Lower trait frontal theta activity in mindfulness meditators

Acute and long-term effects of mindfulness meditation on theta-band activity are not clear. The aim of this study was to investigate frontal theta differences between long- and short-term mindfulness practitioners before, during, and after mindfulness meditation. Twenty participants were recruited, of which 10 were experienced Buddhist meditators. Despite an acute increase in the theta activity during meditation in both the groups, the meditators showed lower trait frontal theta activity. Therefore, we suggested that this finding is a neural correlate of the expert practitioners’ ability to limit the processing of unnecessary information (e.g., discursive thought) and increase the awareness of the essential content of the present experience. In conclusion, acute changes in the theta band throughout meditation did not appear to be a specific correlate of mindfulness but were rather related to the concentration properties of the meditation. Notwithstanding, lower frontal theta activity appeared to be a trait of mindfulness practices.

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Sustained BOLD and theta activity in auditory cortex are related to slow stimulus fluctuations rather than to pitch

Journal of Neurophysiology ◽

10.1152/jn.01105.2011 ◽

2012 ◽

Vol 107 (12) ◽

pp. 3458-3467 ◽

Cited By ~ 11

Author(s):

Iris Steinmann ◽

Alexander Gutschalk

Keyword(s):

Auditory Cortex ◽

Primary Auditory Cortex ◽

Specific Area ◽

Theta Activity ◽

Theta Band ◽

Related Activity ◽

Specific Stimulus ◽

Time Frequency ◽

Constant Pitch ◽

Band Activity

Human functional MRI (fMRI) and magnetoencephalography (MEG) studies indicate a pitch-specific area in lateral Heschl's gyrus. Single-cell recordings in monkey suggest that sustained-firing, pitch-specific neurons are located lateral to primary auditory cortex. We reevaluated whether pitch strength contrasts reveal sustained pitch-specific responses in human auditory cortex. Sustained BOLD activity in auditory cortex was found for iterated rippled noise (vs. noise or silence) but not for regular click trains (vs. jittered click trains or silence). In contrast, iterated rippled noise and click trains produced similar pitch responses in MEG. Subsequently performed time-frequency analysis of the MEG data suggested that the dissociation of cortical BOLD activity between iterated rippled noise and click trains is related to theta band activity. It appears that both sustained BOLD and theta activity are associated with slow non-pitch-specific stimulus fluctuations. BOLD activity in the inferior colliculus was sustained for both stimulus types and varied neither with pitch strength nor with the presence of slow stimulus fluctuations. These results suggest that BOLD activity in auditory cortex is much more sensitive to slow stimulus fluctuations than to constant pitch, compromising the accessibility of the latter. In contrast, pitch-related activity in MEG can easily be separated from theta band activity related to slow stimulus fluctuations.

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Glucocorticoid Inhibition of Mineralocorticoid Action in the Rat

Clinical Science ◽

10.1042/cs0670329 ◽

1984 ◽

Vol 67 (3) ◽

pp. 329-335 ◽

Cited By ~ 22

Author(s):

C. J. Kenyon ◽

N. A. Saccoccio ◽

D. J. Morris

Keyword(s):

