22 results on '"Dinavahi, V."'
Search Results
2. Threat and reward imminence processing in the human brain
- Author
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Murty, Dinavahi V. P. S., primary, Song, Songtao, additional, Surampudi, Srinivas Govinda, additional, and Pessoa, Luiz, additional
- Published
- 2023
- Full Text
- View/download PDF
3. Threat and reward imminence processing in the human brain
- Author
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Dinavahi V. P. S. Murty, Songtao Song, Srinivas Govinda Surampudi, and Luiz Pessoa
- Subjects
General Neuroscience ,Article - Abstract
In the human brain, aversive and appetitive processing have been studied with controlled stimuli in rather static settings. In addition, the extent to which aversive- and appetitive-related processing engage distinct or overlapping circuits remains poorly understood. Here, we sought to investigate the dynamics of aversive and appetitive processing while male and female participants engaged in comparable trials involving threat-avoidance or reward-seeking. A central goal was to characterize the temporal evolution of responses during periods ofthreat or reward imminence. For example, in the aversive domain, we predicted that the bed nucleus of the stria terminalis (BST), but not the amygdala, would exhibit anticipatory responses given the role of the former in anxious apprehension. We also predicted that the periaqueductal gray (PAG) would exhibit threat-proximity responses based on its involvement in proximal-threat processes, and that the ventral striatum would exhibit threat-imminence responses given its role in threat escape in rodents. Overall, we uncovered imminence-related temporally increasing (“ramping”) responses in multiple brain regions, including the BST, PAG, and ventral striatum, subcortically, and dorsal anterior insula and anterior midcingulate, cortically. Whereas the ventral striatum generated anticipatory responses in the proximity of reward as expected, it also exhibited threat-related imminence responses. In fact, across multiple brain regions, we observed a main effect of arousal. In other words, we uncovered extensive temporally-evolving, imminence-related processing in both the aversive and appetitive domain, suggesting that distributed brain circuits are dynamically engaged during the processing of biologically relevant information irrespective of valence, findings further supported by network analysis.Significance StatementIn the human brain, aversive and appetitive processing have been studied with controlled stimuli in rather static settings. Here, we sought to investigate the dynamics of aversive/appetitive processing while participants engaged in trials involving threat-avoidance or reward-seeking. A central goal was to characterize the temporal evolution of responses during periods ofthreat or reward imminence. We uncovered imminence-related temporally increasing (“ramping”) responses in multiple brain regions, including the bed nucleus of the stria terminalis, periaqueductal gray, and ventral striatum, subcortically, and dorsal anterior insula and anterior midcingulate, cortically. Overall, we uncovered extensive temporally-evolving, imminence-related processing in both the aversive and appetitive domain, suggesting that distributed brain circuits are dynamically engaged during the processing of biologically relevant information irrespective of valence.
- Published
- 2023
4. Gamma oscillations weaken with age in healthy elderly in human EEG.
- Author
-
Dinavahi V. P. S. Murty, Keerthana Manikandan, Wupadrasta Santosh Kumar, Ranjini Garani Ramesh, Simran Purokayastha, Mahendra Javali, Naren Prahalada Rao, and Supratim Ray
