Biology subjects

Maria-Rios, C. E.

Publications and source records attributed to Maria-Rios, C. E..

3 recordsLinked to original sources

bioRxiv2025

Individual Variation in Intrinsic Neuronal Properties of Nucleus Accumbens Core and Shell Medium Spiny Neurons in Animals Prone to Sign- or Goal-Track

The "sign-tracking" and "goal-tracking" model of individual variation in associative learning permits the identification of rats with different cue-reactivity and predisposition to addiction-like behaviors. Certainly, compared to "goal-trackers" (GTs), "sign-trackers" (STs) show more susceptibility traits such as increased cue-induced relapse of drugs of abuse. Different cue- and reward-evoked patterns of activity in the nucleus accumbens (NAc) have been a hallmark of the ST/GT phenotype. However, it is unknown whether differences in the intrinsic neuronal properties of NAc medium spiny neurons (MSNs) in the core and shell subregions are also a physiological correlate of these phenotypes. We performed whole-cell slice electrophysiology in outbred male rats and found that STs exhibited the lowest excitability in the NAc core, with lower number of action potentials and firing frequency as well as a blunted voltage/current relationship curve in response to hyperpolarized potentials in both the NAc core and shell. Although firing properties of shell MSNs did not differ between STs and GTs, intermediate responders that engage in both behaviors showed greater excitability compared to both STs and GTs. These findings suggest that intrinsic excitability in the NAc may contribute to individual differences in the attribution of incentive salience. Significance StatementDuring associative learning, cues acquire predictive value, but in some instances, they also acquire incentive salience, meaning they take on some of the motivational properties of the reward. The propensity to attribute cues with incentive salience varies between individuals, and excessive attribution can lead to maladaptive behaviors. The "sign-and goal-tracking" model allows us to isolate these two properties and disambiguate the neurobiological processes that govern them. To our knowledge this is the first study characterizing passive and active membrane properties of MSNs in the NAc core and shell of STs and GTs, as well as IRs. These findings are meant to better inform investigations of the distinct role of the NAc in reward learning, particularly in the attribution of incentive salience and addiction predisposition.

neuroscience↗

bioRxiv2020

The lateral hypothalamus and orexinergic transmission in the paraventricular thalamus promote the attribution of incentive salience to reward-associated cues

RationalePrior research suggests that inputs from the lateral hypothalamic area (LHA) to the paraventricular nucleus of the thalamus (PVT) contribute to the attribution of incentive salience to Pavlovian-conditioned reward cues. However, a causal role for the LHA in this phenomenon has not been demonstrated. In addition, it is unknown which hypothalamic neurotransmitter or peptide system(s) are involved in mediating incentive salience attribution. ObjectivesTo examine: 1) the role of the LHA in the propensity to attribute incentive salience to reward cues, and 2) the role of orexinergic signaling in the PVT on the expression of Pavlovian conditioned approach (PavCA) behavior, a reflection of incentive salience attribution. MethodsMale Sprague-Dawley rats received bilateral excitotoxic lesions of the LHA prior to the acquisition of Pavlovian conditioned approach (PavCA) behavior. A separate cohort of male rats acquired PavCA behavior and were characterized as sign-trackers (STs) or goal-trackers (GTs) based on their conditioned response. The orexin 1 receptor (OX1r) antagonist SB-334867, or the orexin 2 receptor (OX2r) antagonist TCS-OX2-29, were then administered directly into the PVT to assess the effects of these pharmacological agents on the expression of PavCA behavior and on the conditioned reinforcing properties of the Pavlovian reward cue. ResultsLesions of the LHA before training attenuated the development of lever-directed (sign-tracking) behaviors in the PavCA paradigm, without affecting magazine-directed (goal-tracking) behaviors. In STs, administration of the OX1r antagonist into the PVT reduced lever-directed behaviors and increased magazine-directed behaviors; while administration of the OX2r antagonist only reduced lever-directed behaviors. Further, OX2r, but not OX1r, antagonism was able to reduce the incentive motivational value of the conditioned stimulus on a conditioned reinforcement test in STs. The behavior of GTs was unaffected by orexinergic antagonism in the PVT. ConclusionsThe LHA is necessary for the attribution of incentive salience to reward cues and, thereby, the development of a sign-tracking conditioned response. Furthermore, blockade of orexin signaling in the PVT attenuates the incentive value of a Pavlovian reward cue. These data suggest that hypothalamic orexin inputs to the PVT are a key component of the circuitry that encodes the incentive motivational value of reward cues and promotes maladaptive cue-driven behaviors.

neuroscience↗

bioRxiv2019

Effects of predictive and incentive value manipulation on sign- and goal-tracking behavior

When a neutral stimulus is repeatedly paired with an appetitive reward, two different types of conditioned approach responses may develop: a sign-tracking response directed toward the neutral cue, or a goal-tracking response directed toward the location of impending reward delivery. Sign-tracking responses have been postulated to result from attribution of incentive value to conditioned cues, while goal-tracking reflects the assignment of only predictive value to the cue. We therefore hypothesized that sign-tracking would be more sensitive to manipulations of incentive value, while goal-tracking would be more responsive to changes in the predictive value of the cue. We tested sign- and goal-tracking before and after devaluation of a food reward using lithium chloride, and tested whether either response could be learned under negative contingency conditions that precluded any serendipitous reinforcement of the behavior that might support instrumental learning. We also tested the effects on sign- and goal-tracking of blocking the predictive value of a cue using simultaneous presentation of a pre-conditioned cue. We found that sign-tracking was sensitive to outcome devaluation, while goal-tracking was not. We also confirmed that both responses are Pavlovian because they can be learned under negative contingency conditions. Goal-tracking was completely blocked by a pre-conditioned cue, while sign-tracking was only partially reduced. These results indicate that sign- and goal-tracking follow different rules of reinforcement learning and suggest a need to revise current models of associative learning to account for these differences.

animal behavior and cognition↗