(Abstract/intro paragraphs)
Communication is an incredibly important subject for biologists that study animal behavior, as it reveals key interactions between organisms and their environments. The way an animal communicates has implications in survival, mating, learning, adaptation, and evolution. Communication in its most basic form consists of a sender relaying a signal to a receiving group or individual with a goal in mind. This goal could be attracting a mate, alerting others of resources, or marking territory. The sender expects a certain outcome or response, while the receiver must process the signal and respond appropriately. This sender-receiver model system is how communication typically occurs in almost all organisms, whether through vocalizations, chemical messengers, or physical movement.
Communication behaviors are distinct and recognizable, making it easy to study them observationally. Therefore, a lot is known about the signals that animals produce, such as the vocalizations that songbirds send to attract mates or the honeybee waggle dance to communicate the location of resources to its colony. While it is important to study these signals, we cannot begin to understand why or how these behaviors occur unless we know what the signals mean, i.e. how they are processed and what behavioral response is elicited in the receiver. The Gentner and Nieh Labs at UC San Diego study these questions using songbirds and honeybees as models for understanding communication behaviors.
Birds, Brains, and Computers
Dr. Timothy Gentner, a neuroscience professor at UC San Diego, studies songbirds to bridge the neuroscience field’s understanding of communication behaviors with their underlying neural mechanisms. Specifically, his lab observes how songbirds learn, understand, and process auditory information as they receive it. Much like human speech, a songbird’s songs are not sequences of sonic events but syllabic patterns. Some birds, like starlings, have flexible vocal repertoires and communicate in ways similar to human language. For example, human understanding is more concerned with how words fit together and what they mean rather than focusing on individual words. Similarly, starlings have a vocabulary of certain sounds and pull from them to create meaning in their songs. Although vocal communication is common among animals, few learn during development and have such an advanced level of learned vocal flexibility, making songbirds an excellent model for studying human communication in a lab.
In collaboration with Dr. Vikash Gilja at UC San Diego’s Jacobs School of Engineering, Dr. Gentner’s lab is working to recreate a bird’s song from its neural activity. This is accomplished by recording neural traces from a region called HVc, which is responsible for learning and producing song, and a motor nucleus RA, which is needed for the motor output of song production. Mathematical models allow neural recordings to be mapped to changes in the vocal production patterns that correspond to certain sounds. The sounds can then be recreated based on the neural outputs observed. The next step for these labs is to produce signals in real time to create an artificial song while the bird thinks it is singing itself.
Dr. Gilja and Dr. Gentner are interested in how this idea can be applied to communication brain-computer interfaces (BCIs) in humans, specifically for speech prosthetics in individuals that cannot communicate vocally. Currently, there is a lot of active research on motor-limb prosthetics and BCIs, while communication interfaces still have a long way to go. The current gold standard speech prostheses still generate frequent errors and do not grant these individuals the same vocal freedom and repertoire that most humans (and songbirds!) have.
Lauren Stanwicks, a Ph.D student in the Gentner Lab, researches communication BCIs and how sensory information integrates into pathways underlying communication in real time. In particular, she studies how animals adapt their communication vocalizations based on incoming sensory information as they speak. She hypothesizes that multiple underlying mechanisms are responsible for integrating external information into a motor output, like a vocal adjustment. For example, if you get interrupted by a loud noise while speaking, such as a car or airplane, you would naturally change your speech to accommodate this change. The same is true if you make an error while speaking and have to self-correct. Lauren either plays white noise at a starling to simulate an auditory interruption or puts the starling in a helium-oxygen tank, which alters the pitch of the starlings’ song, inducing a self-made error. She records and compares neural signals from starlings as they sing, either with an external auditory stimulus or with direct manipulations to the birds’ vocalizations. Her research provides insight into how sensory integration pathways translate to vocal flexibility and adaptability, something that current communication BCIs lack.