- Published
- 2020
- Full Text
- View/download PDF
5. Threat and Reward Imminence Processing in the Human Brain.
- Author
-
Murty, Dinavahi V. P. S., Songtao Song, Govinda Surampudi, Srinivas, and Pessoa, Luiz
- Subjects
- *
REWARD (Psychology) , *SOCIAL networks , *EXPECTATION (Psychology) , *HUMAN beings , *INSULAR cortex - Abstract
In the human brain, aversive and appetitive processing have been studied with controlled stimuli in rather static settings. In addition, the extent to which aversive-related and appetitive-related processing engage distinct or overlapping circuits remains poorly understood. Here, we sought to investigate the dynamics of aversive and appetitive processing while male and female participants engaged in comparable trials involving threat avoidance or reward seeking. A central goal was to characterize the temporal evolution of responses during periods of threat or reward imminence. For example, in the aversive domain, we predicted that the bed nucleus of the stria terminalis (BST), but not the amygdala, would exhibit anticipatory responses given the role of the former in anxious apprehension. We also predicted that the periaqueductal gray (PAG) would exhibit threatproximity responses based on its involvement in proximal-threat processes, and that the ventral striatum would exhibit threat-imminence responses given its role in threat escape in rodents. Overall, we uncovered imminence-related temporally increasing ("ramping") responses in multiple brain regions, including the BST, PAG, and ventral striatum, subcortically, and dorsal anterior insula and anterior midcingulate, cortically. Whereas the ventral striatum generated anticipatory responses in the proximity of reward as expected, it also exhibited threat-related imminence responses. In fact, across multiple brain regions, we observed a main effect of arousal. In other words, we uncovered extensive temporally evolving, imminence-related processing in both the aversive and appetitive domain, suggesting that distributed brain circuits are dynamically engaged during the processing of biologically relevant information regardless of valence, findings further supported by network analysis. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
6. Stimulus-Induced Narrowband Gamma Oscillations are Test–Retest Reliable in Human EEG
- Author
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Wupadrasta Santosh Kumar, Keerthana Manikandan, Dinavahi V P S Murty, Ranjini Garani Ramesh, Simran Purokayastha, Mahendra Javali, Naren Prahalada Rao, and Supratim Ray
- Subjects
healthy aging ,AcademicSubjects/SCI01870 ,test–retest reliability ,General Earth and Planetary Sciences ,Original Article ,AcademicSubjects/MED00310 ,EEG ,intersubject variability ,AcademicSubjects/MED00385 ,gamma oscillations ,General Environmental Science - Abstract
Visual stimulus-induced gamma oscillations in electroencephalogram (EEG) recordings have been recently shown to be compromised in subjects with preclinical Alzheimer’s Disease (AD), suggesting that gamma could be an inexpensive biomarker for AD diagnosis provided its characteristics remain consistent across multiple recordings. Previous magnetoencephalography studies in young subjects have reported consistent gamma power over recordings separated by a few weeks to months. Here, we assessed the consistency of stimulus-induced slow (20–35 Hz) and fast gamma (36–66 Hz) oscillations in subjects (n = 40) (age: 50–88 years) in EEG recordings separated by a year, and tested the consistency in the magnitude of gamma power, its temporal evolution and spectral profile. Gamma had distinct spectral/temporal characteristics across subjects, which remained consistent across recordings (average intraclass correlation of ~0.7). Alpha (8–12 Hz) and steady-state-visually evoked-potentials were also reliable. We further tested how EEG features can be used to identify 2 recordings as belonging to the same versus different subjects and found high classifier performance (AUC of ~0.89), with temporal evolution of slow gamma and spectral profile being most informative. These results suggest that EEG gamma oscillations are reliable across sessions separated over long durations and can also be a potential tool for subject identification.
