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1.  Audition Influences Color Processing in the Sound-Induced Visual Flash Illusion 
Vision research  2013;93:10.1016/j.visres.2013.10.013.
Multisensory interactions can lead to illusory percepts, as exemplified by the sound-induced extra flash illusion (SIFI: Shams et al., 2000, 2002). In this illusion, an audio-visual stimulus sequence consisting of two pulsed sounds and a light flash presented within a 100 ms time window generates the visual percept of two flashes. Here, we used colored visual stimuli to investigate whether concurrent auditory stimuli can affect the perceived features of the illusory flash. Zero, one or two pulsed sounds were presented concurrently with either a red or green flash or with two flashes of different colors (red followed by green) in rapid sequence. By querying both the number and color of the participants visual percepts, we found that the double flash illusion is stimulus specific: i.e., two sounds paired with one red or one green flash generated the percept of two red or two green flashes, respectively. This implies that the illusory second flash is induced at a level of visual processing after perceived color has been encoded. In addition, we found that the presence of two sounds influenced the integration of color information from two successive flashes. In the absence of any sounds, a red and a green flash presented in rapid succession fused to form a single orange percept, but when accompanied by two sounds, this integrated orange percept was perceived to flash twice on a significant proportion of trials. In addition, the number of concurrent auditory stimuli modified the degree to which the successive flashes were integrated to an orange percept versus maintained as separate red-green percepts. Overall, these findings show that concurrent auditory input can affect both the temporal and featural properties of visual percepts.
PMCID: PMC3872962  PMID: 24161662
auditory; visual; multisensory; flash illusion; color fusion; integration
2.  Seemingly Insignificant, but Crucial Cytomorphological Leads in Diagnosis of Pilomatricoma of Parotid Region 
Pilomatricoma is a benign cutaneous appendegeal neoplasm which occurs as dermal nodule on head and neck region of children and young adults. Tumors pose a potential difficulty when diagnosed on fine-needle aspiration cytology. In this communication, we illustrate the cytomorphological features of pilomatricoma in a 38-year-female who presented with a nodule over the parotid region. Repeated aspirations of this nodule revealed low cellularity and cytology was hence inconclusive. The final diagnosis was made on histological examination and then retrospectively when those paucicellular cytological smears were analyzed again; showed features that could have driven the pathologist toward pilomatricoma. Familiarization and careful cytological examination under appropriate clinical conditions is warranted.
PMCID: PMC4212295  PMID: 25368475
Fine needle aspirate; paucicellular; pilomaticoma
3.  Comparable mechanisms of working memory interference by auditory and visual motion in youth and aging 
Neuropsychologia  2013;51(10):1896-1906.
Intrasensory interference during visual working memory (WM) maintenance by object stimuli (such as faces and scenes), has been shown to negatively impact WM performance, with greater detrimental impacts of interference observed in aging. Here we assessed age-related impacts by intrasensory WM interference from lower-level stimulus features such as visual and auditory motion stimuli. We consistently found that interference in the form of ignored distractions and secondary task i nterruptions presented during a WM maintenance period, degraded memory accuracy in both the visual and auditory domain. However, in contrast to prior studies assessing WM for visual object stimuli, feature-based interference effects were not observed to be significantly greater in older adults. Analyses of neural oscillations in the alpha frequency band further revealed preserved mechanisms of interference processing in terms of post-stimulus alpha suppression, which was observed maximally for secondary task interruptions in visual and auditory modalities in both younger and older adults. These results suggest that age-related sensitivity of WM to interference may be limited to complex object stimuli, at least at low WM loads.
PMCID: PMC3752408  PMID: 23791629
4.  A Cognitive Framework for Understanding and Improving Interference Resolution in the Brain 
Progress in brain research  2013;207:351-377.
