NeuroLecture Speaker Series
Changing what you see changes how you see
Analyzing the plasticity of broadband orientation perception
April Schweinhart, University of Louisville (Psychological and Brain Sciences)
Feb 25 • 11:00 am • Reynolds School of Journalism 101
Schweinhart's work using augmented reality shows that changing the way certain features are presented in an observer's environment triggers predictable changes in subsequent perception. Traditionally, vision science examined the perception of stimulus features in isolation. More recently, researchers have begun to investigate the perception of such features in context. Consider, for example, the perception of oriented structure: incoming visual signals are processed by neurons tuned in both size and orientation at the earliest cortical levels of the visual hierarchy. Interestingly, the distribution of orientations in the environment is anti-correlated with human visual perception. Though this correspondence between typical natural scene content and visual processing is compelling, until recently the relationships between visual encoding and natural scene regularities were necessarily limited to being static and correlational. This work takes into account the recent experience of the observer to determine the plasticity of perceptual biases related to environmental regularities.
Attentional gain versus efficient selection
Evidence from human electroencephalography
John Serences, PhD UC San Diego (Psychology)
March 5 • 4:00 pm • Ansari Business 106
Selective attention has been postulated to speed perceptual decision-making via one of three mechanisms: enhancing early sensory responses, reducing sensory noise, and improving the efficiency with which sensory information is read-out by sensorimotor and decision mechanisms (efficient selection). Here we use a combination of visual psychophysics and electroencephalography (EEG) to test these competing accounts. We show that focused attention primarily enhances the response gain of early and late stimulus-evoked potentials that peak in the contralateral posterior-occipital and central posterior electrodes, respectively. In contrast with previous reports that used fMRI, a simple model demonstrates that response enhancement alone can sufficiently account for attention-induced changes in behavior even in the absence of efficient selection. These results suggest that spatial attention facilitates perceptual decision-making primarily by increasing the response gain of stimulus-evoked responses.
The times of their lives
Developmental and circadian timing in C. elegans
Martha Merrow, PhD Ludwig Maximilians University Munich (Institute for Medical Psychology)
March 10 • 4:00 pm • Davidson Math and Science 102
Living organisms have developed a multitude of biological time-keeping mechanisms - from developmental to circadian (daily) clocks. Martha Merrow has been on the forefront of understanding the basic properties and molecular aspects of how the circadian clock synchronizes with environmental cues - from worms to yeast to fungi to humans. In addition to circadian clocks, she has been studying developmental clocks in worms and recently developed a new method to measure timing of larval development, which could be used to measure sleep-like properties in worms. She started working on biological clocks as a Post-Doctoral Fellow at the Darmouth Medical School, and is currently a Full Professor and Teaching Chair in the Institute of Medical Psychology at the Ludwig-Maximilians-Universität in Munich, Germany. Beyond her teaching and research, Martha also works on developing scientific networks for chronobiologists and for women in science.
Introspections about Visual Sensory Memory During the Classic Sperling Iconic Memory Task
Lara Krisst, San Francisco State University (Mind, Brain and Behavior Program)
March 12 • 10:00 am • Reynolds School of Journalism 101
Visual sensory memory (or ‘iconic memory') is a fleeting form of memory that has been investigated by the classic Sperling (1960) iconic memory task. Sperling demonstrated that ‘more is seen than can be remembered,' or that more information is available to observers than what they can normally report about. Sperling established the distinction between ‘whole report' (response to a stimulus set of 12 letters) and what subjects report when cued (to a row of letters in the set), or ‘partial report.' In the whole report condition participants were able to report only between three and five of the 12 letters presented, however, participants' high accuracies across partial report trials revealed that, on a given trial, the information about the complete stimulus set is held in a sensory store momentarily. This finding demonstrates subjects were able to perceive more than they were originally able to report. In a new variant of the paradigm, we investigated participants' trial-by-trial introspections about what participants are, and are not, conscious of regarding these fleeting memories. Consistent with Sperling's findings, data suggest that participants believe that they could report, identify, or remember only a subset of items (~ 4 items). Further investigation with this paradigm, including examination of the neural correlates of the introspective process, may shed light on the neural correlates of visual consciousness.
