Neuroscience Letters
November 1, 2021
P. Bauer, C. Sabourdy, Benoit Chatard et al.
Intracranial electroencephalography (iEEG) can be used to compare brain activity during mind wandering, mindfulness meditation, and hypnosis. In three patients new to meditation and hypnosis, widespread amplitude modulations were common across all three states, especially in low-frequency bands (delta, theta, alpha) with positively correlated activity. Unique connectivity patterns for each state predominated in the gamma band, where about one-third of correlations were negative. The findings suggest iEEG is feasible for directly comparing these states and that gamma-band activity warrants further investigation.
Neuroscience Letters
September 15, 2021
A. Hajizadeh Moghaddam, Khadijeh Maboudi, Bita Bavaghar et al.
Curcumin, an antioxidant natural herb, has poor bioavailability that limits its effects. A curcumin-loaded nanophytosome (CNP) formulation was developed and tested in a mouse model of schizophrenia induced by ketamine (KET). Mice received oral curcumin or CNP (20 mg/kg) for 30 days, with KET injections (30 mg/kg/day) from days 16 to 30. CNP showed greater neuroprotective effects than free curcumin, reducing depressive and anxiety-like behaviors, memory deficits, and oxidative stress markers in brain tissues. CNP may improve curcumin bioavailability and offer stronger protection against KET-induced behavioral and oxidative damage.
Neuroscience Letters
April 23, 2018
Yan Zhou, Rachel S Crowley, Thomas E Prisinzano et al.
A single injection of the kappa opioid receptor agonist Mesyl Salvinorin B (MSB) at 3 mg/kg prevented the alcohol deprivation effect—a model of relapse—in both male and female mice that had developed excessive alcohol intake. A lower dose combination of MSB (0.3 mg/kg) with naltrexone (1 mg/kg) also reduced the effect, suggesting synergy. MSB alone or combined with naltrexone shows potential for treating alcohol relapse.
Neuroscience Letters
June 9, 2017
Ji-Ho Ryu, Pil-Jong Kim, Hong-Gee Kim et al.
In healthy adults inhaling nitrous oxide to induce sedation while maintaining consciousness, electroencephalography revealed that functional connectivity between frontal and parietal brain regions is significantly altered. Low-frequency power increased in frontal regions during sedation and reversed after discontinuation. Granger causality analysis showed that feedback and feedforward connections changed differently across EEG frequency bands. Specifically, spectral Granger causality in the theta, alpha, and beta bands from parietal to frontal directions significantly decreased during sedation, while the reverse direction showed no significant change. This reduced parietal-to-frontal interaction may underlie the sedated state and cognitive impairment.
Neuroscience Letters
March 11, 2016
Junling Gao, Jicong Fan, B. W. Wu et al.
Mindfulness-Based Stress Reduction (MBSR) training alters electrical activity in the brain and heart, making them more coordinated. During an 8-week standard MBSR course, EEG recordings showed increased alpha and beta wave power and decreased delta wave power compared to normal rest. Wavelet entropy analysis indicated that MBSR meditation reduces chaotic activity in both EEG and heart rate as a temporary state change, though longer training may be needed for lasting trait changes. For the first time, the data demonstrated that chaotic brain and heart activities become more coordinated during MBSR, suggesting mindfulness enhances mind-body entrainment. Specific 3D brain regions involved in these mental state changes were identified.
Neuroscience Letters
March 17, 2015
Mei-Kei Leung, Chetwyn C H Chan, Jing Yin et al.
Meditation experts show stronger connections between the left amygdala and brain regions involved in emotion regulation and body awareness—specifically the dorsal anterior cingulate cortex, premotor cortex, and primary somatosensory cortex—when viewing positive emotional stimuli, compared to novices. This suggests that long-term meditation practice may lead to neuroplastic changes in how the brain processes positive emotions.
Neuroscience Letters
November 27, 2013
Rebecca Erwin Wells, Gloria Y Yeh, Catherine E. Kerr et al.
In adults with mild cognitive impairment (MCI), an 8-week Mindfulness Based Stress Reduction (MBSR) program increased functional connectivity between the posterior cingulate cortex and both the medial prefrontal cortex and hippocampus, and showed trends of reduced hippocampal atrophy compared to usual care. These preliminary results suggest MBSR may positively affect brain regions linked to MCI and Alzheimer's disease, though larger studies with longer follow-up are needed.
Neuroscience Letters
December 3, 2008
Pieter Beerepoot, Vincent M Lam, Alice Luu et al.