Blood Pressure ◽

Plasma Renin Activity ◽

Plasma Renin ◽

Renin Activity ◽

Plasma Sodium ◽

Long Term Effects ◽

Physiological Dose ◽

Acute Changes ◽

Adrenalectomized Rats

1. The mineralocorticoid activity of corticosterone based on acute changes in urinary Na+/K+ ratios in adrenalectomized rats was 1000 times less than that of aldosterone. However, corticosterone had only kaliuretic actions whereas aldosterone had both antinatriuretic and kaliuretic properties. Corticosterone inhibited the antinatriuretic actions of aldosterone. 2. Adrenalectomized rats infused continuously with a physiological dose of corticosterone (1 mg/day) were 5 times less sensitive to the antinatriuretic and 25 times less sensitive to the kaliuretic actions of aldosterone when administered acutely than were control adrenalectomized rats. 3. The long term effects of infusions of physiological doses of aldosterone and corticosterone were assessed in adrenalectomized rats maintained in metabolic cages. Aldosterone lowered plasma renin activity and reduced fluid (0.3% NaCl) intake; these effects were diminished when aldosterone and corticosterone were infused simultaneously. Plasma renin activity and fluid intake were correlated in long term infusion experiments. Both hormones had hypokalaemic effects but these were not additive. Corticosterone, but not aldosterone, increased systolic blood pressure and plasma sodium levels. 4. We conclude that glucocorticoid effects on water and electrolyte metabolism are different from those of mineralocorticoids, that glucocorticoids may antagonize mineralocorticoid effects and that interactions between mineralocorticoids and glucocorticoids may be important in long term blood pressure regulation.

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Norepinephrine, olfactory bulb and memory stability

10.1101/2020.06.17.153502 ◽

2020 ◽

Author(s):

Christiane Linster ◽

Maellie Midroit ◽

Jeremy Forest ◽

Yohann Thenaisie ◽

Christina Cho ◽

...

Keyword(s):

Olfactory Bulb ◽

Network Effect ◽

Long Term Effects ◽

Concept Model ◽

Long Time ◽

Learning Flexibility ◽

The Stability ◽

Acute Changes ◽

Pharmacological Manipulations

AbstractMemory stability is essential for animal survival when environment and behavioral state change over short or long time spans. The stability of a memory can be expressed by its duration, its perseverance when conditions change as well as its specificity to the learned stimulus. Using optogenetic and pharmacological manipulations, we show that stability of an odor-reward association can be modulated by noradrenergic inputs to the first olfactory network, the olfactory bulb. We show that while manipulations of noradrenaline during an odor-reward acquisition have no acute effects, they impact learning flexibility as well as the duration and the specificity of the memory. We use a computational approach to propose a proof of concept model showing that a single, simple network effect of noradrenaline on olfactory bulb dynamics can underlie these seemingly different behavioral effects. Our results show how acute changes in network dynamics can have long term effects that extend beyond the network that was manipulated.

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Three-Year Follow-up and Clinical Implications of a Mindfulness Meditation-Based Stress Reduction Intervention in the Treatment of Anxiety Disorders

International Journal of Yoga Therapy ◽

10.17761/ijyt.8.1.f5654n6515513127 ◽

1998 ◽

Vol 8 (1) ◽

pp. 45-53 ◽

Cited By ~ 2

Author(s):

John Miller ◽

Ken Fletcher ◽

Jon Kabat-Zinn

Keyword(s):

Anxiety Disorders ◽

Stress Reduction ◽

Repeated Measures ◽

Mindfulness Meditation ◽

Original Study ◽

Panic Attacks ◽

Medical Patients ◽

Long Term Effects

A previous study of 22 medical patients with DSM-III-R-defined anxiety disorders showed clinically and statistically significant improvements in subjective and objective symptoms of anxiety and panic following an 8-week outpatient physician-referred group stress reduction intervention based on mindfulness meditation. Twenty subjects demonstrated significant reductions in Hamilton and Beck Anxiety and Depression scores post-intervention and at 3-month follow-up. In this study, 3-year follow-up data were obtained and analyzed on 18 of the original 22 subjects to probe long-term effects. Repeated measures analysis showed maintenance of the gains obtained in the original study on the Hamilton {F(2,32)= 13.22; p < 0.001} and Beck {F(2,32) = 9.83; p<0.001} anxiety scales as well as on their respective depression scalgs, on the Hamilton panic score, in the number and severity of panic attacks, and on the Mobility Index—Accompanied and the Fear Survey. A 3-year follow-up comparison of this cohort with a larger group of subjects from the intervention who had met criteria for scredning for the original study suggests generalizability of the results obtained with the smaller, more intensively studied cohort. Ongoing compliance with the meditation practice was also demonstrated in the majority of subjects at 3 years. We conclude that an intensive but time-limited group stress reduction intervention based on mindfulness meditation can have long-term beneficial effects in the treatment of people diagnosed with anxiety disorders.

