Papers for the month of March 2019

Collins, E., Freud, E., Kainerstorfer, J.M., Cao, J., Behrmann, M.

"Temporal Dynamics of Shape Processing Differentiate Contributions of Dorsal and Ventral Visual Pathways"
Journal of Cognitive Neuroscience, 0:1-16

Mouse over here for a brief summary or click to open article in a new tab.Although shape perception is primarily considered a function of the ventral visual pathway, previous research has shown that both dorsal and ventral pathways represent shape information. Here, we examine whether the shape-selective electrophysiological signals observed in dorsal cortex are a product of the connectivity to ventral cortex or are independently computed. We conducted multiple EEG studies in which we manipulated the input parameters of the stimuli so as to bias processing to either the dorsal or ventral visual pathway. Participants viewed displays of common objects with shape information parametrically degraded across five levels. We measured shape sensitivity by regressing the amplitude of the evoked signal against the degree of stimulus scrambling. The first experiment, which included grayscale versions of the stimuli, served as a benchmark establishing the temporal pattern of shape processing during typical object perception. These stimuli evoked broad and sustained patterns of shape sensitivity beginning as early as 50 msec after stimulus onset. In the other experiments, we calibrated the stimuli such that visual information was delivered primarily through parvocellular inputs, which mainly project to the ventral pathway, or through koniocellular inputs, which mainly project to the dorsal pathway. In both experiments, shape sensitivity was observed, but in distinct spatio-temporal configurations from each other and from that elicited by grayscale inputs. Of particular interest, in the koniocellular condition, shape selectivity emerged earlier than in the parvocellular condition. These findings support the conclusion of distinct dorsal pathway computations of object shape, independent from the ventral pathway.

Zhou X., Tien R.N., Ravikumar, S.

"Distinct types of neural reorganization during long-term learning"
Journal of Neurophysiology, 121:1329-1341

Mouse over here for a brief summary or click to open article in a new tab.What are the neural mechanisms of skill acquisition? Many studies find that long-term practice is associated with a functional reorganization of cortical neural activity. However, the link between these changes in neural activity and the behavioral improvements that occur is not well understood, especially for long-term learning that takes place over several weeks. To probe this link in detail, we leveraged a brain-computer interface (BCI) paradigm in which rhesus monkeys learned to master non-intuitive mappings between neural spiking in primary motor cortex and computer cursor movement. Critically, these BCI mappings were designed to disambiguate several different possible types of neural reorganization. We found that during the initial phase of learning, lasting minutes to hours, rapid changes in neural activity common to all neurons led to a fast suppression of motor error. In parallel, local changes to individual neurons gradually accrued over several weeks of training. This slower timescale cortical reorganization persisted long after the movement errors had decreased to assymptote and was associated with more efficient control of movement. We conclude that long-term practice evokes two distinct neural reorganization processes with vastly different timescales, leading to different aspects of improvement in motor behavior.

Neumann, J-W., Stretcu O., Lipski W., Bush A., Dastolfo-Hromack C., Wang D., Crammond D.J., Shaiman S., Dickey M.W., Holt L.L., Turner R.S., Fiez J.A., Richardson RM.

"Subthalamic nucleus and sensorimotor cortex activity during speech production"
The Journal of Neuroscience, 39:2698-2708

Mouse over here for a brief summary or click to open article in a new tab.The paper examines articulatory encoding in the sensorimotor cortex and the subthalamic nucleus and demonstrates that articulator-specific speech information is contained within high-gamma activity of the STN, but with different spatial and temporal organization compared with similar information encoded in the sensorimotor cortex.

"Addressing misconceptions of fast mapping in adults"
Cognitive Neuroscience, 0:0

Mouse over here for a brief summary or click to open article in a new tab.Studies of fast mapping (FM) in adults have included both positive results and failures to replicate. I argue that although conflicting studies warrant caution, FM findings are nonetheless promising and intriguing. I separate the issue into distinct questions: whether FM has hippo- campal independence, and whether it has unique cognitive consequences. I clarify some mis- understandings and identify limitations that may contribute to failures to find learning from FM in some amnesic patients. Finally, I argue that the array of behavioral findings in healthy adults is consistent with computational and neural models.

