Bart Krekelberg - US grants

[unreadable] DESCRIPTION (provided by applicant): During rapid eye movements, we are not aware of the motion of the retinal image, nor do we perceive the world to be in a different place after every eye movement. This shows that, somehow, the brain corrects for the movement of the eyes when translating the retinal input into a visual percept. This project combines cellular approaches in monkeys, with behavioral studies, and functional imaging in humans to investigate the neural mechanisms underlying perceptual stability in the presence of eye movements. We propose and test a specific implementation of the dual mechanism theory of perceptual stability. In this theory, one mechanism uses eye-position information to transform eye-centered retinal information into stable, world-centered information. This transform is assumed to be imperfect while rapid eye movements are underway. Another mechanism -called saccadic suppression- is therefore invoked to blunt visual perception and hide imperfections in the coordinate transform during saccades. Our hypothesis is that both mechanisms are implemented in early visual cortical areas. As others have pointed out, the presence of eye-position signals in those areas in principle provides the information needed to perform the required coordinate transform. The presence of sufficient information, however, does not necessarily mean that the signal is actually used for the coordinate transform. In our first specific aim we test a strong prediction of the hypothesis, namely that errors in the eye-position signal should cause errors in perception. We will use single cell recordings to test whether, around the time of saccades, there is a mismatch between the true eye-position and the eye-position signals in early visual areas (V1, MT). Crucially, this mismatch should match the perceptual errors in localization that are known to occur around saccades. Our second aim is to measure changes in the visual response of these neurons around the time of a saccade. Our hypothesis predicts first, that these changes explain why errors in localization and detection of visual stimuli occur in the temporal vicinity of eye movements. Second, we will test whether random trial-by-trial variations in the neural response are correlated with trial-by-trial variation in the behavioral response of the animal. Together these behavioral and electrophysiological experiments would provide strong evidence for our hypothesis. The significance of this project is that it will enhance our understanding of the neural mechanisms that solve a fundamental problem in visual perception. This will help to develop treatment programs for neurological disorders of vision and rehabilitation after trauma and disease. [unreadable] [unreadable] [unreadable]

This award from the Major Research Instrumentation program is for the acquisition of a functional magnetic resonance imaging scanner to be housed at Rutgers University main campus in Newark in the Center for Molecular and Behavioral Neuroscience. It will be available to researchers from all three Rutgers campuses (Newark, New Brunswick, and Camden) as well as to those from nearby institutions, especially New Jersey Institute of Technology, University of Medicine and Dentistry of New Jersey, and the Kessler Foundation Research Center. The scanner will allow work to proceed on investigating brain-behavior relationships. The specific questions addressed are organized around six clusters of research: 1) neuroeconomics, 2) learning, memory, and plasticity, 3) human development, 4) perception and sensation, 5) mechanisms of mental illness, and 6) computational neuroimaging. The overarching theme that links the clusters is that they all broadly relate to the learning sciences.

Brains influence who people are; how people see, hear, and smell, how they move, touch, and talk, how they remember and forget, how they feel, expect, and plan. Understanding how the brain, with all its neurons and interconnections, generates complex behavior is a tremendous scientific challenge and modern technology is indispensable in this endeavor. This project will make a new state-of-the-art instrument available at Rutgers University - Newark. The instrument allows brain researchers to not only measure brain activity in humans with unsurpassed spatio-temporal fidelity, but also modulate that activity by passing small electrical currents through the scalp. The instrument will be used by a broad range of researchers, and offer training opportunities to students across departments of Psychology, Biomedical Engineering, and Neuroscience, and at all levels; ranging from high-school summer interns to postgraduate research fellows. The impact of this training is expected to be particularly broad at Rutgers University - Newark due to its exceptionally diverse student body and the large number of programs focused on increasing the participation of underrepresented minorities.
The new instrument can record and modulate electrical brain activity inside a magnetic resonance imaging scanner. Its 256 small electrodes have the capability to perform high-density electroencephalography as well as high-density transcranial current stimulation. This addresses three shortcomings of standard approaches in cognitive brain research. First, the instrument will complement the slow, but spatially precise recording of brain activity based on functional imaging with the simultaneous measurement of rapidly changing electrical activity. This will allow researchers to study the fundamental physiology of perception, thought, and action in humans. Second, the instrument can modulate brain activity in a safe and noninvasive manner. This creates a powerful research paradigm to investigate the causal role of brain areas. Third, the new instrument will help build bridges between animal and human neuroscience approaches by obtaining experimental data noninvasively in humans that can be compared more directly with those obtained in animals. Specific new projects will focus on improving perception using transcranial stimulation, the role of oscillations in memory formation and sleep, the interaction among prefrontal and striatal areas in reward processing, and the rapid neural control of the heart, to name just a few.