- Published
- 2022
7. Distributed and Multifaceted Effects of Threat and Safety
- Author
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Murty, Dinavahi V. P. S., primary, Song, Songtao, additional, Morrow, Kelly, additional, Kim, Jongwan, additional, Hu, Kesong, additional, and Pessoa, Luiz, additional
- Published
- 2022
- Full Text
- View/download PDF
8. Stimulus-Induced Narrowband Gamma Oscillations are Test–Retest Reliable in Human EEG
- Author
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Kumar, Wupadrasta Santosh, primary, Manikandan, Keerthana, additional, Murty, Dinavahi V P S, additional, Ramesh, Ranjini Garani, additional, Purokayastha, Simran, additional, Javali, Mahendra, additional, Rao, Naren Prahalada, additional, and Ray, Supratim, additional
- Published
- 2022
- Full Text
- View/download PDF
9. Stimulus-induced narrowband gamma oscillations are test-retest reliable in healthy elderly in human EEG
- Author
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Mahendra Javali, Ranjini Garani Ramesh, Simran Purokayastha, Supratim Ray, Dinavahi V. P. S. Murty, Keerthana Manikandan, Naren Prahalada Rao, and Wupadrasta Santosh Kumar
- Subjects
medicine.medical_specialty ,medicine.diagnostic_test ,Intraclass correlation ,business.industry ,Alpha (ethology) ,Healthy elderly ,Magnetoencephalography ,Audiology ,Stimulus (physiology) ,Electroencephalography ,Narrowband ,medicine ,Biomarker (medicine) ,business - Abstract
Visual stimulus-induced narrowband gamma oscillations in electroencephalogram (EEG) recordings have been recently shown to be compromised in subjects with Mild Cognitive Impairment or Alzheimer’s Disease (AD), suggesting that gamma could be an inexpensive and easily accessible biomarker for early diagnosis of AD. However, to use gamma as a biomarker, its characteristics should remain consistent across multiple recordings, even when separated over long intervals. Previous magnetoencephalography studies in young subjects have reported that gamma power remains consistent over recordings separated by a few weeks to months. Here, we assessed the consistency of slow (20-35 Hz) and fast gamma (36-66 Hz) oscillations induced by static full-field gratings in male (N=20) and female (N=20) elderly subjects (>49 years) in EEG recordings separated by more than a year, and tested the consistency in the magnitude of gamma power, its temporal evolution and spectral profile. Gamma oscillations had distinct spectral and temporal characteristics across subjects, which remained consistent across recordings (average intraclass correlation, ICC of ∼0.7). Alpha oscillations (8-12 Hz) and steady-state-visually-evoked-potentials (SSVEPs) were also found to be reliable. We further tested how EEG features can be used to identify two recordings as belonging to the same versus different subjects and found high classifier performance (area under ROC curve of ∼0.89), with the temporal evolution of slow gamma and spectral profile emerging as the most informative features. These results suggest that EEG gamma oscillations are reliable across recordings and can be used as a clinical biomarker as well as a potential tool for subject identification.Significance statementWe demonstrate the reliability of stimulus-induced gamma oscillations in elderly humans for the first time in EEG. Since gamma has recently been shown to be compromised in patients with Mild Cognitive Impairment or early Alzheimer’s Disease (AD), together these results mark the first steps towards an EEG based clinical biomarker for early diagnosis of AD. We observed high reliability in the power spectrum, gamma power and its temporal characteristics, within the test-retest period of one year. Alpha and steady-state-visually-evoked potential power were also found to be reliable. These spectral and temporal features could also be used to identify EEG recordings as belonging to the same versus different subjects with high performance, suggesting a potentially key role in subject identification also.
