Computational models of naturalistic sensorimotor decisions and actions
Dec 1st, 2022, 3 PM; Michael-Lankeit-Hörsaal, German Primate Center

Models of human behavior ranging from decision making to sensorimotor control have been classically dichotomized as either being normative, i.e. prescribing how people ought to act, or as descriptive, i.e. capturing how people actually do act, often with the notion that they violate the prescriptions of normative theories. We will present a string of work from my lab, in which we use probabilistic inference methods to invert normative models thereby asking: for what uncertainties about the state of the world, subjective utilities including effort, and for what, possibly false, internal models is observed human behavior optimal? This not only reconciles normative and descriptive models but additionally allows recovering meaningful cognitive quantities describing participants’ behavior on an individual by individual and trial by trial basis. This framework provides computational level explanations and predictions for phenomena ranging from the adaptability of human blinking strategies, learning of active vision behaviors, to perceptual biases in continuous psychophysics, and strategies in visuomotor behavior such as ball catching or navigation.

Coding of actions of self and others in the monkey presupplementary motor cortex
October 20th, 2022, 2 PM; via zoom

The presupplementary motor cortex (pre-SMA, or area F6 in the macaque) is one of the brain areas most frequently activated in fMRI studies, and it is thought to play a role in a variety of motor and executive functions. A hallmark of this area is its rich set of connections with prefrontal regions, on one side, and dorso-lateral premotor regions, on the other, thereby acting as a bridge between high-order cognitive functions and motor planning. In recent years, the research on this region has gained momentum because of its role in social interactions and in the encoding of actions of self and others. I will overview recent evidence indicating that largely shared neural mechanisms and substrates underlie the motor processing of objects, contextual cues, observed actions and nonbiological motion in area F6, suggesting that a basic property of this area consists in a multimodal and flexible recruitment of motor plans based on a variety of stimuli from the outside world. This unitary and coding principle may be shared by a variety of different processes, enabling to account for the manifold of functional properties and roles attributed to this brain area.

Social connection in primates: adaptive function and underlying neural circuitry
October 12th, 2022: 11.30 AM, Old lecture hall, German Primate Center

Social distancing measures implemented to slow the spread of COVID-19 have triggered a worldwide craving for social contact, leading to surges in anxiety and depression. This social desire is deeply rooted in our evolutionary history: most of our closest nonhuman primate relatives live in groups in which they form strong friendships. After a devastating hurricane destroyed over 60% of the vegetation on a small Caribbean island, instead of being more competitive, resident rhesus macaques became more tolerant of each other, less aggressive, and expanded their social networks. However, some monkeys increased their social connectedness by a lot –leading to better chances of survival almost 5 years after the storm– while others did not. What are the neurobiological underpinnings of macaques’ ability to socially connect? In this same free-ranging rhesus macaque population before the storm, we found that the number of social connections individuals maintained predicted the volume of specific structures –the mid–superior temporal sulcus (mSTS) and ventral-dysgranular insula– implicated in social decision-making and empathy, respectively. Moreover, single-unit recordings in anatomically connected areas to the mSTS in freely-moving, socially-interacting rhesus macaques demonstrate that neural ensembles carry a wealth of information about species-typical social behavior and contexts important for success in the wild –including neighboring monkeys’ identity and preceding interactions.

Population Codes and their Correlates in Decision Making
October 12th, 2022: 12.15 PM, Old lecture hall, German Primate Center

My goal is to understand the neural correlates of natural decision-making. During my Ph.D., I pursued this goal by investigating the coordinated activity of neurons in visual cortices of macaques prior to the animals’ reports, discriminating between two natural scenes. The accuracy of animals’ reports was correlated with the strength of coordination within a mid-way visual cortex (area V4), and between this area and the primary visual cortex (area V1), but not within V1. The results indicate that while stimulus encoding is related to the spiking rates of neurons, perceptual accuracy is correlated with the precise spiking coordination within visual cortical populations. I also investigated the foraging behavior of unrestrained macaques and the representation of reward expectation and choices in the dorsolateral prefrontal cortex (dlPFC). We found that monkeys predict the reward outcomes to subsequently decide ‘when’ and ‘where’ to forage. Canonical components of the neural population activity represented animals’ reward expectations. These components predicted the next choices better than the true reward expectation and as well as the entire neural population. Together, the findings of the mentioned projects shaped my curiosity to study natural decision-making, highlighting the importance of linking behavior and neural activity in multiple dimensions and the significance of inter-area cortical communication.

