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Neuronal circuits of fear

3D Technology Animations and Motion Pictures
Area of expertise: 
Neurosciences Optogenetics
Client reference: 
Cyril Herry Neurocentre Magendie, Bordeaux, France

Prefrontal parvalbumin interneurons shape neuronal activity to drive fear expression. Nature. 2014 Jan 2;505(7481):92-6.
Courtin J1, Chaudun F1, Rozeske RR1, Karalis N1, Gonzalez-Campo C1, Wurtz H1, Abdi A2, Baufreton J2, Bienvenu TC1, Herry C1.
Synchronization of spiking activity in neuronal networks is a fundamental process that enables the precise transmission of information to drive behavioural responses. In cortical areas, synchronization of principal-neuron spiking activity is an effective mechanism for information coding that is regulated by GABA (γ-aminobutyric acid)-ergic interneurons through the generation of neuronal oscillations. Although neuronal synchrony has been demonstrated to be crucial for sensory, motor and cognitive processing, it has not been investigated at the level of defined circuits involved in the control of emotional behaviour. Converging evidence indicates that fear behaviour is regulated by the dorsomedial prefrontal cortex (dmPFC). This control over fear behaviour relies on the activation of specific prefrontal projections to the basolateral complex of the amygdala (BLA), a structure that encodes associative fear memories. However, it remains to be established how the precise temporal control of fear behaviour is achieved at the level of prefrontal circuits. Here we use single-unit recordings and optogenetic manipulations in behaving mice to show that fear expression is causally related to the phasic inhibition of prefrontal parvalbumin interneurons (PVINs). Inhibition of PVIN activity disinhibits prefrontal projection neurons and synchronizes their firing by resetting local theta oscillations, leading to fear expression. Our results identify two complementary neuronal mechanisms mediated by PVINs that precisely coordinate and enhance the neuronal activity of prefrontal projection neurons to drive fear expression.