test Browse by Author Names Browse by Titles of Works Browse by Subjects of Works Browse by Issue Dates of Works
       

Advanced Search
Home   
 
Browse   
Communities
& Collections
  
Issue Date   
Author   
Title   
Subject   
 
Sign on to:   
Receive email
updates
  
My Account
authorized users
  
Edit Profile   
 
Help   
About T-Space   

T-Space at The University of Toronto Libraries >
School of Graduate Studies - Theses >
Doctoral >

Please use this identifier to cite or link to this item: http://hdl.handle.net/1807/24363

Title: The Effects of Maternal Deprivation, Through Artificial Rearing, on Impulsiveness in Rats
Authors: Lovic, Vedran
Advisor: Fleming, Alison S.
Department: Psychology
Keywords: rats
maternal
deprivation
impulsivity
isolation
discounting
artificial
rearing
development
pups
Issue Date: 21-Apr-2010
Abstract: Mammalian brain and behaviour are plastic, particularly early in development when offspring are under the care of their mothers. Adverse early life events, such as maternal and social deprivation, have short- and long-term consequences for neurobiology and consequently for behaviour. The purpose of this thesis was to investigate the effects of maternal and social deprivation, through artificial rearing (AR), on adult impulsive behaviour. Rats were raised in isolation from mothers and siblings (AR) or with their mothers and siblings in the nest [maternal rearing (MR)]. In addition, half of the AR rats were provided with replacement somatosensory stimulation designed to simulate mothers’ licking (see Gonzalez et al., 2001). As adults, rats were tested on impulsive action using the differential reinforcement of low rates (DRL) operant task and locomotor activity. Both male and female AR rats were more impulsive than MR rats; they made more responses and they were less efficient at earning rewards. In addition, they displayed greater levels of locomotor activity. These effects were partially reversed by replacement somatosensory stimulation. Furthermore, impulsivity was positively correlated with locomotor activity. Impulsive choice was then assessed using a delay discounting operant schedule. On this task, AR rats were less likely to discount the value of large-delayed reward, suggesting that they were better able to tolerate delays to large reward and were less impulsive. However, performance on a modified version of delay discounting revealed that AR rats were less efficient at switching their responses; that is, they displayed reduced behavioural flexibility. To address this finding, impulsive choice was next assessed in fixed consecutive chain operant schedule of reinforcement, but there were no differences between AR and MR animals. Finally, the relationship between impulsive action and a species-characteristic behaviour, maternal behaviour, was investigated. Consistent with the literature, AR rats were less maternal and more impulsive. Moreover, there was a negative correlation between impulsivity and maternal behaviour. Overall, this set of studies demonstrates that maternal and social deprivation produces an increase in impulsive action without an effect on impulsive choice. Furthermore, increased action impulsiveness is a significant moderator of disrupted maternal behaviour observed in artificially reared rats.
URI: http://hdl.handle.net/1807/24363
Appears in Collections:Doctoral
Department of Psychology - Doctoral theses

Files in This Item:

File Description SizeFormat
Lovic_Vedran_201003_PhD_thesis.pdf347.15 kBAdobe PDF
View/Open

Items in T-Space are protected by copyright, with all rights reserved, unless otherwise indicated.

uoft