scholarly journals MAPSSIC, a communicating MAPS-based intracerebral positrons probe for deep brain imaging in awake and freely-moving rats

2020 ◽  
Vol 225 ◽  
pp. 09002
Author(s):  
F. Gensolen ◽  
L. Ammour ◽  
M. Bautista ◽  
J. Heymes ◽  
S. Fieux ◽  
...  
Keyword(s):  
Human Brain ◽  
Neural Mechanisms ◽  
Small Animals ◽  
Biological Mechanisms ◽  
Behavioral Experiments ◽  
Freely Moving ◽  
The Brain ◽  
Significant Model ◽  
Deep Brain

Radioisotope imaging is a powerful tool to understand the biological mechanisms in-vivo, especially in the brain of small animals, providing a significant model to study the human brain. In this context, we have developed and built a pixelated intracerebral positron probe to be embedded on awake and freely moving small animals, typically rats. This pixelated probe will represent a key instrument for neuroscientists to study neural mechanisms and correlate them to behavioral experiments. We describe in this paper the simulations carried out to design the intracerebral sensor, its architecture, and the detection of positrons in a volume with a couple of sensors assembled back-to-back. We also depict the architecture of the wireless acquisition system. Finally, we present the first measurements performed in real-time by this miniaturized probe with sealed radioactive sources and a 18F solution.

scholarly journals In vivo photopharmacology enabled by multifunctional fibers

2020 ◽  
Author(s):  
James A. Frank ◽  
Marc-Joseph Antonini ◽  
Po-Han Chiang ◽  
Andres Canales ◽  
David B. Konrad ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Optical Switch ◽  
Brain Regions ◽  
Behavioral Experiments ◽  
Mesolimbic Pathway ◽  
Molecular Neuroscience ◽  
Freely Moving ◽  
Thermal Drawing ◽  
Deep Brain

ABSTRACTTo reversibly manipulate neural circuits with increased spatial and temporal control, photoswitchable ligands can add an optical switch to a target receptor or signaling cascade. This approach, termed photopharmacology, has been enabling to molecular neuroscience, however, its application to behavioral experiments has been impeded by a lack of integrated hardware capable of delivering both light and compounds to deep brain regions in moving subjects. Here, we devise a hybrid photochemical genetic approach to target neurons using a photoswitchable agonist of capsaicin receptor (TRPV1), red-AzCA-4. Using the thermal drawing process we created multifunctional fibers that can deliver viruses, photoswitchable ligands, and light to deep brain regions in awake, freely moving mice. We implanted our fibers into the ventral tegmental area (VTA), a midbrain hub of the mesolimbic pathway, and used them to deliver a transgene coding for TRPV1. This sensitized excitatory VTA neurons to red-AzCA-4, and allowed us to optically control conditioned place preference using a mammalian ion-channel, thus extending applications of photopharmacology to behavioral experiments. Applied to endogenous receptors, our approach may accelerate studies of molecular mechanisms underlying animal behavior.

scholarly journals Injectable Nanoelectrodes Enable Wireless Deep Brain Stimulation of Native Tissue in Freely Moving Mice

2020 ◽  
Author(s):  
Kristen L. Kozielski ◽  
Ali Jahanshahi ◽  
Hunter B. Gilbert ◽  
Yan Yu ◽  
Önder Erin ◽  
...  
Keyword(s):  
Behavioral Changes ◽  
Less Invasive ◽  
Magnetoelectric Materials ◽  
The Central Nervous System ◽  
Freely Moving ◽  
The Brain ◽  
Deep Brain ◽  
Stimulation Of

AbstractDevices that electrically modulate the central nervous system have enabled important breakthroughs in the management of neurological and psychiatric disorders. Such devices typically have centimeter-scale dimensions, requiring surgical implantation and wired-in powering. Using smaller, remotely powered materials could lead to less invasive neuromodulation. Herein, we present injectable magnetoelectric nanoelectrodes that wirelessly transmit electrical signals to the brain in response to an external magnetic field. Importantly, this mechanism of modulation requires no genetic modification of the brain, and allows animals to freely move during stimulation. Using these nanoelectrodes, we demonstrate neuronal modulation in vitro and in deep brain targets in vivo. We also show that local thalamic modulation promotes modulation in other regions connected via basal ganglia circuitry, leading to behavioral changes in mice. Magnetoelectric materials present a versatile platform technology for less invasive, deep brain neuromodulation.

