58 research outputs found
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From low to high cognition: A multi-level model of behavioral control in theprimate brain
The basic cognitive architecture of the human brain remainsunknown. However, there is evidence for the existence ofdistinct behavioral control systems shared by humans andnonhumans; and there is further evidence pointing to distincthigher-level problem solving systems shared by humans andother primates. To clarify the nature of these proposedsystems and examine how they may interact in the brain, wepresent a four-level model of the primate brain and compareits performance to three other brain models in the face of achallenging foraging problem (i.e., with transparent, and thus,invisible barriers). In all manipulations (e.g., size of problemspace, number of obstacles), our model never performed thebest outright; however, it was always among the best,appearing to be a jack-of-all-trades. Thus, the virtues of ourprimate brain lie not only in the heights of thinking it canreach, but also in its range and versatility
Too Good to Be True: Rhesus Monkeys React Negatively to Better-than-Expected Offers
To succeed in a dynamically changing world, animals need to predict their environments. Humans, in fact, exhibit such a strong desire for consistency that one of the most well-established findings in social psychology is the effort people make to maintain consistency among their beliefs, attitudes, and behavior. However, displeasure with unpredictability leads to a potential paradox, because a positive outcome that exceeds one’s expectations often leads to increased subjective value and positive affect, not the opposite. We tested the hypothesis that two evolutionarily-conserved evaluation processes underlie goal-directed behavior: (1) consistency, concerned with prediction errors, and (2) valuation, concerned with outcome utility. Rhesus monkeys (Macaca mulatta) viewed a food item and then were offered an identical, better, or worse food, which they could accept or reject. The monkeys ultimately accepted all offers, attesting to the influence of the valuation process. However, they were slower to accept the unexpected offers, and they exhibited aversive reactions, especially to the better-than-expected offers, repeatedly turning their heads and looking away before accepting the food item. Our findings (a) provide evidence for two separable evaluation processes in primates, consistency and value assessment, (b) reveal a direct relationship between consistency assessment and emotional processes, and (c) show that our wariness with events that are much better than expected is shared with other social primates
Nucleus accumbens shell moderates preference bias during voluntary choice behavior
The nucleus accumbens (NAc) shell lies anatomically at a critical intersection within the brain's reward system circuitry, however, its role in voluntary choice behavior remains unclear. Rats with electrolytic lesions in the NAc shell were tested in a novel foraging paradigm. Over a continuous two-week period they freely chose among four nutritionally identical but differently flavored food pellets by pressing corresponding levers. We examined the lesion's effects on three behavioral dynamics components: motivation (when to eat), preference bias (what to choose) and persistence (how long to repeat the same choice). The lesion led to a marked increase in the preference bias: i.e., increased selection of the most-preferred choice option, and decreased selection of the others. We found no effects on any other behavioral measures, suggesting no effect on motivation or choice persistence. The results implicate the NAc shell in moderating the instrumental valuation process by inhibiting excessive bias toward preferred choice options.11Ysciessciscopu
When Less is More: Evolutionary Origins of the Affect Heuristic
The human mind is built for approximations. When considering the value of a large aggregate of different items, for example, we typically do not summate the many individual values. Instead, we appear to form an immediate impression of the likeability of the option based on the average quality of the full collection, which is easier to evaluate and remember. While useful in many situations, this affect heuristic can lead to apparently irrational decision-making. For example, studies have shown that people are willing to pay more for a small set of high-quality goods than for the same set of high-quality goods with lower-quality items added [e.g. 1]. We explored whether this kind of choice behavior could be seen in other primates. In two experiments, one in the laboratory and one in the field, using two different sets of food items, we found that rhesus monkeys preferred a highly-valued food item alone to the identical item paired with a food of positive but lower value. This finding provides experimental evidence that, under certain conditions, macaque monkeys follow an affect heuristic that can cause them to prefer less food. Conservation of this affect heuristic could account for similar ‘irrational’ biases in humans, and may reflect a more general complexity reduction strategy in which averages, prototypes, or stereotypes represent a set or group
25th annual computational neuroscience meeting: CNS-2016
