信鸽利用地标指引自己安全返航。然而当这种鸟以65千米每小时的速度掠过天空时，它们如何追踪身下几百米处的那些熟悉的地点呢？科学家们正在尝试用一种新的装置来解答这一问题，而这种装置能够让他们在信鸽飞行时记录鸟类的大脑活动。
信鸽在严格意义上究竟是如何找到回家之路的一直是个未解之谜。一些研究推测，鸟类能够利用嗅觉、太阳的方向，或地球磁场来导航，科学家同时还知道，信鸽能够利用视觉地标。为了搞清信鸽的大脑如何处理这些视觉信号，瑞士苏黎世大学的Alexei Vyssotski和同事研制出了一种名为Neurologger2的装置，后者能够在跟踪鸟类路径的同时记录其飞越熟悉地点时的大脑活动。
Neurologger2的重量仅为两克，它使用一种脑电图来记录大脑活动。研究人员首先训练26只信鸽将一座阁楼当做自己的家。随后，他们在这些鸟类的大脑中植入微电极，并将其与Neurologger2相连。研究人员为这些信鸽配备了全球定位系统监视器，最后在距离阁楼10公里到30公里沿线的不同地点放飞了这些信鸽。研究人员在最近的《当代生物学》杂志网络版上报告了这一研究成果。
在这些信鸽飞回家后，研究人员取下相关装置，随后将鸟类大脑活动的记录与它们当时的位置进行了比较。Vyssotski发现，当信鸽沿着地标飞行时，例如一条熟悉的高速公路、它们大脑中的高频脑电波突然变得更加密集。研究人员同时注意到，与飞越一片没什么特色的水面相比，这些信鸽在飞过熟悉的地形时，高频脑电波会产生更多的峰值。Vyssotski推测，高频脑电波可能与鸟类识别已知的地点有关。
从事动物认知研究的美国达勒姆市新罕布什尔大学的Brett Gibson指出，这项研究提供了鸟类在飞行期间大脑内部的一个有趣景象。Gibson说：“尽管如此，我还是想知道这些大脑活动是否仅仅与导航有关，还是更广泛地涉及到事物的认知，以及到底是什么触发了这些活动。”而这正是Vyssotski的研究小组在接下来试图解释的问题。
从事鹦鹉研究的美国哈佛大学的心理学家Irene Pepperberg也十分热衷于这项新的技术。她说：“这是第一篇论文，表明我们能够利用一种实时系统来分析鸟类大脑的神经生物学特征。”Pepperberg表示：“鸟类大脑究竟是如何处理大量不同类型的感官信息的，这项技术真的能够告诉我们很多。”
而Neurologger2也并非仅仅适用于鸟类。Vyssotski如今正在同世界各地研究树懒、小鼠和海洋哺乳动物——例如海豚和海豹——的科学家进行合作。（生物谷Bioon.com）
生物谷推荐原始出处：
Current Biology, 25 June 2009 doi:10.1016/j.cub.2009.05.070
EEG Responses to Visual Landmarks in Flying Pigeons
Alexei L. Vyssotski1,7,,,Giacomo Dell'Omo1,Gaia Dell'Ariccia1,Andrei N. Abramchuk2,Andrei N. Serkov1,3,Alexander V. Latanov3,Alberto Loizzo4,David P. Wolfer1,5,6andHans-Peter Lipp1
1 Institute of Anatomy, University of Zurich, Winterthurerstr. 190, 8057 Zurich, Switzerland
2 Moscow Institute of Electronic Technology, Passage 4806, Bldg. 5, 124498 Zelenograd, Russia
3 Chair of Higher Nervous System Activity, Faculty of Biology, Moscow State University, Vorobievi Gori 1-12, 119992 Moscow, Russia
4 Department of Therapeutic Research and Medicines Evaluation, Istituto Superiore di Sanita, 299 Viale Regina Elena, 00161 Rome, Italy
5 Institute of Human Movement Sciences and Sport, ETH Zurich, Winterthurerstr. 190, 8057 Zurich, Switzerland
6 Zurich Center for Integrative Human Physiology, University of Zurich, Winterthurerstr. 190, 8057 Zurich, Switzerland
7 Present address: Institute of Neuroinformatics, University of Zurich/ETH Zurich, Winterthurerstr. 190, 8057 Zurich, Switzerland
GPS analysis of flight trajectories of pigeons can reveal that topographic features influence their flight paths. Recording electrical brain activity that reflects attentional processing could indicate objects of interest that do not cause changes in the flight path. Therefore, we investigated whether crossing particular visual landmarks when homing from a familiar release site is associated with changes in EEG.Birds carried both data-loggers for recording GPS position and EEG during flight. First, we classified characteristic EEG frequencies of caged birds and found five main bands: A: 03, B: 312, C: 1260, D: 60130, and E: 130200 Hz. We analyzed changes in these activity bands when pigeons were released over sea (a featureless environment) and over land. Passing over the coastline and other prominent landmarks produced a pattern of EEG alterations consisting of two phases: activation of EEG in the high-frequency bands (D and/or E), followed by activation of C.Overlaying the EEG activity with GPS tracks allowed us to identify topographical features of interest for the pigeons that were not recognizable by distinct changes of their flight path.We provide evidence that EEG analysis can identify landmarks and objects of interest during homing. Middle-frequency activity (C) reflects visual perception of prominent landmarks, whereas activation of higher frequencies (D and E) is linked with information processing at a higher level. Activation of E bands is likely to reflect an initial process of orientation and is not necessarily linked with processing of visual information.
