Conditioning to magnetic directions.
Conditioning to magnetic directions.
复制标题
适应磁方向。
DOI：
10.1097/wnr.0b013e32818b2a38
复制
发表时间：
2007
期刊：
影响因子：
1.7
通讯作者：
R. Wiltschko
中科院分区：
文献类型：
--
作者：
W. Wiltschko;R. Wiltschko
在神经生物学、心理学和感觉生理学中，操作性条件反射是进入动物感觉世界的重要工具。条件反射实验揭示了感觉品质检测能力的特征，如阈值、范围和辨别能力，并探索了感觉机制的功能模式、神经元通路和所涉及的大脑区域。我们对动物视觉和听觉敏感性的认识主要是基于条件反射实验。至于对地磁场的敏感性，情况就不同了。虽然候鸟和信鸽的自发反应清楚地表明这些动物对地磁场敏感[1]，但条件反射的尝试基本上失败了，负面结果超过了少数正面结果。许多神经生物学家更相信条件反射实验，因为在条件反射实验中，反应可以随意引发，而不是只在一年中的特定时间或特定条件下发生的自发行为。因此，未能获得适当的条件反射开始破坏接受磁一般。在坚定的“信念”的指导下，“我们不知道有任何情况下，已经证明的外部感受敏感性仍然不可能用条件反射技术清楚地证明”[2]，许多神经生物学家质疑动物感知磁场的能力，这反过来又延迟了对这种能力的神经基础的分析。自20世纪50年代以来，人们一直在努力使动物适应磁刺激。在世纪的最后几十年里，蜜蜂和几种鱼类可以适应磁场，最近报道了新的积极成果。在大多数实验中，刺激包括磁场强度的变化，动物必须区分磁场异常的存在和不存在。然而，对于鸟类和哺乳动物，类似的尝试基本上没有成功。直到最近，还没有已知的哺乳动物成功适应磁刺激的案例，偶尔从鸟类报告的阳性结果被证明很难繁殖，而且阴性结果的数量超过了阳性结果。特别是在鸟类中，这似乎相当奇怪，因为许多基于自发行为的积极实验：例如，在受控的实验室条件下，候鸟更喜欢与它们季节性适当的迁徙方向相对应的方向;当环境磁场向北移动时，它们以相应的方式改变它们的方向。这引发了关于磁刺激条件反射的普遍问题--为什么它很少成功？传统的条件反射技术失败的三个可能原因已经提出[3]。首先，像地磁场这样的因素，自然用于与定向和导航有关的空间任务，可能不容易与食物奖励联系起来，并且在实验室的有限空间中，对磁刺激的条件反射可能会满足学习的限制。第二个可能的原因是，在自然界中，地磁场从未经历过任何快速变化。因此，动物可能不会预料到这些变化，也不会意识到这些变化，无法对它们做出反应。第三个原因可能是动物的一种习惯，即不总是参考它们的磁罗盘。自我产生的运动会改变磁感受器的输入，为了避免处理由此产生的问题，动物通常会忽略磁方向信息，只有在需要定向和导航时才会调用它。在这种情况下，考虑鸟类和哺乳动物中磁条件反射的少数积极案例是有趣的。在20世纪70年代，第一次成功的鸽子条件反射涉及双向选择，鸽子必须通过一个更大的飞行隧道，选择右侧或左侧的喂食箱，正确的选择由更高或更低的磁场强度指示[4]。它最近被复制使用的存在或不存在的磁异常作为刺激[5]。另一项最近对鸽子的研究使用异常作为“磁性地标”，以指示开放竞技场中隐藏的食物[6]，在对大鼠的研究中，磁性异常指示八臂放射状迷宫的正确臂[7]。这些成功的研究都有共同的特点：动物并没有被限制在一个小的斯金纳盒子里，而是有活动的空间，刺激包括磁场强度的变化。更令人吃惊的是动物对磁场方向的适应，这在很长一段时间里似乎是不可能的。这种条件作用首先在印在一个红色乒乓球上的年轻家鸡身上获得：小鸡被训练将球定位在正方形测试装置四个角上的四个相等屏幕之一后面，磁场方向指示正确的屏幕。当磁北移动时，小鸡们会移动到现在正确的磁场方向的角落。Voss等人[9]在这本杂志上发表的论文是鸟类条件性罗盘反应的另一个明显例子，并使用了类似的测试范式：斑胸草雀必须在正确的编辑神经报告中选择喂食器。
In neurobiology, psychology and sensory physiology, operant conditioning is a valuable tool for gaining access to the sensory world of animals. Conditioning experiments have revealed features of the capacity to detect sensory qualities, such as thresholds, range and the ability to discriminate, and have explored the functional mode of sensory mechanisms, the neuronal pathways and the areas of the brain involved. Our knowledge of the visual and auditory sensitivity of animals is largely based on conditioning experiments. With regard to the sensitivity for the geomagnetic field, the situation is different. Although spontaneous responses of migratory birds and homing pigeons clearly indicated that these animals are sensitive to the geomagnetic field [1], attempts at conditioning largely failed, with the negative results outnumbering the few positive ones. Many neurobiologists have more trust in conditioning experiments, in which responses can be elicited at will, than in spontaneous behavior that occurs only during certain times of the year or in certain conditions. Hence the failure to obtain proper conditioned responses began to undermine the acceptance of magnetoreception in general. Guided by the firm ‘belief’ that ‘we know of no case in which a proven exteroreceptive sensitivity has remained impossible to demonstrate clearly with conditioning techniques’ [2], many neurobiologists questioned the ability of animals to perceive magnetic fields, which, in turn, delayed and still delays the analysis of the neuronal basis of this ability. Efforts to condition animals to magnetic stimuli have been carried out since the 1950s. In the last decades of the 20th century, honey bees and several species of fish could be conditioned to magnetic fields, with new positive results reported recently. In most of these experiments, the stimulus consisted of changes in