Surface Modelling of Neuronal Populations and Brain Structures: Use of Implicitly Represented Geometries

AbstractIt is though that only a subset of brain structures can encode emotional states. This can be investigated though a set of properties, including the ability of neurons to respond to a conditioned stimulus (CS) preceding an aversive unconditioned stimulus (US). The dorsolateral periacqueductal gray (dPAG) is a midbrain structure though to have an essential role in coordinating defensive behaviors in response to aversive stimulation. But its ability of dPAG neurons to encode a CS following fear conditioning as not been sufficiently studied.Here we used calcium imaging by fiber photometry to record the activity of dPAGVGluT2+ and dPAGGAD2+ neuronal populations during unconditioned and conditioned aversive stimulation. Then, following an unconditioned stimulation we performed a retrieval experiment to quantify memory-like responses of dPAG neurons. This shown that whilst both dPAGVGluT2+ and dPAGGAD2+ neuronal populations respond to direct US stimulation, and to CS stimulation during conditioning, only the dPAGVGluT2+ population persisted in responding to the CS stimulation during retrieval. Finally, to better understand dPAGVGluT2+ and dPAGGAD2+ connectivity patterns, we performed a cell specific monosynaptic retrograde rabies virus tracing experiment. This revealed that different patterns of fibers projects to dPAGVGluT2+ and dPAGGAD2+, further complementing our recording showing divergences between PAGVGluT2+ and dPAGGAD2+ populations.

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Use of Mutant Mouse Lines to Investigate Origin of Gonadotropin-Releasing Hormone-1 Neurons: Lineage Independent of the Adenohypophysis

Endocrinology ◽

10.1210/en.2009-0875 ◽

2010 ◽

Vol 151 (2) ◽

pp. 766-773 ◽

Cited By ~ 16

Author(s):

Hillery Metz ◽

Susan Wray

Keyword(s):

Anterior Pituitary ◽

Double Mutant ◽

Mutant Mouse ◽

Vomeronasal Organ ◽

Brain Structures ◽

Neuronal Population ◽

Mutant Mice ◽

Neuronal Populations ◽

Embryonic Origin ◽

Mouse Lines

Mutant mouse lines have been used to study the development of specific neuronal populations and brain structures as well as behaviors. In this report, single- and double-mutant mice were used to examine the lineage of GnRH-1 cells. GnRH is essential for vertebrate reproduction, with either GnRH-1 or GnRH-3 controlling release of gonadotropins from the anterior pituitary, depending on the species. It is clear that the neuroendocrine GnRH cells migrate from extracentral nervous system locations into the forebrain. However, the embryonic origin of GnRH-1 and GnRH-3 cells is controversial and has been suggested to be nasal placode, adenohypophyseal (anterior pituitary) placode, or neural crest, again dependent on the species examined. We found that mutant mice with either missing or disrupted anterior pituitaries (Gli2−/−, Gli1−/−Gli2−/−, and Lhx3−/−) exhibit a normal GnRH-1 neuronal population and that these cells are still found associated with the developing vomeronasal organ. These results indicate that in mice, GnRH-1 cells develop independent of the adenohypophyseal placode and are associated early with the formation of the nasal placode.

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A Morphometric Analysis of the Geniculate Bodies in Selected Mammalian Species

Bulletin of the Veterinary Institute in Pulawy ◽

10.2478/v10213-012-0037-x ◽

2012 ◽

Vol 56 (2) ◽

pp. 205-210 ◽

Cited By ~ 1

Author(s):

Janusz Najdzion ◽

Barbara Wasilewska ◽

Krystyna Bogus-Nowakowska ◽

Maciej Równiak ◽

Witold Żakowski ◽

...