Developing a monkey model to drive streamlined translation and clinical impact for autism
October 6th, 2022; 5 PM (via Zoom)

Autism spectrum disorder (ASD) is a prevalent and poorly understood neurodevelopmental disorder. There are currently no laboratory-based diagnostic tests to detect ASD, nor are there any disease-modifying medications that effectively treat ASD’s core behavioral symptoms. Scientific progress has been impeded, in part, by overreliance on model organisms that fundamentally lack the sophisticated social and cognitive abilities essential for modeling ASD. We therefore saw significant value in studying naturally low-social rhesus monkeys to model human social impairment, taking advantage of a large outdoor-housed colony for behavioral screening and biomarker identification. Careful development and validation of our animal model, combined with a strong commitment to evaluating the translational utility of our preclinical findings directly in patients with ASD, yielded a robust neurochemical marker (cerebrospinal fluid vasopressin concentration) of trans-primate social impairment and a medication (intranasal vasopressin) shown to improve social cognition in naturally low-social monkeys and in children with ASD. This translational primate research approach stands to advance our understanding of ASD in a manner not readily achievable with existing animal models, and can be adapted to investigate a variety of other human brain disorders which currently lack valid preclinical options, thereby streamlining translation and amplifying clinical impact more broadly.

Questioning and model-free meta-cognition
September 28th, 2022, 3 PM (via zoom)

There has been a flurry of recent work on the cognitive neuroscience of curiosity. But everyone in the field offers definitions of curiosity that are metacognitive in nature. Curiosity is said to be a desire for knowledge, or a motivation to learn about something, and so on. This appears problematic. It either makes it difficult to see how curiosity can properly be attributed to cats and rats (let alone birds and bees), or it commits us to attributing capacities for self-awareness in these creatures for which we lack evidence. The goal of the talk is to offer a re-interpretation of the main findings in the literature, showing how it is possible for creatures to be curious while lacking any conception of their own or others’ minds. But at the same time I will argue that there is something that a metacognitive conception of curiosity gets right. The talk will first situate curiosity among affective states generally, before going on to elucidate both its contents and its dependence on forms of model-free sensitivity to one's own ignorance.

Curious, cooperative and communicative: How we learn from others and help others learn
July 7, 2022; 3 PM, Michael-Lankeit-Hörsaal, German Primate Center

Humans are not the only species that learns from others, but only humans learn and communicate in rich, diverse social contexts, and build repertoires of abstract, structured knowledge. What makes human social learning so distinctive, powerful, and smart? In this talk, I argue that social learning is inferential at its core (inferential social learning); rather than copying what others do or trusting what others say, humans learn from others by drawing rich inferences from others’ behaviors, and help others learn by generating evidence tailored to others’ goals and knowledge states. I will present a series of studies that support this view and describe how they reveal the remarkably curious minds of young children, not only about the physical world but also about others and themselves. Children are curious about what others do & what their actions mean, what others know & what they ought to know, and even what others think of them and how to change their beliefs. The results collectively paint a picture of young children as active social learners who voraciously yet intelligently gather useful information from others to learn about the world, and generously share what they know with those around them.

You say "tomato", I say "tumatu" - The influence of prior expectations on perception in social interaction
June 27, 2022, 11 AM, Room 1.136, Georg-Elias-Müller-Institute for Psychology

Our ability to successfully interact with other people depends on recognizing and understanding other persons in different contexts. Especially, when sensory signals are degraded, informative priors can improve perception but may also lead to deception. Therefore, unravelling how the human brain combines sensory input from face and voice with prior knowledge is important. In my talk, I will present data from several studies investigating how prior expectations influence perception in social interaction. Firstly, I will contrast two functionally distinct computational mechanisms by which prior expectations can influence sensory representations of speech. Expected features of the input can be enhanced or sharpened. Alternatively, in Prediction Error accounts, expected features are suppressed and unexpected signals are processed further. We aimed at distinguishing between these two accounts by combining behavioural, univariate, and multivariate fMRI measures with computational models. Secondly, I will address the question why we are better in understanding familiar speakers with data from behavioural online studies, in which listeners could use voice context to normalize vowel perception. Finally, I will discuss how the human brain could represent the strength of prior expectations during face-identity recognition.