scholarly journals Nonresonant powering of injectable nanoelectrodes enables wireless deep brain stimulation in freely moving mice

2021 ◽  
Vol 7 (3) ◽  
pp. eabc4189
Author(s):  
K. L. Kozielski ◽  
A. Jahanshahi ◽  
H. B. Gilbert ◽  
Y. Yu ◽  
Ö. Erin ◽  
...  
Keyword(s):  
Neural Tissue ◽  
Behavioral Changes ◽  
Less Invasive ◽  
Magnetoelectric Materials ◽  
Freely Moving ◽  
Risk Of Hemorrhage ◽  
The Brain ◽  
Deep Brain

Devices that electrically modulate the deep brain have enabled important breakthroughs in the management of neurological and psychiatric disorders. Such devices are typically centimeter-scale, requiring surgical implantation and wired-in powering, which increases the risk of hemorrhage, infection, and damage during daily activity. Using smaller, remotely powered materials could lead to less invasive neuromodulation. Here, we present injectable, magnetoelectric nanoelectrodes that wirelessly transmit electrical signals to the brain in response to an external magnetic field. This mechanism of modulation requires no genetic modification of neural tissue, allows animals to freely move during stimulation, and uses nonresonant carrier frequencies. Using these nanoelectrodes, we demonstrate neuronal modulation in vitro and in deep brain targets in vivo. We also show that local subthalamic modulation promotes modulation in other regions connected via basal ganglia circuitry, leading to behavioral changes in mice. Magnetoelectric materials present a versatile platform technology for less invasive, deep brain neuromodulation.

scholarly journals NeuroRoots, a bio-inspired, seamless Brain Machine Interface device for long-term recording

2018 ◽  
Author(s):  
Marc D. Ferro ◽  
Christopher M. Proctor ◽  
Alexander Gonzalez ◽  
Eric Zhao ◽  
Andrea Slezia ◽  
...  
Keyword(s):  
Neurological Diseases ◽  
Signal Amplitude ◽  
Brain Machine Interface ◽  
Behavioral Experiments ◽  
Adult Rats ◽  
Integrative Level ◽  
Machine Interface ◽  
Freely Moving ◽  
The Brain

AbstractMinimally invasive electrodes of cellular scale that approach a bio-integrative level of neural recording could enable the development of scalable brain machine interfaces that stably interface with the same neural populations over long period of time.In this paper, we designed and created NeuroRoots, a bio-mimetic multi-channel implant sharing similar dimension (10µm wide, 1.5µm thick), mechanical flexibility and spatial distribution as axon bundles in the brain. A simple approach of delivery is reported based on the assembly and controllable immobilization of the electrode onto a 35µm microwire shuttle by using capillarity and surface-tension in aqueous solution. Once implanted into targeted regions of the brain, the microwire was retracted leaving NeuroRoots in the biological tissue with minimal surgical footprint and perturbation of existing neural architectures within the tissue. NeuroRoots was implanted using a platform compatible with commercially available electrophysiology rigs and with measurements of interests in behavioral experiments in adult rats freely moving into maze. We demonstrated that NeuroRoots electrodes reliably detected action potentials for at least 7 weeks and the signal amplitude and shape remained relatively constant during long-term implantation.This research represents a step forward in the direction of developing the next generation of seamless brain-machine interface to study and modulate the activities of specific sub-populations of neurons, and to develop therapies for a plethora of neurological diseases.

