Sensory Specific Desires. The Role of Sensory Taste Exposure in Desire for Food with a Similar or Different Taste Profile

The present study investigated how the sensory taste profile of a meal altered the subjective desire, wanting and liking of foods with a sweet, salty, sour, bitter, fatty, and spicy sensory profile, respectively. Participants (n = 85) ate a meal with a pronounced sensory taste profile: (1) sweet, (2) salty, or (3) sweet and salty combined. Self-reports of appetite, pleasantness, and sensory specific desires (SSD) were evaluated over the course of the meal using VAS-scales. SSDs were further studied through alterations in liking and desire for food samples with the main sensory profile being sweet (peach), salty (pretzel), sour (green apple), bitter (dark chocolate), fatty (whipped cream), and spicy (chilli nut), respectively. Consumption of food with a pronounced sensory taste profile was found to suppress the desire for food with a similar sensory taste profile, while the desire for different sensory profiles were enhanced or not affected. Further, when exposed to two pronounced tastes within the same meal, suppression of sensory desires was not only specific for the exposure tastes but tended to go beyond the sensory exposure. The findings suggest that taste variation within a meal holds the potential to create more satisfying meals, which can hinder additional desires after a meal and thus, lower additional calorie intake.

The Effects of the Healthy Primary School of the Future on Children’s Fruit and Vegetable Preferences, Familiarity and Intake

Mere exposure is an often-described strategy to increase children’s food familiarity, preferences, and intake. Research investigating this method in less controlled settings is scarce. This study investigates the effects of repeated fruit and vegetable (FV) exposure through the Healthy Primary School of the Future (HPSF) on children’s FV familiarity, preferences, and intake. The study had a longitudinal quasi-experimental design comparing two full HPSFs (focus: nutrition and physical activity) with two partial HPSFs (focus: physical activity) in the Netherlands. Annual measurements (child-reported questionnaires) were conducted during 2015–2019 in 833 7–12-year-old children. The study was registered on ClinicalTrials.gov (NCT02800616). After correction for baseline, full HPSFs had, on average, a lower number of unfamiliar vegetable items after one (effect size (ES) = −0.28) and three years (ES = −0.35) and a higher number of disliked vegetable items after one year (ES = 0.24) than partial HPSFs. Unfavorable intervention effects were observed for fruit intake after one (odds ratio (OR) = 0.609) and four years (OR = 0.451). Repeated FV exposure had limited effects on children’s FV familiarity, preferences, and intake, likely due to insufficient taste exposure. Considering the widespread implementation of school-based mere exposure efforts, it is highly relevant to further investigate under which circumstances mere exposure effectively contributes to improvements in (determinants of) FV intake.

Taste Learning in Insular Cortex: Plasticity Is Influenced by Experience Type

The gustatory cortex (GC) has long been studied as the main cortical area encoding taste stimuli and likely integrates sensory, visceral, and emotional information to guide taste-related behaviors. However, our understanding of cortical taste coding on a single-cell level has only become clear in recent years. The anatomical location of GC on the lateral and ventral surface of the brain makes it difficult to target with traditional imaging methods. Thus, much of what we know about cortical taste coding and cortical taste plasticity has been derived either from multiunit electrode recordings or anesthetized imaging experiments, techniques which lack the ability to reliably track neurons over time. To address this limitation, we use miniaturized microendoscope (miniscope) imaging of the calcium indicator GCaMP6s to investigate how cortical taste coding changes with different types of experience. In a basic taste experience paradigm, in which animals consume taste stimuli based on innate taste preferences, we address the question of how novelty and familiarity of taste stimuli effect cortical coding. Using multiday cell tracking, we find two populations of neurons: a stable population encoding taste quality information, and a transient cell population whose activity correlates with the animal's behavioral state. We use the associative learning paradigm conditioned taste aversion (CTA) to show changes in the transient cell population depend upon experience type. With basic experience, the number of transient cells decreases as animals become familiar with taste stimuli and the behavioral task. After increasing situational salience using CTA, the number of transient cells increases to levels seen during novel taste exposure. This research demonstrates a clear role for novelty and familiarity in population responses to taste stimuli in GC, and suggests an overall implication for these effects in cortical coding of sensory stimuli.

NO EFFECTS OF SWEET TASTE EXPOSURE AT BREAKFAST FOR 3 WEEKS ON PLEASANTNESS, DESIRE FOR, SWEETNESS OR INTAKE OF OTHER SWEET FOODS: A RANDOMIZED CONTROLLED TRIAL

This work investigated the effects of repeated sweet taste exposure at breakfast on perceptions and intakes of other sweet foods, while also examining effects due to duration of exposure (1/3 weeks), test context (breakfast/lunch), and associations between taste perceptions and intakes. Using a randomised controlled parallel-groups design, participants (N=54, 18 male, mean age: 23.9±5.8yrs, mean BMI: 23.6±3.5kg/m2) were randomized to consume either a sweet breakfast (cereal with sucralose) (N=27) or an equicaloric non-sweet breakfast (plain cereal) (N=27) for 3 weeks. On days 0 (baseline), 7, and 21, pleasantness, desire to eat and sweetness were rated for other sweet and non-sweet foods, and sweet food consumption was assessed in an ad-libitum meal at breakfast and lunch. Using intention-to-treat analyses, no statistically significant effects of exposure were found at breakfast (largest F(2,104)=1.84, p=0.17, ηp2=0.03), or lunch (largest F(1,52)=1.22, p=0.27, ηp2=0.02), and using Bayesian analyses, the evidence for an absence of effect in all rating measures was strong to very strong (smallest BF01=297.97 (BF01error=2.68%)). Associations between ratings of pleasantness, desire to eat and intake were found (smallest r=0.137, p<0.01). Effects over time regardless of exposure were also found: sugars and percent energy consumed from sweet foods increased throughout the study smallest (F(2,104)=4.54, p=0.01, ηp2=0.08). These findings demonstrate no effects of sweet taste exposure at breakfast for 1 or 3 weeks on pleasantness, desire for, sweetness or intakes of other sweet foods in either the same (breakfast) or in a different (lunch) meal context.

Refinement and reactivation of a taste-responsive hippocampal network

SummaryAnimals need to remember the locations of nourishing and toxic food sources for survival, a fact that necessitates a mechanism for associating taste experiences with particular places. We have previously identified such responses within hippocampal place cells [1], the activity of which is thought to aid memory-guided behavior by forming a mental map of an animal’s environment that can be reshaped through experience [2–7]. It remains unknown, however, whether taste-responsiveness is intrinsic to a subset of place cells, or emerges as a result of experience that reorganizes spatial maps. Here, we recorded from neurons in the dorsal CA1 region of rats running for palatable tastes delivered via intra-oral cannulae at specific locations on a linear track. We identified a subset of taste-responsive cells that, even prior to taste exposure, had larger place fields than non-taste-responsive cells overlapping with stimulus delivery zones. Taste-responsive cells’ place fields then contracted, as a result of taste experience, leading to a stronger representation of stimulus delivery zones on the track. Taste-responsive units exhibited increased sharp-wave ripple co-activation during the taste delivery session and subsequent rest periods, which correlated with the degree of place field contraction. Our results reveal that novel taste experience evokes responses within a preconfigured network of taste-responsive hippocampal place cells with large fields, whose spatial representations are refined by sensory experience to signal areas of behavioral salience. This represents a possible mechanism by which animals identify and remember locations where ecologically relevant stimuli are found within their environment.