About

Michael Silver is a Professor of Neuroscience in the Department of Optometry and Neuroscience at Berkeley. His research interests focus on the neurophysiological and neurochemical substrates of human visual perception, attention, and learning. As a faculty member, he contributes to the understanding of how neural mechanisms underpin visual and cognitive functions, advancing knowledge in cognitive neuroscience.

Research topics

• Psychology
• Neuroscience
• Medicine
• Cognitive psychology
• Computer science

Selected publications

• A Randomized Double‐Blind Placebo‐Controlled Trial of Guanfacine Extended Release for Aggression and Self‐Injurious Behavior Associated With Prader‐Willi Syndrome

  American Journal of Medical Genetics Part B Neuropsychiatric Genetics · 2025-05-21 · 2 citations

  article

  Prader-Willi Syndrome (PWS), a rare genetic disorder, affects development and behavior, frequently resulting in self-injury, aggression, hyperphagia, oppositional behavior, impulsivity, and over-activity, causing significant morbidity. Currently, limited therapeutic options are available to manage these neuropsychiatric manifestations. A randomized, placebo-controlled trial was conducted to assess the efficacy of guanfacine-extended release (GXR) in reducing aggression and self-injury in individuals with PWS. Subjects with a diagnosis of PWS, aged 6-35 years with moderate to severe aggressive and/or self-injurious behavior, as determined by the clinical global impression (CGI)-Severity scale, were included in an 8-week double-blind, placebo-controlled, fixed-flexible dose clinical trial of GXR, that was followed by an 8-week open-label extension phase. Validated behavioral instruments and physician assessments measured the efficacy of GXR treatment, its safety, and tolerability. GXR was effective in reducing aggression/agitation and hyperactivity/noncompliance, as measured by the Aberrant Behavior Checklist (ABC) scales (p = 0.03). Overall aberrant behavior scores significantly reduced in the GXR arm. Aggression, as measured by the modified overt aggression scale (MOAS) also showed a significant reduction. Skin-picking lesions, as measured by the self injury trauma (SIT) scale, decreased in response to GXR. No serious adverse events were experienced by any of the study participants. Fatigue/sedation was the only adverse event significantly associated with GXR. The GXR group demonstrated significant overall clinical improvement, as measured by the CGI-Improvement (CGI-I) scale (p < 0.01). Findings of this pragmatic trial strongly support the use of GXR for the treatment of aggression, skin picking, and hyperactivity in children, adolescents, and adults with PWS.

  PublisherDOI

• Top-Down Priors Disambiguate Target and Distractor Features in Simulated Covert Visual Search

  Neural Computation · 2024-08-14

  articleOpen accessSenior author

  Several models of visual search consider visual attention as part of a perceptual inference process, in which top-down priors disambiguate bottom-up sensory information. Many of these models have focused on gaze behavior, but there are relatively fewer models of covert spatial attention, in which attention is directed to a peripheral location in visual space without a shift in gaze direction. Here, we propose a biologically plausible model of covert attention during visual search that helps to bridge the gap between Bayesian modeling and neurophysiological modeling by using (1) top-down priors over target features that are acquired through Hebbian learning, and (2) spatial resampling of modeled cortical receptive fields to enhance local spatial resolution of image representations for downstream target classification. By training a simple generative model using a Hebbian update rule, top-down priors for target features naturally emerge without the need for hand-tuned or predetermined priors. Furthermore, the implementation of covert spatial attention in our model is based on a known neurobiological mechanism, providing a plausible process through which Bayesian priors could locally enhance the spatial resolution of image representations. We validate this model during simulated visual search for handwritten digits among nondigit distractors, demonstrating that top-down priors improve accuracy for estimation of target location and classification, relative to bottom-up signals alone. Our results support previous reports in the literature that demonstrated beneficial effects of top-down priors on visual search performance, while extending this literature to incorporate known neural mechanisms of covert spatial attention.

  PublisherOA PDFDOI

• Modeling retinotopic maps in amblyopia reveals cortical reorganization across the visual hierarchy

  Journal of Vision · 2024-09-15 · 4 citations

  articleOpen access

  Amblyopia is a common cortical developmental disorder affecting 3.7% to 5% of the adult population. It is defined as a monocular visual acuity impairment despite healthy or corrected-to-normal optical components. Deficits associated with amblyopia include reduced contrast sensitivity, impaired foveal localization, and stereoblindness. While traditionally viewed as a developmental cortical pathology given the preserved ocular function, the neural bases of amblyopia remain debated. This study aims at understanding the neural mechanisms underlying amblyopia by modeling fMRI data collected during retinotopic mapping in strabismic, anisometropic, and mixed amblyopia patients. Population receptive field (pRF) parameters were extracted across early and intermediate visual areas and compared between amblyopic patients and controls. We found that amblyopic patients systematically exhibited larger pRF sizes across all visual areas examined, with greater effect sizes from V1 to V3 and in LO/VO. Effect sizes were stronger in foveal stimulation than in the periphery, a result compatible with disordered cortical projection theories of amblyopia. Anisometropic and mixed amblyopia patients showed larger pRF sizes than strabismic patients, unexpectedly given their clinical symptoms. These results advance our understanding of amblyopia’s neural underpinnings. Foveal-peripheral differences point to abnormal cortical projections. Moreover, the increased pRF sizes, mismatching clinically-predicted patterns, suggests a more widespread plastic dysfunction. Overall, our findings point to a substantial receptive field reorganization in amblyopia, mostly in the early visual system.