A Three-Component-System Hypothesis of Psychosis

1989 ◽  
Vol 155 (S5) ◽  
pp. 37-39 ◽  
Author(s):  
Hinderk M. Emrich
Keyword(s):  
Human Brain ◽  
Causative Factor ◽  
Microscopic Level ◽  
Point Of View ◽  
Component System ◽  
Pathogenetic Factor ◽  
Pet Scans ◽  
The Brain ◽  
Different Levels

Hypotheses as to the pathogenesis of schizophrenia can be discussed at different levels of a possible manifestation of the causative factor: the macroscopic-morphological, the microscopic-morphological, and the molecular. Some abnormalities have been observed on all of them: e.g. increased ventricular-brain ratios in CT, hypofrontality in SPECT and in glucographic PET-scans, and other macromorphological abnormalities (for reviews cf. Bogerts 1984; Mundt, 1986; Bogerts et al, 1987), gliosis on a microscopic level (Stevens, 1982), and an increased dopamine-binding in in vivo receptor studies (PET as well as in post-mortem studies; Cazzullo, 1988). However, the diversity and variability of these findings point to the view that rather than there being a single distinct pathogenetic factor responsible for the pathogenesis of schizophrenic psychoses, a constitutional disposition exists, which can be described as a functional dysequilibrium within the human brain. From this point of view, schizophrenia would not appear as an inherited disorder of metabolism, but as a weakness of a neurobiological ‘system’, i.e. as an interactional disorder of a complex of networks, in which the interaction between different substructures is labile in such a way that under special conditions (e.g. ‘stress’), a decompensation (functional breakdown) results. In this sense, ‘vulnerability’ to schizophrenia may be interpreted as a consequence of a constitutional deficiency of the brain which results in an inability to stabilise, under specially challenging conditions, the interaction between different substructures of the human brain. Before this ‘functional dysequilibrium-hypothesis’ (which is a special form of a constitutional structural deficiency-hypothesis) is discussed, and before the question is raised as to which are the relevant dysequilibrated components, some indication will be given as to why such an hypothesis appears plausible.

Sensitive enzyme electrodes

1990 ◽  
Vol 333 (1628) ◽  
pp. 49-61 ◽  
Keyword(s):  
Packed Bed ◽  
Current Time ◽  
Enzyme Electrodes ◽  
Freely Moving ◽  
The Brain ◽  
Nanomolar Range ◽  
Inhibited Enzyme ◽  
Micromolar Range

Conventional enzyme electrodes are relatively insensitive devices capable of measuring analytes in the micromolar range. Inhibited enzyme electrodes work by measuring the inhibition of an enzyme turning over undersaturated conditions. This increased turnover gives greater sensitivity. The detection limits are controlled either by the thermodynamic amplitude or by the kinetic discrimination. Software has been developed to analyse the current time transient to produce concentrations of the inhibitor. Results for CN- and H 2 S are presented. The packed bed wall jet electrode is an electrode assembly that allows complete reaction of the substrate with the enzyme coupled to an efficient hydrodynamic régime for electrochemical detection. Results for the determination of acetylcholine are presented. The electrode can also be used in an immunoassay for the determination of human immunoglobulin in the nanomolar range. Finally results will be presented for in vivo changes in ascorbate in the brain of the freely moving rat as a result of tail pinch; changes on a timescale of half a second can be followed.

scholarly journals Orexin A suppresses in vivo GH secretion

2004 ◽  
pp. 731-736 ◽  
Author(s):  
LM Seoane ◽  
SA Tovar ◽  
D Perez ◽  
F Mallo ◽  
M Lopez ◽  
...  
Keyword(s):  
Nutritional Status ◽  
Area Under The Curve ◽  
Sleep Regulation ◽  
Gh Secretion ◽  
Neuroendocrine Function ◽  
Freely Moving Rats ◽  
Freely Moving ◽  
The Brain

