Effects of Cue-Triggered Expectation on Cortical Processing of Taste

Abstract

SUMMARY Animals are not passive spectators of the sensory world in which they live. In natural conditions they often sense objects on the bases of expectations initiated by predictive cues. Expectation profoundly modulates neural activity by altering the background state of cortical networks and modulating sensory processing. The link between these two effects is not known. Here, we studied how cue-triggered expectation of stimulus availability influences processing of sensory stimuli in the gustatory cortex (GC). We found that expected tastants were coded more rapidly than unexpected stimuli. The faster onset of sensory coding related to anticipatory priming of GC by associative auditory cues. Simultaneous recordings and pharmacological manipulations of GC and basolateral amygdala revealed the role of top-down inputs in mediating the effects of anticipatory cues. Altogether these data provide a new model for how cue-triggered expectation changes the state of sensory cortices to achieve rapid processing of natural stimuli.

Speed and accuracy of taste identification and palatability: impact of learning, reward expectancy, and consummatory licking

“…From the perspective of taste processing, it has been recently shown that expectation of the delivery of tastants delivered via intraoral cannulas can speed taste processing (40,54). We also found that the expectation of a reward can also play an important role for consummatory licking.…”

“…This demonstrates that oromotor output is modulated by reward expectation. In summary, these results indicate that reward expectancy not only modifies taste processing (40,54) but also the oromotor components that accompany reward consumption.…”

“…The longer times are associated with information obtained from neural recordings with tastants delivered either via intraoral cannulas (38) or with the times an animal stopped licking when presented with a tastant for which it had a conditioned taste aversion (CTA) (52). Some of these differences depend on whether rats were trained and familiar with the tastants, when the delivery of a tastant was expected (40,54), and whether they received tastants by freely licking, or through intraoral cannulas. Other factors involve the volume and concentration of the tastant delivered, if the rodent were water-deprived, and if it were conditioned to avoid a tastant (15,52).…”

Sensory Cortical Activity Is Related to the Selection of a Rhythmic Motor Action Pattern

“…To confirm the effectiveness with which we were able to optogenetically inactivate GC, we tested a separate set of infected and control rats on a conditioned taste aversion (CTA) task, with successful CTA learning being dependent on GC (Dunn and Everitt, 1988;Gallo et al, 1992;Schafe and Bernstein, 1998;Roman et al, 2006). Animals were first adapted to obtaining pulses of distilled water through the IOC by inserting their nose into a small port equipped with an infrared beam (60 l/poke; 100 pokes; 3 s enforced delay between each poke; total session length, Ͻ30 min).…”

“…GC projects directly to the CPG (Zhang and Sasamoto, 1990;Shammah-Lagnado et al, 1992;Travers et al, 1997), and stimulation of GC can induce changes in licking and rhythmic jaw movements (Sasamoto et al, 1990;Peng et al, 2015). Moreover, taste responses in GC become palatability related around the onset of ingestive/egestive behavior (Katz et al, 2001;Sadacca et al, 2012), and appear necessary for palatability-related responses to novel tastes (Stehberg et al, 2011;Moraga-Amaro et al, 2014).…”