Integrated Ising Model with global inhibition for decision making.

Humans and other organisms make decisions choosing between different options, with the aim to maximize the reward and minimize the cost. The main theoretical framework for modeling the decision-making process has been based on the highly successful drift-diffusion model, which is a simple tool for explaining many aspects of this process. However, new observations challenge this model.

Inhibitory mechanisms in the prefrontal-cortex differentially mediate Putamen activity during valence-based learning.

Learning from appetitive and aversive stimuli involves interactions between the prefrontal cortex and subcortical structures. Preclinical and theoretical studies indicate that inhibition is essential in regulating the relevant neural circuitry. Here, we demonstrate that GABA, the main inhibitory neurotransmitter in the central nervous system, differentially affects how the dACC interacts with subcortical structures during appetitive and aversive learning in humans.

The neurobehavioral correlates of exploration without learning: Trading off value for explicit, prospective, and variable information gains.

Exploration is typically motivated by gaining information, with previous research showing that potential information gains drive a "directed" type of exploration. Yet, this research usually studies exploration in the context of learning paradigms and does not directly manipulate multiple levels of information gain. Here, we present a task that isolates learning from decision-making and controls the magnitude of prospective information gains.

Irrelevant Threats Linger and Affect Behavior in High Anxiety.

Threat-related information attracts attention and disrupts ongoing behavior, and particularly so for more anxious individuals. Yet, it is unknown how and to what extent threat-related information leave lingering influences on behavior (e.g.

Average reward rates enable motivational transfer across independent reinforcement learning tasks.

Outcomes and feedbacks on performance may influence behavior beyond the context in which it was received, yet it remains unclear what neurobehavioral mechanisms may account for such lingering influences on behavior. The average reward rate (ARR) has been suggested to regulate motivated behavior, and was found to interact with dopamine-sensitive cognitive processes, such as vigilance and associative memory encoding. The ARR could therefore provide a bridge between independent tasks when these are performed in temporal proximity, such that the reward rate obtained in one task could influence performance in a second subsequent task.

The Neural Representations of Emotional Experiences Are More Similar Than Those of Neutral Experiences.

Stimuli that evoke the same feelings can nevertheless look different and have different semantic meanings. Although we know much about the neural representation of emotion, the neural underpinnings of emotional similarity are unknown. One possibility is that the same brain regions represent similarity between emotional and neutral stimuli, perhaps with different strengths.

Two sides of the same amygdala: From shared neural mechanisms to comorbidity of social and affective disorders.

Recent studies identified a circuitry within the primate amygdala that underlies both social and affective processes. Such shared functions within the same circuit, although beneficial for adaptive behavior and make sense in light of evolution, can also contribute to the growing comorbidity between affective and social disorders.

Quantifying the excitatory-inhibitory balance: A comparison of SemiLASER and MEGA-SemiLASER for simultaneously measuring GABA and glutamate at 7T.

The importance of the excitatory-inhibitory (E/I) balance in a wide range of cognitive and behavioral processes has prompted a commensurate interest in methods for reliably quantifying it. Proton Magnetic Resonance Spectroscopy (H-MRS) remains the only method capable of safely and non-invasively measuring the concentrations of the brain's major excitatory (glutamate) and inhibitory (γ-aminobutyric-acid, GABA) neurotransmitters in-vivo. MRS relies on spectral Mescher-Garwood (MEGA) editing techniques at 3T to distinguish GABA from its overlapping resonances.

Automatic Recognition of Macaque Facial Expressions for Detection of Affective States.

Internal affective states produce external manifestations such as facial expressions. In humans, the Facial Action Coding System (FACS) is widely used to objectively quantify the elemental facial action units (AUs) that build complex facial expressions. A similar system has been developed for macaque monkeys-the Macaque FACS (MaqFACS); yet, unlike the human counterpart, which is already partially replaced by automatic algorithms, this system still requires labor-intensive coding.

A neural and behavioral trade-off between value and uncertainty underlies exploratory decisions in normative anxiety.

Exploration reduces uncertainty about the environment and improves the quality of future decisions, but at the cost of provisional uncertain and suboptimal outcomes. Although anxiety promotes intolerance to uncertainty, it remains unclear whether and by which mechanisms anxiety relates to exploratory decision-making. We use a dynamic three-armed-bandit task and find that higher trait-anxiety is associated with increased exploration, which in turn harms overall performance.

Neurons in the Nonhuman Primate Amygdala and Dorsal Anterior Cingulate Cortex Signal Aversive Memory Formation under Sedation.

Background: Anesthetics aim to prevent memory of unpleasant experiences. The amygdala and dorsal anterior cingulate cortex participate in forging emotional and valence-driven memory formation. It was hypothesized that this circuitry maintains its role under sedation.

The geometry of neuronal representations during rule learning reveals complementary roles of cingulate cortex and putamen.

