Irrational choices via a curvilinear representational geometry for value.

We make decisions by comparing values, but it is not yet clear how value is represented in the brain. Many models assume, if only implicitly, that the representational geometry of value is linear. However, in part due to a historical focus on noisy single neurons, rather than neuronal populations, this hypothesis has not been rigorously tested.

Neuroscience: Reevaluating the Role of Orbitofrontal Cortex.

A new optogenetic lesion study shows that the orbitofrontal cortex is essential for integrating information about recent rewards - which may either increase or decrease demand for more - with learned preferences to drive behavior.

Tonic exploration governs both flexibility and lapses.

In many cognitive tasks, lapses (spontaneous errors) are tacitly dismissed as the result of nuisance processes like sensorimotor noise, fatigue, or disengagement. However, some lapses could also be caused by exploratory noise: randomness in behavior that facilitates learning in changing environments. If so, then strategic processes would need only up-regulate (rather than generate) exploration to adapt to a changing environment.

Intense threat switches dorsal raphe serotonin neurons to a paradoxical operational mode.

Survival depends on the selection of behaviors adaptive for the current environment. For example, a mouse should run from a rapidly looming hawk but should freeze if the hawk is coasting across the sky. Although serotonin has been implicated in adaptive behavior, environmental regulation of its functional role remains poorly understood.

Robust Encoding of Spatial Information in Orbitofrontal Cortex and Striatum.

Knowing whether core reward regions carry information about the positions of relevant objects is crucial for adjudicating between choice models. One limitation of previous studies, including our own, is that spatial positions can be consistently differentially associated with rewards, and thus position can be confounded with attention, motor plans, or target identity. We circumvented these problems by using a task in which value-and thus choices-was determined solely by a frequently changing rule, which was randomized relative to spatial position on each trial.

Neuronal responses support a role for orbitofrontal cortex in cognitive set reconfiguration.

We are often faced with the need to abandon no-longer beneficial rules and adopt new ones. This process, known as cognitive set reconfiguration, is a hallmark of executive control. Although cognitive functions like reconfiguration are most often associated with dorsal prefrontal structures, recent evidence suggests that the orbitofrontal cortex (OFC) may play an important role as well.

Rule Encoding in Orbitofrontal Cortex and Striatum Guides Selection.

Unlabelled: Active maintenance of rules, like other executive functions, is often thought to be the domain of a discrete executive system. An alternative view is that rule maintenance is a broadly distributed function relying on widespread cortical and subcortical circuits. Tentative evidence supporting this view comes from research showing some rule selectivity in the orbitofrontal cortex and dorsal striatum.

Differential Contributions of Ventral and Dorsal Striatum to Early and Late Phases of Cognitive Set Reconfiguration.

Flexible decision-making, a defining feature of human cognition, is typically thought of as a canonical pFC function. Recent work suggests that the striatum may participate as well; however, its role in this process is not well understood. We recorded activity of neurons in both the ventral (VS) and dorsal (DS) striatum while rhesus macaques performed a version of the Wisconsin Card Sorting Test, a classic test of flexibility.

Neuronal selectivity for spatial positions of offers and choices in five reward regions.

When we evaluate an option, how is the neural representation of its value linked to information that identifies it, such as its position in space? We hypothesized that value information and identity cues are not bound together at a particular point but are represented together at the single unit level throughout the entirety of the choice process. We examined neuronal responses in two-option gambling tasks with lateralized and asynchronous presentation of offers in five reward regions: orbitofrontal cortex (OFC, area 13), ventromedial prefrontal cortex (vmPFC, area 14), ventral striatum (VS), dorsal anterior cingulate cortex (dACC), and subgenual anterior cingulate cortex (sgACC, area 25). Neuronal responses in all areas are sensitive to the positions of both offers and of choices.

Signatures of Value Comparison in Ventral Striatum Neurons.

The ventral striatum (VS), like its cortical afferents, is closely associated with processing of rewards, but the relative contributions of striatal and cortical reward systems remains unclear. Most theories posit distinct roles for these structures, despite their similarities. We compared responses of VS neurons to those of ventromedial prefrontal cortex (vmPFC) Area 14 neurons, recorded in a risky choice task.

Developmental exposure to concentrated ambient particles and preference for immediate reward in mice.

Background: Recent epidemiological studies indicate negative associations between a diverse group of air pollutants and cognitive functioning in children and adults, and aspects of attention deficit in children. Neuroinflammation and oxidative stress are two putative biological mechanisms by which air pollutants may adversely affect the brain.

Objectives: We sought to determine whether exposure to concentrated ambient particulate matter (CAPS) during the first 2 weeks of life, alone or again in adulthood, could alter responding for delayed reward, a critical component of human decision making.