- Published
- 2021
10. Author response: Stimulus-induced gamma rhythms are weaker in human elderly with mild cognitive impairment and Alzheimer’s disease
- Author
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Bhargavi Nagendra, Keerthana Manikandan, Ranjini Garani Ramesh, M L Abhishek, Mahendra Javali, Aditi Balakrishnan, Simran Purokayastha, Dinavahi V. P. S. Murty, Wupadrasta Santosh Kumar, Supratim Ray, and Naren Prahalada Rao
- Subjects
Stimulus (psychology) ,Rhythm ,business.industry ,Medicine ,Disease ,business ,Cognitive impairment ,Neuroscience - Published
- 2021
11. Gamma oscillations weaken with age in healthy elderly in human EEG
- Author
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Supratim Ray, Mahendra Javali, Naren Prahalada Rao, Keerthana Manikandan, Wupadrasta Santosh Kumar, Ranjini Garani Ramesh, Simran Purokayastha, and Dinavahi V. P. S. Murty
- Subjects
Male ,Aging ,genetic structures ,Health Status ,Normal aging ,Electroencephalography ,Audiology ,Cohort Studies ,0302 clinical medicine ,Gamma Rhythm ,Longitudinal Studies ,EEG ,Cognitive decline ,Gamma oscillations ,Visual Cortex ,Aged, 80 and over ,0303 health sciences ,medicine.diagnostic_test ,05 social sciences ,Middle Aged ,Neurology ,Female ,Microsaccade ,Alzheimer’s disease ,Adult ,medicine.medical_specialty ,Cognitive Neuroscience ,Stimulus (physiology) ,050105 experimental psychology ,Article ,lcsh:RC321-571 ,03 medical and health sciences ,Young Adult ,Alpha oscillations ,Rhythm ,medicine ,Humans ,0501 psychology and cognitive sciences ,lcsh:Neurosciences. Biological psychiatry. Neuropsychiatry ,SSVEP ,030304 developmental biology ,Aged ,business.industry ,Healthy elderly ,medicine.disease ,Autism ,Evoked Potentials, Visual ,business ,030217 neurology & neurosurgery ,Photic Stimulation - Abstract
Gamma rhythms (∼20-70 Hz) have been reported to be abnormal in mental disorders such as autism and schizophrenia in humans, and Alzheimer’s disease (AD) models in rodents. However, the effect of normal aging on these oscillations is not known, especially for elderly subjects (>49 years) for which AD is most prevalent. In a first large-scale (236 subjects; 104 females) electroencephalogram (EEG) study on gamma oscillations on elderly subjects (aged 50-88 years), we presented full-screen Cartesian gratings that induced two distinct gamma oscillations (slow: 20-34 Hz and fast: 36-66 Hz). Power and centre frequency significantly decreased with age for both slow and fast gamma, but not alpha (8-12 Hz). Reduction was more salient for fast gamma than slow. These results were independent of microsaccades and pupillary reactivity to stimulus, as well as variations in power spectral density with age. Steady-state visual evoked potentials (SSVEPs) also reduced with age. These results are crucial first steps towards using gamma/SSVEPs as biomarkers of cognitive decline in elderly.Significance statementNo study in humans has examined visual narrow-band gamma oscillations with healthy aging in elderly subjects. In a first large-scale (236 subjects) EEG study on stimulus-induced narrow band gamma in cognitively normal elderly (>49 years) humans, we show that both power and centre frequency of slow and fast gamma (20-34 Hz and 36-66 Hz respectively) decrease with age, but alpha power does not. Steady-state visual evoked potential (SSVEPs) in gamma range also decrease with age. Any EEG-based biomarker is accessible and affordable to patients of a wide socio-economic spectrum. Our results are important steps for developing such screening/diagnostic tests for aging-related diseases, like Alzheimer’s disease.
- Published
- 2020
12. Stimulus-induced Gamma rhythms are weaker in human elderly with Mild Cognitive Impairment and Alzheimer’s Disease
- Author
-
Supratim Ray, Ranjini Garani Ramesh, M L Abhishek, Bhargavi Nagendra, Naren Prahalada Rao, Keerthana Manikandan, Simran Purokayastha, Dinavahi V. P. S. Murty, Aditi Balakrishnan, and Mahendra Javali
- Subjects
medicine.medical_specialty ,medicine.diagnostic_test ,business.industry ,Clinical Dementia Rating ,Eye movement ,Disease ,Audiology ,Stimulus (physiology) ,Electroencephalography ,Age and gender ,Rhythm ,medicine ,business ,Cognitive impairment - Abstract
Alzheimer’s Disease (AD) in elderly adds substantially to socio-economic burden necessitating early diagnosis. While recent studies in rodent models of AD have suggested diagnostic and therapeutic value for gamma rhythms in brain, the same has not been rigorously tested in humans. We recruited a large population (N=247; 106 females) of elderly (>49 years) individuals from the community, who viewed large gratings that induced strong gamma oscillations in their electroencephalogram (EEG). These individuals were classified as healthy (N=227), mild-cognitively-impaired (MCI; 14) or AD (6) based on clinical history and Clinical Dementia Rating scores. Surprisingly, stimulus-induced gamma rhythms, but not alpha or steady-state-visually-evoked-responses, were significantly lower in both MCI and AD patients compared to their age and gender matched controls. This reduction was not due to differences in eye movements or baseline power. Our results suggest that gamma could be used as potential diagnostic tool for MCI/AD in humans.One Sentence SummaryA large double-blinded EEG study suggests that narrow-band visual gamma rhythms are weaker in MCI/AD patients compared to cognitively healthy controls.