Learning new rules and adopting novel behavioral policies is a prominent adaptive behavior of primates. We studied the dynamics of single neurons in the dorsal anterior cingulate cortex and putamen of monkeys while they learned new classification tasks every few days over a fixed set of multi-cue patterns. Representing the rules and the neuronal selectivity as vectors in the space spanned by a set of stimulus features allowed us to characterize neuronal dynamics in geometrical terms.

Shared yet dissociable neural codes across eye gaze, valence and expectation.

The direction of the eye gaze of others is a prominent social cue in primates and is important for communication. Although gaze can signal threat and elicit anxiety, it remains unclear whether it shares neural circuitry with stimulus value. Notably, gaze not only has valence, but can also serve as a predictor of the outcome of a social encounter, which can be either negative or positive.

Prediction errors bidirectionally bias time perception.

Time perception and prediction errors are essential for everyday life. We hypothesized that their putative shared circuitry in the striatum might enable these two functions to interact. We show that positive and negative prediction errors bias time perception by increasing and decreasing perceived time, respectively.

Local Targeted Memory Reactivation in Human Sleep.

Memory consolidation can be promoted via targeted memory reactivation (TMR) that re-presents training cues or context during sleep. Whether TMR acts locally or globally on cortical sleep oscillations remains unknown. Here, we exploit the unique functional neuroanatomy of olfaction with its ipsilateral stimulus processing to perform local TMR in one brain hemisphere.

Affective memory rehearsal with temporal sequences in amygdala neurons.

Affective learning and memory are essential for daily behavior, with both adaptive and maladaptive learning depending on stimulus-evoked activity in the amygdala circuitry. Behavioral studies further suggest that post-association offline processing contributes to memory formation. Here we investigated spike sequences across simultaneously recorded neurons while monkeys learned to discriminate between aversive and pleasant tone-odor associations.

Prestimulus Activity in the Cingulo-Opercular Network Predicts Memory for Naturalistic Episodic Experience.

Human memory is strongly influenced by brain states occurring before an event, yet we know little about the underlying mechanisms. We found that activity in the cingulo-opercular network (including bilateral anterior insula [aI] and anterior prefrontal cortex [aPFC]) seconds before an event begins can predict whether this event will subsequently be remembered. We then tested how activity in the cingulo-opercular network shapes memory performance.

Re-exploring Mechanisms of Exploration.

Deciding when to exploit what is already known and when to explore new possibilities is crucial for adapting to novel and dynamic environments. Using reinforcement-based decision making, Costa et al. (2019) in this issue of Neuron find that neurons in the amygdala and ventral-striatum differentially signal the benefit from exploring new options and exploiting familiar ones.

A Tradeoff in the Neural Code across Regions and Species.

Many evolutionary years separate humans and macaques, and although the amygdala and cingulate cortex evolved to enable emotion and cognition in both, an evident functional gap exists. Although they were traditionally attributed to differential neuroanatomy, functional differences might also arise from coding mechanisms. Here we find that human neurons better utilize information capacity (efficient coding) than macaque neurons in both regions, and that cingulate neurons are more efficient than amygdala neurons in both species.

Long time-scales in primate amygdala neurons support aversive learning.

Associative learning forms when there is temporal relationship between a stimulus and a reinforcer, yet the inter-trial-interval (ITI), which is usually much longer than the stimulus-reinforcer-interval, contributes to learning-rate and memory strength. The neural mechanisms that enable maintenance of time between trials remain unknown, and it is unclear if the amygdala can support time scales at the order of dozens of seconds. We show that the ITI indeed modulates rate and strength of aversive-learning, and that single-units in the primate amygdala and dorsal-anterior-cingulate-cortex signal confined periods within the ITI, strengthen this coding during acquisition of aversive-associations, and diminish during extinction.

Inhibitory and excitatory mechanisms in the human cingulate-cortex support reinforcement learning: A functional Proton Magnetic Resonance Spectroscopy study.

The dorsal anterior cingulate cortex (dACC) is crucial for motivation, reward- and error-guided decision-making, yet its excitatory and inhibitory mechanisms remain poorly explored in humans. In particular, the balance between excitation and inhibition (E/I), demonstrated to play a role in animal studies, is difficult to measure in behaving humans. Here, we used functional magnetic-resonance-spectroscopy (H-fMRS) to measure the brain's major inhibitory (GABA) and excitatory (Glutamate) neurotransmitters during reinforcement learning with three different conditions: high cognitive load (uncertainty); probabilistic discrimination learning; and a control null-condition.

Visual Aversive Learning Compromises Sensory Discrimination.

Aversive learning is thought to modulate perceptual thresholds, which can lead to overgeneralization. However, it remains undetermined whether this modulation is domain specific or a general effect. Moreover, despite the unique role of the visual modality in human perception, it is unclear whether this aspect of aversive learning exists in this modality.