  PublisherDOI

• A randomized double-blind placebo-controlled clinical trial of Guanfacine Extended Release for aggression and self-injurious behavior associated with Prader-Willi Syndrome

  medRxiv · 2024-08-22 · 2 citations

  preprintOpen accessSenior author

  Introduction: Prader-Willi Syndrome (PWS), a rare genetic disorder, affects development and behavior, frequently resulting in self-injury, aggression, hyperphagia, oppositional behavior, impulsivity and over-activity causing significant morbidity. Currently, limited therapeutic options are available to manage these neuropsychiatric manifestations. The aim of this clinical trial was to assess the efficacy of guanfacine-extended release (GXR) in reducing aggression and self-injury in individuals with PWS. Trial Design: Randomized, double-blind, placebo-controlled trial conducted under IRB approval. Methods: Subjects with a diagnosis of PWS, 6-35 years of age, with moderate to severe aggressive and/or self-injurious behavior as determined by the Clinical Global Impression (CGI)-Severity scale, were included in an 8-week double-blind, placebo-controlled, fixed-flexible dose clinical trial of GXR, that was followed by an 8-week open-label extension phase. Validated behavioral instruments and physician assessments measured the efficacy of GXR treatment, its safety and tolerability. Results: GXR was effective in reducing aggression/agitation and hyperactivity/noncompliance as measured by the Aberrant Behavior Checklist (ABC) scales (p=0.03). Overall aberrant behavior scores significantly reduced in the GXR arm. Aggression as measured by the Modified Overt Aggression Scale (MOAS) also showed a significant reduction. Skin-picking lesions as measured by the Self Injury Trauma (SIT) scale decreased in response to GXR. No serious adverse events were experienced by any of the study participants. Fatigue /sedation was the only adverse event significantly associated with GXR. The GXR group demonstrated significant overall clinical improvement as measured by the CGI-Improvement (CGI-I) scale. (p&lt;0.01). Conclusion: Findings of this pragmatic trial strongly support the use of GXR for treatment of aggression, skin picking, and hyperactivity in children, adolescents, and adults with PWS. Trial Registration: ClinicalTrials.gov Identifier - NCT05657860

  PublisherOA PDFDOI

• A novel method for quantitative analysis of subjective experience reports: application to psychedelic visual experiences

  Frontiers in Psychology · 2024-12-06 · 5 citations

  articleOpen accessSenior author

  Introduction: Psychedelic compounds such as LSD, psilocybin, mescaline, and DMT can dramatically alter visual perception. However, the extent to which visual effects of psychedelics consistently vary for different substances is an open question. The visual effects of a given psychedelic compound can range widely both across and within individuals, so datasets with large numbers of participants and descriptions of qualitative effects are required to adequately address this question with the necessary sensitivity. Methods: Here we present an observational study with narrative self-report texts, leveraging the massive scale of the Erowid experience report dataset. We analyzed reports associated with 103 different psychoactive substances, with a median of 217 reports per substance. Thirty of these substances are standardly characterized as psychedelics, while 73 substances served as comparison substances. To quantitatively analyze these semantic data, we associated each sentence in the self-report dataset with a vector representation using an embedding model from OpenAI, and then we trained a classifier to identify which sentences described visual effects, based on the sentences' embedding vectors. Results: We observed that the proportion of sentences describing visual effects varies significantly and consistently across substances, even within the group of psychedelics. We then analyzed the distributions of psychedelics' visual effect sentences across different categories of effects (for example, movement, color, or pattern), again finding significant and consistent variation. Discussion: Overall, our findings indicate reliable variation across psychedelic substances' propensities to affect vision and in their qualitative effects on visual perception.

