Current projects in our lab investigate thalamo-cortical interactions during:
- Cognitive control, including rule-processing, prediction and decision-making
- Memory processes, e.g., maturation of memory and recall
- Conscious and anesthetized states, to (i) develop deep brain stimulation approaches for treating disorders of consciousness and (ii) test theories of consciousness
Background: Information from the world around us is first transmitted to our cerebral cortex via the primary sensory, or first-order, thalamic nuclei. Higher-order thalamic nuclei, like the pulvinar (PUL) and mediodorsal nucleus (MD), receive relatively little input from the sensory periphery and instead form pathways between cortical areas, which can strongly influence cortical activity from sensory to prefrontal cortex (PFC). The cortex and high-order thalamus form local and long-range cortico-thalamic-cortical pathways. Local pathways are well-suited to support working memory; whereas long-range pathways are well-suited to broadcasting information across cortex. There are also multiple levels of converging inputs to the thalamus – from the cortex through basal ganglia to thalamus, and from the cortex directly to thalamus – which may typically serve to amplify relevant information.
Our vision is to establish the general principle across sensory, motor and cognitive domains that the higher-order thalamus sets the state of information processing across the cerebral cortex, i.e., configuring sensory and cognitive processes underlying flexible behavior and different conscious states. A key idea is that the thalamus extracts latent variables, e.g. behavioral rules, from cortical input then broadcasts these variables to the cortex. This involves the higher-order thalamus controlling the excitability and functional connectivity of cortical neurons.
To realize this vision, we combine three main methodological approaches:
- Simultaneous multi-site neural recordings using electrode arrays in higher-order thalamic and cortical areas of behaving animals as a model for human cognition. This involves precise targeting of electrode arrays to interconnected network sites using neuroimaging techniques, particularly diffusion MRI, necessary because cortical areas project to circumscribed zones of higher-order thalamus
- Manipulation of brain networks by mimicking endogenous neural dynamics, e.g., by simultaneously microstimulating across multiple contacts of electrode arrays, to control higher-order thalamus and its effect on the cortex and behavior
- Intracranial neural recordings from epilepsy patients performing cognitive tasks
The significance of this research is that it advances our understanding of fundamental cognitive processes, particularly how information is coded and flexibly transmitted in brain networks. Disruption of brain networks lies at the heart of many disorders, e.g., schizophrenia, Alzheimer’s disease and coma. Our research is an essential step towards effectively treating such disorders.