Keyword(s):

Mammalian Species ◽

Common Shrew ◽

Medial Geniculate Body ◽

Lateral Geniculate Body ◽

Brain Structures ◽

Numerical Density ◽

Neuronal Populations ◽

Percentage Volume ◽

Medial Geniculate ◽

The Common

Abstract Unbiased stereological methods were used to examine and compare morphometrically the geniculate bodies (GB) in representatives of four mammalian orders (Insectivora, Rodentia, Lagomorpha, and Carnivora). The significant disproportion was observed between the relative sizes of both geniculate nuclei and their neuronal populations in the common shrew and the bank vole. The medial geniculate body (MGB) in the common shrew definitely surpassed the lateral geniculate body (LGB) in terms of percentage volume and percentage number of neurons. The volume of the GB and their nuclei correlated with their mean neuronal populations, whereas the negative correlation was observed between volumes and neuronal density; however, not as distinct as in the non-sensory brain structures. In all examined species, the LGB always had a higher numerical density than the MGB, while the MGB neurons were always distinctly larger than that of the LGB, which clearly differentiated both neuronal complexes. Analysis of these data shows that the GB differs in terms of the morphometric characteristics in the studied species.

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Ultra-sparse connectivity within the lateral hypothalamus

10.1101/2020.04.25.061564 ◽

2020 ◽

Author(s):

Denis Burdakov ◽

Mahesh M. Karnani

Keyword(s):

Lateral Hypothalamus ◽

Brain Slices ◽

Brain Structures ◽

Gamma Oscillations ◽

Local Network ◽

Excitatory Synapses ◽

Neuronal Populations ◽

Reward Seeking ◽

Intrinsic Connectivity ◽

Sparse Connectivity

AbstractThe lateral hypothalamus (LH) contains neuronal populations which generate fundamental behavioural actions such as feeding, sleep, movement, attack and evasion. Their activity is also correlated with various appetitive and consummatory behaviours as well as reward seeking. It is unknown how neural activity within and among these populations is coordinated. One hypothesis postulates that they communicate using inhibitory and excitatory synapses, forming local microcircuits. We inspected this hypothesis using quadruple whole cell recordings and optogenetics to screen thousands of potential connections in brain slices. In contrast to the neocortex, we found near zero connectivity within the LH. In line with its ultra-sparse intrinsic connectivity, we found that the LH does not generate local beta and gamma oscillations. This suggests that LH neurons integrate incoming input within individual neurons rather than through local network interactions, and that input from other brain structures is decisive for selecting active populations in LH.

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The Reaction of Brain Structures with OsO4-Zinc-Iodide Stain

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100065419 ◽

1971 ◽

Vol 29 ◽

pp. 272-273

Author(s):

Werner J. Niklowitz

Keyword(s):

Electron Microscope ◽

Structural Changes ◽

Mossy Fiber ◽

Toxic Metal ◽

Staining Technique ◽

Brain Structures ◽

Oxidase Inhibitor ◽

Fiber Layer ◽

Hippocampal Tissue ◽

Zinc Iodide

After intoxication of rabbits with certain substances such as convulsant agents (3-acetylpyridine), centrally acting drugs (reserpine), or toxic metal compounds (tetraethyl lead) a significant observation by phase microscope is the loss of contrast of the hippocampal mossy fiber layer. It has been suggested that this alteration, as well as changes seen with the electron microscope in the hippocampal mossy fiber boutons, may be related to a loss of neurotransmitters. The purpose of these experiments was to apply the OsO4-zinc-iodide staining technique to the study of these structural changes since it has been suggested that OsO4-zinc-iodide stain reacts with neurotransmitters (acetylcholine, catecholamines).Domestic New Zealand rabbits (2.5 to 3 kg) were used. Hippocampal tissue was removed from normal and experimental animals treated with 3-acetylpyridine (antimetabolite of nicotinamide), reserpine (anti- hypertensive/tranquilizer), or iproniazid (antidepressant/monamine oxidase inhibitor). After fixation in glutaraldehyde hippocampal tissue was treated with OsO4-zinc-iodide stain and further processed for phase and electron microscope studies.

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