- Published
- 2020
- Full Text
- View/download PDF
13. Large Visual Stimuli Induce Two Distinct Gamma Oscillations in Primate Visual Cortex
- Author
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Supratim Ray, Dinavahi V. P. S. Murty, Poojya Ravishankar, and Vinay Shirhatti
- Subjects
Male ,0301 basic medicine ,Visual perception ,LFP ,Fixation, Ocular ,Stimulus (physiology) ,Electroencephalography ,rhythm ,Young Adult ,03 medical and health sciences ,0302 clinical medicine ,Rhythm ,Systems/Circuits ,biology.animal ,Gamma Rhythm ,medicine ,Animals ,Humans ,Primate ,EEG ,Research Articles ,Visual Cortex ,biology ,medicine.diagnostic_test ,General Neuroscience ,Cognition ,oscillation ,Macaca radiata ,030104 developmental biology ,Visual cortex ,medicine.anatomical_structure ,area V1 ,Evoked Potentials, Visual ,gamma ,Female ,Neuroscience ,Algorithms ,Photic Stimulation ,030217 neurology & neurosurgery - Abstract
Recent studies have shown the existence of two gamma rhythms in the hippocampus subserving different functions but, to date, primate studies in primary visual cortex have reported a single gamma rhythm. Here, we show that large visual stimuli induce a slow gamma (25–45 Hz) in area V1 of two awake adult female bonnet monkeys and in the EEG of 15 human subjects (7 males and 8 females), in addition to the traditionally known fast gamma (45–70 Hz). The two rhythms had different tuning characteristics for stimulus orientation, contrast, drift speed, and size. Further, fast gamma had short latency, strongly entrained spikes and was coherent over short distances, reflecting short-range processing, whereas slow gamma appeared to reflect long-range processing. Together, two gamma rhythms can potentially provide better coding or communication mechanisms and a more comprehensive biomarker for diagnosis of mental disorders.SIGNIFICANCE STATEMENTGamma rhythm has been associated with high-level cognitive functions such as attention and feature binding and has been reported to be abnormal in brain disorders such as autism and schizophrenia. Unlike previous studies that have shown a single gamma rhythm in the primate visual cortex, we found that large visual gratings induce two distinct gamma oscillations in both monkey LFP and human EEG. These rhythms, termed slow (25–45 Hz) and fast (45–70 Hz), exhibited distinct tuning preferences, latencies, and coherence profiles, potentially reflecting processing at two different ranges. Multiple gamma oscillations in visual cortex may provide a richer representation of external visual stimuli and could be used for developing brain–machine interfacing applications and screening tests for neuropsychiatric disorders.
- Published
- 2018
14. Stimulus-induced Gamma rhythms are weaker in human elderly with Mild Cognitive Impairment and Alzheimer’s Disease
- Author
-
Murty, Dinavahi V. P. S., primary, Manikandan, Keerthana, additional, Ramesh, Ranjini Garani, additional, Purokayastha, Simran, additional, Nagendra, Bhargavi, additional, Abhishek, M. L., additional, Balakrishnan, Aditi, additional, Javali, Mahendra, additional, Rao, Naren Prahalada, additional, and Ray, Supratim, additional