Martin, L., Durisko, C., Moore, M.W., Chen, D., Fiez, J. A.

"The VWFA is the home of orthographic learning when house images are used as letters"
eNeuro, 6:1

Mouse over here for a brief summary or click to open article in a new tab.Learning to read specializes a portion of the left mid-fusiform cortex for printed word recognition, the putative visual word form area (VWFA). This study examined whether a VWFA specialized for English is sufficiently malleable to support learning a perceptually atypical second writing system. The study utilized an artificial orthography, HouseFont, in which house images represent English phonemes. House images elicit category-biased activation in a spatially distinct brain region, the so-called parahippocampal place area (PPA). Using house images as letters made it possible to test whether the capacity for learning a second writing system involves neural territory that supports reading in the first writing system, or neural territory tuned for the visual features of the new orthography. Twelve human adults completed two weeks of training to establish basic HouseFont reading proficiency and underwent functional neuroimaging pre and post-training. Analysis of three functionally defined regions of interest (ROIs), the VWFA, and left and right PPA, found significant pre-training versus post-training increases in response to HouseFont words only in the VWFA. Analysis of the relationship between the behavioral and neural data found that activation changes from pre-training to post-training within the VWFA predicted HouseFont reading speed. These results demonstrate that learning a new orthography utilizes neural territory previously specialized by the acquisition of a native writing system.

Carlos, B. J., Hirshorn, E. A., Durisko, C., Fiez, J. A.

"Word inversion sensitivity as a marker of visual word form area lateralization: An application of a novel multivariate measure of laterality"
NeuroImage, 191:493-502

Mouse over here for a brief summary or click to open article in a new tab.An area within the ventral occipitotemporal cortex (vOTC), the "visual word form area" (VWFA), typically exhibits a strongly left-lateralized response to orthographic stimuli in skilled readers. While individual variation in VWFA lateralization has been observed, the behavioral significance of laterality differences remains unclear. Here, we test the hypothesis that differences in VWFA lateralization reflect differing preferences for holistic orthographic analysis. To examine this hypothesis, we implemented a new multivariate method that uses machine learning to assess functional lateralization, along with a traditional univariate lateralization method. We related these neural metrics to behavioral indices of holistic orthographic analysis (inversion sensitivity). The multivariate measure successfully detected the lateralization of orthographic processing in the VWFA, and as hypothesized, predicted behavioral differences in holistic orthographic analysis. An exploratory whole brain analysis identified further regions with a relationship between inversion sensitivity and lateralization: one near the junction of the inferior frontal and precentral sulci, and another along the superior temporal gyrus. We conclude that proficient native readers of English exhibit differences in cortical lateralization of the VWFA that have significant implications for reading behavior.

Montez, D.F., Calabro FJ

"Working memory improves developmentally as neural processes stabilize"
PLOS ONE, 14(3):1-15

Mouse over here for a brief summary or click to open article in a new tab.Working memory performance is a key indicator of cognitive and developmental status. While recent evidence indicates that stabilizing neural gain supports the stabilization of working memory during adolescence, the computational mechanisms linking neural stabilization to behavior are poorly understood. We develop a mechanistic account of behavior during the memory-guided saccade task based on a stochastic accumulator framework. Results indicate that a specific balance of independent gain signals affecting working memory representations and oculomotor response thresholds can account for a peculiar Ushaped feature of the speed-accuracy relationship. Additionally, aspects of behavioral variability and mean behavioral performance, as well as subtle shifts in the shape of the speedaccuracy relationship across development, can be accounted for by the stabilization of these two sources of variability. Thus, the stabilization of neural variability can, in part, account for developmental improvements in behavioral variability as well as some improvement in mean behavioral performance.

