11 research outputs found
Magnetic isotope effects: a potential testing ground for quantum biology
One possible explanation for magnetosensing in biology, such as avian magnetoreception, is based on the spin dynamics of certain chemical reactions that involve radical pairs. Radical pairs have been suggested to also play a role in anesthesia, hyperactivity, neurogenesis, circadian clock rhythm, microtubule assembly, etc. It thus seems critical to probe the credibility of such models. One way to do so is through isotope effects with different nuclear spins. Here we briefly review the papers involving spin-related isotope effects in biology. We suggest studying isotope effects can be an interesting avenue for quantum biology
Entangled radicals may explain lithium effects on hyperactivity
It is known that bipolar disorder and its lithium treatment involve the
modulation of oxidative stress. Moreover, it has been observed that lithium's
effects are isotope-dependent. Based on these findings, here we propose that
lithium exerts its effects by influencing the recombination dynamics of a
naturally occurring radical pair involving oxygen. We develop a simple model
inspired by the radical-pair mechanism in cryptochrome in the context of avian
magnetoreception and xenon-induced anesthesia. Our model reproduces the
observed isotopic dependence in the lithium treatment of hyperactivity in rats.
It predicts a magnetic-field dependence of the effectiveness of lithium, which
provides one potential experimental test of our hypothesis. Our findings show
that Nature might harness quantum entanglement for the brain's cognitive
processes
Magnetic isotope effects: a potential testing ground for quantum biology
One possible explanation for magnetosensing in biology, such as avian
magnetoreception, is based on the spin dynamics of certain chemical reactions
that involve radical pairs. Radical pairs have been suggested to also play a
role in anesthesia, hyperactivity, neurogenesis, circadian clock rhythm,
microtubule assembly, etc. It thus seems critical to probe the credibility of
such models. One way to do so is through isotope effects with different nuclear
spins. Here we briefly review the papers involving spin-related isotope effects
in biology. We suggest studying isotope effects can be an interesting avenue
for quantum biology
Radical Pair Model for Magnetic Field Effects on NMDA Receptor Activity
The N-methyl-D-aspartate receptor is a prominent player in brain development
and functioning. Perturbations to its functioning through external stimuli like
magnetic fields can potentially affect the brain in numerous ways. Various
studies have shown that magnetic fields of varying strengths affect these
receptors. We propose that the radical pair mechanism, a quantum mechanical
process, could explain some of these field effects. Radicals of the form
[\mbox{RO}^\bullet \mbox{ Mg(\mbox{H}_2)_n}^{+\bullet}], where R is a
protein residue that can be Serine or Tyrosine, are considered for this study.
The variation in the singlet fractional yield of the radical pairs, as a
function of magnetic field strength, is calculated to understand how the
magnetic field affects the products of the radical pair reactions. Based on the
results, the radical pair mechanism is a likely candidate for explaining the
magnetic field effects observed on the receptor activity. The model predicts
changes in the behaviour of the system as magnetic field strength is varied and
also predicts certain isotope effects. The results further suggest that similar
effects on radical pairs could be a plausible explanation for various magnetic
field effects within the brain
Network analysis of the human structural connectome including the brainstem: a new perspective on consciousness
The underlying anatomical structure is fundamental to the study of brain
networks and is likely to play a key role in the generation of conscious
experience. We conduct a computational and graph-theoretical study of the human
structural connectome incorporating a variety of subcortical structures
including the brainstem, which is typically not considered in similar studies.
Our computational scheme involves the use of Python DIPY and Nibabel libraries
to develop an averaged structural connectome comprised of 100 healthy adult
subjects. We then compute degree, eigenvector, and betweenness centralities to
identify several highly connected structures and find that the brainstem ranks
highest across all examined metrics. Our results highlight the importance of
including the brainstem in structural network analyses. We suggest that
structural network-based methods can inform theories of consciousness, such as
global workspace theory (GWT), integrated information theory (IIT), and the
thalamocortical loop theory.Comment: 23 pages, 5 figure
Exploring the roles of radical pairs in the brain
Magnetic field effects are abundant throughout biology, including plants, animals, and humans. Of particular interest are the magnetic field effects on neuronal activities and the brain functions. The corresponding energies induced by applied magnetic fields are far below the thermal energies, particularly for low-intensity magnetic fields. Thus far there is no clear explanation for the mechanisms behind these effects. On the other hand, the radical pair mechanism provides a promising hypothesis for the animal magnetoreception. The model is based on the spin dynamics of naturally occurring transient correlated radicals. In this thesis, I review magnetic field and isotope effects on various physiological functions. Next, I introduce the radical pair mechanism. I also review plausible radical pairs that may act as the magnetic sensing agents in magnetosensitivity of biological functions. Moving on, this thesis contains recent studies that propose that radical pairs may explain magnetic field and isotope effects in microtubule reorganization, the circadian clock, and lithium treatment for hyperactivity. Lastly, I also summarize projects in which I have contributed to exploring the roles of radical pairs in xenon-induced anesthesia and hypomagnetic field effects on neurogenesis
Network analysis of the human structural connectome including the brainstem
The underlying anatomical structure is fundamental to the study of brain networks, but the role of brainstem from a structural perspective is not very well understood. We conduct a computational and graph-theoretical study of the human structural connectome incorporating a variety of subcortical structures including the brainstem. Our computational scheme involves the use of Python DIPY and Nibabel libraries to develop structural connectomes using 100 healthy adult subjects. We then compute degree, eigenvector, and betweenness centralities to identify several highly connected structures and find that the brainstem ranks highest across all examined metrics, a result that holds even when the connectivity matrix is normalized by volume. We also investigated some global topological features in the connectomes, such as the balance of integration and segregation, and found that the domination of the brainstem generally causes networks to become less integrated and segregated. Our results highlight the importance of including the brainstem in structural network analyses
and group theoretical study of properties of the carbon trimer defect in h-BN
Hexagonal boron nitride (h-BN) is a promising platform for quantum
information processing due to its potential to host optically active defects
with attractive optical and spin properties. Recent studies suggest that carbon
trimers might be the defect responsible for single-photon emission in the
visible spectral range in h-BN. In this theoretical study, we combine group
theory together with density functional theory (DFT) calculations to predict
the properties of the neutral carbon
trimer defect. We find the multi-electron states of this defect along with
possible radiative and non-radiative transitions assisted by the spin-orbit and
the spin-spin interactions. We also investigate the Hamiltonian for external
magnetic field and ground-state hyperfine interactions. Lastly, we use the
results of our investigation in a Lindblad master equation model to predict an
optically detected magnetic resonance (ODMR) signal and the
correlation function. Our findings can have important outcomes in quantum
information applications such as quantum repeaters used in quantum networks and
quantum sensing.Comment: 18 pages, 12 figures, 7 table