All of us are familiar with the negative impact of interference on achieving our task goals. We are referring to interference by information, which either impinges on our senses from an external environmental source or is internally generated by our thoughts. Informed by more than a decade of research on the cognitive and neural processing of interference, we have developed a framework for understanding how interference impacts our neural systems and especially how it is regulated and suppressed during efficient on-task performance. Importantly, externally and internally generated interferences have distinct neural signatures, and further, distinct neural processing emerges depending on whether individuals must ignore and suppress the interference, as for distractions, or engage with them in a secondary task, as during multitasking. Here, we elaborate on this cognitive framework and how it changes throughout the human lifespan, focusing mostly on research evidence from younger adults and comparing these findings to data from older adults, children, and cognitively impaired populations. With insights gleaned from our growing understanding, we then describe three novel translational efforts in our lab directed at improving distinct aspects of interference resolution using cognitive training. Critically, these training approaches were specifically developed to target improved interference resolution based on neuroplasticity principles and have shown much success in randomized controlled first version evaluations in healthy aging. Our results show not only on-task training improvements but also robust generalization of benefit to other cognitive control abilities. This research showcases how an in-depth understanding of neural mechanisms can then inform the development of effective deficit-targeted interventions, which can in turn benefit both healthy and cognitively impaired populations.
PMCID: PMC4067257  PMID: 24309262
interference; distraction; multitasking; attention; cognitive control; cognitive training; neuroplasticity; aging
5.  Harnessing the neuroplastic potential of the human brain & the future of cognitive rehabilitation 
PMCID: PMC3990041  PMID: 24782745
cognitive training; neurotherapeutics; cognitive control; neuroplasticity; closed loop
6.  Photostimulable Near-Infrared Persistent Luminescent Nanoprobes for Ultrasensitive and Longitudinal Deep-Tissue Bio-Imaging 
Theranostics  2014;4(11):1112-1122.
In vivo fluorescence imaging suffers from suboptimal signal-to-noise ratio and shallow detection depth, which is caused by the strong tissue autofluorescence under constant external excitation and the scattering and absorption of short-wavelength light in tissues. Here we address these limitations by using a novel type of optical nanoprobes, photostimulable LiGa5O8:Cr3+ near-infrared (NIR) persistent luminescence nanoparticles, which, with very-long-lasting NIR persistent luminescence and unique photo-stimulated persistent luminescence (PSPL) capability, allow optical imaging to be performed in an excitation-free and hence, autofluorescence-free manner. LiGa5O8:Cr3+ nanoparticles pre-charged by ultraviolet light can be repeatedly (>20 times) stimulated in vivo, even in deep tissues, by short-illumination (~15 seconds) with a white light-emitting-diode flashlight, giving rise to multiple NIR PSPL that expands the tracking window from several hours to more than 10 days. Our studies reveal promising potential of these nanoprobes in cell tracking and tumor targeting, exhibiting exceptional sensitivity and penetration that far exceed those afforded by conventional fluorescence imaging.
PMCID: PMC4173761  PMID: 25285164
LiGa5O8:Cr3+ nanoparticles; near-infrared; persistent luminescence; photostimulated persistent luminescence; in vivo imaging.
7.  Preserved Discrimination Performance and Neural Processing during Crossmodal Attention in Aging 
PLoS ONE  2013;8(11):e81894.
In a recent study in younger adults (19-29 year olds) we showed evidence that distributed audiovisual attention resulted in improved discrimination performance for audiovisual stimuli compared to focused visual attention. Here, we extend our findings to healthy older adults (60-90 year olds), showing that performance benefits of distributed audiovisual attention in this population match those of younger adults. Specifically, improved performance was revealed in faster response times for semantically congruent audiovisual stimuli during distributed relative to focused visual attention, without any differences in accuracy. For semantically incongruent stimuli, discrimination accuracy was significantly improved during distributed relative to focused attention. Furthermore, event-related neural processing showed intact crossmodal integration in higher performing older adults similar to younger adults. Thus, there was insufficient evidence to support an age-related deficit in crossmodal attention.
PMCID: PMC3835740  PMID: 24278464
8.  Accessible online neuroplasticity-targeted training for children with ADHD 
Childhood Attention Deficit Hyperactivity Disorder (ADHD) is a growing mental health concern worldwide. Effective, accessible and low-cost therapeutics for the disorder are urgently needed. Here we introduce a novel internet-based cognitive training intervention: Online Neuroplasticity-based Training for the Remediation of ADHD in Children (ONTRAC). The intervention is deployed in the home setting; it is customized to the cognitive capacities of each child and progressively improves performance in the specific neuro-cognitive domains deficient in ADHD. A feasibility trial of ONTRAC is being conducted in a resource limited clinical setting in New Delhi, India and is an exemplar of hi-tech global psychiatry.
