main focus of our research is to understand how different regions in
the brain interact and exchange information to mediate behavior in
health and neurological disorders.
Our laboratory focuses on three main topics:
Electrophysiology and Function of Intrinsic Activity; and, Neurological
Mechanisms of Recovery.
Our interest in attention stems from its
importance as one of the
foundations of cognition. Without attention no other cognitive function
is possible. Attention involves the selection of important stimuli and
responses, thus the coordination of activity in space and time across
regions and networks of the brain. We have discovered two
networks (the dorsal and ventral attention networks) that are
specialized for attention control, and we are studying their spatial
and temporal properties as people perform cognitive tasks.
The coordination among brain regions requires
among other things an
interaction between ongoing patterns of intrinsic activity and
task-evoked activity/networks. The brain contains 1012 neurons
and each neuron is connected approximately with 104 other neurons
leading to an estimate of about 1016 synapses in the brain.
Interestingly, only about 1 million axons enter the brain from the
retina, and about only 1 million axons exit the brain toward the spinal
cord to control movement. Therefore, the majority of brain
activity is intrinsic, not sensory or motor-driven. Furthermore,
through fMRI studies we know that intrinsic activity is organized in a
finite number of brain networks that are synchronized at rest, but
combined in different motifs during behavior. We are currently
investigating not only the neurophysiological basis of intrinsic
activity, but also its modification during task performance.
Finally, networks of intrinsic or task-driven
activity are disrupted by
focal brain injuries (stroke, traumatic brain injury). We have shown
that behavioral deficits depend on the physiological disruption of
brain regions/networks that are not directly damaged. Similarly,
recovery of function may depend on the functional reorganization of
structurally intact regions of the brain. We are currently
characterizing patterns of network damage for different types of
behavioral impairment (motor, attention, memory, language), and assess
the relative importance of structural vs. functional damage.
These studies will not only elucidate the normal organization of the
brain, but also identify patterns of activity that are potentially
treatable through a variety of different approaches (rehabilitation,
stimulation, brain-computer interface) to improve function.