A brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as vision. It is the most complex organ in a vertebrate's body. In a human, the cerebral cortex contains approximately 14–16 billion neurons, and the estimated number of neurons in the cerebellum is 55–70 billion. Each neuron is connected by synapses to several thousand other neurons. These neurons typically communicate with one another by means of long fibers called axons, which carry trains of signal pulses called action potentials to distant parts of the brain or body targeting specific recipient cells.
The hypothalamus is a portion of the brain that contains a number of small nuclei with a variety of functions. One of the most important functions of the hypothalamus is to link the nervous system to the endocrine system via the pituitary gland. The hypothalamus is located below the thalamus and is part of the limbic system. In the terminology of neuroanatomy, it forms the ventral part of the diencephalon. All vertebrate brains contain a hypothalamus. In humans, it is the size of an almond.
Bird vocalization includes both bird calls and bird songs. In non-technical use, bird songs are the bird sounds that are melodious to the human ear. In ornithology and birding, songs are distinguished by function from calls.
Glia, also called glial cells or neuroglia, are non-neuronal cells in the central nervous system and the peripheral nervous system that do not produce electrical impulses. They maintain homeostasis, form myelin in the peripheral nervous system, and provide support and protection for neurons. In the central nervous system, glial cells include oligodendrocytes, astrocytes, ependymal cells, and microglia, and in the peripheral nervous system glial cells include Schwann cells and satellite cells. They have four main functions: (1) to surround neurons and hold them in place; (2) to supply nutrients and oxygen to neurons; (3) to insulate one neuron from another; (4) to destroy pathogens and remove dead neurons. They also play a role in neurotransmission and synaptic connections, and in physiological processes like breathing. While glia were thought to outnumber neurons by a ratio of 10:1, recent studies using newer methods and reappraisal of historical quantitative evidence suggests an overall ratio of less than 1:1, with substantial variation between different brain tissues.
Adult neurogenesis is the process in which neurons are generated from neural stem cells in the adult. This process differs from prenatal neurogenesis.
Known as the Society finch in North America and the Bengalese finch elsewhere, Lonchura striata domestica is a domesticated finch not found in nature. It became a popular cage and trade bird after appearing in European zoos in the 1860s where it was imported from Japan. There have been many theories of the origin of domestication for the Bengalese finch, and we now know it took place primarily in Japan. Coloration and behavior were modified through centuries of selection in Asia, then later in Europe and North America. Another aspect of the Bengalese finch that evolved throughout the centuries is song production. Extensive research has been done and continues to be done on the different ways Bengalese finch songs are produced, how they are processed in the brain, what characteristics of the songs are preferred by females, and how their songs compare to the also commonly studied zebra finch.
Animal song is not a well-defined term in scientific literature, and the use of the more broadly defined term 'vocalizations' is in more common use. Song generally consists of several successive vocal sounds incorporating multiple syllables. Some sources distinguish between simpler vocalizations, termed “calls”, reserving the term “song” for more complex productions. Song-like productions have been identified in several groups of animals, including cetaceans, avians (birds), anurans (frogs), and humans. Social transmission of song has been found in groups including birds and cetaceans.
The domestic canary, often simply known as the canary, is a domesticated form of the wild canary, a small songbird in the finch family originating from the Macaronesian Islands.
Neuropoiesis is the process by which neural stem cells differentiate to form mature neurons, astrocytes, and oligodendrocytes in the adult mammal. This process is also referred to as adult neurogenesis.
HVC is a nucleus in the brain of the songbirds necessary for both the learning and the production of bird song. It is located in the lateral caudal nidopallium and has projections to both the direct and the anterior forebrain pathways.
Fernando Nottebohm is a neuroscientist and is the Dorothea L. Leonhardt Professor at Rockefeller University as well as being head of the Laboratory of Animal Behavior and director of the Field Research Center for Ecology and Ethology.
Erich Jarvis is an American professor at The Rockefeller University. He leads a team of researchers who study the neurobiology of vocal learning, a critical behavioral substrate for spoken language. The animal models he studies include songbirds, parrots, and hummingbirds. Like humans, these bird groups have the ability to learn new sounds and pass on their vocal repertoires culturally, from one generation to the next. Jarvis focuses on the molecular pathways involved in the perception and production of learned vocalizations, and the development of brain circuits for vocal learning.
Passerine birds produce song through the vocal organ, the syrinx, which is composed of bilaterally symmetric halves located where the trachea separates into the two bronchi. Using endoscopic techniques, it has been observed that song is produced by air passing between a set of medial and lateral labia on each side of the syrinx. Song is produced bilaterally, in both halves, through each separate set of labia unless air is prevented from flowing through one side of the syrinx. Birds regulate the airflow through the syrinx with muscles—M. syringealis dorsalis and M. tracheobronchialis dorsalis—that control the medial and lateral labia in the syrinx, whose action may close off airflow. Song may, hence, be produced unilaterally through one side of the syrinx when the labia are closed in the opposite side.
Vocal learning is the ability to modify acoustic and syntactic sounds, acquire new sounds via imitation, and produce vocalizations. "Vocalizations" in this case refers only to sounds generated by the vocal organ as opposed to by the lips, teeth, and tongue, which require substantially less motor control. A rare trait, vocal learning is a critical substrate for spoken language and has only been detected in eight animal groups despite the wide array of vocalizing species; these include humans, bats, cetaceans, pinnipeds, elephants, and three distantly related bird groups including songbirds, parrots, and hummingbirds. Vocal learning is distinct from auditory learning, or the ability to form memories of sounds heard, a relatively common trait which is present in all vertebrates tested. For example, dogs can be trained to understand the word "sit" even though the human word is not in its innate auditory repertoire. However, the dog cannot imitate and produce the word "sit" itself as vocal learners can.
The study of memory incorporates research methodologies from neuropsychology, human development and animal testing using a wide range of species. The complex phenomenon of memory is explored by combining evidence from many areas of research. New technologies, experimental methods and animal experimentation have led to an increased understanding of the workings of memory.
Masakazu "Mark" Konishi was a Japanese neurobiologist, known for his research on the neuroscience underlying the behavior of owls and songbirds.
Conspecific song preference is the ability songbirds require to distinguish conspecific song from heterospecific song in order for females to choose an appropriate mate, and for juvenile males to choose an appropriate song tutor during vocal learning. Researchers studying the swamp sparrow have demonstrated that young birds are born with this ability, because juvenile males raised in acoustic isolation and tutored with artificial recordings choose to learn only songs that contain their own species' syllables. Studies conducted at later life stages indicate that conspecific song preference is further refined and strengthened throughout development as a function of social experience. The selective response properties of neurons in the songbird auditory pathway has been proposed as the mechanism responsible for both the innate and acquired components of this preference.
Endogenous regeneration in the brain is the ability of cells to engage in the repair and regeneration process. While the brain has a limited capacity for regeneration, endogenous neural stem cells, as well as numerous pro-regenerative molecules, can participate in replacing and repairing damaged or diseased neurons and glial cells. Another benefit that can be achieved by using endogenous regeneration could be avoiding an immune response from the host.
Donald Eugene Kroodsma is an American author and ornithologist, one of the world's leading experts on the science of birdsong.
Constance Scharff, Ph.D., is a German zoologist and neuroethologist and Professor at the Free University of Berlin. She is particularly notable for her research on birdsong, neurogenesis and regeneration.