Robo-pigeon is a special robot that controls the behavior of a live pigeon by applying electrical stimulation to its brain nerve or muscle tissue. The Frontal Region of the Mesopallium (FRM) is the commonly used stimulus region for robot pigeons at present, and the electric stimulation FRM region is mainly used for the steering control of pigeons. This study devised an experimental paradigm aimed at stimulating the FRM brain region to induce spatial cognition and facilitate memory formation in pigeons. During the experiment, pigeons were placed inside a specifically marked circle, and whenever the pigeon tried to leave the circle, its FRM brain region was electrically stimulated. Experiments have shown that pigeons can form a solid spatial memory of the marked area after about a week, and a small amount of stimulation can cause pigeons to move within a certain area. This study introduces a novel control function for the robot pigeon achieved through electrical stimulation of the FRM brain region, thereby broadening the application scope of the robo-pigeon.
Animal robot is a new type of robot, which is diferent from traditional robots in both structure
and principle. Animal robot is based on animals and stimulates its neural targets through
electrical signals generated by electronic devices to achieve artificial regulation of animal
movement behavior [
Current research on animal robots covers many species, such as insects [
The FRM is an important region in the brain of pigeons, located in the prefrontal part of the
mesotemporal cortex. This region plays a key role in the regulation of cognition and behavior
in pigeons. Studies have shown that FRM are involved in the navigation, memory and
decisionmaking processes of pigeons in complex environments. Specifically, it plays a crucial role in
controlling movement and postural regulation in birds because it is a group of neurons widely
connected to the spinal cord and cerebral cortex, and it is these neurons that are responsible
for the processing and integration of motor instructions and regulate the motor behavior of
pigeons by controlling the output of descending motor pathways [
Four adult pigeons (Columba livia, two males and two females, 450-550 g) were selected for this experiment, and their numbers were 007, 044, 068, and 075. Each pigeon was kept in solitary confinement and fed only during the experiment, which was conducted at a fixed time each day. Before the experiment began, the pigeons had their wings clipped and lost their ability to fly. Approval for all experiments in this study was obtained from the Life Science Ethical Review Committee of Huanghuai University (no. 20231103003).
Before the experiment, electrodes were surgically implanted into the FRM brain region. After the surgery, the pigeons recovered for seven days, and then the experiment was carried out.
The experiments in this study were all conducted in a 3×3×0.7 m unroofed frame, as shown in Figure 1b. An appropriate amount of pigeon food (mainly soybean) was evenly distributed in the experimental site, and pigeons could forage freely in the site. There was a 1.5m diameter circle in the center area of the site, and the circle was surrounded by 18mm wide electrical insulation tape.
The experiment was divided into three stages. In the first stage, two days of environmental adaptation were carried out, during which pigeons were put into the field to forage freely until they stopped foraging. This process was mainly to familiarize the pigeons with the environment of the field, enable them to adapt to the subsequent experiment more quickly, and collect the movement tracks of pigeons without intervention. After the end of adaptation, the stage with the longest duration and the participation of electrical stimulation is carried out. The feeding range of pigeons is controlled in the central region. If there is a behavior of circling, the FRM brain region will be stimulated by electrical stimulation. In the third stage, the electric stimulation was stopped, the pigeons were put into the experimental field to forage freely, and the movement of the pigeons was observed and recorded.
Adult pigeons over 6 months of age (450-550 g, male and female) were first anesthetized with
3% pentobarbital sodium (0.12 mL/100g) into the chest muscle. After anesthesia, the head fur of
the pigeons was shaved. A mixture of 2% lidocaine reagent and 5% epinephrine reagent was
injected subcutaneously into the operating area for further local anesthesia. After the pain
reflex disappeared, the pigeon’s head was placed on a custom-made stereotaxic stand [
The neural stimulator (size 1.8×2.1×1.2 cm, weight 5 g) and wireless neural stimulation controller
(Figure 1f) were designed by our team, including wireless communication module, control
module, constant current source excitation module and battery. Through the wireless neural
stimulation controller, the stimulation parameters of the neural stimulator can be controlled,
and the parameters are transmitted to the wireless communication module of the stimulator
through radio frequency. The control module enables the constant current source stimulation
module to generate stimulus signals corresponding to the parameters received by the wireless
communication module [
We need to find the stimulus parameters corresponding to each pigeon to achieve the best
stimulus efect. The current intensity is 0.6 mA, the number of pulse train is 3, the duty cycle
is 50%, and the frequency is 100 Hz (Figure 1e). The stimulation parameters are constantly
adjusted, so that the steering Angle of pigeons is between 120° and 180° to achieve the best
efect [
First of all, the first stage experiment was carried out. Pigeons were allowed to adapt in the experimental field for two days. The movement trajectory of the first day during the adaptation was shown in Figure 3a. In the process of adaptation, through the statistics of the movement distance of pigeons per minute, it was found that pigeons had the longest movement distance in the first ten minutes and showed a strong willingness to exercise. Therefore, in the follow-up experiment, we only counted the data of the first ten minutes.
