11:53am Monday 23 October 2017

A fascinating new study combines snakes with brain imaging in order to uncover neural mechanisms associated with ‘courage’.

The research, published by Cell Press in the June 24th issue of the journal Neuron, provides fascinating insight into what happens in the brain when an individual voluntarily performs an action opposite to that promoted by ongoing fear and may even lead to new treatment strategies for those who exhibit a failure to overcome their fear.

Although there is a substantial body of research examining brain mechanisms associated with fear, far less is known about the brain mechanisms associated with courage, defined here as action in the face of ongoing fear. ‘By gauging properly defined actions of either overcoming fear or succumbing to it in an acute controllable fearful situation, one can render certain neural substrates of courage amenable to investigation in a brain research laboratory setting,’ explains senior study author, Dr. Yadin Dudai from the Weizmann Institute of Science in Rehovot, Israel.

To study the neural mechanisms associated with moments of real-life courage, Dr. Dudai, Uri Nilli and their colleagues devised an experimental paradigm where participants had to choose whether to advance an object closer or farther away from them while their brain was scanned with functional magnetic resonance imaging (fMRI). The objects used in the study were either a toy bear or a live corn snake. Prior to the study, participants were categorized as ‘fearful’ or ‘fearless’ depending on how they responded to a validated snake-fear questionnaire. 

As might be expected, the researchers observed that both high subjective fear and high somatic arousal were associated with succumbing to fear and moving the snake farther away.  However, somewhat surprisingly, bringing the snake closer was associated with either high somatic arousal (assessed by skin conductance response) accompanied by low subjective fear (assessed by fear self-ratings) or high subjective fear accompanied by low somatic arousal.

Brain imaging during the task revealed that activity in a brain region called the subgenual anterior cingulate cortex (sgACC) correlated positively with the level of subjective fear when choosing to act courageously but not when choosing to succumb to fear. Further, activity in a series of temporal lobe structures was decreased when the level of fear increased and the individual chose to overcome their fear.

‘Our results propose an account for brain processes and mechanisms supporting an intriguing aspect of human behavior, the ability to carry out a voluntary action opposite to that promoted by ongoing fear, namely courage,’ concludes Dr. Dudai.  ‘Specifically, our findings delineate the importance of maintaining high sgACC activity in successful efforts to overcome ongoing fear and point to the possibility of manipulating sgACC activity in therapeutic intervention in disorders involving a failure to overcome fear.’

Prof. Yadin Dudai’s research is supported by the Norman and Helen Asher Center for Human Brain Imaging; the Nella and Leon Benoziyo Center for Neurological Diseases; the Nella and Leon Benoziyo Center for Neurosciences; the Carl and Micaela Einhorn-Dominic Center for Brain Research; the Rowen Family Fund for Neurocognitive Research; the Abe and Kathryn Selsky Memorial Research Project; Miel de Botton Aynsley, UK; and Dr. Henry Kaminer, New York, NY. Prof. Dudai is the incumbent of the Sara and Michael Sela Professorial Chair of Neurobiology.

The Weizmann Institute of Science in Rehovot, Israel, is one of the world’s top-ranking multidisciplinary research institutions. Noted for its wide-ranging exploration of the natural and exact sciences, the Institute is home to 2,600 scientists, students, technicians and supporting staff. Institute research efforts include the search for new ways of fighting disease and hunger, examining leading questions in mathematics and computer science, probing the physics of matter and the universe, creating novel materials and developing new strategies for protecting the environment.

CONTACT:  Yivsam Azgad, Tel: 972-8-934-3856/2
EMAIL:  Yivsam.azgad@weizmann.ac.il / news@weizmann.ac.il

(Press release by the research journal ‘Neuron’)


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