研究のタイプ: 医学/生物学の研究 (experimental study)

[帰巣中のハトにおける磁覚とその三叉神経による調節] med./bio.

Magnetoreception and its trigeminal mediation in the homing pigeon.

掲載誌: Nature 2004; 432 (7016): 508-511

この研究は、帰巣性のハト(Columba livia)が条件付け選択実験において磁気異常の有無を識別できるか否かを調べた。その結果、実験ではハトは磁気異常の有無を識別することが示された;この識別は、小脳への磁石の付着、上くちばし領域または三叉神経眼枝の両側部分の局所麻酔によって損なわれたが、嗅神経の局所麻酔では損なわれなかった;これらの知見は、ハトの上くちばし領域で磁気受容(おそらくマグネタイトが基盤となる)が行われることを示唆している、と報告している。

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研究目的(acc. to editor)

To study if homing pigeons can discriminate between the presence and absence of a magnetic anomaly in a conditioned choice experiment.

詳細情報

Two conflicting hypotheses compete to explain how a homing pigeon can return to its loft over great distances: One proposes the use of atmospheric odours and the other the use of geomagnetic field.
The pigeons were conditioned to jump onto a platform at one end of the cage when the anomaly was present and onto an identical platform at the other end of the cage when the anomaly was absent.; correct answers were rewarded with food whereas incorrect choices were punished with a time penalty. Two female and two male experienced racing pigeons were studied.
Different impairment experiments were performed (e.g. attachment of a magnet to the cere, local anaesthesia of the upper beak area, and bilateral section of the ophthalmic branch of the trigeminal nerve or of the olfactory nerve).

影響評価項目

ばく露

ばく露 パラメータ
ばく露1:
  • DC/static

ばく露1

主たる特性
周波数
  • DC/static
タイプ
  • magnetic field
Additional information Four individual trained pigeons were required to discriminate the presence or absence of an induced magnetic field anomaly while freely walking in a wooden tunnel. The birds were conditioned to jump onto a platform at one end of the tunnel or to an identical platform at the other end depending on the presence or absent of field. The correct choices were rewarded with food while the incorrect choices were punished with a time penalty.
ばく露装置
ばく露の発生源/構造
  • two identical single wrapped circular coils of 1.11 m diameter, 100 turns of 0.05 mm copper wire
チャンバの詳細 Wooden tunnel (3.3 m long x 1.06 m wide x 0.96 m high) with two identical platforms (48 cm high) located at the opposite ends. Each platform was fitted with micro-switches to detect the pigeon and a rotating feeder disc for accessing food. Two transparent curtains were suspended from the ceiling of the tunnel forced the pigeon to walk and not fly between the platforms. The coils were located above and below the center of the tunnel.
Additional information During the control experiment, five 6.8 ohm resistors were wired parallel to match the effect of the coils load on the power source. Successful discrimination of the MF anomaly permitted a series of impairment experiments. In the first series of experiments, a small but strong rare earth magnets (NdFeB cylinders of 3 mm diameter and 2 mm in length with a field strength of 2500 µT at 1 cm) were attached to the cere. The orientation of the magnet was either south-up or north-up for two groups each consisting of 2 pigeons. Control session were carried out by replacing magnets with brass weights. In the second series of experiments, the olfactory cavity (upper beak area) was locally anesthetized using a 2% lignocaine hydrochloride solution. In the third series of experiments bilateral sectioning of the ophthalmic branch of trigeminal nerve was performed.
パラメータ
測定量 種別 Method Mass 備考
磁束密度 44 µT minimum 指定なし - inclination of -64°
磁束密度 189 µT maximum 指定なし - inclination of -80°

ばく露を受けた生物:

方法 影響評価項目/測定パラメータ/方法

研究対象とした生物試料:
研究対象とした臓器系:
調査の時期:
  • ばく露中

研究の主なアウトカム(著者による)

The data demonstrate that homing pigeons can discriminate between the presence and absence of a magnetic anomaly. This discrimination is impaired by attachment of a magnet to the cere, local anaesthesia of the upper beak area, and bilateral section of the ophthalmic branch of the trigeminal nerve, but not of the olfactory nerve.
These results indicate that magnetoreception (probably magnetite-based) occurs in the upper beak area of the pigeon.

研究の種別:

研究助成

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