Within-session decrement of the emission of licking bursts following reward devaluation in rats licking for sucrose

Abstract

We previously observed that dopamine D2-like receptor blockade in rats licking for sucrose produced a within-session decrement of the emission of licking bursts similar to the effect of either reward devaluation, or neuroleptics, on operant responding for different rewards, which, accordingly, we interpreted as an extinction-like effect. This implies that exposing animals to reward devaluation would result in a drop of burst number taking place only after the contact with the devalued reward. To test this prediction, we compared the difference in the within-session time course of burst number in response to high (10%) versus low (2%) concentration sucrose solutions, either in a condition of reward devaluation (exposure to 2% after daily 10%), or in a condition which does not involve changes in the reward value (two groups of subjects each repeatedly exposed to only one of the two concentrations). Reward devaluation resulted in a within-session decrement of the burst number, with the response rate dropping only after the contact with the devalued reward, as predicted. This response pattern was reliably observed only in subjects at their first devaluation experience. In contrast, exposure of separate groups of animals to the two different concentrations yielded lower levels of burst number in the low concentration group apparent since the beginning of the session, as previously observed with dopamine D1-like receptor blockade. These results show that the analysis of burst number, but not of burst size, reveals a specific activation pattern in response to reward devaluation, which differs from the pattern observed comparing the response to two different sucrose concentrations in separate groups of subjects, i.e. in a condition not involving reward devaluation. Finally, the characterisation of the experimental measures of the analysis of licking microstructure in behaviourally (and psychologically) meaningful functional terms, might be relevant for the investigation of the mechanisms underlying behavioural activation and the related evaluation processes.

Decrease in Operant Responding Under Obesogenic Diet Exposure is not Related to Deficits in Incentive or Hedonic Processes

“…To do so, we analyzed the licking microstructures during the consumption of the freely accessible reward, which allows assessing several components of consummatory behavior, such as basal hunger, postingestive negative feedback, and palatability of the ingested tastant (Figure A). The number of licks per burst ( t [40] = 0.20; P = 0.842) (Figure F), burst duration ( t [40] = 1.382; P = 0.175) (Figure G), interlick interval ( t [40] = 0.944; P = 0.351) (Figure H), and lick frequency in bursts ( t [40] = 0.234; P = 0.817) (Figure I) were identical in both groups, suggesting similar hedonic reactivity to the reward.…”

Differential effects of dopamine D1‐like and D2‐like receptor agonists on water drinking behaviour under thirsty conditions in mice with reduced dopamine secretion

“…The analysis of licking microstructure, including the numbers of total licks, which indicate the extent of feeding activity, is commonly used to evaluate changes in fluid ingestion and thus general drinking behaviour (D'Aquila et al., ; Davis, ; Higgs & Cooper, ; Mendez, Maidment, & Murphy, ). Rodents typically cluster their licks into separate sets known as bursts or bouts (D'Aquila & Galistu, ; Johnson, ). The number of bursts reflects the incentive motivation triggered by cues because it indicates the activation of responses (Johnson, Sherwood, Smith, Gallagher, & Holland, ; Johnson et al., ; Smith, ).…”

“…The mesolimbic dopamine (DA) system is involved in reward‐oriented behaviours (Berridge, ; Flagel & Robinson, ), and DA antagonism in rodents changes their ingestive behaviours (Galistu & D'Aquila, ; Robles & Johnson, ; Salamone, Correa, Yang, Rotolo, & Presby, ). The licking behaviour of rodents is widely used as a means to explore how liking (hedonic impact of reward), wanting (incentive motivation), and learning (reward prediction) modulate animal behaviours (Berridge, ; Berridge, Robinson, & Aldridge, ; D'Aquila & Galistu, ; Dastugue, Merlin, Maquart, Bernard, & Besnard, ; Davies et al., ; Johnson, ; Taha & Fields, ; Uematsu et al., ). Pharmacology studies showed that dopaminergic (DAergic) stimulation of the nucleus accumbens (NAc) triggers an intense response to obtain a reward, even if a rat has undergone extinction training (Peciña & Berridge, ; Saunders & Robinson, ; Singer et al., ).…”

“…The DSI mouse line enables the study of phenotypes related to DA loss and the role of DAergic neurons and DA receptors in drinking behaviour. In the present study, we assessed water drinking behaviour by analysing licking microstructure (number of licks and bursts, size of bursts and intraburst lick speed) (D'Aquila & Galistu, ; Johnson, ) in DSI mice and control mice receiving a DA D1 receptor agonist (A68930 or SKF38393) or a DA D2/D3 receptor agonist (ropinirole).…”

Memantine effects on ingestion microstructure and the effect of administration time: A within-subject study

“…Repeated exposure to sucrose reward—which depends both on taste and on caloric content—can induce neuroadaptations leading to the release of eating behaviour from the control of homeostatic mechanisms, thus resulting in compulsive overeating [ 14 ]. The analysis of the licking microstructure reveals specific responses to taste or hunger/satiety internal cues [ 15 – 20 ], which are related to the process by which reward evaluation regulates behavioural activation [ 15 , 21 – 25 ]. In more detail, the number of lick bursts—i.e.…”