Invited Symposium 4 - The Cognitive Thalamus: Thalamocortical Mechanisms in Attention and Cognitive Control

Invited Symposium 4: Tuesday, April 1, 2025, 10:00 am – 12:00 pm EDT, Constitution Ballroom

Chair: Kai Hwang¹; ¹University of Iowa
Presenters: Kai Hwang, Sabine Kastner, James Bourne, Stephanie Jones

This symposium will showcase the critical role of the thalamus in cognitive control and attention. By highlighting diverse methodologies—including population recordings, representational analyses, computational modeling, and developmental investigations—the symposium will present thalamocortical motifs as fundamental building blocks for a variety of cognitive processes.The four invited talks will cover the following topics: (1) Kai Hwang (University of Iowa) will discuss findings on the human mediodorsal thalamus, highlighting its low-dimensional activity structure, its role in encoding context for flexible cognitive control, and its influence on cortical task representations. (2) Sabine Kastner (Princeton University) will examine the functional role of the pulvinar, focusing on transthalamic pathways that regulate cortical interactions and integrate contextual signals for attention and perception, particularly under conditions of uncertainty. (3) James Bourne (NIMH) will explore the medial pulvinar's role in developing thalamocortical circuits. Lesion studies in marmosets reveal its essential contributions to the maturation of prefrontal cortex circuits and executive functions such as working memory and cognitive flexibility, underscoring its relevance to neurodevelopmental disorders. (4) Stephanie Jones (Brown University) will introduce the Human Neocortical Neurosolver (HNN), a modeling tool for interpreting the biophysical underpinnings of EEG/MEG signals. HNN bridges macro-scale recordings with cellular-level thalamocortical dynamics, providing insights into how these interactions generate neural signals critical for higher-level cognitive functions. Together, these talks will provide an integrated perspective on how thalamocortical interactions underpin attention, cognitive control, and neurocognitive development.

Presentations

What is the role of the human mediodorsal thalamus in cognitive control?

Kai Hwang¹; ¹The University of Iowa

In a series of studies, we investigated the connectivity and representational properties of the human mediodorsal thalamus (MD) and its contributions to cognitive control. Our findings revealed several key insights. First, using fMRI data from subjects performing a diverse set of tasks, we found that task-evoked thalamic responses converge onto a low-dimensional structure. This architecture reflects a compact set of basis activity patterns in the thalamus, with anterior, medial, and posterior-medial regions exhibiting broad, domain-general activity profiles. These findings align with evidence identifying these thalamic regions as multi-domain network hubs. Second, this low-dimensional representation preferentially encodes context in the MD during hierarchical cognitive control and influences cortical activity to select context-relevant representations. To further understand how task-evoked thalamic responses contribute to hierarchical cognitive control, we developed a thalamocortical network model. This model demonstrated that MD representations, through functional connectivity with cortical networks, transform task-specific activity into cognitive representations. It outperformed models based on other brain structures, underscoring the critical role of thalamocortical interactions in supporting cognition. We validated the model through simulations and empirical data from patients with focal thalamic lesions. These lesions selectively disrupted task-specific cortical activity and impaired executive functions, directly linking thalamic network properties to cognitive deficits. Finally, our recent work revealed that MD context representations integrate with error signals, promoting context-dependent flexibility. Together, these studies demonstrate how the MD serves an active, representational role in cognition, facilitating flexible, goal-directed behavior.

What is the role of the ascending superior colliculus – pulvinar pathway in attention control?

Sabine Kastner¹, Yujie Wu¹, Rober Boshra¹; ¹Princeton University

In recent years, evidence has emerged regarding the functional role of pulvinar supporting cognition. Specifically, it has been shown that that indirect transthalamic pathways are important for regulating inter-areal cortical interactions, gating signals in cortex and integrating contextual signals from diverse cortical and subcortical sources. First, transthalamic pulvino-cortical pathways have been shown to temporally coordinate cortical networks that are recruited during cognition to enhance the efficiency of information transmission across the cortical network. Specifically, pulvinar has been shown to synchronize cortical areas in the alpha-frequency band during cue-target intervals in attention tasks, when the attention network is set up and optimized for the selection process. Second, transthalamic pathways may gate, or even enable information processing by controlling local responses of cortical neurons. Third, pulvinar has been shown to track contextual signals related to perceptual uncertainty in guiding decisions. Together, these studies suggest that pulvinar has unique functions in supporting cognitive behaviors. In addition to cortical inputs, particularly medial and lateral pulvinar also receive projections from the superior colliculus (SC) – a midbrain structure involved with the control of saccadic eye movements as well as higher order cognitive processes such as target selection and spatial attention. We will discuss recent studies that explore influences that SC has on pulvinar and pulvino-cortical interactions before and during reversible SC inactivation.

The role of the medial pulvinar in developing thalamocortical circuits for executive function in primates

James Bourne¹, Jack Scott¹; ¹National Institute of Mental Health

The thalamus, particularly the medial pulvinar (PM), is vital for postnatal brain development, influencing cortical functions essential for adult cognition. PM supports complex cognition in primates by linking multimodal sensory areas with the prefrontal cortex (PFC). Recent studies suggest that PM also promotes the maturation of PFC circuits during early development, but whether this is essential for cognitive development remains unclear. We investigated this by bilaterally lesioning PM in marmoset monkeys (Callithrix jacchus) during infancy (postnatal day 14) or adulthood and examining the effects on PFC function and cognition. We assessed cognitive flexibility (reversal learning) and working memory (delayed match-to-sample, DMTS) using a touchscreen-based task battery. Concurrently, we recorded PFC activity with EEG. Results revealed that early-life PM lesions caused significant deficits in working memory (p<0.01) and a modest reduction in cognitive flexibility (p<0.05), while adult PM lesions had no such impact. EEG analysis showed a selective decrease in baseline gamma power (30-80 Hz) in the PFC of early-lesion animals (-3.2%; p<0.05), along with altered neural patterns during working memory tasks. These findings highlight PM’s critical role in early PFC development and suggest that disruptions in thalamic-cortical interactions may contribute to cognitive deficits in neurodevelopmental disorders.

Interpreting thalamocortical dynamics of EEG/MEG measures of cognition with the Human Neocortical Neurosolver (HNN) modeling software

Stephanie Jones¹; ¹Brown University

Electro- and magneto-encephalography (EEG/MEG) are the leading methods to non-invasively record human thalamocortical dynamics with millisecond temporal resolution. However, it can be extremely difficult to infer the underlying cellular and circuit level origins of these macro-scale signals. This limits the translation of E/MEG into novel principles of human information processing and cognition. To address this need, we developed the Human Neocortical Neurosolver (HNN: https://hnn.brown/edu ), a user-friendly neural modeling tool designed for multiscale thalamocortical interpretation of human E/MEG signals. A unique feature of HNN’s model is that it accounts for the biophysics generating the primary electric currents underlying EEG/MEG with enough detail to connect to cell and circuit level phenomena that can be studied with invasive techniques in animal models. In this talk, I will give an overview of the theory behind the development of HNN and demonstrate its use in uncovering the mechanisms and meaning of brain rhythms in attention and perception. I will also briefly describe applications to clinical studies of Aging and Alzheimer’s disease. Overall, HNN provides a novel inferential tool for translational neuroscience discovery.