Understanding how the brain supports behavior and cognition necessitates the unraveling of fundamental interactions within brain areas. In particular, neuroimaging can reveal the physiological forms, chemical functions, and electrical and metabolic activities of the brain. Therefore, the Lin Brain Lab focuses on developing and applying novel neuroimaging techniques that clarify the metabolic interactions in the brain. Through hardware development, nonclinical trials, and data analysis, we hope to acquire unprecedented neuroimaging and modeling. Developments of such techniques will help to enhance understanding of neural networks and functional connectivity throughout behavioral and cognitive performances.
We focus on the methodological devlopment of human neuroimaging and neuromodulation methods to study neuroscientific questions and translate these technologies to improve health care.
MRI uses a strong magnetic field to delineate brain structure, function, and metabolism. We continuously develop imaging acquisition and analysis for brain imaging. Specifically, a subset of MRI neuroimaging technology used in cognitive neuroscience experiments is the functional magnetic resonance imaging (fMRI). It uses intrinsic hemodynamic response contrast to map human brain functions and study the structural and metabolics of the brain. When a particular neural region is stimulated, there is an increase of blood flow due to the increased demand for energy to process the stimulus. This technology has versatile contrasts, high sensitivity depth, and precise millimeter spatial resolution to quantify and delineate the spatial distribution of metabolites. However, MRI fails to provide good temporal resolution as the blood-oxygen response takes place within seconds.
Figure 1. An image of the research-purpose Siemens MRI machine.
Electroencephalography (EEG) is another technology used in studying the human brain function non-invasively by using extracranial measurements of aggregates and concerts of electric potentials that manifest from the neurons’ response to stimulus. EEG is directly sensitive to neuronal activities and has a millisecond temporal resolution. However, it fails to yield good spatial resolution as it poorly localizes the signal sources.
Figure 2. An image of the 64 channel MRI-compatible EEG system from Brain Products, Germany.
Because the flaws of both EEG and fMRI are complemented by each part’s benefits, many cognitive neuroscientists are switching gears into integrating these technologies together into a multimodal EEG-fMRI system. Subjects will wear the EEG cap while lying inside the MRI, and data is collected simultaneously. Although there are artifacts involved with this multimodal system, such as pulse and gradient artifacts, corrections to these artifacts can be made when cleaning and processing the data by using Brain Vision Analyzer. In a recent publication by the Lin Brain lab, we proposed the recording of continuous EEG with sparse fast fMRI to minimize the EEG artifacts caused by the gradient coil switching. With the achieved results, we can also determine inter-subject correlation which is a modal-free approach that examines fMRI data in naturalistic environments. It provides statistical summaries of synchrony in prolonged time periods and measures the consistency of neural response to naturalistic stimuli across all subjects.
EEG and MEG non-invasively measuers the post-synaptic neural activity. We seek technological advancement of EEG and MEG and synergic combination of these methods with MRI.
SEEG provides an unprecedented spatiotemporal resolution of neuronal activities. These invasive measurements are done in epilepsy patients. SEEG can not only benefit epilepsy management but also advance our understanding of neuronal activity during cognition and behaviours.
TMS non-invasively activates the neural activity via a transiently strong magnetic field. It is a powerful interventional device for modulating neuoronal dynamics and managing mental disorders. Coupling TMS with neuroimaging methods has the promise of sensitive and spatiotemporally accurate modulation of the neuronal activity.