Parvizi Labin the Department of Neurology and Neurological Sciences
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Welcome to
Laboratory of Behavioral and Cognitive Neuroscience
(LBCN)

Our lab specializes in the study of human brain using a combination of intracranial electrocorticography (ECoG), electrical brain stimulation (EBS), and functional neuroimaging (fMRI) methods. The general theme of our research is the study of functional specializations in the human cerebral cortex and the dynamics of activity across cortical regions. We study human brain networks in experimental and naturalistic settings as well as during rest and sleep. We record simultaneously from multiple nodes of the same functional network and test their causal role in a given behavior or cognitive function. Our goal is to understand the anatomical and physiological basis for human behavior and cognitive experience and how these might be affected in patients with neurological disorders.

Ongoing Projects

The ongoing projects in the lab aim to provide meaningful contributions in following three domains:

INTRACRANIAL EEG RECORDINGS IN THE HUMAN DEFAULT MODE NETWORK

Since studies of the default mode network, almost entirely, rely on functional imaging methods, our recent work has tried to fill the gap of knowledge about the fast temporal dynamics of activity within this network by recording directly from the population of neurons in the main hubs of the network, e.g., posteromedial cortex (PMC) and angular gyrus (AG).

In a series of publications, we have established:

  1. the activation of neuronal populations in the PMC during cued rest within ~200-300ms suggesting that the increased activity during cued rest cannot be due to conscious mind wandering, but may facilitate such thought processes.
  2. strong activations in the PMC and AG during autobiographical memory retrieval.
  3. significant deactivation of the same neuronal populations in the PMC and AG during externally directed, attention demanding, mathematical cognition tasks.
  4. fast temporal dynamics of interactions across the two nodes of the network. This was made possible by recording simultaneously from PMC and AG
  5. electrophysiological connectivity (phase-phase locking) between the medial temporal lobe and PMC.

Sample Publications:

  • Dastjerdi et al (2011): Differential electrophysiological response during rest, self-referential and non-self-referential tasks in human posteromedial cortex. PNAS108(7): 3023-3028
  • Foster et al (2012): Neural populations in human posteromedial cortex display opposing responses during memory and numerical processing. PNAS 109(38): 15514-15519.
  • Foster BL and Parvizi J. Resting oscillations and cross-frequency coupling in the human posteromedial cortex. Neuroimage. 2012 Mar;60(1):384-91.
  • Foster BL et al (2013) Human Retrosplenial Cortex Displays Transient Theta Phase Locking with Medial Temporal Cortex Prior to Activation during Autobiographical Memory Retrieval. Journal of Neuroscience 33:10439-10446.
  • Foster et al (2015). Intrinsic and Task-Dependent Coupling of Neuronal Population Activity in Human Parietal Cortex. Neuron (in press).
THE MATH NETWORK IN THE HUMAN BRAIN

Our earlier recordings with intracranial EEG in the PMC revealed a strong deactivation of neuronal populations in this region when subjects were engaged in solving mathematical equations. By contrast, we could see opposite patterns of activation in brain regions such as the intraparietal sulcus region (IPS).

One of the contributions of our lab has been to highlight the precise anatomical location of responses in the IPS during numerical cognition tasks.

We have also demonstrated the activation patterns of the IPS region during naturalistic daily life scenarios when patients with implanted electrodes over the IPS interact with their environment. For instance, referring to numbers, uttering words associated with numerosity in magnitude, time, or space reliably elicited responses in the IPS.

The third contribution of our lab in the domain of mathematical cognition has been the discovery of the precise coordinates of a cortical area within the ventral temporal cortex that has a selective response to visual numerals, i.e., visual numeral area (VNA).

Our past recordings from a large mantle of the brain have given rise to a concise and comprehensive map of areas of the human brain that are activated during numerical tasks. In the series of currently ongoing studies, we have begun to address the unique functional contribution of each distinct region of the brain during numerical functions.

Sample Publications:

  • Shum J., Hermes D., Foster B.L., Dastjerdi M., Rangarajan V., Winawer J., Miller K.J., Parvizi J.(2013) A human brain area for seeing numbers. Journal of Neuroscience 33:6709-6715.
  • Dastjerdi M, Ozker M, Foster BL, Rangarajan V, Parvizi J (2013): Numerical Processing in the Human Parietal Cortex During Experimental and Natural Conditions. Nature Communications 4: 2528 doi:10.1038/ncomms3528

ELECTRICAL BRAIN STIMULATION

While functional imaging and electrophysiology provides correlative evidence, direct electrical stimulation of the cortical tissue provides unique evidence about the causal importance of that region (along with the anatomical network connected to it), in specific set of functions. In a series of experiments, we have probed the causal importance of specific regions of the human cerebral cortex in functions ranging from perception of movement in the visual field and object recognition to motivation. For instance, in two series of studies, we have shown that only the right fusiform gyrus is causally important for visual recognition of faces. In a study of two other patients with directed stimulation of the salience network, we have also shown the importance of the mid-dorsal anterior cingulate cortex and its connected network in a positive emotional state of mind that is associated with high confidence ad motivation to fight anticipated challenges.

Sample Publications:

  • Selimbeyoglu A. and Parvizi, J. (2010): Electrical Stimulation of the Human Brain: Perceptual and Behavioral Phenomena Reported in the Old and New Literature. Frontiers in Human Neuroscience 4(191) doi: 10.3389/fnhum.2010.00046
  • Rauschecker, A., Dastjerdi, M., Selimbeyoglu, A., Witthoft, N., Weiner, K.S., Chen, J, Parvizi, J. (2011): Illusion of Visual Motion Elicited by Electrical Stimulation of Human Area MT+. PLoS ONE (6 (7): e21798. doi:10.1371/journal.pone.0021798
  • Parvizi J, Jacques C, Foster BL, Withoft N, Rangarajan V, Weiner KS, Grill-Spector K (2012) Electrical stimulation of human fusiform face-selective regions distorts face perception. Journal of Neuroscience 32:14915-14920.
  • Parvizi J, Rangarajan V, Shirer W, Desai N, and Greicius M. (2013): The will to persevere induced by electrical stimulation of the human cingulate gyrus. Neuron 80(6): 1359-1367.
  • Rangarajan V, Hermes D, Foster BL, Weiner KS, Jacques C, Grill-Spector K, Parvizi J. (2014): Electrical stimulation of the left and right human fusiform gyrus causes different effects in conscious face perception. Journal of Neuroscience. 34(38):12828-36
BEHAVIORAL NEUROLOGY

Given the PI’s training in clinical neurology and neuroanatomy, our lab has been involved in a series of clinical anatomical studies to map the functional anatomical networks whose pathological changes might explain the pathophysiology and the clinical phenotypes seen in patients with various neurological problems. One of the key contributions in this domain was our imaging study in hundred patients with hypothalamic hamartomas where we highlighted the involvement of mammillary nuclei and their surrounding tissue in patients with laughing seizures.

Sample Publications:


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