Avniel Singh Ghuman, PhDAssistant Professor of Neurological Surgery
Director, MEG Research
Avniel Singh Ghuman, PhD, joined the Department of Neurological Surgery in September of 2011.
Dr. Ghuman received his undergraduate education in math and physics at The Johns Hopkins University. He completed his doctoral education in biophysics at Harvard University. He completed his postdoctoral training at the National Institute of Mental Health prior to joining the faculty at the University of Pittsburgh.
As director of MEG (Magnetoencephalography) Research, one of Dr. Ghuman’s primary roles is to facilitate, develop, and advance clinical and basic neuroscience research using MEG. To this end, he is helping to develop new research applications for MEG in collaboration with researchers throughout the community. MEG is the most powerful functional neuroimaging technique for noninvasively recording magnetic fields generated by electrophysiological brain activity, providing millisecond temporal resolution and adequate spatial resolution of neural events.
In addition, Dr. Ghuman’s research interest focuses on using MEG to understand the dynamics of how brain regions interact with an eye towards determining the biological and biophysical underpinnings of these dynamics. He also examines how abnormalities in these dynamics are manifested in autism spectrum disorders and how they might relate to the cognitive impairments in these disorders. Finally, he studies the neural and cognitive processes involved in high-level visual perception.
Dr. Ghuman's publications can be reviewed through the National Library of Medicine's publication database.
Professional Organization Membership
Society for Neuroscience
Cognitive Neuroscience Society
Organization for Human Brain Mapping
Vision Sciences Society
Assessing the correspondence between spontaneous and stimulus-driven neural activity can reveal intrinsic properties of the brain. Recent studies have demonstrated that many large-scale functional networks have a similar spatial structure during spontaneous and stimulus-driven states. However, it is unknown whether the temporal dynamics of network activity are also similar across these states. Here, Dr. Ghuman has demonstrated that, in the human brain, interhemispheric coupling of auditory cortices is preferentially synchronized in the alpha frequency band (~7-12 Hz) and interhemispheric coupling of somatosensory regions is preferentially synchronized in the high beta frequency band (~20-30 Hz). Critically, these stimulus-driven synchronization frequencies were also dominant during spontaneous activity. This similarity between stimulus-driven and spontaneous states suggests that frequency-specific oscillatory dynamics are intrinsic to the interactions between the nodes of these brain networks.
Although there is considerable evidence that autism spectrum disorders (ASD) are associated with aberrant functional brain connectivity, little is known about its temporal dynamics. To address this issue Dr. Ghuman uses magnetoencephalography (MEG) and a wavelet-based analysis to measure neural synchrony during auditory click stimulation and during rest. Specifically, researchers examined phase locking between left hemisphere primary auditory cortex (LAud) and RAud in 16 non-hearing impaired, high functioning individuals with ASD and 18 typically developing (TD) age and IQ matched controls.
No group differences were noted in the auditory evoked magnetic fields in and around LAud or RAud. In addition, no group differences were found in the click-specific phase locking between LAud and RAud in the alpha band. In marked contrast, the TD subjects had significantly greater spontaneous LAud-RAud phase locking in the alpha frequency range than ASD subjects (t=2.91, p=.0078). Significantly reduced alpha band phase locking was also seen in the baseline during the click presentation, in support of the result that ASDs display diminished spontaneous phase locking between LAud and RAud. The significant difference in spontaneous phase locking between the TD and ASD groups was only found in the alpha band (p<.05 corrected for multiple frequency comparisons).
These results demonstrate that individuals with ASD have reduced spontaneous, but not stimulus-driven neural synchrony. These results suggest that aberrant ongoing synchrony may reflect a biological trait of ASD.