- Published
- 2020
- Full Text
- View/download PDF
15. Stimulus-induced gamma rhythms are weaker in human elderly with mild cognitive impairment and Alzheimer's disease.
- Author
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Murty, Dinavahi V. P. S., Manikandan, Keerthana, Santosh Kumar, Wupadrasta, Garani Ramesh, Ranjini, Purokayastha, Simran, Nagendra, Bhargavi, M. L., Abhishek, Balakrishnan, Aditi, Javali, Mahendra, Prahalada Rao, Naren, and Ray, Supratim
- Subjects
- *
MILD cognitive impairment , *ALZHEIMER'S disease , *OLDER people , *BRAIN waves , *ALPHA rhythm , *EYE movements , *VECTION - Abstract
Alzheimer's disease (AD) in elderly adds substantially to socioeconomic burden necessitating early diagnosis. While recent studies in rodent models of AD have suggested diagnostic and therapeutic value for gamma rhythms in brain, the same has not been rigorously tested in humans. In this case-control study, we recruited a large population (N = 244; 106 females) of elderly (>49 years) subjects from the community, who viewed large gratings that induced strong gamma oscillations in their electroencephalogram (EEG). These subjects were classified as healthy (N = 227), mild cognitively impaired (MCI; N = 12), or AD (N = 5) based on clinical history and Clinical Dementia Rating scores. Surprisingly, stimulus-induced gamma rhythms, but not alpha or steady-state visually evoked responses, were significantly lower in MCI/AD subjects compared to their age- and gender-matched controls. This reduction was not due to differences in eye movements or baseline power. Our results suggest that gamma could be used as a potential screening tool for MCI/AD in humans. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
16. Gamma oscillations weaken with age in healthy elderly in human EEG
- Author
-
Murty, Dinavahi V. P. S., primary, Manikandan, Keerthana, additional, Kumar, Wupadrasta Santosh, additional, Ramesh, Ranjini Garani, additional, Purokayastha, Simran, additional, Javali, Mahendra, additional, Rao, Naren Prahalada, additional, and Ray, Supratim, additional
- Published
- 2019
- Full Text
- View/download PDF
17. A Benchmark System for Hardware-in-the-Loop Testing of Distributed Energy Resources
- Author
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Kotsampopoulos, Panos, primary, Lagos, Dimitris, additional, Hatziargyriou, Nikos, additional, Faruque, M. Omar, additional, Lauss, Georg, additional, Nzimako, Onyi, additional, Forsyth, Paul, additional, Steurer, Michael, additional, Ponci, F., additional, Monti, A., additional, Dinavahi, V., additional, and Strunz, Kai, additional
