CCNP Meetings

Rivka Cohen
Department of Psychology
University of Pennsylvania

Memory processes prioritizing the activation of negative cognitions, including thoughts, images, and memories, have long been implicated in major depression. We introduce a model of major depression that characterizes the role of developmental history, emotional context, and retrieval processes in persistent emotional states. Building from the Context Maintenance and Retrieval (CMR) family of models, our theory characterizes how emotional attributes combine with other attributes within the cognitive system, how they are encoded and retrieved, and the influence of these processes on the persistence of emotional attributes within a person’s internal contextual state. The model presents a novel computational account of the development and maintenance of depression, as well as cognitive resilience factors and the time-course of recovery. Finally, the model accounts for the mechanisms underlying empirically validated psychotherapies and factors contributing to subsequent relapse.

Kathryn Biernacki
Centre for Molecular and Behavioral Neuroscience
Rutgers University Newark

Opioid users often demonstrate substantial decision-making impairments, which not only impair everyday functioning, but may also hinder treatment success and contribute to relapse in this population. However, it is still unclear what underlying factors may contribute to this deficit. In this talk, I will discuss the results of a meta-analysis of decision-making in opioid use disorder (OUD), as well as the results behavioral and psychophysiological experiments examining the potential underlying contributors to the decision-making impairment in long-term opioid users. Briefly, the results of the meta-analysis indicated that the decision-making impairment in opioid users is relatively severe. Further, the psychophysiological experiment revealed that the impairment is not due to an impairment in emotional signaling, while the behavioral experiment demonstrated that this impairment may be more restricted to specific decision-making scenarios (i.e., risky compared to ambiguous situations). I will also present some preliminary data regarding computational modelling of decision-making in OUD, as well as other substance use disorders.  By taking a computational psychiatry approach to OUD, this research program may help to identify specific components of decision-making that become impaired in this group and may inform future treatment practice to better support opioid users.

Robb Rutledge
Max Planck UCL Centre for Computational Psychiatry and Ageing Research
University College London

The subjective well-being or happiness of individuals is an important metric for societies, but we know little about how the cumulative influence of daily life events are aggregated into subjective feelings. Using computational modeling, I show that momentary happiness in a decision-making task is explained not by task earnings, but by the combined influence of past rewards and expectations. The robustness of this account was evident in a large-scale smartphone-based replication. I use a combination of neuroimaging and pharmacology to investigate the neural basis of mood dynamics, finding that it relates to dopamine. I then show that this computational approach can be used to investigate the link between mood and behavior and the dynamics of mood in psychiatric disorders including major depression and bipolar disorder.

Guillermo Sapiro
Electrical and Computer Engineering
Duke University

In this talk I will describe our activities related to the use ubiquitous technology for increasing access to developmental and mental health. In particular, we will concentrate on our experience with Autism Spectrum Disorder (ASD), where we have deployed computer vision and machine learning tools both in the clinic and in the wild to automatically encode behaviors elicited by carefully designed movie stimuli. We will describe the projects, some of the results, lessons, and plans for the future. We hope also to engage the audience in the description of some of our current activities and plans related to ADHD, eating disorders, PTSD, combination of behavior and neural recordings, and potentially new collaborations. The work to be presented is based on a very close collaboration between my team
(EE/CS/BME/Math), Duke Health, the Duke Autism Center, and industry. The need for such close collaboration will be stressed and discussed.

Katy Thakkar
Department of Psychology
Michigan State University

The notion of disordered prediction features prominently in mechanistic theories of psychosis, which highlight the influence of past experiences on how we perceive and interpret our current situation. When stimuli are consistent with predictions, we do not pay them much mind, sparing resources for stimuli that violate predictions. Likewise, predictions support cognition and behavior by providing context when momentary input is inconclusive. It is argued that psychosis arises due to an abnormality in forming or using stored regularities, leading to misinterpretation of sensory information, over-interpretation of meaningless associations and, in general, to a fragmented interaction with the external world and a disjointed idea of self. These prediction abnormalities should manifest both in a failure to predict stimuli and events from prior experience and a failure to predict sensory consequences of action. The visuomotor system provides a test bed for investigating these abnormalities, as predictive processes in the brain influence how we see and where we look. I will present data from a series of studies showing a failure to appropriately predict and compensate for the perceptual consequences of an eye movement in schizophrenia patients. As these sensory predictions of action are crucial to achieving a subjective sense of agency over action, the results speak to a possible mechanism of self-disturbances in schizophrenia. I will also show evidence for a reduced influence of prior information on current perceptual processing using basic visual adaptation paradigms in the schizophrenia spectrum. Neural prediction in the visuomotor system lends itself to systematic investigation and may be extrapolated to understand general principles that guide prediction in the brain as a whole, thus enabling a link between core phenomenological experiences in schizophrenia to activity of single neurons.

Alex Dombrovski
Department of Psychiatry
University of Pittsburgh

Laboratory studies of decision-making often involve choosing among a few actions. Yet in natural environments, we encounter a multitude of options whose values may be unknown. Given that our cognitive capacity is bounded, in complex environments, it becomes hard to solve the challenge of whether to exploit an action with known value or search for even better alternatives. In reinforcement learning, approaches to the intractable exploration/exploitation tradeoff typically involve controlling the temperature parameter of the softmax policy or encouraging the selection of uncertain options. To what extent such approaches capture the range of human behavior remains unclear, in part because they do not consider the memory constraints on maintaining multiple learned values across episodes.

