Integrating Clinical Neuropsychology and Cognitive Neuroscience

With roots in clinical psychology, neurology, and neuroscience, clinical neuropsychology is a true "hub" discipline. However, innovation in the field has stagnated, as methods and procedures have remained largely unchanged since the mid-20th century despite advances in the basic sciences upon which the field was built. My work seeks to bridge the gap between the latest advances in basic cognitive neuroscience with the practice in order to advance both theories of brain-behavior relationships and clinical neuropsychology. I specialize in the following methods to advance this goal: lesion-behavior mapping, lesion network mapping, psychometrics, and intracranial high frequency electrical stimulation.

Lesion-Behavior Mapping (Lesion-Symptom Mapping)

The use of focal brain lesions to infer brain-behavior relationships has been central to cognitive neuroscience since at least the mid-19th century when Paul Broca described the anatomical correlates of expressive aphasia.  The lesion method remains a critical tool in cognitive neuroscience for its unique ability to infer the necessity of neuroanatomical structures for human cognition and behavior. The advent of lesion-behavior mapping - statistical techniques for associating lesion locations to cognitive and behavioral deficits - revolutionized the scale and precision of the lesion method. My work uses lesion-behavior mapping to (1) study how competing cognitive models map onto brain anatomy, and (2) develop methods for predicting cognitive deficits among patients with focal brain lesions (e.g., patients with stroke).

Lesion Network Mapping

In the mid-20th century, neurologist Norman Geschwind authored a landmark treatise concerning the localization of neurological syndromes to disconnections of long range white matter projections - the highways that allow neurons to communicate with one another. It is now widely recognized that complex thought and behavior likely arise from complex circuitry across distributed anatomical regions of the brain. Lesion network mapping is a statistical approach that integrates the lesion method with techniques from network neuroscience. My work uses lesion network mapping to (1) infer the shared and unique brain networks that are critical for different aspects of complex cognition and behavior, (2) generate new hypotheses about the structure of the mind, and (3) predict neurological deficits.

Intracranial High Frequency Electrical Stimulation (HFS)

Direct electrical stimulation of the brain has been a pillar of neurosurgery, and has been a powerful tool for cognitive neuroscience. My work in this area leverages the proliferation of intracranial stereo-EEG with a novel method of electrical stimulation at high frequencies. By stimulating sEEG nodes at 1-2 kHz, we can safely and temporarily prevent the propagation of action potentials along deep axonal fibers in the brain that interconnect distinct cortical modules. Thus, we can, in effect, create a transient disconnection effect that allows us to infer the necessity of brain networks for cognitive functions. Moreover, we can apply these techniques with a high degree of spatial and temporal precision, which allows us to perform cutting-edge experiments regarding the neural mechanisms of precise cognitive processes. I seek to interrogate current models of cognitive functions to improve our understanding how cognitive information processing  happens in the brain.

Cognitive Modeling/Psychometrics

The measurement of cognition and behavior - psychometrics - is critical to cognitive neuroscience. Advanced psychometric techniques - such as Bifactor Modeling and Item Response Theory - have not made recent impacts on clinical neuropsychology, and remain under-utilized in cognitive neuroscience. My work uses psychometric models to test competing hypotheses about cognitive ontologies, and define psychological variables that will be used in lesion-behavior mapping and lesion network mapping analyses.