The transformative aspect of the research enabled by this device is the combination of high spatial and temporal resolution brain imaging and the focus on active manipulations of brain activity that allow researchers to move beyond correlation and towards a causal understanding of brain function.

Project Summary A novel technique called transcranial current stimulation (TCS) creates small electrical fields in the brain through electrodes placed on the scalp. As a method for neuromodulation, TCS carries with it many practical benefits: it is portable (battery-operated), inexpensive, and easily deployable in the clinic and at home. Due to this simplicity and apparent versatility there has been an explosion in the number of studies currently underway using either direct or alternating transcranial currents (over 500 clinical trials are listed with clinicaltrials.gov). Despite this ubiquitous use of the technique in clinical and basic research, there is substantial uncertainly as to its mechanism of action, and even its basic dosage/response relationships are poorly understood. This project will use intracranial recordings in the primary visual cortex of nonhuman primates to understand how TCS changes neural activity. The first aim is to understand the parameters (e.g. current strength, electrode montage, duration) that affect the ability of direct currents to modulate neural excitability (tDCS). The second aim is to understand the parameters that affect the neuromodulatory efficacy of transcranial random noise currents (tRNS). The third aim is to understand the parameters that affect the efficacy of alternating currents (tACS).

Project Summary This project investigates the use of repetitive visual stimulation as a tool to improve visual cognition. Surprisingly, the repeated presentation of simple visual patterns can result in long-term plasticity, reflected in increased neural responses, but also in behavioral improvements that last for hours, even days. In current approaches using RVS, however, these improvements are limited to the specific, repeated patterns; this limits the practical usefulness of RVS. The proposed project builds on recent findings in the nonhuman primate demonstrating widespread and general increases in neural responses after the repeated presentation of a uniform grey screen with sinusoidally modulated luminance. The first aim is to show, using EEG, that such long-lasting increases in neural responses also occur in the human brain. The second aim is to determine which aspects of visual cognition are improved by this boost in neural responses. The project will assess improvements in low-level vision such as detection and visual acuity, but also higher-level visual processes such as visuospatial attention, and visual working memory. The pilot data already show widespread neural changes in the human brain and substantial behavioral improvements in, for instance, visual acuity. A successful tool to improve visual cognition would have a significant impact, as it could be used therapeutically in low vision conditions (e.g., amblyopia), but also in the elderly or healthy human subjects, to deliver a boost in performance.

Abstract for "Brain network mechanisms of task-general cognition" <br/><br/>What are the special properties of the human brain that make us intelligent? What is the brain circuitry underlying the intelligence of geniuses such as Leonardo da Vinci, Marie Curie, Albert Einstein and the neural basis for normal human intelligence, which surpasses machine and artificial intelligence in a broad spectrum of cognitive and social tasks? Understanding the neural basis of different varieties of human intelligence is one of the great challenges in neuroscience. In addition to the scientific quest to understand the nature of human cognition and intelligence, knowing what makes the human brain intelligent would have many useful applications. For example, this knowledge could potentially be used to guide brain stimulation to help those with learning disabilities. This knowledge could also help develop brain-computer interfaces and enhance artificial intelligence, with many applications in science, engineering, and business. This project will use brain imaging and brain stimulation to learn about some of the key brain network processes that make human intelligence possible.<br/><br/>Converging evidence indicates that general human intelligence is primarily implemented by activity and connectivity in subnetworks of the brain termed cognitive control networks (CCNs). However, there is a critical need to determine how CCN activity and connectivity together generate intelligent goal-directed behavior. The overall objective of this project is to determine how CCNs implement intelligent behavior across a wide variety of different tasks. Researchers will use brain activity flow models – a novel method for determining how activity and connectivity together generate brain function –to investigate how CCNs implement task-general cognition underlying intelligent behavior. The project will utilize brain imaging and brain stimulation to build and test activity flow models of intelligent human behavior. This combined experimental and computational approach will allow testing of the hypothesis that CCNs dynamically re-route activity flows between sensory inputs and motor outputs, implementing intelligent behavior via conjunctive activations as well as dynamic connectivity changes. In addition to scientific research, this project will enhance Outreach and increase participation of underrepresented groups in STEM via supporting continuation and expansion of participation in the NSF-funded nationwide LSAMP (Louis Stokes Alliance for Minority Participation) program.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.