Biology subjects

Salemi, T.

Publications and source records attributed to Salemi, T..

3 recordsLinked to original sources

bioRxiv2026

Excitatory and inhibitory neurons in the dorsal periaqueductal gray encode decisions to assess and escape natural threats

Prey species are able to engage hardwired neural pathways to rapidly escape from an imminent predator attack. However, when predator threat is less probable they typically show a stereotypical sequence of approach toward the threat aimed at gathering more information, followed by escape to safety when the threat threshold is reached. The brainstem dorsal periaqueductal gray (dPAG) is required for the expression of escape behavior to predator threats and stimulation of dPAG elicits goal-directed flight. However, in vivo neural recordings in dPAG have identified separate populations of neurons that are tuned to either the approach or escape phase of the behavior suggesting that the structure may also be involved in threat assessment. The genetic identity and connectivity of these Assessment+ and Escape+ neurons have not been defined, although optogenetic activation of glutamatergic, but not GABAergic neurons elicits high-speed flight, suggesting that Escape+ neurons might be exclusively excitatory in nature. Moreover, it is not clear whether non-predator threats such as those elicited by conspecific or other animate threats are encoded by independent or overlapping neurons in dPAG. Here we report the activity pattern of ensembles of glutamatergic and GABAergic dPAG neurons during approach and escape from predator, social, and prey threats. Unexpectedly, we found that both glutamatergic and GABAergic neurons harbor Assessment+ and Escape+ neurons, suggesting that both cell-types are engaged in the approach-to-avoidance transition. Consistent with the functional involvement of both cell-types in approach-to-avoidance behavior, optogenetic activation of GABAergic cells elicited a reduction of risk assessment behavior towards the predator. Finally, we found that exposure to predator, social or prey threat recruited largely overlapping neurons in dPAG, demonstrating a convergence of threat processing in this structure. These findings point to a tightly coordinated role for dPAG excitatory and inhibitory neurons in the generalized control of innate threat assessment and avoidance behavior.

neuroscience↗

bioRxiv2023

Functional imaging of nine distinct neuronal populations under a miniscope in freely behaving animals

Head-mounted miniscopes have enabled functional fluorescence imaging in freely moving animals. However, current technology is limited to recording at most two spectrally distinct fluorophores, severely restricting the number of identifiable cell types. Here we introduce multiplexed neuronal imaging (Neuroplex), a pipeline combining miniscope Ca2+ recordings with in vivo multiplexed confocal spectral imaging to distinguish nine projection-defined neuronal subtypes through the same GRIN lens. By co-registering defined neurons with fluorophore-specific spectral fingerprints via linear unmixing, we link projection-defined identities to behaviorally relevant neuronal activity. This approach overcomes spectral constraints of miniscopes, enabling circuit-level dissection of behavior in single animals.

neuroscience↗

bioRxiv2020

A neural circuit for competing approach andavoidance underlying prey capture

Predators must frequently balance competing approach and avoidance behaviors elicited by a moving and potentially dangerous prey. Several brain circuits supporting predation have recently been localized. However, the mechanisms by which these circuits balance the conflict between approach and avoidance responses remain unknown. Laboratory mice initially show alternating approach and avoidance responses toward cockroaches, a natural prey, but with repeated exposure become avid hunters. Here we used in vivo neural activity recording and cell-type specific manipulations in hunting mice to identify neurons in the lateral hypothalamus and periaqueductal grey that encode and control predatory approach and avoidance. We found a subset of GABAergic neurons in lateral hypothalamus that specifically encoded hunting behaviors and whose stimulation triggered predation, but not feeding. This population projects to the periaqueductal grey and stimulation of these projections promoted predation. Neurons in periaqueductal grey encoded both approach and avoidance behaviors, but only initially when the mouse showed high levels of fear of the prey. Our findings allow us to propose that GABAergic neurons in lateral hypothalamus facilitate predation in part by suppressing defensive responses to prey encoded in the periaqueductal grey. Our findings reveal a neural circuit mechanism for controlling the balance between conflicting approach and avoidance behaviors elicited by the same stimulus.

neuroscience↗