At face value
An introduction to fast periodic visual stimulation
Talia Retter, Catholic University of Louvain, Belgium (Psychological Sciences Research Institute)
March 12 • 1:00 pm • Reynolds School of Journalism 101
Fast periodic visual stimulation (FPVS) is a technique in which the presentation of stimuli at a constant rate elicits a neural response at that frequency, typically recorded with electroencephalogram (EEG). A Fourier Transform is applied to the EEG data to objectively characterize this response at a pre-determined frequency of interest. Although this technique has traditionally been applied to study low-level vision, it has recently been developed to implicitly measure high-level processes in the field of face perception. In the Face Categorization Lab at the University of Louvain, FPVS has been used to study individualization of facial identities (e.g., Liu-Shuang et al., 2014) and the discrimination of faces from other object categories (e.g., Rossion et al., 2015). During my time in this lab, I have tested experiments using FPVS regarding: 1) category-selective responses to natural face and non-face images; 2) examining the spatio-temporal dynamics of face-selective responses; and 3) adaptation to a specific facial identity. The results of these studies will be discussed both in light of their implications for our understanding of face perception and, more generally, as examples of the richness of this methodology for understanding high-level vision in humans.
Auditory perception and cortical plasticity after long-term blindness
Libby Huber, University of Washington (Vision and Cognition Group)
March 24 • 1:00 pm • Reynolds School of Journalism 101
Early onset blindness is associated with enhanced auditory abilities, as well as plasticity within auditory and occipital cortex. In particular, pitch discrimination is found to be superior among early-blind individuals, although the neural basis of this enhancement is unclear. In this talk, I will present recent work suggesting that blindness results in an increased representation of behaviorally relevant acoustic frequencies within both auditory and occipital cortex. Moreover, we find that individual differences in pitch discrimination performance can be predicted from the cortical data. The functional significance of group and individual level differences in frequency representation will be discussed, along with the relative importance of auditory and occipital cortical responses for acoustic frequency discrimination after long-term blindness.
New Tools for Real-time Imaging of Single Live Cells
Nancy Xu, PhD Old Dominion University (Chemistry and Biochemistry)
April 30 • 1:00 pm • Davidson Math and Science 105
Current technologies are unable to real-time detect, image and study multiple types of molecules in single live cells with sufficient spatial and temporal resolutions and over an extended period of time. To better understand the cellular function in real-time, we have developed several new ultrasensitive nanobiotechnologies, including far-field photostable-optical-nanoscopy (PHOTON), photostable single-molecule-nanoparticle-optical-biosensors (SMNOBS) and single nanoparticle spectroscopy for mapping of dynamic cascades of membrane transport and signaling transduction pathways of single live cells in real time at single molecule and nanometer resolutions. We have demonstrated that these powerful new tools can be used to quantitatively image single molecules and study their functions in single live cells with superior temporal and spatial resolutions and to address a wide range of crucial biochemical and biomedical questions. The research results and experimental designs will be discussed in this seminar.
Endogenous RNAi and behavior in C. elegans
Noelle L’Etoile, PhD UCSF (Department of Cell and Tissue Biology)
April 30 • 4:00 pm • Ansari Business 106
Understanding kids who don’t talk
Using EEG to measure language in minimally verbal children with ASD
Charlotte DiStefano, PhD UCLA (Center for Autism Research and Treatment)
May 8 • 4:00 pm • Ansari Business 106
Olivier Collignon, PhD
University of Tento, Italy (Center for Mind/Brain Sciences)
May 22 • 11:00 am • Reynolds School of Journalism
Bruno Rossion, PhD
Catholic University of Louvain, Belgium (Psychological Sciences Research Institute)
May 26 • 1:00 pm • Reynolds School of Journalism 101