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Implicit learning and exploitation of regularities involve hippocampal and prefrontal theta activity

10.1101/611129 ◽

2019 ◽

Author(s):

Eelke Spaak ◽

Floris P. de Lange

Keyword(s):

Visual Search ◽

Implicit Learning ◽

Computational Modelling ◽

Theta Activity ◽

Contextual Cueing ◽

Spatial Context ◽

Theta Band ◽

Initial Learning ◽

Statistical Regularities ◽

Band Activity

AbstractObservers rapidly and seemingly automatically learn to predict where to expect relevant items when those items are repeatedly presented in the same spatial context. This form of statistical learning in visual search has been studied extensively using a paradigm known as contextual cueing. The neural mechanisms underlying the learning and exploiting of such regularities remain unclear. We sought to elucidate these by examining behaviour and recording neural activity using magneto-encephalography (MEG) while observers were implicitly acquiring and exploiting statistical regularities. Computational modelling of behavioural data suggested that after repeated exposures to a spatial context, participants’ behaviour was marked by an abrupt switch to an exploitation strategy of the learnt regularities. MEG recordings showed that the initial learning phase was associated with larger hippocampal theta band activity for repeated scenes, while the subsequent exploitation phase showed larger prefrontal theta band activity for these repeated scenes. Strikingly, the behavioural benefit of repeated exposures to certain scenes was inversely related to explicit awareness of such repeats, demonstrating the implicit nature of the expectations acquired. This elucidates how theta activity in the hippocampus and prefrontal cortex underpins the implicit learning and exploitation of spatial statistical regularities to optimize visual search behaviour.

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Unconscious learning and automatic inhibition are accompanied by frontal theta and sensorimotor interactions

10.1101/777961 ◽

2019 ◽

Author(s):

Silvia L. Isabella ◽

J. Allan Cheyne ◽

Douglas Cheyne

Keyword(s):

Response Inhibition ◽

Cognitive Activity ◽

Reaction Times ◽

Theta Activity ◽

Pattern Learning ◽

Stimulus Probability ◽

Theta Band ◽

Response Preparation ◽

Frontal Activity ◽

Band Activity

AbstractCognitive control of behavior is often accompanied by theta-band activity in the frontal cortex, and is crucial for overriding habits and producing desired actions. However, the functional role of theta activity in controlled behavior remains to be determined. Here, we used a behavioral task (Isabella et al., 2019) that covertly manipulated the ability to inhibit (and switch) motor responses using a repeating pattern of stimuli that reduced reaction times (RT) to probable over unexpected stimuli, without participants’ awareness of the pattern. We combined this task with concurrent measures of brain activity and pupil diameter (as a measure of cognitive activity) of 16 healthy adults during response preparation and inhibition during changes in stimulus probability. Observed RT provided evidence of pattern learning and pupillometry revealed parametric changes in cognitive activity with stimulus probability. Critically, reliable pupillary effects (Hedge’s g = 1.38) in the absence of RT differences (g = 0.10) indicated that cognitive activity increased without overt changes in behavior (RT). Such increased cognitive activity was accompanied by parametric increases in frontal theta and sensorimotor gamma. In addition, correlation between pre-stimulus beta and pre-response gamma in the motor cortex and post-stimulus frontal theta activity suggest bidirectional interactions between motor and frontal areas. These interactions likely underlie recruitment of preparatory and inhibitory neural activity during rapid motor control. Furthermore, pupillary and frontal theta effects during learned switches demonstrate that increases in inhibitory control of behavior can occur automatically, without conscious awareness.Significance StatementGoal-directed control is crucial for overriding habits and producing desired actions, which can fail during errors and accidents, and may be impaired in addiction, attention-deficit disorders, or dementia. This type of control, including response inhibition, is typically accompanied by frontal theta-band activity. We examined the relationship between frontal theta and response inhibition during unconscious pattern learning. First, we found that frontal activity was sensitive to changes in control and correlated with reaction times. Second, insufficient motor preparation predicted greater frontal activity, reflecting a greater need for control, which in turn predicted greater response-related motor activity. These results link the frontal and motor cortices, providing possible mechanisms for controlled behavior while demonstrating that goal-directed control can proceed automatically and unconsciously.

