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Taste preference learning: behavioural and neural basis.

Reference	BB/C006380/1
Principal Investigator / Supervisor	Professor Dominic Dwyer
Co-Investigators / Co-Supervisors
Institution	Cardiff University
Department	Sch of Psychology
Funding type	Research
Value (£)	244,826
Status	Completed
Type	Research Grant
Start date	03/10/2005
End date	02/05/2009
Duration	43 months

Abstract

Flavour preferences have important effects on diet (both in terms of determining food choice and by influencing amount consumed of preferred and non-preferred substances) and most flavour preferences are learnt. Despite these facts there is a paucity of knowledge with respect to the neural and behavioural mechanisms underpinning the learning of food preferences. While palatability- and nutrient-based preferences have been hypothesised to be based on different processes there is little behavioural evidence and almost no neuroscientific evidence to support this claim. Unambiguous demonstration of nutrient-based preference requires that the nutrient itself is not tasted during training. This is achieved by inserting a gastric cannula and directly infusing a quantity of the nutrient solution to the gut matched to the concurrent consumption of the non-nutrient cue solution. Palatability-based preferences simply pair consumption of the cue solution with a second highly palatable solution (with the restriction that neither solution supports nutrient conditioning). Both types of preference are indicated by greater consumption of a cue solution which had been paired with a reinforcer than of another solution which has not. Behavioural experiments, designed to elucidate the psychological processes underpinning flavour preference, will contribute both to the basic understanding of this process by discovering to what extent palatability- and nutrient-based preferences are underpinned by a common mechanism as well as whether either type of preference reflects other, more general, forms of learning. Such studies will also guide the neural manipulations by suggesting parallels with the investigation of other forms of learning. Key manipulations here will be the investigation of cue competition (eg. in overshadowing or blocking), extinction, and the role of the representation of the outcome in performance. Recent results suggest that the amygdala may be crucially involved in flavour preferences and one theoretical perspective on the role of sub-nuclei of the amygdala in reward processes (Killcross and Blundell, 2002) suggests they may also have separable roles in flavour preferences learning. In particular the basolateral amygdala (BLA) may be part of the system underpinning palatability based preferences while the central nucleus (CeN) of the amygdala might be more involved in nutrient based preferences. The initial focus of the project will be on comparing the learning of palatability- and nutrient-based preferences in rats with excitotoxic lesions of the BLA and CeN with non lesioned animals. This will be followed by disconnection lesions of the amygdala nuclei with the nucleus accumbens and lateral hypothalamus to investigate the neural circuits involved. Subsequent experiments will use temporary inactivation methods directed at individuals and interacting structures to discover whether these structures contribute to the learning and or expression of flavour preferences. Examining behavioural and neural inventions will allow for analytical modelling of the neural circuits involved in flavour preference. It will also integrate the analysis of flavour preference with the analysis of other forms of learning both in terms of its behavioural profile and the neural circuits underpinning such learning.

Summary

unavailable

Committee	Closed Committee - Animal Sciences (AS)
Research Topics	Diet and Health, Neuroscience and Behaviour
Research Priority	X – Research Priority information not available
Research Initiative	X - not in an Initiative
Funding Scheme	X – not Funded via a specific Funding Scheme

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