However, recent promising work based on tractographic connectivity profiles suggests that a similar parcellation might also exist in the human ventral striatum ( 6– 8). The human ventral striatum is also known to be a heterogeneous structure, but its subdivision into core and shell is not as well defined as it is in rodents and non-human primates. These nuclei are anatomically distinct, occupying the dorsolateral and ventromedial regions of the ventral striatum. Studies conducted on rodents and non-human primates typically distinguish between the core and shell nuclei. The ventral striatum itself is not an unitary and homogeneous structure. The motivational mechanisms determine how much effort an individual mobilizes to obtain a reward, whereas the hedonic mechanisms determine how much pleasure an individual experiences during reward consumption ( 5). Affective processes involved in reward processing are often categorized into motivational and hedonic mechanisms. Moreover, the ventral striatum has also been consistently implicated in the affective processing of rewarding stimuli ( 3, 4). The most notorious findings have highlighted the role of the ventral striatum in the computation of reward prediction errors ( 1) and in the anticipation of reward delivery ( 2). It is widely held that the ventral striatum is implicated in reward processing. Parsing the neural mechanisms and the interplay between Pavlovian incentive processes and hedonic processes might have important implications for understanding compulsive reward-seeking behaviors such as addiction, binge eating, or gambling. Our findings show that different subregions of the ventral striatum are dissociable in their contributions to the motivational and the hedonic component of the affective processing of the reward. Both tasks involved an olfactory reward, thereby allowing us to measure Pavlovian-triggered motivation and sensory pleasure for the same reward within the same participants.

We used a high-resolution fMRI protocol targeting the ventral striatum combined with a Pavlovian-instrumental task and a hedonic reactivity task. Here, we examined whether these two components rely on distinct neural substrates within the ventral striatum in humans. The hedonic threshold methodology is a recently proposed methodology therefore, given the differences in the way consumers use scales and the type of response obtained, it is necessary to investigate whether hedonic thresholds are influenced by the use of different scales.The ventral striatum is implicated in the affective processing of the reward, which can be divided into a motivational and a hedonic component. Quality sensory measurements are increasingly required, given that unreliable data may lead to dreadful decisions as well as long-lasting financial losses. This occurs when a product is intended to be reformulated by increasing the concentration of desirable substances such as health-beneficial compounds (e.g., ferrous sulfate and omega-3) and reducing the concentration of undesirable substances, such as sucrose, sodium, and fat, to promote better health. Industries often need to modify their products, changing as much as possible of a certain characteristic without changing the sensorial acceptance of the product. The importance of determining hedonic thresholds covers areas such as food, pharmaceutical, and cosmetic. The “ULSWC,” in addition to meeting the prerequisite, showed accuracy and is considered an alternative for the HTM. The “1 to 9” met the prerequisite and presented high discriminant potential. This indicates that consumers may have had difficulty understanding and properly using these scales. However, they indicated no significant difference in the second session. The “−4 to +4” and “ULSOC” scales were not suitable for use in the HTM, because they do not meet the prerequisite that there is no significant difference between acceptance of the control samples and the first stimulus sample. Four hedonic scales were used: unipolar (“1 to 9”) and bipolar (“−4 to +4”) numbered structured scales and unstructured line (“ULSOC”) and hybrid line scales (“ULSWC”). The HTM was applied to grape nectar, varying the sucrose concentration, and to cookies, varying the butter concentration. The aim of this study was to investigate if hedonic thresholds are influenced by the use of different types of hedonic scales. However, there are other scales that can be used. The hedonic threshold methodology (HTM) allows for the determination of the compromised acceptance threshold and the hedonic rejection threshold, using the unipolar nine-point numbered structured hedonic scale.

Hedonic threshold