magnetic intensity and the animals had to discriminate between the absence and the presence of a magnetic anomaly. With birds and mammals, however, similar attempts were largely unsuccessful. Until recently, there was no known case of a mammal successfully conditioned to magnetic stimuli, and occasional positive results reported from birds proved hard to reproduce and were outnumbered by negative results. In particular, in birds this seemed rather odd, given the many positive experiments based on spontaneous behavior: for example, migratory birds prefer directions that correspond to their seasonally appropriate migratory direction under controlled laboratory conditions; when north of the ambient magnetic field is shifted, they change their headings in a corresponding way. This raised general questions about conditioning to magnetic stimuli – why was it so seldom successful? Three possible reasons why traditional conditioning techniques may have failed have been suggested [3]. The first is that a factor like the geomagnetic field, naturally used for spatial tasks in connection with orientation and navigation, might not be easily associated with a food reward, and in the limited space of a laboratory, conditioning to magnetic stimuli might meet constraints of learning. The second possible reason is that, in nature, the geomagnetic field never undergoes any rapid changes. Hence animals might not expect such changes and, not realizing them, fail to respond to them. The third reason may be a habit of animals not to consult their magnetic compass all the time. Self-produced motion would change the input of the magnetoreceptors, and to avoid dealing with problems arising from this, animals might normally ignore magnetic directional information, calling upon it only when it is required for orientation and navigation. In this light, it is interesting to consider the few positive cases of magnetic conditioning in birds and mammals. A first successful conditioning with pigeons in the 1970s involved a two-way choice, in which the pigeons had to move though a larger flight tunnel and select a feeding box at the right or left side, with the correct alternative indicated by a higher or lower magnetic intensity [4]. It was recently reproduced using the presence or absence of a magnetic anomaly as stimulus [5]. Another recent study with pigeons used an anomaly as a ‘magnetic landmark’ to indicate hidden food in an open arena [6], and in a study with rats, a magnetic anomaly indicated the correct arm of an eight-arm radial maze [7]. These successful studies had common features: the animals were not confined to a small Skinner box, but had room to move about, and the stimuli consisted of changes in magnetic intensity. Even more striking is the conditioning of animals to magnetic directions, which, for a long time, had seemed impossible. Such conditioning was first obtained in young domestic chickens imprinted on a red table-tennis ball: the chicks were trained to locate the ball behind one of four equal screens in the corners of the square test apparatus, with the magnetic direction indicating the correct screen. When the magnetic north had been shifted, the chicks moved to the corner that was now in the correct magnetic direction [8]. The paper by Voss et al. [9] in this journal is another clear example of the conditioned compass response in birds and uses a similar test paradigm: the zebra finches had to select the feeder in the correct EDITORIAL NEUROREPORT
影响因子：
3.4
作者：
Ritz, T;Adem, S;Schulten, K
通讯作者：
Schulten, K