http://hdl.handle.net/2144/1260 2013-05-21T19:43:19Z 2013-05-21T19:43:19Z Otto, Michael W. O'Cleirigh, Conall M. Pollack, Mark H. http://hdl.handle.net/2144/3166 2012-01-12T07:00:53Z 2007-04-01T00:00:00Z

Attending to Emotional Cues for Drug Abuse: Bridging the Gap Between Clinic and Home Behaviors Otto, Michael W.; O'Cleirigh, Conall M.; Pollack, Mark H. Classical conditioning models of addiction provide keys to understanding the vexing discrepancy between substance abuse patients' desire to abstain when they are in therapy sessions and their tendency to relapse. Experiments using these models demonstrate the power of environmental relapse cues and support clinical approaches, including active exposure, aimed at helping patients recognize and withstand them. Internal cues, including emotions and somatic states such as withdrawal, can trigger urges as powerfully as external cues such as people, places, and things associated with prior abuse. The authors describe a cognitive-behavioral therapy approach that focuses on identifying and actively inducing each patient's high-risk emotions, then helping him or her develop and practice healthy responses. Clinical trials support the approach for patients with panic disorder who have trouble discontinuing benzodiazepines, and early trials suggest it may be useful for patients addicted to other drugs as well.

2007-04-01T00:00:00Z Zilli, Eric A. Yoshida, Motoharu Tahvildari, Babak Giocomo, Lisa M. Hasselmo, Michael E. http://hdl.handle.net/2144/3160 2012-01-12T07:00:52Z 2009-11-20T00:00:00Z

Evaluation of the Oscillatory Interference Model of Grid Cell Firing through Analysis and Measured Period Variance of Some Biological Oscillators Zilli, Eric A.; Yoshida, Motoharu; Tahvildari, Babak; Giocomo, Lisa M.; Hasselmo, Michael E. Models of the hexagonally arrayed spatial activity pattern of grid cell firing in the literature generally fall into two main categories: continuous attractor models or oscillatory interference models. Burak and Fiete (2009, PLoS Comput Biol) recently examined noise in two continuous attractor models, but did not consider oscillatory interference models in detail. Here we analyze an oscillatory interference model to examine the effects of noise on its stability and spatial firing properties. We show analytically that the square of the drift in encoded position due to noise is proportional to time and inversely proportional to the number of oscillators. We also show there is a relatively fixed breakdown point, independent of many parameters of the model, past which noise overwhelms the spatial signal. Based on this result, we show that a pair of oscillators are expected to maintain a stable grid for approximately t = 5µ3/(4πσ)2 seconds where µ is the mean period of an oscillator in seconds and σ2 its variance in seconds2. We apply this criterion to recordings of individual persistent spiking neurons in postsubiculum (dorsal presubiculum) and layers III and V of entorhinal cortex, to subthreshold membrane potential oscillation recordings in layer II stellate cells of medial entorhinal cortex and to values from the literature regarding medial septum theta bursting cells. All oscillators examined have expected stability times far below those seen in experimental recordings of grid cells, suggesting the examined biological oscillators are unfit as a substrate for current implementations of oscillatory interference models. However, oscillatory interference models can tolerate small amounts of noise, suggesting the utility of circuit level effects which might reduce oscillator variability. Further implications for grid cell models are discussed. Author Summary For many animals, including rats, accurate spatial memory over relatively large areas is important in order to find food and shelter. Just as unique points in time can be efficiently represented by combinations of repeating elements like hours, days, and months, points in space can be represented as combinations of elements that repeat at different spatial scales. Just such a code has been identified in the brains of rats and it shows an intriguing triangular spacing of encoded locations. Two different explanations have been developed as to what general mechanism in the brain might be able to generate this unusual code. However, to date there is not conclusive experimental evidence indicating whether either of the two explanations is correct. Here we show in detail that one of the explanations, called oscillatory interference, has specific requirements regarding the amount of variability in the system that implements it. We then report data experimentally examining candidate systems to evaluate their levels of noise. The large amount of noise that we find presents a challenge to the currently suggested biological implementations of oscillatory interference, but it does not provide support for the alternative explanation.

2009-11-20T00:00:00Z Seitz, Aaron R. Nanez, Jose E. Holloway, Steve R. Watanabe, Takeo http://hdl.handle.net/2144/3161 2012-01-12T07:00:52Z 2006-12-20T00:00:00Z

Perceptual Learning of Motion Leads to Faster Flicker Perception Seitz, Aaron R.; Nanez, Jose E.; Holloway, Steve R.; Watanabe, Takeo Critical flicker fusion thresholds (CFFT) describe when quick amplitude modulations of a light source become undetectable as the frequency of the modulation increases. The threshold at which CFF occurs has been shown to remain constant under repeated testing. Additionally, CFF thresholds are correlated with various measures of intelligence, and have been regarded by clinicians as a general measure of cortical processing capacity. For these reasons, CFF is used as a cognitive indicator in drug studies, as a measure of fatigue, and has been suggested as a diagnostic measure for various brain diseases. Here we report that CFFT increases dramatically in subjects who are trained with a motion-direction learning procedure. Control tasks demonstrate that CFFT changes are tightly coupled with improvements in discriminating the direction of motion stimuli, and are likely related to plasticity in low-level visual areas that are specialized to process motion signals. This plasticity is long-lasting and is retained for at least one year after training. Combined, these results show that CFFT relates to a specialized sensory process and bring into question that CFFT is a measure of high-level, or general, processes.

2006-12-20T00:00:00Z Kim, Robyn S. Seitz, Aaron R. Shams, Ladan http://hdl.handle.net/2144/3162 2012-01-12T07:00:52Z 2008-01-30T00:00:00Z

Benefits of Stimulus Congruency for Multisensory Facilitation of Visual Learning Kim, Robyn S.; Seitz, Aaron R.; Shams, Ladan BACKGROUND. Studies of perceptual learning have largely focused on unisensory stimuli. However, multisensory interactions are ubiquitous in perception, even at early processing stages, and thus can potentially play a role in learning. Here, we examine the effect of auditory-visual congruency on visual learning. METHODOLOGY/PRINCIPLE FINDINGS. Subjects were trained over five days on a visual motion coherence detection task with either congruent audiovisual, or incongruent audiovisual stimuli. Comparing performance on visual-only trials, we find that training with congruent audiovisual stimuli produces significantly better learning than training with incongruent audiovisual stimuli or with only visual stimuli. CONCLUSIONS/SIGNIFICANCE. This advantage from stimulus congruency during training suggests that the benefits of multisensory training may result from audiovisual interactions at a perceptual rather than cognitive level.

2008-01-30T00:00:00Z