PMCID: PMC3828475  PMID: 24225015
Attention Deficit Hyperactivity Disorder; ADHD; Cognitive training; Neuroplasticity; Neurotherapeutic; Global mental health
9.  How to Assess Gaming-Induced Benefits on Attention and Working Memory 
Games for Health Journal  2012;1(3):192-198.
Our daily actions are driven by our goals in the moment, constantly forcing us to choose among various options. Attention and working memory are key enablers of that process. Attention allows for selective processing of goal-relevant information and rejecting task-irrelevant information. Working memory functions to maintain goal-relevant information in memory for brief periods of time for subsequent recall and/or manipulation. Efficient attention and working memory thus support the best extraction and retention of environmental information for optimal task performance. Recent studies have evidenced that attention and working memory abilities can be enhanced by cognitive training games as well as entertainment videogames. Here we review key cognitive paradigms that have been used to evaluate the impact of game-based training on various aspects of attention and working memory. Common use of such methodology within the scientific community will enable direct comparison of the efficacy of different games across age groups and clinical populations. The availability of common assessment tools will ultimately facilitate development of the most effective forms of game-based training for cognitive rehabilitation and education.
PMCID: PMC3833365  PMID: 24761314
10.  Attention distributed across sensory modalities enhances perceptual performance 
This study investigated the interaction between top-down attentional control and multisensory processing in humans. Using semantically congruent and incongruent audiovisual stimulus streams, we found target detection to be consistently improved in the setting of distributed audiovisual attention versus focused visual attention. This performance benefit was manifested as faster reaction times for congruent audiovisual stimuli, and as accuracy improvements for incongruent stimuli, resulting in a resolution of stimulus interference. Electrophysiological recordings revealed that these behavioral enhancements were associated with reduced neural processing of both auditory and visual components of the audiovisual stimuli under distributed vs. focused visual attention. These neural changes were observed at early processing latencies, within 100–300 ms post-stimulus onset, and localized to auditory, visual, and polysensory temporal cortices. These results highlight a novel neural mechanism for top-down driven performance benefits via enhanced efficacy of sensory neural processing during distributed audiovisual attention relative to focused visual attention.
PMCID: PMC3449148  PMID: 22933811
11.  Spatial Attention Boosts Short-Latency Neural Responses in Human Visual Cortex 
NeuroImage  2011;59(2):1968-1978.
In a previous study of visual-spatial attention, Martinez et al. (2007) replicated the well-known finding that stimuli at attended locations elicit enlarged early components in the averaged event-related potential (ERP), which were localized to extrastriate visual cortex. The mechanisms that underlie these attention-related ERP modulations in the latency range of 80-200 ms, however, remain unclear. The main question is whether attention produces increased ERP amplitudes in time-domain averages by augmenting stimulus-triggered neural activity, or alternatively, by increasing the phase-locking of ongoing EEG oscillations to the attended stimuli. We compared these alternative mechanisms using Morlet wavelet decompositions of event-related EEG changes. By analyzing single-trial spectral amplitudes in the theta (4-8 Hz) and alpha (8-12 Hz) bands, which were the dominant frequencies of the early ERP components, it was found that stimuli at attended locations elicited enhanced neural responses in the theta band in the P1 (88-120 ms) and N1 (148-184 ms) latency ranges that were additive with the ongoing EEG. In the alpha band there was evidence for both increased additive neural activity and increased phase-synchronization of the EEG following attended stimuli, but systematic correlations between pre- and post- stimulus alpha activity were more consistent with an additive mechanism. These findings provide the strongest evidence to date in humans that short-latency neural activity elicited by stimuli within the spotlight of spatial attention is boosted or amplified at early stages of processing in extrastriate visual cortex.
