Embracing Complexity in Defensive Networks

Single cell plasticity and population coding stability in auditory thalamus upon associative learning

“…This is reminiscent of recent findings that heterogenous behaviour-related neural activity of projection neurons of a given brain area is broadcast simultaneously and in parallel to different downstream targets irrespective of the output pathway (Gründemann et al, 2019;Weglage et al, 2020). Future work including simultaneous multi-site recordings (Jun et al, 2017), targeted-activity dependent neural manipulations (Emiliani et al, 2015) and computational neuroscience tools will be required to delineate how this heterogeneous, widely distributed population code is interpreted by different downstream regions (Headley et al, 2019;Mobbs et al, 2020).…”

“…It is currently unknown if individual MGB neurons exhibit complex response dynamics upon adaptive associative and defensive behaviours and how this potential heterogeneity is balanced with reliable representations of sensory inputs from the environment. Furthermore, we are currently lacking a concept of the ensemble level activity and dynamics in this widely projecting thalamic auditory relay site, which is crucial to delineate the distributed population code underlying associative learning and adaptive defensive behaviours (Headley et al, 2019;Mobbs et al, 2020). Here we used a combination of deep brain Ca 2+ imaging, miniature microscopy and fear conditioning in freely moving mice to reveal the response dynamics and plasticity of large populations of auditory thalamus neurons (Ghosh et al, 2011;Grewe et al, 2017;Gründemann et al, 2019).…”

Assaying Fear Memory Discrimination and Generalization: Methods and Concepts

“…While generalization is widely accepted as an adaptive behavioral response (Richards & Frankland, ), overgeneralization to non‐threating or irrelevant signals is maladaptive and considered an etiological factor in the development of anxiety disorders and post‐traumatic stress disorder (PTSD; Dunsmoor & Paz, ; Laufer, Israeli, & Paz, ). Therefore, the study of fundamental principles in how fear generalization and discrimination is processed in the brain may advance our understanding of anxiety disorders and PTSD (Headley et al., )…”

“…The study of stimulus generalization is highly pertinent in the context of potential danger. All organisms have evolved a set of defensive systems that facilitate survival in the face of threat (Headley, Kanta, Kyriazi, & Pare, 2019). Some of these defensive responses are learned.…”

“…While generalization is widely accepted as an adaptive behavioral response (Richards & Frankland, 2017), overgeneralization to non-threating or irrelevant signals is maladaptive and considered an etiological factor in the development of anxiety disorders and post-traumatic stress disorder (PTSD; Dunsmoor & Paz, 2015;Laufer, Israeli, & Paz, 2016). Therefore, the study of fundamental principles in how fear generalization and discrimination is processed in the brain may advance our understanding of anxiety disorders and PTSD (Headley et al, 2019) Pavlovian "fear" conditioning is a leading model for studying the neuronal circuits underlying associative learning and memory mechanisms. In Pavlovian fear conditioning, a neutral stimulus acquires the ability to elicit a defensive response after being paired with a stimulus that naturally evokes a defensive response.…”