Laboratory rats show a positive response to low- and nonstressful novel events. The novel event may involve a number of aspects of the stimulus field. It is usually associated with a change in amount of environmental complexity. Most studies concerning novelty-related behavior involve the introduction of novel objects or the rearrangement of familiar objects. The present purpose was to measure exploratory behavior in response to environments of increased and decreased complexity. Both directions of environmental change are conditions of novelty. A two-way manipulation of increasing and decreasing the complexity of the environment was used. Rats of both sexes showed increased exploration to exposure to novelty, no matter which manipulation was applied; however, female and male rats behaved differently to the two types of novelty. Males responded more to novelty from the introduction of an unfamiliar object. The results indicate novel stimulation, whether of increasing or decreasing complexity, has reward properties. Perhaps the male-specific behavior directed toward unfamiliar objects may serve an adaptive function.
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"The main advantage of this method is that sleep is prevented due to an endogenous drive to explore a novel environment, rather than an external perturbation of the animal itself. On the other hand, well-balanced controls are nearly impossible to achieve, due to the intrinsic variability of the behavioral responses to novel object exposure (Thor et al. 1988; Dellu et al. 1996; Bevins et al. 1997; Kabbaj and Akil 2001; Pisula and Siegel 2005; Clinton et al. 2010; Duclot et al. 2011). Moreover, one caveat that must be taken into account is the fact that gene expression following a period of sleep deprivation by exposure to novel objects will confound the effects of novel object exploration with the effects of sleep loss per se. "
[Show abstract][Hide abstract] ABSTRACT: Sleep occurs in a wide range of animal species as a vital process for the maintenance of homeostasis, metabolic restoration, physiological regulation, and adaptive cognitive functions in the central nervous system. Long-term perturbations induced by the lack of sleepSleep are mostly mediated by changes at the level of transcription and translation. This chapter reviews studies in humans, rodents, and flies to address the various ways by which sleep deprivation affects gene expressionGene expression in the nervous system, with a focus on genes related to neuronal plasticity, brain function, and cognitionCognition . However, the effects of sleep deprivation on gene expression and the functional consequences of sleep loss are clearly not restricted to the cognitive domain but may include increased inflammationInflammation , expression of stress-related genes, general impairment of protein translation, metabolic imbalance, and thermalThermoregulation deregulation.
Current Topics in Behavioral Neurosciences 02/2015; 25. DOI:10.1007/7854_2014_360
"Pre-task foraging behavior was examined for evidence that the rats recognized the shifted platform as a change in the environment (Anderson et al. 2006). Rats respond to novelty with increased exploratory activity (Pisula and Siegel 2005). The first time rats experienced the platform-shift condition they explored significantly more of the platform (visited more tracking camera pixels) relative to that of the second shift or during standard conditions (F 3 = 4.57, p = 0.005; Fisher's post-hoc LSD, p < 0.02 for all comparisons including Shift 1, all other comparisons were n.s.; the amount of time in the pre-task foraging condition was not different across standard and platform-shifted conditions, F 3 = 0.89, p = 0.46, range = 196.6 – 269.8 sec). "
[Show abstract][Hide abstract] ABSTRACT: The place-specific activity of hippocampal cells provides downstream structures with information regarding an animal's position within an environment and, perhaps, the location of goals within that environment. In rodents, recent research has suggested that distal cues primarily set the orientation of the spatial representation, whereas the boundaries of the behavioral apparatus determine the locations of place activity. The current study was designed to address possible biases in some previous research that may have minimized the likelihood of observing place activity bound to distal cues. Hippocampal single-unit activity was recorded from six freely moving rats as they were trained to perform a tone-initiated place-preference task on an open-field platform. To investigate whether place activity was bound to the room- or platform-based coordinate frame (or both), the platform was translated within the room at an "early" and at a "late" phase of task acquisition (Shift 1 and Shift 2). At both time points, CA1 and CA3 place cells demonstrated room-associated and/or platform-associated activity, or remapped in response to the platform shift. Shift 1 revealed place activity that reflected an interaction between a dominant platform-based (proximal) coordinate frame and a weaker room-based (distal) frame because many CA1 and CA3 place fields shifted to a location intermediate to the two reference frames. Shift 2 resulted in place activity that became more strongly bound to either the platform- or room-based coordinate frame, suggesting the emergence of two independent spatial frames of reference (with many more cells participating in platform-based than in room-based representations).
Journal of Neurophysiology 02/2008; 99(1):60-76. DOI:10.1152/jn.00731.2007 · 2.89 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: When given a locomotor/exploratory test in the laboratory, rats form one or more home bases, operationally defined as places where they spend a disproportionate period of their time and from which they make excursions. Because exploratory tests in the laboratory necessarily restrict the animals' movements, the cause of exploration (e.g., fear, curiosity, innate disposition) and the extent to which organization is imposed by the restriction of the testing environment has not been fully examined. In the present study, rats received exploratory tests in environments in which restrictions were remote; in a parking lot or on a playing field. Each rat began a test in one of three conditions: in a small refuge, within a transparent open home cage, or beside a landmark. In the parking lot, the rats failed to leave the small refuge, made excursions from the home cage, and left the landmark, usually at a gallop, and made no movements of returning. On the playing field they remained in the small refuge, left and returned to the open home cage, and were more likely to permanently leave the landmark at a gallop. Rats that displayed a strong preference for the landmark over three test sessions in a laboratory, also immediately left the same landmark when tested on the playing field. The pattern of behavior, in which the rats failed to explore from a secure starting position and were increasingly likely to run away as security decreased, suggests that a primary function of locomotor behavior in a novel environment is to optimize security. The results are discussed in relation to the advantages of investigating the influence of neural processes on exploration in terms optimization theory versus motivational theory.
Behavioural Brain Research 09/2006; 171(2):230-9. DOI:10.1016/j.bbr.2006.03.037 · 3.03 Impact Factor