Hive Harmony
The evolution of communication behaviors has led to remarkably complex signals like birdsong, which provides an advantage in sexual selection. Another consideration for biologists who study communication is how a given behavior functions within a society or group as a whole. Dr. James Nieh at UC San Diego researches honeybees, an excellent model for this type of communication, thanks to their extremely sophisticated societies and efficient communication behaviors. They are eusocial, meaning that societies involve multiple generations living together, collective nurturing of young ones, and a structured system in which different groups have specialized roles. For bees, communication is key to allocating tasks, locating resources, and maintaining a healthy hive.
The honeybee ‘waggle dance’ serves as a remarkable tool for communication, as it facilitates transmission of vital details concerning resource location. At first glance, a honeybee shaking side to side seems like a simple behavior. However, by changing features of their dance, they can convey crucial information about the distance, direction, and quality of various resources like flowers, new nest sites, or water. To encode this information accurately, dancing requires memory, precise movements, and real-time feedback. During the dance, the dancer rapidly moves her body in a figure-eight pattern. The angle of the waggle relative to the sun indicates the direction of the food source, the duration of the dance corresponds to the distance, and the number of repetitions of the dance relates to resource quality. The Nieh lab discovered that when colonies are older and larger, bees tend to signal high quality food sources more prominently by increasing the number of runs per dance and performing shorter return phases between waggles. This adaptability ensures that the colony effectively distributes its foraging endeavors and maximizes its resource intake.
Ashley Kim, a Ph.D. student in the Nieh Lab, studies a different signal in bees called the shaking signal. While the waggle dance informs conspecifics about resources, the shaking signal regulates task reallocation among workers. Efficient task allocation is important for honeybees, as they live in colonies with thousands of individuals. The division of labor ensures the colony’s efficiency and survival in changing environmental conditions, making it an important area of study for populations that are declining due to environmental stressors. For example, during periods of heat stress, bees may need to switch from foraging to cooling the hive. Kim uses 24-hour cameras to constantly monitor bee activity, as well as a robot that mimics the shaking signal to elicit natural responses in a controlled way. She then observes the behaviors that occur during and after a worker receives a shaking signal, its involvement in task reallocation can be better understood.
The Nieh Lab’s work also provides insights into broader biological and behavioral paradigms. Species or population-level considerations, such as how hives adapt to environmental stressors, can be better understood through the lens of communication and social behaviors. Sociality within a honey bee colony is a testament to the complexity of nature’s communication systems, and the adaptability of organisms in response to dynamic environmental challenges.
Beyond Birds and Bees
Though the research from these two groups have wildly different approaches and applications, the underlying questions are the same: how and why do animals learn to communicate, what aspects of communication are important for relaying a message, and what happens when a communication signal is received and processed? These questions are universally important for understanding behavior, whether it is in bees, birds, humans, or other species. Studying how animals learn and adapt their behaviors for effective communication can uncover much about cognition and learning and memory pathways. Ecological interactions help to understand survival strategies and population dynamics. Finally, understanding communication’s underlying mechanisms can provide a better quality of life, through advancements in communication technology and understanding communication disorders. As the Gentner and Nieh Laboratories study the complexities of communication, they pave the way for a deeper understanding of this essential aspect of animal life.
Pull Quotes Suggestions
- Communication behaviors are distinct and recognizable
- …making songbirds an excellent model for studying human communication in a lab.
- [honeybees] can convey crucial information about the distance, direction, and quality of various resources
- Understanding communication’s mechanisms can provide a better quality of life.
Figure Captions
- Song synthesis, process of translating neural patterns into songbird vocalizations. Step toward advanced speech prosthetics.
- The honeybee’s waggle dance, this illustration highlights how the angle of the dance communicates the direction of resources relative to the sun.
- A honeybee’s dance duration indicates the distance to a food source, with longer dances signifying farther locations.
- Depicting a starling’s neural response to auditory changes, illustrating the adaptability of communication.