Neuroscientists develop models to identify internal states of the brain

November 25, 2019

Imagine an attractive person walking toward you. Do you look up and smile? Turn away? Approach but avoid eye contact? The setup is the same, but the outcomes depend entirely on your "internal state," which includes your mood, your past experiences, and countless other variables that are invisible to someone watching the scene.

So how can an observer decode internal states by watching outward behaviors? That was the challenge facing a team of Princeton neuroscientists. Rather than tackling the intricacies of human brains, they investigated fruit flies with fewer behaviors and, one imagines, fewer internal states. They built on prior work studying the songs and movements of amorous Drosophila melanogaster males.

"Our previous work was able to predict a portion of singing behaviors, but by estimating the fly's internal state, we can accurately predict what the male will sing over time as he courts a female," said Mala Murthy, a professor of neuroscience and the senior author on a paper appearing in today's issue of Nature Neuroscience with co-authors Jonathan Pillow, a professor of psychology and neuroscience, and PNI postdoctoral research fellow Adam Calhoun.

Their models use observable variables like the speed of the male or his distance to the female. The researchers identified three separate types of songs, generated by wing vibration, plus the choice not to sing. They then linked the song decisions to the observable variables.

The key was building a machine learning model with a new expectation: animals don't change their behaviors at random, but based on a combination of feedback that they are getting from the female and the state of their own nervous system. Using their new method, they discovered that males pattern their songs in three distinct ways, each lasting tens to hundreds of milliseconds. They named each of the three states: "Close," when a male is closer than average to a female and approaching her slowly; "Chasing," when he is approaching quickly; and "Whatever," when he is facing away from her and moving slowly. The researchers showed that these states correspond to distinct strategies, and then they identified neurons that can control how the males switch between strategies.

"This is an important breakthrough," said Murthy. "We anticipate that this modeling framework will be widely used for connecting neural activity with natural behavior."
"Unsupervised identification of the internal states that shape natural behavior" by Adam J. Calhoun, Jonathan W. Pillow and Mala Murthy appears in the Nov. 25 issue of the journal Nature Neuroscience (DOI: 10.1038/s41593-019-0533-x. This work was funded by the Simons Foundation (AWD494712, AWD1004351, and AWD543027), the Brain Research through Advancing Innovative Neurotechnologies (BRAIN) Initiative at the National Institutes of Health (NS104899), and the Howard Hughes Medical Institute.

Princeton University

Related Neuroscience Articles from Brightsurf:

Researchers rebuild the bridge between neuroscience and artificial intelligence
In an article in the journal Scientific Reports, researchers reveal that they have successfully rebuilt the bridge between experimental neuroscience and advanced artificial intelligence learning algorithms.

The evolution of neuroscience as a research
When the first issue of the JDR was published, the field of neuroscience did not exist but over subsequent decades neuroscience has emerged as a scientific field that has particular relevance to dentistry.

Diabetes-Alzheimer's link explored at Neuroscience 2019
Surprising links exist between diabetes and Alzheimer's disease, and researchers are beginning to unpack the pathology that connects the two.

Organoid research revealed at Neuroscience 2019
Mini-brains, also called organoids, may offer breakthroughs in clinical research by allowing scientists to study human brain cells without a human subject.

The neuroscience of autism: New clues for how condition begins
UNC School of Medicine scientists found that a gene mutation linked to autism normally works to organize the scaffolding of brain cells called radial progenitors necessary for the orderly formation of the brain.

Harnessing reliability for neuroscience research
Neuroscientists are amassing the large-scale datasets needed to study individual differences and identify biomarkers.

Blue Brain solves a century-old neuroscience problem
In a front-cover paper published in Cerebral Cortex, EPFL's Blue Brain Project, a Swiss Brain Research Initiative, explains how the shapes of neurons can be classified using mathematical methods from the field of algebraic topology.

Characterizing pig hippocampus could improve translational neuroscience
Researchers have taken further steps toward developing a superior animal model of neurological conditions such as traumatic brain injury and epilepsy, according to a study of miniature pigs published in eNeuro.

The neuroscience of human vocal pitch
Among primates, humans are uniquely able to consciously control the pitch of their voices, making it possible to hit high notes in singing or stress a word in a sentence to convey meaning.

Study tackles neuroscience claims to have disproved 'free will'
For several decades, some researchers have argued that neuroscience studies prove human actions are driven by external stimuli -- that the brain is reactive and free will is an illusion.

Read More: Neuroscience News and Neuroscience Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to