The kappa opioid receptor agonist salvinorin A, the active compound in Salvia divinorum, can either increase or decrease locomotor sensitization caused by the dopamine agonist quinpirole, depending on dose. Rats received biweekly injections of quinpirole plus salvinorin A (0.04, 0.4, or 2.0 mg/kg) or the synthetic kappa agonist U69593 (0.3 mg/kg) for ten sessions. The highest salvinorin A dose and U69593 both potentiated sensitization; the middle dose had no effect; the lowest dose attenuated it. Structural differences between salvinorin A and U69593 do not affect potentiation, and salvinorin A can bidirectionally modulate dopamine agonist sensitization.
Neuroscience Letters
June 21, 2007
Britta K. Hölzel, Ulrich Ott, Hannes Hempel et al.
During mindfulness of breathing, experienced Vipassana meditators show stronger brain activation in the rostral anterior cingulate cortex and dorsal medial prefrontal cortex compared to non-meditators. The rostral anterior cingulate cortex activation may reflect enhanced processing of distracting events, while medial prefrontal cortex activation suggests stronger engagement in emotional processing. Fifteen meditators with an average of 7.9 years of daily two-hour practice and fifteen matched non-meditators participated in an fMRI study comparing meditation to mental arithmetic.
Neuroscience Letters
January 9, 2006
Nadine Buck, Sebat Cali, Joachim Behr
The subiculum relays information from the hippocampus to brain regions involved in schizophrenia. Using the MK-801 model of psychosis in rats, the study examined changes in synaptic transmission and plasticity at CA1-subiculum synapses 4 hours, 24 hours, and 4 weeks after treatment. Systemic MK-801 facilitated long-term potentiation (LTP) at 24 hours compared to controls, but LTP returned to normal levels after 4 weeks. This delayed facilitation suggests a novel form of metaplasticity, offering insight into how NMDA receptor antagonists affect synaptic efficacy over time.
Neuroscience Letters
February 11, 2000
T Hori, S Abe, A Baba et al.
Repeated treatment with phencyclidine (PCP) over 14 days at 7.5 mg/kg per day significantly reduced the frequency of backpedalling, a serotonergic stereotyped behavior, indicating tolerance. This repeated treatment also decreased the equilibrium dissociation constant (Kd) of [3H]paroxetine binding to serotonin transporters in whole brain excluding the cerebellum, without changing the maximum number of binding sites (Bmax). A single PCP treatment did not alter binding parameters. The results suggest that repeated PCP treatment induces tolerance in serotonergic stereotyped behavior and increases the affinity of serotonin transporters, possibly as a compensatory response to chronic inhibition of serotonin uptake.
Neuroscience Letters
May 10, 1996
J P Zacny, A M Cho, D W Coalson et al.
Inhaling nitrous oxide at increasing doses (10–40%) reduces pain intensity and the bother of pain from cold-water immersion, but this analgesic effect weakens over a 120-minute inhalation period (acute tolerance). Some pleasant subjective effects, such as elation and drug liking, also show acute tolerance. Other subjective effects and psychomotor impairment do not change significantly during the inhalation period, indicating no acute tolerance for those measures. The differing patterns of tolerance suggest that distinct neurochemical systems may mediate different effects of nitrous oxide.
Neuroscience Letters
October 9, 1989
Y Itzhak
The dissociative anesthetics phencyclidine (PCP) and ketamine block the NMDA receptor, a type of excitatory amino acid receptor. This study examined how NMDA receptor activators (agonists) and blockers (antagonists) affect the binding of PCP-like drugs to different sites in rat brain membranes. Glutamate and NMDA (agonists) did not alter binding to the high-affinity sigma/PCP site or the sigma/haloperidol site. However, they increased binding to the low-affinity PCP-selective site by 4- to 5-fold, and this increase was competitively reduced by the antagonist AP-5. The noncompetitive NMDA antagonist MK-801 potently inhibited binding to both the high- and low-affinity sites. These results suggest that the high- and low-affinity PCP binding sites are distinct and are modulated differently by NMDA receptor activity.
Neuroscience Letters
May 6, 1987
G E Fagg
Phencyclidine (PCP) and similar drugs block NMDA-type glutamate receptors. In rat brain postsynaptic densities, binding of a PCP analogue was enhanced nearly 4-fold by the excitatory amino acids L-glutamate and NMDA, but not by other related compounds. Excitatory amino acid agonists and antagonists showed potencies in the PCP analogue binding assay that matched their affinities for NMDA-sensitive glutamate binding sites. Dissociative anesthetics and sigma-opiates inhibited PCP analogue binding but did not affect glutamate binding. The data indicate that PCP binding sites are linked to NMDA receptors, and that PCP and related drugs bind preferentially to the activated configuration of the NMDA receptor channel complex.