General News:

 

In press/Recent publications:

  • Priming Effects in the Fusiform Gyrus: Changes in Neural Activity beyond the Second Presentation , Reber, P.J, Gitelman, D.R., Parrish, T.B. & Mesulam, M.-M. (2004) Cerebral Cortex, 09/15/2004. [pdf]
  • Dissociating explicit and implicit category knowledge with fMRI, Reber, P.J, Gitelman, D.R., Parrish, T.B. & Mesulam, M.-M. (2003). Journal of Cognitive Neuroscience, 15, 574-685. (pdf)
  • Intact artificial grammar learning in Alzheimer's disease, Reber, P.J., Martinez, L.A. & Weintraub, S. (in press). Cognitive, Affective and Behavioral Neuroscience.
  • Neural correlates of successful encoding identified using fMRI, Reber, Siwiec, Gitelman, Parrish, Mesulam& Paller (2002). Journal of Neuroscience. (pdf)
  • Neural Correlates of Artificial Grammar Learning, Skosnik, Mirza, Gitelman, Parrish, Mesulam & Reber (2002). NeuroImage. pdf
  • Encoding Activity in the Medial Temporal Lobe Examined with Anatomically Constrained fMRI Analysis, Reber, Buxton & Wong (2002). Hippocampus. pdf
  • Comparing the brain areas supporting nondeclarative categorization and recognition memory, Reber, Wong, & Buxton, R.B. (2002). Cognitive Brain Research. pdf
  • Attempting to model dissociations of memory, Reber (2002). Trends in Cognitive Sciences. pdf

Recent Abstracts

Neural Correlates of Word Priming During Lexical Decision

Murray KD, Paller, KA, & Reber PJ; Society for Neuroscience 2005
The behavioral phenomenon of priming is characterized by a reduction in reaction time to a stimulus as a result of previous experience with that stimulus. The neural correlates of priming are typically reported to be a reduction in evoked activity for a repeated stimulus (Schacter & Buckner, 1998, Neuron), which may reflect increased perceptual fluency. Functional neuroimaging (fMRI) was used to assess neural correlates of priming during lexical decision. Participants (n=16) initially encountered a set of words by using them to generate sentences. FMRI data were collected while participants made lexical decisions about new and old words (35 3mm slices, TR=2000ms, TE=25ms, using a Siemens 3T Trio MR scanner). Reliable behavioral priming was observed in that lexical decisions were faster for old than new words. Old words evoked increased activity bilaterally in posterior parietal areas compared to new words and no evidence for reduced visual activity (fluency) was observed. This novel pattern of activity may reflect a different neural process by which behavioral priming can be accomplished. However, high levels of declarative memory for studied words on a subsequent recognition test suggest that contamination from explicit memory may have affected the assessment of neural correlates of priming. A second study aims to replicate this pattern and determine whether the same pattern of activity is produced with study conditions that limit explicit contamination. Following the design of Paller, Kutas & McIssac (1995, Psychological Science) reliable priming during lexical decision was observed after either shallow (reiteration) or deep (sentence generation) encoding of the studied words. While behavioral priming is similar after either type of initial study, explicit memory of the study words is much more robust after deep encoding. Assessment of the neural correlates of priming is expected to reveal separate neural correlates of priming in the two encoding conditions with fluency (reduced visual activity) occurring after shallow encoding and increased bilateral parietal activity after deep encoding.

 

A Monte Carlo simulation method for setting statistical thresholds in fMRI data analysis

Nomura EM, Murray KD, Reber PJ
The technique of functional MRI has revolutionized cognitive neuroscience research. However, a consistent statistical model to establish reliability thresholds for group data analysis has yet to be developed. One of the principle challenges is to identify a threshold based on both a statistical parameter threshold (e.g., t>4) and a cluster size threshold (e.g., meeting the statistical threshold across a contiguous volume greater than 350 mm3). A secondary challenge is to extend the threshold identification technique to small and potentially irregularly shaped regions of interest (ROIs) whose boundaries are determined anatomically. Here we propose a method based on Monte Carlo simulation of matched noise data to assess the false positive rate of any particular data analysis approach regardless of the number of conditions, groups, or ROI methods. In this simulation, a Gaussian noise dataset is created that matches the mean and standard deviation of each voxel, of each run, of each subject for all collected data in a study. This noise data is subjected to identical processing as the observed data, including spatial smoothing, normalization and random effects analysis. Any findings observed in the random noise data for a particular statistical threshold are false positives since this noise data lacks stimulus-locked functional activity. A final threshold incorporating both statistical threshold and cluster size can therefore be selected that appropriately achieves a corrected .05 false positive rate across the entire brain or ROI for the study. To maximize accuracy the process is repeated, but the computationally intensive nature of creating and analyzing matched noise typically limits the simulation dataset to 15-20 full simulations of the fMRI dataset. Here, analysis of 100 full simulations is presented, demonstrating the simulation technique, the observed false positive rates and an extrapolation method for estimating appropriate statistical thresholds from smaller simulation datasets (e.g., 15-20 runs).

