M. Dhamala's Research
The human brain
consists of a large number of highly interconnected neuronal
populations that
are organized as functionally relevant local-area ensembles and
large-scale
networks associated with perception, thought and behavior. These
large-scale
functional networks, which can exist even under a rest condition in the
absence
of entrained task performance or in the absence of explicit external
stimulus,
involve the activities of individual neural systems and the signal flow
among
them. In addition, the brain processes are linked with peripheral
physiological
activities, e.g. heart rate, respiration rate, skin conductance
associated with
cognitive or affective functions. Thus, studying the patterns
of neural interactions and interactions with peripheral physiological
systems
can enhance our understanding of the human brain and other
physiological systems associated with different perceptual, cognitive
and affective processes. We utilize various neuroimaging techniques
(simultaneous fMRI/EEG, fMRI, MRI ,
DTI) to
understand the structures and functions of the human brain and the
relationship with cardiorespiratory system. This is a top-down approach towards
understanding a complex system- the human brain. We also utilize a bottom-up approach by modeling
brain subsystems with coupled model neurons in oder to understand the
origin of the patterns of brain activity. Our research group is
currently involved in several experimental and theoretical neuroscience
projects: characterization of sensorimotor networks, somatosensory
perceptual processes, human decision-making processes,
cortico-cardio-respiratory network interactions, development of
biomedical imaging devices, neuronal phase synchronization, and effects
of axonal time-delays in neuronal synchrony.
Characterization of Sensorimotor
Networks .
The purpose of this research is to evaluate
functional interactions within the networks of brain sensorimotor
regions
responsive to rhythmic movements using simultaneous recordings of
functional
magnetic resonance imaging (fMRI) and electroencephalography (EEG) time
series
and newly developed nonparametric Granger causality techniques.
Simultaneous EEG/fMRI of Somatosensory Perceptions . The purpose of this research is to evaluate functional interactions within the networks of somatosensory regions using simultaneous recordings of functional magnetic resonance imaging (fMRI) and electroencephalography (EEG) time series and Granger causality linear and nonlinear techniques.
Collaborators: Prof. Krish Sathian and Prof. Charles M. Epstein, Department of Veterans Affairs, and Department of Neurology, Emory University.
The Neurobiology of Human Decision-Making. The purpose of this research project is to identify the human brain networks involved in decision-making processes and characterize the dynamics on the networks. This study will help us not only to understand how different areas exchange information during perceptual and economic decision-making processes, but also to formulate a general theory of neural interactions in decision-making in general.
Collaborator: Dr. Sarah Brosnan, Department of Psychology, Georgia State University.
Development of Near-Infrared Spectroscopy Based NeuroImaging and Physiological Monitoring Systems. The purpose of this research project is to develop a functional near-infrared spectroscopy based human brain imaging and cortico-cardiorespiratory network activity monitoring devices with maximum performance and portability. The proposed imaging device will utilize near-infrared laser diodes and photodetectors in the optimal light wavelength range and the cortico-cardiorespiratory monitoring system will utilize this optimized imaging system, electrocardiogram and respiration probe, and can simultaneously measure the brain and cardio-respiratory activities. These portable devices will be useful not only in biomedical research but also in physiological monitoring of patients in hospitals and clinics.
Collaborators: Prof. Unil Perera, Physics and Astronomy, Georgia State University, and Prof. Charles M. Epstein, Department of Neurology, Emory University.