Mark Bowren

I'm hopeful that this work will ultimately lead to improvements in pre-surgical mapping of cognition to brain networks, and better cognitive outcomes after neurosurgery for patients with epilepsy.

With it, our team at the University of Iowa will seek to understand the cognitive and neurophysiological impacts of a new method of intracranial electrical stimulation.

​I'm extremely grateful to the American Brain Foundation, the American Epilepsy Society, and the Epilepsy Foundation for jointly supporting this award and for their investment in early-career scientists. ​This funding is a game changer at this early stage of my career.

​I'm incredibly honored to share that I have been selected to receive one of the American Brain Foundation's Next Generation Research Grants, specifically the award in epilepsy!

#Neuropsychology

Thanks @insneuro.bsky.social for the conference! I got to present my lab's electrical stimulation mapping work, listen to inspiring talks (big fan of the "main thing" talk/Dr. Bauer's ideas on neural mechanisms of behavior!), and introduce my Iowa and Florida friends! Plus I made a new canine friend

A huge shout out to the first full-time RA for the BLNL, Lara Sozer, and to the entire Iowa Lesion Registry team, including Aaron Boes, Dan Tranel, and their labs. Hopefully this puts the BLNL off to a good start!

This project has been in the making for years, with the idea for this growing from my dissertation work with Dan Tranel in lesion-symptom mapping of g.

In the manuscript, we discuss the nuances of our conclusions in more detail, but the take home message is that consideration of g is important for lesion-deficit studies seeking to investigate dissociable neuroanatomy for higher-order cognitive abilities.

This shows how there can be two routes to low scores on a cognitive task: damage to brain systems for domain-general cognitive ability, and damage to systems unique to the given domain. Without explicitly modeling these sources of variance, we might conflate these two on accident!

Let's bring this to life with case examples. On the right, a lesion affecting a region only see in mapping of the bifactor version of visuospatial ability. The left, a lesion of g regions. Both had low scores on the visuospatial factor from the correlated factors model, but not the bifactor version.

Here is how g affected mapping of visuospatial ability. Top=lesions only, middle row=structural disconnections, bottom=functional lesion network mapping. Across all 3, the results change quite dramatically if we partitioned out g-variance from the factor (right column) vs if we didn't (left column).

We found that this was in fact the case. We compared spatial correlations among domain-specific maps from the two models and found statistically significantly lower correlations (Fisher r-to-Z transformed) for the bifactor model on average.

If g's influence is embedded within any given lesion-deficit mapping, then the resultant maps should be more similar if g is left unaccounted for in the model (correlated factors model) versus if it is explicitly separated from domain-specific abilities (bifactor model).

Specifically, we used "correlated factors" and "bifactor" models to create latent variables for cognitive abilities both with (model on the right) and without (model on the left) g-variance embedded within each factor.

In this study, we used structural equation modeling and lesion-deficit mapping to investigate whether or how formal consideration of g matters for lesion-deficit mapping.

Despite the ubiquity of this g signal in cognitive test data, it is rarely addressed in lesion-deficit mapping studies of cognitive abilities. This could be an issue if the goal is the tease apart neural correlates of different abilities, or test the idea whether two abilities are indeed distinct.

We've known for over a century that cognitive tests are positively intercorrelated. The most popular explanation for this "positive manifold" of correlations is the existence of a domain-general cognitive ability (g) which exists alongside domain-specific functions like memory or visual processing.

Since the inception of voxel-wise lesion-symptom mapping, we have seen a boom in large-scale lesion-deficit mapping studies. However, I've always felt that there was something missing from some of these studies: explicit psychometric modeling of behavior/cognition.

The lesion method (or, lesion-deficit mapping) of cognitive neuroscience/neuropsychology is a widely used technique for investigating whether cognitive abilities have different neuroanatomical correlates. This dates at least all the way back to Broca/Phineas Gage.

Cognition Disconnected: The Influence of Domain-General Cognition (g) in Lesion-Deficit Mapping Lesion-deficit mapping is a premier technique for dissociating neural correlates of cognitive functions. However, the contribution of domain-general cognition (g) to the performance of virtually all c...

The Brain Lesion & Neuromodulation Lab (BLNL; @iowablnl.bsky.social) just posted our first preprint on a topic near and dear to my heart: the influence of domain-general cognition on lesion-deficit mapping of other cognitive domains.

www.biorxiv.org/content/10.1...

#Neuroscience #Neuropsychology

The ideal candidates will have experience in signal processing (e.g., local field potentials from EEG/iEEG). General technical skills are also valuable.

The link above is to work primarily with Dr. Christopher Petkov, who has been a great mentor to myself and others. This role will involve working with a large team that includes me, Dr. Matthew Howard, and others!

#NeuroJobs

Post-Doctoral Positions on Human Laminar Circuits and Neuronal System Perturbation - University of Iowa, Department of Neurosurgery job with University of Iowa, Department of Neurosurgery | 39254 Neurophysiology of Cognition and Language, Laminar fMRI and Neuronal Recordings with Brain Stimulation.

Our neurosurgery research team is recruiting to fill a few open postdoc slots. Want to do cutting-edge work in neuromodulation? Then reach out! One of those positions is already posted (see the link below). Other slots are available so don't hesitate to reach out!

neurojobs.sfn.org/job/39254/po...

Lastly, I'm always happy to answer questions about living in Iowa City, but the short answer is that it is a gem!

Learn more about the program and how to apply through the link below, and through the attached program brochure.
 
medicine.uiowa.edu/neurology/ed...

Referrals come from a number of departments, including Neurology, Neurosurgery, Internal Medicine, Oncology, Psychiatry, and Family Practice. The patient population primarily comprises adults, though a small percentage of slots are provided to children (approximately 5%).

Founded by Arthur Benton in 1950s, the Benton Neuropsychology Clinic today serves approximately 2000 patients per year with specialized diagnostic and rehabilitation services. Referral sources are located throughout the UI Healthcare System and other hospitals in Iowa and surrounding states.

The principal training site is the historic Benton Neuropsychology Clinic, which is housed in the University of Iowa Healthcare Medical Center / Carver College of Medicine, one of the largest university-owned teaching hospitals in the United States.