Keilholz Mind Lab

The Keilholz Mind Lab is part of the Wallace H. Coulter Department of Biomedical Engineering at Emory University and Georgia Tech.

The Keilholz Mind lab (located on the Emory campus) studies functional connectivity mapping, based on correlations in the blood oxygenation dependent (BOLD) MRI signal. The exact relationship between these measures and the electrical signals of the brain is poorly understood, and the lab uses combined MRI and electrophysiological techniques in rodent models to elucidate the neural basis of functional connectivity. They plan to use these tools to build a multi-scale model of the brain capable of providing insight into the origin and relevance of functional networks observed with BOLD.

Keilholz Mind lab members meet remotely during the COVID pandemic to push their research projects forward efficiently.
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[May 06 2020] | New paper was published:

Aberrant static and dynamic functional patterns of frontoparietal control network in antipsychotic‐naïve first‐episode psychosis subjects, Frederic Briend William P. Armstrong Nina V. Kraguljac Shella D. Keilhloz Adrienne C. LahtiPsychotic disorders are disabling clinical syndromes characterized by widespread alterations in cortical information processing. Disruption of frontoparietal network (FPN) connectivity has emerged as a common footprint across the psychosis spectrum. Our goal was to characterize the static and dynamic resting‐state functional connectivity (FC) of the FPN in antipsychotic‐naïve first‐episode psychosis (FEP) subjects. We compared the static FC of the FPN in 40 FEP and 40 healthy control (HC) subjects, matched on age, sex, and …

[Feb 03 2020] | New paper was published:

The relationship between BOLD and neural activity arises from temporally sparse events, Xiaodi Zhang, Wen-Ju Pan and Shella Keilholz*Resting state functional magnetic resonance (rs-fMRI) imaging offers insights into how different brain regions are connected into functional networks. It was recently shown that networks that are almost identical to the ones created from conventional correlation analysis can be obtained from a subset of high-amplitude data, suggesting that the functional networks may be driven by instantaneous co-activations of multiple brain regions rather than ongoing oscillatory processes. The rs-fMRI studies, however, rely on the blood oxygen level dependent (BOLD) signal, which is only indirectly sensitive to neural activity through neurovascular coupling. To provide more direct evidence that the neuronal co-activation events produce the time-varying network patterns seen in rs-fMRI studies, we examined the simultaneous rs-fMRI and local field potential (LFP) recordings in rats performed in our lab over the past several years ….

[Nov 04 2019] | Amrit Kashyap will give a talk at Intelligent Interactions with the Brain (I2B) Symposium:

The talk will happen at noon on Thursday Nov. 7th, Kendeda Building – Room 210.

[Oct 25 2019] | New paper was published:

The Relationship Between Local Field Potentials and the Blood-Oxygenation-Level Dependent MRI Signal Can Be Non-linear, Xiaodi Zhang, Wen-Ju Pan and Shella Keilholz*Functional magnetic resonance imaging (fMRI) is currently one of the most important neuroimaging methods in neuroscience. The image contrast in fMRI relies on the blood-oxygenation-level dependent (BOLD) signal, which indirectly reflects neural activity through neurovascular coupling. Because the mechanism that links the BOLD signal to neural activities involves multiple complicated processes, where neural activity, regional metabolism, hemodynamics, and the BOLD signal are all inter-connected, understanding the quantitative relationship between the BOLD signal and the underlying neural activities is crucial for interpreting fMRI data. Simultaneous local field potential (LFP) and fMRI recordings provide a method to study neurovascular coupling. There were a few studies that have shown non-linearities in stimulus related responses, but whether there is any non-linearity in LFP—BOLD relationship at rest has not been specifically quantified. In this study, we analyzed the simultaneous LFP and resting state-fMRI data acquired from rodents, and found that the relationship between LFP and BOLD is non-linear under isoflurane (ISO) anesthesia, but linear under dexmedetomidine (DMED) anesthesia. Subsequent analysis suggests that such non-linearity may come from the non-Gaussian distribution of LFP power and switching from LFP power to LFP amplitude can alleviate the problem to a degree. We also confirmed that, despite the non-linearity in the mean LFP—BOLD curve, the Pearson correlation between the two signals is relatively unaffected.

News:

[Nov 4 2020] Congratulation to Amrit Kashyap for defending his PhD Thesis!

Amrit's PhD Thesis is entitles "Understanding Whole Brain Activity through Brain Network Models". Most specifically in his work, Amrit directly compared transient short-term trajectories by synchronizing the outputs of a BNM in relation to observed fMRI timeseries using a novel Machine Learning Algorithm, Neural Ordinary Differential Equations (ODE). He showed that the Neural ODE can be used as its own stand-alone generative model and is able to simulate the most realistic fMRI signals so far. He also demonstrated a significant progress in developing and quantifying BNMs and advanced the research of more realistic whole brain simulations.
[Jun 23 2020] | 2020 OHBM ANNUAL MEETING happening now (June 23 - July 3).

BRAINHACK ATL will be held at the Center for Translational Research in Neuroimaging and Data Science.

Wednesday, November 13 – Friday, November 15

Congratulations to Behnaz, who successfully defended her thesis! She's Dr. Yousefi now. Her dissertation is entitled "Quasi-periodic patterns of brain intrinsic activity dominantly coordinate the functional connections in humans "

Dr. Shella Keilholz participated in a panel discussion at 2019 OHBM Annual Meeting at Rome, Italy.

Dr. Shella Keilholz serves as the secretary of OHBM. The Organization for Human Brain Mapping (OHBM) is an international society focused on promoting the future of the anatomical and functional organization of the human brain using neuroimaging.

Dr. Keilholz, the director of the Keilholz lab, Speaks to audience at OHBM 2019

Global signal versus large-scale spatiotemporal patterns was the subject of Dr. Keilholz' talk at OHBM 2019.

Xiaodi Zhang, a Keilholz lab member, is giving a talk in OHBM 2019 in Italy

So many people want to see Xioadi's talk that they're crowded into the hallway outside watching the live stream because the room is full.

Keilholz Lab members celebrate a grant win

Keilholz Lab celebrates wining grant regarding spatiotemporal signatures of neural activity and neurophysiology in the bold signal.