PMCID: PMC3230783  PMID: 21983181
ERPs; EEG synchrony; spatial attention; theta; alpha
12.  A comparative study of Shankhapushpyadi Ghana Vati and Sarpagandhadi Ghana Vati in the management of “Essential Hypertension” 
Ayu  2012;33(1):54-61.
Hypertension is a major public health problem of this era. Hypertension related morbidity and mortality rates have dramatically increased over the last 25 years. Stressful life style is one of the leading causes of Hypertension. The treatment of hypertension remains a primary goal in the effort to reduce morbidity and mortality from cardiovascular disease, stroke and kidney disease. In this study, 20 patients were randomly divided in two groups and treated along with restricted diet pattern for 8 weeks. Patients of Group A received poly-herbal compound formulation Shankhapushpyadi Ghana Vati (2gm/day). It was found that, relief in overall symptoms (63.93%) elevated blood pressure (8.91% in Systolic blood pressure and 8.44% in diastolic blood pressure). In group-B, with Sarpagandhadi Ghana Vati (2gm/day) the percent relief was better on elevated blood pressure (12.00% in Systolic blood pressure and 11.02% in diastolic blood pressure). When data is subjected in between both the groups, it is found that, both drugs are equally effective.
PMCID: PMC3456865  PMID: 23049185
Diastolic blood pressure; essential hypertension; Shankhapushpyadi Ghana Vati; Sarpagandhadi Ghana Vati; systolic blood pressure
13.  Early Cross-Modal Interactions in Auditory and Visual Cortex Underlie a Sound-Induced Visual Illusion 
When a single flash of light is presented interposed between two brief auditory stimuli separated by 60 –100 ms, subjects typically report perceiving two flashes (Shams et al., 2000, 2002). We investigated the timing and localization of the cortical processes that underlie this illusory flash effect in 34 subjects by means of 64-channel recordings of event-related potentials (ERPs). A difference ERP calculated to isolate neural activity associated with the illusory second flash revealed an early modulation of visual cortex activity at 30 – 60 ms after the second sound, which was larger in amplitude in subjects who saw the illusory flash more frequently. These subjects also showed this early modulation in response to other combinations of auditory and visual stimuli, thus pointing to consistent individual differences in the neural connectivity that underlies cross-modal integration. The overall pattern of cortical activity associated with the cross-modally induced illusory flash, however, differed markedly from that evoked by a real second flash. A trial-by-trial analysis showed that short-latency ERP activity localized to auditory cortex and polymodal cortex of the temporal lobe, concurrent with gamma bursts in visual cortex, were associated with perception of the double-flash illusion. These results provide evidence that perception of the illusory second flash is based on a very rapid dynamic interplay between auditory and visual cortical areas that is triggered by the second sound.
PMCID: PMC2905511  PMID: 17428990
ERPs; auditory cortex; visual cortex; illusory flash; cross-modal interaction; source analysis
14.  Endogenous Attention Selection during Binocular Rivalry at Early Stages of Visual Processing 
Vision research  2008;49(10):1073-1080.
Directing attention to one of two superimposing surfaces composed of dot fields rotating in opposing directions facilitates processing of brief translations of the attended surface (Valdes-Sosa et al., 1998). Here we used ERP recordings to investigate the mechanisms of endogenous attentional selection of such competing dot surfaces under conditions of dichoptic viewing (one surface to each eye) and monocular viewing (both surfaces to one eye). Under dichoptic conditions, which induced binocular rivalry, translations of the attended surface presented to one eye elicited enhanced visual P1 and N1 ERP components relative to translations of the unattended surface presented to the other eye. In comparison, during monocular viewing the attended surface translations elicited a significantly larger N1 component in the absence of any P1 modulation. These results indicate that processing of the attended surface is biased at an earlier level in extrastriate visual cortex under conditions of inter-ocular versus intra-ocular competition.
PMCID: PMC2758091  PMID: 18384833
attention; binocular rivalry; inter-ocular competition; monocular; ERPs; P1; N1
15.  Psychiatric morbidity among diabetic patients: A hospital-based study 
Industrial Psychiatry Journal  2010;19(1):47-49.
