鳥の網膜における塩状軸索伝導
Christoph T Block1, Malte T Ahlers1, Christian Puller1
1Visual Neuroscience, Department of Neuroscience, Carl von Ossietzky University Oldenburg, Oldenburg, Germany.
The Journal of physiology
|August 29, 2025
まとめ
ほとんどの脊椎動物とは異なり 鳥の網膜には 神経繊維がミエリン化されています この研究では 網膜内ミエリネーションが 神経信号伝導を加速し 光学的なトレードオフにもかかわらず 進化上の利点を提供することが示されています
科学分野:
- 神経科学
- 比較解剖学
- 進化生物学
背景:
- 脊椎動物の網膜のギャングリア細胞軸索は通常,網膜内ではミエリン化されていない.
- 鳥の網膜は例外で,神経繊維層のギャングリオン細胞軸索の部分的なミエリン化が特徴です.
- ミエリネーションはスパイク伝導速度を向上させ,潜在的な光学的なダメージを相殺する.
研究 の 目的:
- 哺乳類と比較して鳥類の内伝導速度を調査する.
- 網膜におけるミエリン化,軸索構造,伝導速度との関係を決定する.
- 神経信号伝達に対する 網膜の骨髄形成の進化的影響を探求する
主な方法:
- 高解像度マルチ電極配列の記録は,鳥類と哺乳類の網膜のスパイク伝導を分析するために使用されました.
- 軸索の直径,内部節の長さ,およびランヴィエの節は,解剖学的分析によって調べられた.
- 導電速度は,骨髄形成状態と解剖学的特徴と相関していた.
主要な成果:
- 鳥類は哺乳類よりも 網膜内伝導速度が高い.
- 骨髄性軸索は一般的により速い伝導性を示したが,骨髄性軸索の一部は骨髄性軸索でないものよりも遅かった.
- 導電速度は,同時に活動しているノードと軸索の直径の空間的な範囲と正に相関しています.
結論:
- 鳥の網膜内ミエリン化は,急速なスパイク伝導を促進し,進化上の優位性を提供します.
- アクソナル構造,特に内部ノード長とノード活性化は,伝導速度に影響する.
- 発見は鳥の網膜のユニークな適応と 神経信号伝達におけるミエリン化の機能的役割を強調しています
関連する概念動画
Anatomy of the Eyeball
7.6K
The eye is a spherical, hollow structure composed of three tissue layers. The outer layer — the fibrous tunic, comprises the sclera — a white structure — and the cornea, which is transparent. The sclera encompasses some of the ocular surface, most of which is not visible. However, the 'white of the eye' is distinctively visible in humans compared to other species. The cornea, a clear covering at the front of the eye, enables light penetration. The eye's middle...
7.6K
The Retina
70.5K
The retina is a layer of nervous tissue at the back of the eye that transduces light into neural signals. This process, called phototransduction, is carried out by rod and cone photoreceptor cells in the back of the retina.
70.5K
Action Potential
8.3K
Neurons communicate by firing action potentials—the electrochemical signal that is propagated along the axon. The signal results in the release of neurotransmitters at axon terminals, thereby transmitting information to the nervous system. An action potential is a specific "all-or-none" change in membrane potential that results in a rapid spike in voltage.
Membrane potential in neurons
Neurons typically have a resting membrane potential of about -70 millivolts (mV). When they receive...
Membrane potential in neurons
Neurons typically have a resting membrane potential of about -70 millivolts (mV). When they receive...
8.3K
Action Potentials
133.4K
Overview
133.4K
Vision
55.3K
Vision is the result of light being detected and transduced into neural signals by the retina of the eye. This information is then further analyzed and interpreted by the brain. First, light enters the front of the eye and is focused by the cornea and lens onto the retina—a thin sheet of neural tissue lining the back of the eye. Because of refraction through the convex lens of the eye, images are projected onto the retina upside-down and reversed.
55.3K
Propagation of Action Potentials
6.8K
The propagation of an action potential refers to the process by which a nerve impulse, or "action potential," travels along a neuron.
Neurons (nerve cells) have a resting membrane potential, with a slightly negative charge inside compared to outside. This is maintained by ion channels, such as sodium (Na+) and potassium (K+) channels, which control the flow of ions. When a stimulus, like a touch or a signal from another neuron, triggers the neuron, sodium channels open, allowing sodium ions to...
Neurons (nerve cells) have a resting membrane potential, with a slightly negative charge inside compared to outside. This is maintained by ion channels, such as sodium (Na+) and potassium (K+) channels, which control the flow of ions. When a stimulus, like a touch or a signal from another neuron, triggers the neuron, sodium channels open, allowing sodium ions to...
6.8K