The same neuron may play different functional roles in the neural circuits to which it belongs. For example, neurons in the Tritonia pedal ganglia may participate in variable phases of the swim motor rhythms [1]. While such neuronal functional variability is likely to play a major role the delivery of the functionality of neural systems, it is difficult to study it in most nervous systems. We work on the pyloric rhythm network of the crustacean stomatogastric ganglion (STG) [2]. Typically network models of the STG treat neurons of the same functional type as a single model neuron (e.g. PD neurons), assuming the same conductance parameters for these neurons and implying their synchronous firing [3, 4]. However, simultaneous recording of PD neurons shows differences between the timings of spikes of these neurons. This may indicate functional variability of these neurons. Here we modelled separately the two PD neurons of the STG in a multi-neuron model of the pyloric network. Our neuron models comply with known correlations between conductance parameters of ionic currents. Our results reproduce the experimental finding of increasing spike time distance between spikes originating from the two model PD neurons during their synchronised burst phase. The PD neuron with the larger calcium conductance generates its spikes before the other PD neuron. Larger potassium conductance values in the follower neuron imply longer delays between spikes, see Fig. 17.Neuromodulators change the conductance parameters of neurons and maintain the ratios of these parameters [5]. Our results show that such changes may shift the individual contribution of two PD neurons to the PD-phase of the pyloric rhythm altering their functionality within this rhythm. Our work paves the way towards an accessible experimental and computational framework for the analysis of the mechanisms and impact of functional variability of neurons within the neural circuits to which they belong
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A Sociocognitive-Neuroeconomic Model of Social Information Communication:To Speak Directly or To Gossip
Communication is a powerful means to disseminate socialinformation, and gossip is an effective way of obtainingupdated information about others. However, without acomprehensive theoretical framework of socialcommunication, it is difficult to predict a priori when and whysocial information will be disseminated. There are generaltheories of human social interaction, however, they do notsufficiently capture the sociocognitive components underlyinghuman decision-making in social settings. Therefore, we havedeveloped a model of social communication, enabling thecharacterization of specific conditions under which socialinformation will be spread: for example, when an agent shoulddirectly communicate with the target of the information, gossipit to others, or simply do nothing. We describe the model, themethods used to generate model predictions, and then list ninepredictions derived from it as the current results. We next planto test the predictions empirically and develop the modelcomputationally
Choice order and preference in Experiment 2.
<p>(A) The choice order matrix representing the choice percentages of different colored items for given choice order averaged across all monkeys in Condition 1. (B) The winning percentage of different color items in Condition 2 (binary choice). (C) The winning percentage of different color items in Condition 2 (binary choice) sorted by individual rank order, revealing a significant individual preference among the colors. (D) The relationship between choice order and winning percentage that reflects the degree of preference among alternatives<b>.</b> Error bars depict standard error of the mean (SEM).</p
Choice order and preference in Experiment 1.
<p>(A) The choice rate of food items for a given choice order averaged over all monkeys in Condition 1; peanut half (PN), yellow fruity gem (FG), pellet (PL), and krisp (KR). (B) The winning percentage of different food items in Condition 2 (binary choice). (C) The winning percentage of different food items in Condition 2 (binary choice) sorted by individual rank order, showing a significant preference towards the favorite options. (D) The relationship between choice order and winning percentage reflecting the degree of preference among alternatives<b>.</b> Error bars depict standard error of the mean (SEM).</p
How 'who someone is' and 'what they did' influences gossiping about them.
To understand, predict, and help correct each other's actions we need to maintain accurate, up-to-date knowledge of people, and communication is a critical means by which we gather and disseminate this information. Yet the conditions under which we communication social information remain unclear. Testing hypotheses generated from our theoretical framework, we examined when and why social information is disseminated about an absent third party: i.e., gossiped. Gossip scenarios presented to participants (e.g., "Person-X cheated on their exam") were based on three key factors: (1) target (ingroup, outgroup, or celebrity), (2) valence (positive or negative), and (3) content. We then asked them (a) whether they would spread the information, and (b) to rate it according to subjective valence, ordinariness, interest level, and emotion. For ratings, the scenarios participants chose to gossip were considered to have higher valence (whether positive or negative), to be rarer, more interesting, and more emotionally evocative; thus showing that the paradigm was meaningful to subjects. Indeed, for target, valence, and content, a repeated-measures ANOVA found significant effects for each factor independently, as well as their interactions. The results supported our hypotheses: e.g., for target, more gossiping about celebrities and ingroup members (over strangers); for valence, more about negative events overall, and yet for ingroup members, more positive gossiping; for content, more about moral topics, with yet all domains of social content communicated depending on the situation-context matters, influencing needs. The findings suggest that social knowledge sharing (i.e., gossip) involves sophisticated calculations that require our highest sociocognitive abilities, and provide specific hypotheses for future examination of neural mechanisms
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