- Published
- 2018
- Full Text
- View/download PDF
18. Large Visual Stimuli Induce Two Distinct Gamma Oscillations in Primate Visual Cortex.
- Author
-
Murty, Dinavahi V. P. S., Shirhatti, Vinay, Ravishankar, Poojya, and Ray, Supratim
- Subjects
- *
VISUAL perception , *VISUAL cortex , *OSCILLATIONS , *PRIMATES as laboratory animals , *BIOLOGICAL tags - Abstract
Recent studies have shown the existence of two gamma rhythms in the hippocampus subserving different functions but, to date, primate studies in primary visual cortex have reported a single gamma rhythm. Here, we show that large visual stimuli induce a slow gamma (25- 45 Hz) in area V1 of two awake adult female bonnet monkeys and in the EEC of 15 human subjects (7 males and 8 females), in addition to the traditionally known fast gamma (45-70 Hz). The two rhythms had different tuning characteristics for stimulus orientation, contrast, drift speed, and size. Further, fast gamma had short latency, strongly entrained spikes and was coherent over short distances, reflecting short-range processing, whereas slow gamma appeared to reflect long-range processing. Together, two gamma rhythms can potentially provide better coding or communication mechanisms and a more comprehensive biomarker for diagnosis of mental disorders. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
19. A study on prevalence of tobacco consumption among school students studying from fifth to eighth standards and assessment of their risk behavior by studying their knowledge, attitude, and practices regarding tobacco consumption in Ahmedabad city, Gujarat, India
- Author
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Darshana R Hirani and Dinavahi V Balaramanamma
- Subjects
Consumption (economics) ,Passive smoking ,business.industry ,education ,Risk behavior ,medicine.disease_cause ,Officer ,Multistage sampling ,Environmental health ,Medicine ,Health education ,Risk factor ,Peer pressure ,business - Abstract
Background: Global Youth Tobacco Survey (GYTS) represented that the prevalence of tobacco by adolescents was around 19% in Gujarat. It shows the alarming statistics of tobacco use by adolescents. Objective: (1) To study the sociodemographic profile of students (from fifth to eighth standards), (2) to assess the knowledge, attitude, and practices regarding tobacco consumption among them, (3) to study the prevalence of tobacco consumption among them, (4) to study the association between tobacco consumption and other variables and (5)to impart them health education regarding the hazards of tobacco. Materials and Methods: A cross-sectional study was done by multistage sampling method from February 2013 to December 2014 after obtaining ethical consideration from the district education officer (DEO) and principals of the schools. According to the 14.6% prevalence of GYTS, the sample size was calculated, and 2,842 students from fifth to eighth standards from 18 schools of six zones of Ahmedabad were enrolled and studied using a predesigned, pretested, structured questionnaire. Health education session was organized by using audiovisual aids regarding the harmful effects of tobacco. The study was conducted, and data were analyzed by using appropriate statistical software. Result: Of the 2,842 students, 69.1% of them were aware that tobacco is hazardous to health and 26.3% students knew that passive smoking is harmful. One-fourth of them were aware about antitobacco messages. Regarding attitude, more than one-third of the students believed that tobacco consumption makes one smart and helps in making a number of friends. If tobacco was offered free of cost, 14.5% were ready to use. Regarding their practices, the prevalence of tobacco use was 12.2%. The mean age of initiation was 11.66 ± 1.89 years. The mean number of pouches consumed per week was 1.8 ± 1.65. About 35% students attempted to quit tobacco in the last 1 year and 47% were unable to quit. Conclusion: Tobacco use is an important risk behavior among adolescents. Peer pressure was the most predominant risk factor for tobacco consumption.
- Published
- 2016
20. Threat and reward imminence processing in the human brain.
- Author
-
Murty DVPS, Song S, Surampudi SG, and Pessoa L
- Abstract
In the human brain, aversive and appetitive processing have been studied with controlled stimuli in rather static settings. In addition, the extent to which aversive- and appetitive-related processing engage distinct or overlapping circuits remains poorly understood. Here, we sought to investigate the dynamics of aversive and appetitive processing while male and female participants engaged in comparable trials involving threat-avoidance or reward-seeking. A central goal was to characterize the temporal evolution of responses during periods of threat or reward imminence . For example, in the aversive domain, we predicted that the bed nucleus of the stria terminalis (BST), but not the amygdala, would exhibit anticipatory responses given the role of the former in anxious apprehension. We also predicted that the periaqueductal gray (PAG) would exhibit threat-proximity responses based on its involvement in proximal-threat processes, and that the ventral striatum would exhibit threat-imminence responses given its role in threat escape in rodents. Overall, we uncovered imminence-related temporally increasing ("ramping") responses in multiple brain regions, including the BST, PAG, and ventral striatum, subcortically, and dorsal anterior insula and anterior midcingulate, cortically. Whereas the ventral striatum generated anticipatory responses in the proximity of reward as expected, it also exhibited threat-related imminence responses. In fact, across multiple brain regions, we observed a main effect of arousal. In other words, we uncovered extensive temporally-evolving, imminence-related processing in both the aversive and appetitive domain, suggesting that distributed brain circuits are dynamically engaged during the processing of biologically relevant information irrespective of valence, findings further supported by network analysis., Significance Statement: In the human brain, aversive and appetitive processing have been studied with controlled stimuli in rather static settings. Here, we sought to investigate the dynamics of aversive/appetitive processing while participants engaged in trials involving threat-avoidance or reward-seeking. A central goal was to characterize the temporal evolution of responses during periods of threat or reward imminence . We uncovered imminence-related temporally increasing ("ramping") responses in multiple brain regions, including the bed nucleus of the stria terminalis, periaqueductal gray, and ventral striatum, subcortically, and dorsal anterior insula and anterior midcingulate, cortically. Overall, we uncovered extensive temporally-evolving, imminence-related processing in both the aversive and appetitive domain, suggesting that distributed brain circuits are dynamically engaged during the processing of biologically relevant information irrespective of valence.