  PublisherOA PDFDOI

• Lack of Racial and Ethnic Diversity in Surgical Education, as Reflected by Skin Tone in General Surgery Textbooks

  Journal of surgical education · 2024-09-20 · 4 citations

  article
  PublisherDOI

• Figure S5 from A Noninvasive Blood-based Combinatorial Proteomic Biomarker Assay to Detect Breast Cancer in Women over age 50 with BI-RADS 3, 4, or 5 Assessment

  2023-03-31

  preprintOpen access

  &lt;p&gt;Figure S5: Individual ROC curves for Videssa Breast model training and validation. Curves shown correspond to those in Fig. 2.&lt;/p&gt;

  PublisherDOI

• Effects of involuntary and voluntary attention on critical spacing of visual crowding

  Journal of Vision · 2023-03-02 · 8 citations

  articleOpen accessSenior authorCorresponding

  Visual spatial attention can be allocated in two distinct ways: one that is voluntarily directed to behaviorally relevant locations in the world, and one that is involuntarily captured by salient external stimuli. Precueing spatial attention has been shown to improve perceptual performance on a number of visual tasks. However, the effects of spatial attention on visual crowding, defined as the reduction in the ability to identify target objects in clutter, are far less clear. In this study, we used an anticueing paradigm to separately measure the effects of involuntary and voluntary spatial attention on a crowding task. Each trial began with a brief peripheral cue that predicted that the crowded target would appear on the opposite side of the screen 80% of the time and on the same side of the screen 20% of the time. Subjects performed an orientation discrimination task on a target Gabor patch that was flanked by other similar Gabor patches with independent random orientations. For trials with a short stimulus onset asynchrony between cue and target, involuntary capture of attention led to faster response times and smaller critical spacing when the target appeared on the cue side. For trials with a long stimulus onset asynchrony, voluntary allocation of attention led to faster reaction times but no significant effect on critical spacing when the target appeared on the opposite side to the cue. We additionally found that the magnitudes of these cueing effects of involuntary and voluntary attention were not strongly correlated across subjects for either reaction time or critical spacing.

  PublisherOA PDFDOI

• Data from A Noninvasive Blood-based Combinatorial Proteomic Biomarker Assay to Detect Breast Cancer in Women over age 50 with BI-RADS 3, 4, or 5 Assessment

  2023-03-31

  preprintOpen access

  &lt;div&gt;AbstractPurpose:&lt;p&gt;With improvements in breast cancer imaging, there has been a corresponding increase in false-positives and avoidable biopsies. There is a need to better differentiate when a breast biopsy is warranted and determine appropriate follow-up. This study describes the design and clinical performance of a combinatorial proteomic biomarker assay (CPBA), Videssa Breast, in women over age 50 years.&lt;/p&gt;Experimental Design:&lt;p&gt;A BI-RADS 3, 4, or 5 assessment was required for clinical trial enrollment. Serum was collected prior to breast biopsy and subjects were followed for 6–12 months and clinically relevant outcomes were recorded. Samples were split into training (70%) and validation (30%) cohorts with an approximate 1:4 case:control ratio in both arms.&lt;/p&gt;Results:&lt;p&gt;A CPBA that combines biomarker data with patient clinical data was developed using a training cohort (469 women, cancer incidence: 18.5%), resulting in 94% sensitivity and 97% negative predictive value (NPV). Independent validation of the final algorithm in 194 subjects (breast cancer incidence: 19.6%) demonstrated a sensitivity of 95% and a NPV of 97%. When combined with previously published data for women under age 50, Videssa Breast achieves a comprehensive 93% sensitivity and 98% NPV in a population of women ages 25–75. Had Videssa Breast results been incorporated into the clinical workflow, approximately 45% of biopsies might have been avoided.&lt;/p&gt;Conclusions:&lt;p&gt;Videssa Breast combines serum biomarkers with clinical patient characteristics to provide clinicians with additional information for patients with indeterminate breast imaging results, potentially reducing false-positive breast biopsies.&lt;/p&gt;&lt;/div&gt;

  PublisherDOI

• Figure S1 from A Noninvasive Blood-based Combinatorial Proteomic Biomarker Assay to Detect Breast Cancer in Women over age 50 with BI-RADS 3, 4, or 5 Assessment

  2023-03-31

  preprintOpen access

  &lt;p&gt;Figure S1: Breakdown of imaging modalities used to enroll subjects in Provista-002. Some subjects underwent multiple imaging procedures prior to enrollment, these are noted in side boxes for screening mammogram and diagnostic mammogram.&lt;/p&gt;

  PublisherDOI

Recent grants

• fMRI of human LGN: Functional subdivisions and geniculocortical connectivity

  NIH · $404k · 2014–2017

• NIH Grant R21EY017926

  NIH · $422k · 2010

• Neural mechanisms of perceptual learning in the human brain

  NIH · $413k · 2010–2012

• Effects of attention and acetylcholine on cortical stimulus representations

  NIH · $1.8M · 2016–2020

• NIH Grant F32EY014520

  NIH · $150k · 2005

Frequent coauthors

• Guy Faulkner

  University of British Columbia

  50 shared

• David A. Alter

  50 shared

• Marc Mitchell

  Western University

  50 shared

• Paul Oh

  Cleveland Clinic

  50 shared

• Ravi R. Bajaj

  50 shared

• Aviroop Biswas

  Institute for Work & Health

  50 shared

• Rachel N. Denison

  Boston University

  22 shared

• Ariel Rokem

  University of Washington

  20 shared