The Next 25 Years of Cognitive Neuroscience: Opportunities and Challenges
Sunday, March 25, 3:00 – 5:00 pm, Grand Ballroom
Chair: Brad Postle, University of Wisconsin–Madison
Speakers: Dean Buonomano, Gyorgy Buzsaki, Steve Chang, Nina Dronkers, Dora Hermes.
As we contemplate 25 years of remarkable advances in cognitive neuroscience, this symposium is intended to offer a (necessarily selective) cross sampling of ideas and approaches that will be important during our society’s next quarter century. It is bookended by talks that, broadly speaking, address how we conceptualize, and carry out, our science. Gyorgy Buzsaki will kick it off by considering how we approach the problem of interpreting neural coding, and Nina Drokers will conclude by addressing whether our discipline’s oldest method – deficit lesion correlation – remains relevant today. And because (spoiler alert!) the answer is, of course, “yes,” she’ll also cover 21st century techniques that would most certainly have impressed Flourens and Ferrier. The theme of time, introduced in the first talk, will carry into Dean Buonomano’s demonstration of how principles and methods from nonlinear dynamical systems theory can be applied to problems in cognitive neuroscience. Studies of field potentials and of hemodynamic signals have played central roles in cognitive neuroscience research to date, and seem likely to continue to do so for the foreseeable future. Dora Hermes will discuss important advances in our understanding of how both of these classes of neurophysiological measurement relate to the neuronal activity that is ultimately of primary interest to most of us. Note that, although the abstract has emphasized the methodological dimension, the presentations summarized up to this point will also cover a broad range of cognition, including temporal and spatial cognition, visual perception, and language. The penultimate presentation, from Steve Chang, will address principles that are shaping the study in another exciting, and rapidly expanding, research domain, social behavior.
Talk 1: Grounding models of neural function in first principles.
Gyorgy Buzsaki, NYU Medical Center
Nothing is more intuitive, yet more complex, than the concepts of space and time. In contrast to spacetime in physics, space and time in neuroscience remain separate coordinates to which we attach our observations. Investigators of navigation and memory relate neuronal activity to position, distance, time point, and duration and compare these parameters to units of measuring instruments. Although spatial-temporal sequences of brain activity often correlate with distance and duration measures, these correlations may not correspond to neuronal representations of space or time. Neither instruments nor brains sense space or time. Neuronal activity can be described as a succession of events without resorting to the concepts of space or time. Instead of searching for brain representations of our preconceived ideas, we suggest investigating how brain mechanisms give rise to inferential, model-building explanations.
Talk 2: Neural Dynamics, Recurrent Neural Networks and the Problem of Time
Dean Buonomano, UCLA
Much of the information the brain processes and stores is temporal in nature—a spoken word or a handwritten signature is defined as much by how it unfolds in time as by its spatial structure at any moment. The brain seamlessly assimilates and process temporal information, an ability that is critical to most behaviors: from reward anticipation to sensorimotor processing. We have proposed that timing on the scale of milliseconds to seconds relies on the inherent dynamics of recurrent neural networks (RNNs). And more generally, that the neural dynamics of RNNs represent a fundamental modus operandi for neural computation. Under this view information is stored and generated by dynamic attractors—locally stable neural trajectories. Thus, in contrast to the conventional view that memories are stored in static fixed-point attractors, under this view, many computations emerge from the voyage through neural state space as opposed to the destination
Talk 3: Field potentials, fMRI, and the order of operations: why the two measures are blind to different parts of the neuronal responses.
Dora Hermes, Stanford
The most widespread measures of human brain activity are the blood oxygen level dependent (BOLD) signal measured with fMRI and surface field potentials (EEG, MEG, ECoG). Prior studies report a variety of relationships between these signals. I will describe our efforts to develop an understanding of how to interpret these signals and the relationship between them. We developed a model of (a) neuronal population responses, and (b) transformations from neuronal responses into the fMRI BOLD signal and electrocorticographic (ECoG) field potential. Rather than seeking a transformation between the two measures directly, this approach interprets each measure with respect to the underlying neuronal population responses. This approach shows that BOLD and field potential measures provide complementary information about human brain activity and we infer that features of the field potential that are uncorrelated with BOLD arise largely from changes in synchrony, rather than level, of neuronal activity.
Talk 4: Establishing neural principles of dynamic and interactive social behaviors.
Steve Chang, Yale
How do we interact with others, and why? Social interactions are characterized by a dynamic and contingent series of behaviors occurring between at least two individuals. Although various abstractions used to capture snapshots of social interactions have been traditionally employed, recent evidence is beginning to favor experimentations involving well controlled, real-life interactions to better mimic natural social behaviors. In this talk, I will discuss the progress made from two lines of neuroscience research toward this goal involving pairs of nonhuman primates, presented with specific empirical results from the studies of social decision-making and social gaze interaction. First, at the single-neuron level, the encoding of social variables across self and other will be examined in the anterior cingulate cortex, orbitofrontal cortex, basolateral amygdala, and striatum. At the inter-regional level, unique signatures associated with diverse types of social decisions will be examined through the lens of oscillatory dynamics between the gyrus of the anterior cingulate cortex and the basolateral amygdala. Second, after empirically demonstrating the benefits of studying dyadic social gaze interactions in real-time, I will present neuronal correlates of interactive gaze interactions in the gyrus of the anterior cingulate cortex and the basolateral amygdala, from the perspectives of both local encoding and inter-regional oscillatory dynamics related to social gaze events. Finally, I will summarize our understanding as to how the brain utilizes various coding schemas to represent social variables that may be useful in guiding social interactions.
Talk 5: Is lesion analysis still relevant for contemporary cognitive neuroscience?
Nina Dronkers, UC Davis
The field of cognitive neuroscience began with observations that behavioral deficits could occur after injury to the brain. One famous case, that of Paul Broca’s patient, Leborgne, is a classic example. Broca attributed the speech deficits in his patient to the lesion in the inferior frontal lobe that he discovered in the brain at autopsy. Over the years, new neuroimaging tools have carried on the tradition of lesion analysis, but with techniques that have far surpassed those available to the early pioneers. This presentation will review some of these new methods, what they have revealed, and how they continue to enhance our field.