We describe how selectively maintaining high-value actions in a manner that reduces information content helps to resolve the exploration/exploitation dilemma during a reinforcement-based timing task. By definition, the information content (i.e., Shannon’s entropy) of the value representation controls the shift from exploration to exploitation. When subjective values for different actions are similar, the entropy is high, inducing exploration. Under selective maintenance, entropy declines as the agent preferentially maps the most valuable parts of the environment and forgets the rest, facilitating exploitation. We demonstrate in silico that this memory-constrained algorithm performs as well as cognitively demanding uncertainty-driven exploration, even though the latter yields a more accurate representation of the contingency.

Human behavior is best captured by a selective maintenance model. Information dynamics consistent with selective maintenance are most pronounced in better-performing subjects, in those with higher non-verbal intelligence, and in learnable vs. unlearnable contingencies. In summary, when the action space is large, strategic maintenance of value information reduces cognitive load and facilitates the transition from exploration to exploitation. High entropy recruited a dorsal attention network, the activity of which was blunted in individuals with borderline personality disorder.

Bart Krekelberg
Center for Molecular and Behavioral Neuroscience
Rutgers University

Transcranial current stimulation is a promising technique used in clinical trials for the treatment of numerous neurological pathologies, including depression, stroke, and epilepsy. In healthy humans it is claimed to enhance perception and learning. However, little is known about how small currents applied to the scalp could achieve all of this and some skepticism about these claims is certainly warranted. We investigate the underlying neural mechanisms in mice, monkeys, and humans.

By recording intracranially while stimulating transcranially, we have discovered a range of neural consequences of transcranial alternating current stimulation. The most prominent of these is a reduction in neural adaptation. I will review the evidence to support this claim, while also pointing out a number of other neural changes that cannot easily be described by a single underlying mechanism. The rational development of noninvasive neuromodulation requires acknowledging and understanding the multiplicity of effects induced by transcranial current stimulation.

Avram Holmes
Department of Psychology
Yale University

Research in my laboratory seeks to establish reliable links between genetic variation, system-level brain function, and behavior in the general population. A core motivation that drives this work is the search for specific network-level signatures or “fingerprints” that co-vary with heritable behavioral variation in the general population and mark vulnerability for psychiatric illness onset. To date, research on the biological origins of psychopathology has largely focused on discrete illness categories. Although patient groups within this diagnostic system are treated as distinct entities, there are often murky boundaries between health and disease and across the disorders themselves. To establish the etiology of these complex syndromes, we must account for diagnostic heterogeneity, both relatively selective and disorder-spanning symptoms, and the dimensional nature of genetic risk. In this talk, I will present two converging lines of research from my laboratory that aim to identify neurobiological markers of psychiatric illness. First, I will discuss a recent effort to link individual variation in the collective set of functional brain connections with the nature and severity of symptom profiles across unipolar depression, bipolar depression, and schizophrenia. Second, I will discuss an ongoing line of research that examines the molecular mechanisms that support the formation and maintenance of functional networks. The results of these analyses suggest that gene expression patterns recapitulate the topography of distributed brain networks and provide novel insights into potential molecular mechanisms contributing to psychiatric illnesses marked by abnormal cortico-striatal function.

Douglas P Munoz
Centre for Neuroscience Studies
Queen’s University

Understanding how humans perceive and act upon complex natural environments is one of the most pressing challenges in neuroscience. Recent work has demonstrated that pupil size is modulated by many cognitive processes in the brain. How does the brain generate cognitive signals that modulate pupil size? This talk will focus on identification of brain circuits that control pupil size and account for the presence of sensory/perceptual, pre-motor/attention, and other cognitive orienting signals on the pupil. Understanding this circuitry for pupil orienting responses allows pupil measures to be used to study normal human development and aging and various disease processes. The pupil provides a rich source of clinical biomarkers that can be easily mapped onto pupil control circuits in the brain.

Ida Momennejad
Princeton Neuroscience Institute
Princeton University

Memory is organized in relational structures. When we remember something due to perceptual exposure or via replay, activation of the retrieved item itself activates other memories that are directly related to it, as well as memories that are multiple relations away. This cascade of activation renders the relations between memories malleable (known as plasticity). I will present a computational model, which demonstrates how the spread of activation in a memory network together with nonmonotonic plasticity can restructure memory. Using simulations, I will show that selective remembering, i.e. repeated re-activation of some but not other memories, can gradually change the structure of memory networks. This model can account for a range of memory phenomena, from retrieval-induced forgetting to conversational mnemonic convergence and consolidation. I will then discuss how these models, together with my previous work on prioritized offline replay can: (1) explain psychiatric phenomena in PTSD, (2) account for selective replay of negative memories and pruning of positive trajectories in rumination, and (3) provide a computational account of how cognitive therapy can leverage selective activation and forgetting to reorganize memory structures and alleviate symptoms. Finally, I will briefly discuss how this computational account might inform future interactive therapy apps that would interactively help users map and restructure the relational structure of their memories.