Liu, S.T., Montes-Lourido, P., Wang X.

"Optimal Features for Auditory Categorization"
Nature Communications, 10:1302

Mouse over here for a brief summary or click to open article in a new tab.The auditory system uses characteristic features of complex sounds such as vocalizations to categorize them, invariant to the variability inherent in their production.

Witherspoon, E.

"Teachers’ goals predict computational thinking gains in robotics"
Information and Learning Sciences, 0:0

Mouse over here for a brief summary or click to open article in a new tab.Computational thinking (CT) is widely considered to be an important component of teaching generalizable computer science skills to all students in a range of learning environments, including robotics. However, despite advances in the design of robotics curricula that can teach CT, actual enactment in classrooms may often fail to reach this target. Understanding the various instructional goals teachers’ hold when using these curricula may offer one potential explanation for disparities in outcomes.In this study, the authors examine results from N = 206 middle school students’ pre- and post-tests of computational thinking, attitudinal surveys and surveys of their teacher’s instructional goals to determine if student attitudes and learning gains in computational thinking are related to the instructional goals their teachers endorsed while implementing a shared robotics programming curriculum.

Khanna, Sanjeev, Snyder, Adam

"Distinct sources of variability affect eye movement preparation"
Journal of Neuroscience, 1:1

Mouse over here for a brief summary or click to open article in a new tab.The transition from perception to action involves coordination among neurons across the brain. We found that the time required for subjects to produce an eye movement could be predicted from the statistics of the neuronal response of populations of frontal eye field neurons, suggesting that these neurons coordinate their activity to optimize the transition from perception to action.

Fu Weisi, Nelson Tyler, Santos Diogo, Doolen Suzanne, Gutierrez Javier, Ye Na, Zhou Jia, Taylor Bradley

"An NPY Y1 receptor antagonist unmasks latent sensitization and reveals the contribution of Protein Kinase A and EPAC to chronic inflammatory pain"
Pain, **:**

Mouse over here for a brief summary or click to open article in a new tab.We conclude that PKA and Epac are sufficient to maintain long-lasting latent sensitization of dorsal horn neurons that is kept in remission by the NPY-Y1 receptor system. Furthermore, we have identified and characterized two novel molecular signaling pathways in the dorsal horn that drive latent sensitization in the setting of chronic inflammatory pain: NMDAR→AC1→PKA→TRPA1/V1 and NMDAR→AC1→Epac1/2.

Dunovan, Kyle

"Errors in action timing and inhibition facilitate learning by tuning distinct mechanisms in the underlying decision process"
Journal of Neuroscience, 0:1924-28

Mouse over here for a brief summary or click to open article in a new tab.We show how different feedback signals modify different processes in the accumulation of evidence during decision making.

Norton CM, Speer LE, Tremel JJ, Ibinson JW, Reder LM, Fiez JA

"Memory for non-painful auditory items is influenced by whether they are experienced in a context involving painful electrical stimulation"
Experimental Brain Research, ePub:4/2/19

Mouse over here for a brief summary or click to open article in a new tab.Compares recognition memory for alternating items paired versus not paired with acute painful stimulation, to items experienced in a completely pain-free context.

Belsey P., Nicholas M.A.,

"Build a better mouse task: can an open-source rodent joystick enhance reaching behavior outcomes through improved monitoring of real-time spatiotemporal kinematics?"
Biorxiv, 0:1

Mouse over here for a brief summary or click to open article in a new tab.Here, we assess the hypothesis that a mouse can learn a cued reaction time reach task. Additionally, we include a step-by-step manual for inexpensive implementation and use of a rodent joystick for behavioral analysis. Task and analysis code for the evaluated behaviors are included such that they may be replicated and tested further. With these, we also include code for a probabilistic reward "two-arm bandit" task.


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