Biology subjects

Issa, J. B.

Publications and source records attributed to Issa, J. B..

3 recordsLinked to original sources

bioRxiv2025

Distinct neocortical and entorhinal networks for time, space, and reward

Variables relevant to behavior and cognition are often synthesized via computations that combine external cues and internal states. Especially salient and ubiquitous among these variables are time, space, and reward, but how they are represented throughout the neocortex and the entorhinal cortex is not well understood. Here, we utilized a behavioral task in virtual reality that includes timing, navigation, and reward components. Using a multifocus microscope that permits simultaneous mesoscopic Ca2+ imaging of neocortex and entorhinal cortex, we uncover dedicated and distinct subnetworks for interval timing, spatial navigation, and reward. Interestingly, the timing subnetwork demonstrated more prominent signaling in expert mice and features a strong contribution from barrel cortex that is not explained by ongoing whisking, pointing towards a role for this cortex in interval timing. Our results provide previously unknown details about the brainwide networks related to time, space, and reward and will allow for future interrogation of their interactions and computations.

neuroscience↗

bioRxiv2023

Lateral entorhinal cortex subpopulations represent experiential epochs surrounding reward

During goal-directed navigation, "what" information, which describes the experiences occurring in periods surrounding a reward, can be combined with spatial "where" information to guide behavior and form episodic memories1,2. This integrative process is thought to occur in the hippocampus3, which receives spatial information from the medial entorhinal cortex (MEC)4; however, the source of the "what" information and how it is represented is largely unknown. Here, by establishing a novel imaging method, we show that the lateral entorhinal cortex (LEC) of mice represents key experiential epochs during a reward-based navigation task. We discover a population of neurons that signals goal approach and a separate population of neurons that signals goal departure. A third population of neurons signals reward consumption. When reward location is moved, these populations immediately shift their respective representations of each experiential epoch relative to reward, while optogenetic inhibition of LEC disrupts learning of the new reward location. Together, these results indicate the LEC provides a stable code of experiential epochs surrounding and including reward consumption, providing reward-centric information to contextualize the spatial information carried by the MEC. Such parallel representations are well-suited for generating episodic memories of rewarding experiences and guiding flexible and efficient goal-directed navigation5-7.

neuroscience↗

bioRxiv2019

Spectral Hallmark of Auditory-Tactile Interactions in Somatosensory Cortex

To synthesize a coherent representation of the external world, the brain must integrate inputs across stimulus modalities. Yet the mechanistic basis of this computation at the level of neuronal populations remains obscure. Here, we investigate tactile-auditory integration using two-photon Ca2+ imaging in the mouse primary (S1) and secondary (S2) somatosensory cortices. Pairing sound with whisker stimulation modulates tactile responses in both S1 and S2, with the most prominent modulation being robust inhibition in S2. The degree of inhibition depends on tactile stimulation frequency, with lower frequency responses the most severely attenuated. Alongside these neurons, we identify sound-selective neurons in S2 whose responses are inhibited by high tactile frequencies. These results are consistent with a hypothesized local mutually-inhibitory S2 circuit that spectrally selects tactile versus auditory inputs. Our findings enrich mechanistic understanding of multisensory integration and suggest a key role for S2 in combining auditory and tactile information.

neuroscience↗