familiarity. The rats demonstrated no memory of the odorants previously presented during anesthesia. In order to assess odor-induced brain changes, rats were sacrificed for histological analysis 2 hours after exposure to the odorants during anesthesia, or 2 hours after re-exposure while awake the following day. We quantified the protein expression of c-fos, an immediate early gene thought to be critical for memory consolidation, in cortical olfactory regions. During anesthesia, a novel odorant mixture activated c-Fos similar to that found in awake animals. Repeated exposure to the odorants caused an attenuation of c-Fos regardless of whether the initial exposure occurred while anesthetized or awake. This suggests that memory-related protein changes can occur in olfactory cortical regions despite anesthesia. Given, the potential information consolidation observed in these ketamine/xylazine anesthetized animals, we attempted to retrieve olfactory memories using additional behavioral paradigms and memory-enhancing drugs in chapter 3, but were unable to reveal any explicit memory formation. However, we found subtle changes in odorant approach latency, suggesting a potential implicit memory. Further histological investigation in chapter 4 revealed that changes in odor-induced neurogenesis could also occur despite ketamine/xylazine anesthesia, similar to that found with c-Fos labeling, thus supporting the permissive role of this anesthetic. However, odor-related changes in c-Fos did not occur with the anesthetics pentobarbital or propofol, suggesting these traits are not universal amongst all anesthetics. Nevertheless, these data indicate a functional disconnection between the cortical representation of an environmental stimulus and the corresponding perceptual experience or memory.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Samuelsson, Andrew R.ars66@pitt.eduARS66
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairUrban,
Committee MemberThiels, Eddathiels@pitt.eduTHIELS
Committee MemberHomanics, GreggHomanicsGE@anes.upmc.eduGEH2
Committee MemberAlbers, Kathykaa2@pitt.eduKAA2
Committee MemberMiller,
Committee MemberXu,
Date: 2 August 2011
Date Type: Completion
Defense Date: 21 July 2011
Approval Date: 2 August 2011
Submission Date: 2 August 2011
Access Restriction: 5 year -- Restrict access to University of Pittsburgh for a period of 5 years.
Institution: University of Pittsburgh
Schools and Programs: School of Medicine > Neurobiology
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: Anesthesia; Immediate Early Genes; Olfaction
Other ID:, etd-08022011-143415
Date Deposited: 10 Nov 2011 19:56
Last Modified: 19 Dec 2016 14:37


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