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Ovarian Dysfunction in Fetally Irradiated Beagles

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100080717 ◽

1977 ◽

Vol 35 ◽

pp. 658-659

Author(s):

T. M. Seed ◽

M. H. Sanderson ◽

D. L. Gutzeit ◽

T. E. Fritz ◽

D. V. Tolle ◽

...

Keyword(s):

Gamma Rays ◽

Low Dose ◽

Long Term Effects ◽

Ovarian Dysfunction ◽

Dose Rates ◽

Highly Sensitive ◽

Microscopic Evaluation ◽

Ovarian Pathology ◽

Normal Offspring

The developing mammalian fetus is thought to be highly sensitive to ionizing radiation. However, dose, dose-rate relationships are not well established, especially the long term effects of protracted, low-dose exposure. A previous report (1) has indicated that bred beagle bitches exposed to daily doses of 5 to 35 R 60Co gamma rays throughout gestation can produce viable, seemingly normal offspring. Puppies irradiated in utero are distinguishable from controls only by their smaller size, dental abnormalities, and, in adulthood, by their inability to bear young.We report here our preliminary microscopic evaluation of ovarian pathology in young pups continuously irradiated throughout gestation at daily (22 h/day) dose rates of either 0.4, 1.0, 2.5, or 5.0 R/day of gamma rays from an attenuated 60Co source. Pups from non-irradiated bitches served as controls. Experimental animals were evaluated clinically and hematologically (control + 5.0 R/day pups) at regular intervals.

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Ultrastructural investigations of MDL 19,660-induced effects on the canine platelet and megakaryocyte

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100159412 ◽

1990 ◽

Vol 48 (3) ◽

pp. 374-375

Author(s):

D.E. Loudy ◽

J. Sprinkle-Cavallo ◽

J.T. Yarrington ◽

F.Y. Thompson ◽

J.P. Gibson

Keyword(s):

Antidepressant Drug ◽

Beagle Dogs ◽

Long Term Effects ◽

Short Term ◽

Platelet Counts ◽

Toxicological Studies ◽

Induced Aggregation ◽

Internal Architecture

Previous short term toxicological studies of one to two weeks duration have demonstrated that MDL 19,660 (5-(4-chlorophenyl)-2,4-dihydro-2,4-dimethyl-3Hl, 2,4-triazole-3-thione), an antidepressant drug, causes a dose-related thrombocytopenia in dogs. Platelet counts started to decline after two days of dosing with 30 mg/kg/day and continued to decrease to their lowest levels by 5-7 days. The loss in platelets was primarily of the small discoid subpopulation. In vitro studies have also indicated that MDL 19,660: does not spontaneously aggregate canine platelets and has moderate antiaggregating properties by inhibiting ADP-induced aggregation. The objectives of the present investigation of MDL 19,660 were to evaluate ultrastructurally long term effects on platelet internal architecture and changes in subpopulations of platelets and megakaryocytes.Nine male and nine female beagle dogs were divided equally into three groups and were administered orally 0, 15, or 30 mg/kg/day of MDL 19,660 for three months. Compared to a control platelet range of 353,000- 452,000/μl, a doserelated thrombocytopenia reached a maximum severity of an average of 135,000/μl for the 15 mg/kg/day dogs after two weeks and 81,000/μl for the 30 mg/kg/day dogs after one week.

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