BACKGROUND/AIMS: Orexins (OXs) are a newly described family of hypothalamic neuropeptides. Based on the distribution of OX neurons and their receptors in the brain, it has been postulated that they could play a role in the regulation of neuroendocrine function. GH secretion is markedly influenced by nutritional status and body weight. To investigate the role OX-A plays in the neuroregulation of GH secretion we have studied its effect on spontaneous GH secretion as well as GH responses to GHRH and ghrelin in freely moving rats. Finally, we also assessed the effect of OX-A on in vitro GH secretion. METHODS: We administered OX-A (10 microg, i.c.v.) or vehicle (10 microl, i.c.v.) to freely moving rats. Spontaneous GH secretion was assessed over 6 h with blood samples taken every 15 min. RESULTS: Administration of OX-A led to a decrease in spontaneous GH secretion in comparison with vehicle-treated rats, as assessed by mean GH levels (means+/-s.e.m. 4.2+/-1.7 ng/ml vs 9.4+/-2.2 ng/ml; P<0.05), mean GH amplitude (3.6+/-0.5 ng/ml vs 20.8+/-5.6 ng/ml; P<0.01) and area under the curve (848+/-379 ng/ml per 4 h vs 1957+/-458 ng/ml per 4 h; P<0.05). In contrast, OX-A failed to modify in vivo GH responses to GHRH (10 microg/kg, i.v.) although it markedly blunted GH responses to ghrelin (40 microg/kg, i.v.) (mean peak GH levels: 331+/-71 ng/ml, vehicle, vs 43+/-11 ng/ml in OX-A-treated rats; P<0.01). Finally, OX-A infusion (10(-7), 10(-8) or 10(-9) M) failed to modify in vitro basal GH secretion or GH responses to GHRH, ghrelin and KCl. CONCLUSIONS: These data indicate that OX-A plays an inhibitory role in GH secretion and may act as a bridge among the regulatory signals that are involved in the control of growth, nutritional status and sleep regulation.

scholarly journals Scaling up to meet new challenges of brain and behaviour: Deep brain electrophysiology in freely moving sheep

2021 ◽  
Author(s):  
Nikolas Perentos ◽  
Marino Krstulovic ◽  
A Jennifer Morton
Keyword(s):  
Brain Function ◽  
Large Scale ◽  
Electrophysiological Recording ◽  
Large Animal ◽  
Freely Moving ◽  
Hippocampal Theta ◽  
Exceptional Stability ◽  
Oscillatory Rhythms ◽  
Deep Brain

While rodents are arguably the easiest animals to use for studying brain function, relying on them as model species for translational research comes with its own sets of limitations. Here, we propose sheep as a practical large animal species for in vivo brain function studies performed in naturalistic settings. To demonstrate their experimental usefulness, we performed proof-of-principle deep brain electrophysiological recording experiments from unrestrained sheep. Recordings were made from cortex and hippocampus both whilst sheep performed goal-directed behaviours (two-choice discrimination tasks), and across states of vigilance that included natural sleep. Hippocampal and cortical oscillatory rhythms were consistent with those seen in rodents and non-human primates, and included cortical alpha oscillations during immobility, hippocampal theta oscillations (5-6Hz) during locomotion and hippocampal sharp wave ripple oscillations (~150 Hz) during immobility. Moreover, we found clear examples of neurons whose activity was modulated by task, speed of locomotion, spatial position, reward and vigilance states. Recordings were conducted over a period of many months. Due to the exceptional stability of individual electrodes we were able to record from some neurons continuously for more than 1 month. Together these experiments demonstrate that sheep are an excellent experimental animal model to use in longitudinal electrophysiological and imaging studies, particularly those requiring a large brained mammal, large scale recordings across distributed neuronal networks, experimentation outside the confounds of the traditional laboratory, or all the above concomitantly.

scholarly journals In vivo detection of optically-evoked opioid peptide release

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Ream Al-Hasani ◽  
Jenny-Marie T Wong ◽  
Omar S Mabrouk ◽  
Jordan G McCall ◽  
Gavin P Schmitz ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Opioid Peptide ◽  
Neuronal Circuitry ◽  
Endogenous Peptide ◽  
In Vivo Detection ◽  
Highly Sensitive ◽  
Peptide Release ◽  
Freely Moving ◽  
The Brain

Though the last decade has seen accelerated advances in techniques and technologies to perturb neuronal circuitry in the brain, we are still poorly equipped to adequately dissect endogenous peptide release in vivo. To this end we developed a system that combines in vivo optogenetics with microdialysis and a highly sensitive mass spectrometry-based assay to measure opioid peptide release in freely moving rodents.

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