Class 6, September 30:
Neurobiology of acoustic communication
1. You will be able to describe brain regions involved in vocal communication and compare and contrast neural pathways for several taxonomic groups.
First, read this short popular science article:
Next, read through the following summaries and carefully study the diagrams. Get in touch with me with any questions or if something doesn't make sense. Once you've read through the article and this page, answer the thought questions on Piazza: https://piazza.com/class/id62cohuq7d2p8.
Overview of neural pathways for signal production – Across animal taxa, signal production process begins when environmental cues (including daily and seasonal changes in light levels, temperature, social stimuli and other input from multiple senses) trigger release of hormones from several endocrine centers in the brain and peripheral structures in the body (adrenal glands, testes, ovaries, etc.). Brain regions that have receptors for these hormones or receive direct innervation from neuroendocrine centers are stimulated and as a result, they send impulses via neuronal connections to other brain regions that determine several characteristics (like initiation, duration, frequency and timing) of the motor output. Brain regions involved in the production of a certain type of acoustic signal can make up a neural network. Motor neurons are the last node in the network, and they relay the motor command to nerves that in turn innervate sound producing muscles. Nerve impulses feedback between brain regions and can connect with regions sending and receiving auditory input and with regions involved in memory. Feedback and modulation from hormones are possible at several levels of the central network as well as peripheral structures.
Overview and figures below compiled with help from the Andrew Bass’s lab in NBB. Much of what we know about the basic neurobiology of acoustic communication comes from their research (http://www.nbb.cornell.edu/Basslab/index.html).
Here is a diagram of the brain of a Midshipman fish. Each colored area is a different set of nerve cell nuclei that represent a node. Together, the nodes make up the vocal central pattern generator network.
Diagram 1 (from Chagnaud, B. P., Baker, R., & Bass, A. H. (2011). Vocalization frequency and duration are coded in separate hindbrain nuclei. Nature Communications, 2, 346–11. http://doi.org/10.1038/ncomms1349)
In fish, we understand the function of each node and how each influences signal characteristics:
Diagram 2 (from Chagnaud, B. P., Baker, R., & Bass, A. H. (2011). Vocalization frequency and duration are coded in separate hindbrain nuclei. Nature Communications, 2, 346–11. http://doi.org/10.1038/ncomms1349)
The network is similar for amphibians and the nodes likely have similar functions (note: this diagram is oriented in the opposite direction):
Diagram 3 (From Bass, A. H., & Remage-Healey, L. (2008). Central pattern generators for social vocalization: Androgen-dependent neurophysiological mechanisms. Hormones and Behavior, 53(5), 659–672. http://doi.org/10.1016/j.yhbeh.2007.12.010.)
In birds, the story gets a bit more complicated.
Diagram 4 (from Bolhuis et al. Nature Reviews Neuroscience 7, 347–357 (May 2006) | doi:10.1038/nrn1904):
Diagram 5 (from Brenowitz, E. A., Margoliash, D., & Nordeen, K. W. (2007). An introduction to birdsong and the avian song system, J Neurobiol. 1997 Nov. 33(5):495-500).
And in mammals (especially primates), even more complicated:
Diagram 6 (from Jurgens, U. (2002). Neural pathways underlying vocal control. Neuroscience and Biobehavioral Reviews, 26(2), 235–258):