The relationship between glucose metabolism and psychiatric illness is under the focus of clinicians for centuries. Depending on the definition used, the prevalence of depression among diabetics ranges from 8.5% to 32.5%, while that for anxiety disorders it is up to 30%.
Aims and Objectives:
To assess the prevalence of psychiatric morbidity among diabetic patients using standardized rating scales for depression and anxiety.
Materials and Methods:
One hundred diagnosed patients of diabetes were assessed on the Hamilton rating scale for depression and the Hamilton rating scale for anxiety, who were attending the diabetic clinic. They were assessed on sociodemographic profile, duration of illness, type of treatment, and oral vs insulin, and then the data were analyzed on different domains.
About 84% of the patients had comorbid depression. Females showed a high percentage of depression and anxiety, and the severity level was also higher in the females. Genital symptoms were usually reported by the males, while somatic symptoms were more prevalent in the females.
PMCID: PMC3105558  PMID: 21694791
Anxiety; depression; diabetes mellitus; psychiatric morbidity
16.  Cortical Processes Underlying Sound-Induced Flash Fusion 
Brain research  2008;1242:102-115.
When two brief flashes presented in rapid succession (< 100 ms apart) are paired with a single auditory stimulus, subjects often report perceiving only a single flash (Andersen et al., 2004, Shams et al., 2005). We used event-related potentials (ERPs) to investigate the timing and localization of the cortical processes that underlie this sound induced flash fusion, which is complementary to the sound-induced extra flash illusion that we analyzed previously (Mishra et al., 2007). The difference ERP that represented the cross-modal interaction between the visual (two flashes) and auditory (one sound) constituents of the bimodal stimulus revealed a positive component elicited 160–190 ms after stimulus onset, which was markedly attenuated in subjects who did not perceive the second flash. This component, previously designated as PD180 (Mishra et al., 2007), was localized by dipole modeling to polysensory superior temporal cortex. PD180 was found to covary in amplitude across subjects with the visual evoked N1 component (148–184 ms), suggesting that inter-individual differences in perceiving the illusion are based at least in part on differences in visual processing. A trial-by-trial analysis found that the PD180 as well as a subsequent modulation in visual cortex at 228–248 ms was diminished on trials when the two flashes were perceived as one relative to trials when two flashes were correctly reported. These results suggest that the sound induced flash fusion is based on an interaction between polysensory and visual cortical areas.
PMCID: PMC2584169  PMID: 18585695
ERPs; visual illusion; flash fusion; multisensory; cross-modal interaction; polymodal cortex
17.  Selective Attention Through Phase Relationship of Excitatory and Inhibitory Input Synchrony in a Model Cortical Neuron 
Neurons in area V2 and V4 exhibit stimulus specific tuning to single stimuli, and respond at intermediate firing rates when presented with two differentially preferred stimuli (‘pair response’). Selective attention to one of the two stimuli causes the neuron’s firing rate to shift from the intermediate pair response towards the response to the attended stimulus as if it were presented alone. Attention to single stimuli reduces the response threshold of the neuron and increases spike synchronization at gamma frequencies. The intrinsic and network mechanisms underlying these phenomena were investigated in a multi-compartmental biophysical model of a reconstructed cat V4 neuron. Differential stimulus preference was generated through a greater ratio of excitatory to inhibitory synapses projecting from one of two input V2 populations. Feedforward inhibition and synaptic depression dynamics were critical to generating the intermediate pair response. Neuronal gain effects were simulated using gamma frequency range correlations in the feedforward excitatory and inhibitory inputs to the V4 neuron. For single preferred stimulus presentations, correlations within the inhibitory population out of phase with correlations within the excitatory input significantly reduced the response threshold of the V4 neuron. The pair response to simultaneously active preferred and non-preferred V2 populations could also undergo an increase or decrease in gain via the same mechanism, where correlations in feedforward inhibition are out of phase with gamma band correlations within the excitatory input corresponding to the attended stimulus. The results of this model predict that top-down attention may bias the V4 neuron’s response using an inhibitory correlation phase shift mechanism.
PMCID: PMC1815390  PMID: 17027225
selective attention; V4; gain modulation; gamma band synchrony; out of phase inhibition

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