- Published
- 2023
- Full Text
- View/download PDF
21. Stimulus-induced Robust Narrow-band Gamma Oscillations in Human EEG Using Cartesian Gratings.
- Author
-
Murty DVPS and Ray S
- Abstract
Stimulus-induced narrow-band gamma oscillations (20-70 Hz) are induced in the visual areas of the brain when particular visual stimuli, such as bars, gratings, or full-screen hue, are shown to the subject. Such oscillations are modulated by higher cognitive functions, like attention, and working memory, and have been shown to be abnormal in certain neuropsychiatric disorders, such as schizophrenia, autism, and Alzheimer's disease. However, although electroencephalogram (EEG) remains one of the most non-invasive, inexpensive, and accessible methods to record brain signals, some studies have failed to observe discernable gamma oscillations in human EEG. In this manuscript, we have described in detail a protocol to elicit robust gamma oscillations in human EEG. We believe that our protocol could help in developing non-invasive gamma-based biomarkers in human EEG, for the early detection of neuropsychiatric disorders., Competing Interests: Competing interestsThe authors declare no competing financial interests., (Copyright © The Authors; exclusive licensee Bio-protocol LLC.)
- Published
- 2022
- Full Text
- View/download PDF
22. Gamma oscillations weaken with age in healthy elderly in human EEG.
- Author
-
Murty DVPS, Manikandan K, Kumar WS, Ramesh RG, Purokayastha S, Javali M, Rao NP, and Ray S
- Subjects
- Adult, Aged, Aged, 80 and over, Cohort Studies, Female, Humans, Longitudinal Studies, Male, Middle Aged, Photic Stimulation methods, Young Adult, Aging physiology, Electroencephalography trends, Evoked Potentials, Visual physiology, Gamma Rhythm physiology, Health Status, Visual Cortex physiology
- Abstract
Gamma rhythms (~20-70 Hz) are abnormal in mental disorders such as autism and schizophrenia in humans, and Alzheimer's disease (AD) models in rodents. However, the effect of normal aging on these oscillations is unknown, especially for elderly subjects in whom AD is most prevalent. In a first large-scale (236 subjects; 104 females) electroencephalogram (EEG) study on gamma oscillations in elderly subjects (aged 50-88 years), we presented full-screen visual Cartesian gratings that induced two distinct gamma oscillations (slow: 20-34 Hz and fast: 36-66 Hz). Power decreased with age for gamma, but not alpha (8-12 Hz). Reduction was more salient for fast gamma than slow. Center frequency also decreased with age for both gamma rhythms. The results were independent of microsaccades, pupillary reactivity to stimulus, and variations in power spectral density with age. Steady-state visual evoked potentials (SSVEPs) at 32 Hz also reduced with age. These results are crucial for developing gamma/SSVEP-based biomarkers of cognitive decline in elderly., Competing Interests: Declaration of competing interest The authors declare no competing financial interests., (Copyright © 2020 The Author(s). Published by Elsevier Inc. All rights reserved.)
- Published
- 2020
- Full Text
- View/download PDF
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