After acclimating to the field, we took the next step of the experiment, restricting the movement of the pigeons to the designated area. Every time the pigeon tried to come out of the circle, we gave it an electrical stimulus. During the nine-day experiment, the trajectory of 007 during the first ten minutes of daily foraging is shown in Figure 2a. Over time, the pigeons became less and less willing to confront and try outside the circle and gradually gave in to foraging only inside the circle. Less and less electrical stimulation occurs with each experiment (Figure 2b). After nine days, the number of stimuli dropped to zero for three pigeons, and these three pigeons reached the maximum residence time in the area, and they were able to stay in the area for the entire duration of the experiment.
Next, we conducted the last stage of the experiment, cancelling the electrical stimulation in the previous stage and no longer interfering with the movement of pigeons, and observed the movement trajectory of pigeons at this time in Figure 3b, 3c. At this time, the pigeons mostly moved within the circle, in sharp contrast to the trajectory of the first stage.
In the experiments we observed individual diferences between diferent pigeons. Over the course of the electrical stimulation experiment, some pigeons were more responsive to the electrical stimulation, showing faster adaptation and reduced attempts to step out of their enclosure. Other pigeons showed more resistance and probing behavior. Despite individual diferences, all subjects formed stable spatial memory in a specific region, indicating that electrical stimulation has a certain universality and repeatability in spatial memory formation.
This study successfully induced the formation of spatial memory of specific regions in pigeons by designing experiments and stimulating FRM brain region with electrical stimulation technology. The experimental results showed that after a certain period of intervention with electrical stimulation of FRM brain region, pigeons’ residence time in the specific region increased significantly, and their behavior of exploring outside the circle gradually decreased, showing stable memory of the specific region. This finding not only provides new experimental evidence for the study of the formation mechanism of spatial memory in animals, but also explores the new function of FRM brain region in the movement regulation of robo-pigeon.
In this study, pigeons did not undergo any training in the first stage, when they had the largest foraging range and moved the farthest distance, and most tracks were distributed at the edge of the site, with little activity in the center (Figure 3a). The trajectory of this stage is in sharp contrast to that of subsequent stages, which is a strong evidence that pigeons have generated spatial memories of specific areas. The above experiments are suficient to prove that the FRM brain region can be electrically stimulated to make pigeons generate spatial memory for a specific region and stay in it for a long time, which expands the application scenario of animal robots in real life.
In this study, electrical stimulation was used as an intervention method, which has the advantages of simple operation and obvious efect. By fine-tuning the electrical stimulation parameters, we succeeded in controlling the pigeons’ stay behavior in a specific area. However, electrical stimulation technology also has some limitations, such as the stimulation efect may be afected by individual diferences and environmental factors, which need to be further studied and optimized.
In this experiment, we observed that pigeons gradually showed a learned helplessness
after experiencing multiple electrical stimuli, that is, giving up and reacting negatively to
uncontrollable situations. This psychological phenomenon has been widely studied in the
ifeld of animal behavior and psychology [
In addition to the FRM used in this study, there are many other control nuclei present in pigeons’ brains that may play an important role in memory and cognition of specific regions of space, which can be electrically stimulated to regulate pigeons. For example, Substantia grisea et ifbrosa periventricularis (SGP), one of the brain regions closely related to navigation and spatial cognition in birds, is involved in the formation of landmark navigation and path memory, and stimulation of SGP can produce fear. The Lateral Hypothalamus (LHy) is involved in learning and memory in birds, especially spatial memory and landmark learning, and stimulation of LHy can produce pleasant emotions. Therefore, in future studies, we can try to use these diferent control nuclei to regulate the behavior of pigeons, in order to further study the memory mechanism of pigeons in specific regional space. By manipulating these nuclei, it is possible to explore their influence on pigeons’ spatial cognition and behavioral choices, as well as their functions and interactions in diferent contexts. This research contributes to a more comprehensive understanding of the neural mechanism of spatial memory in pigeons, and provides theoretical basis and practical guidance for designing more efective control methods and developing more intelligent robotic pigeon systems. At the same time, the study of other control nuclei in pigeon brain will also help to reveal the deeper neural basis of bird spatial cognition, and provide new research directions and ideas for the development of animal cognitive behavior and neuroscience.
In this paper, a new control method of robo-pigeon is developed through the study of pigeon
movement regulation by electrical stimulation of FRM brain region, which solves the need of
animal robot staying in a specific area for a long time in practical applications, such as disaster
area search and rescue and natural environment monitoring by robo-pigeon. The formation
process and representation of cognitive behavior of birds are analyzed, which provides a
new research idea for the study of animal behavior. Looking forward, the integration of
artificial intelligence (AI) with animal robotics holds tremendous potential. AI can enable more
sophisticated and autonomous decision-making capabilities, allowing robo-pigeons and other
animal robots to perform complex tasks with greater eficiency and adaptability [
This work was supported by the National Natural Science Foundation of China (62003146); Program for Science & Technology Innovation Talents in Universities of Henan Province (24HASTIT041); Training Plan for Young Backbone Teachers in Higher Education Institutions of Henan Province (2023GGJS156).