 

Neural Correlates of Sexual Arousal in Heterosexual and Homosexual Men

J.M. Bailey, Paul J. Reber, Ben Barch, Adam Safron
Men exhibit category-specific sexual arousal; their highest level of genital and subjective arousal is to erotic stimuli containing their preferred sex. This study used event-related fMRI to study whether this pattern would be reflected in the brains of homosexual (N = 11) and heterosexual (N = 11) men. Comparisons between preferred sexual stimuli and non-preferred stimuli revealed large networks of activity spanning multiple cortical and sub-cortical areas. Aggregate data from multiple nodes of a postulated arousal network were used to determine the sexual orientation of participants. This method had a high degree of fidelity (16/18) in discriminating heterosexual and homosexual men and represents a significant advance in psychophysiological measures of arousal. In addition, region of interest analysis revealed differential activity in the amygdala, a structure believed to mediate sexually dimorphic reproductive behaviors. Group differences are probably due to the more intensely positive responses to preferred sexual stimuli and less emotional responses to non-preferred stimuli in homosexual than heterosexual participants.

Recent and upcoming presentations

Society for Neuroscience 2005

  • Neural Correlates of Word Priming During Lexical Decision; Murray, K.D, Paller, K.A., Reber, P.J. pdf
  • A Monte Carlo simulation method for setting statistical thresholds in fMRI data analysis; Nomura EM, Murray KD, Reber PJ

Society for Neuroscience 2004

  • Nomura EM, Maddox WT, Ing AD, Filoteo JV, Reber PJ (2004). Neural correlates of rule-based and information integration category learning: converging results from fMRI and computational modeling. 34th Annual Meeting of the Society for Neuroscience.
  • Fisher, J., Mesulam, M.M., Gitelman, D.R., Parrish, T.B. & Reber, P.J. (2004). The development of perceptual expertise In the visual categorization of sleep stages. 34th Annual Meeting of the Society for Neuroscience.
  • Westerberg, C.E., Paller, K.A., Weintraub, S., Mesulam, M.M., Holcombe, J.S., Mayes, A.R. & Reber, P.J. (2004). Relative preservation of forced-choice recognition in mild cognitive impairment and Alzheimer's disease. 34th Annual Meeting of the Society for Neuroscience.

Cognitive Neuroscience Society 2004

  • Nomura EM, Maddox WT, Filoteo JV, Gitelman DR, Parrish TB, Mesulam MM, Reber PJ (2004). Neural correlates of rule-based (RB) and information integration (II) categorization: An event-related fMRI study of category learning. 11th Annual Meeting of the Cognitive Neuroscience Society.



Recent Awards by lab members

Adam Safron
Northwestern Cognitive Science Program Summer Undergraduate Research Fellowship,2003
Benton J. Underwood Summer Research Fellowship, 2004
Northwestern Undergraduate Research Grant, 2005

Vickie Huang
Northwestern Cognitive Science Program Summer Undergraduate Research Fellowship, 2004
Benton J. Underwood Summer Research Fellowship, 2004

Bennett Barch
Graduated with Honors, 2003
Hunt Award Winner, 2003

Rob Siwiec
American Academy of Neurology Summer Fellowship, 2003 (Finch-Chicago Medical School)
Graduated with Honors, 2001
Underwood Summer Fellowship from the Psychology Department, 2000
Undergraduate Research Council Summer Research Award, 2000

Anjali Raja
Fulbright award, 2002

Becca Schwarzlose
Graduated with Honors, 2002
NSF Graduate Fellowship, 2002

Farheen Mirza
Graduated with Honors, 2002
Cognitive Science Summer Research Award, 2001

Mike Levitt
Graduated with Honors, 2002
Undergraduate Research Council Summer Research Award, 2001

Yoko Okado
Graduated with Honors, 2001
Hunt award winner for best Senior Honors Thesis, 2001
Undergraduate Research Council Summer Research Award, 2000
Cognitive Science Summer Research Award, 2000

Luke Velders
Graduated with Honors, 2001
Cognitive Science Summer Research Award, 2000

 

P.J. Reber (PI) Recent Grant Funding


Current
NIMH award, R01-MH58748
"Functional Neuroimaging of Nondeclarative Memory"
07/01/00-06/30/05

Past
Pilot project award from NU Alzheimer's Disease Center
"Memory encoding in AD & MCI"
07/01/00-06/30/01

Illinois Department of Public Health, Alzheimer's Disease Research Fund
"Nondeclarative skill learning in AD"
07/01/99-06/30/00

Co-Investigator

  • Executive Committee Member and Investigator, "Interdisciplinary Collaborative Consortium on the Cognitive Neuroscience of Category Learning" PI: Mark Gluck (Rutgers University), $295,000, 4/2002-3/2005
  • Investigator, "Electrophysiological measures of human memory functions", NS-34639-07, PI: Ken A. Paller (Northwestern University), $1,140,750 total costs, 8.33% effort, 7/2000-6/2005
  • Investigator, "Cerebellum, Problem Solving & High-Resolution Imaging", PI: Jim Houk (Northwestern University), $825,000 direct costs, 5% effort, 2002-2005.
  • Investigator, "An fMRI investigation of language in both hemispheres", DC-04052 R01, PI: Mark Jung-Beeman (Northwestern University).

Training grants (preceptor)
Mechanisms of aging and dementia. PI: John F. Disterhoft.
General Motor Control Mechanisms and Disease. PI: James Surmeier.
Neurobiology of Information Storage. PI: Aryeh Routtenberg.

Intramural awards
Computational facilities to establish the Evanston Neuroimaging Analysis Center, Weinberg College of Arts and Sciences, $13,000, Aug. 2000.