Biology subjects

Jadi, M.

Publications and source records attributed to Jadi, M..

6 recordsLinked to original sources

bioRxiv2025

Causal Dynamics of Social Gaze in Primate Prefrontal-Amygdala Networks Revealed by Dynamic Bayesian Modeling

Social gaze is a fundamental channel of primate communication, shaping dynamic interactions and fostering mutual understanding. While prior studies have mapped the behavioral correlates of social gaze across the prefrontal-amygdala circuits, the causal architecture of these interactions remains poorly understood. Here, we introduce a novel algorithm to integrate independently recorded sessions into "super-sessions", validated using ground-truth synthetic data, enabling the reconstruction of simultaneous multi-area recordings aligned to matched gaze sequences. Applying Dynamic Bayesian Network analysis to these super-sessions, we uncover temporally structured, behavior-dependent causal interactions among the amygdala, orbitofrontal cortex, dorsomedial prefrontal cortex (dmPFC), and anterior cingulate cortex. When macaques were the targets of social gaze, the brain-behavior network exhibited positive temporal modulations, with the dmPFC emerging as the dominant source and the amygdala as a primary recipient of influence. When macaques directed their gaze toward their partners, the dmPFC and amygdala retained their respective roles. Prefrontal regions positively modulated one another, while the amygdala acted solely as a downstream target receiving exclusively negatively modulated prefrontal inputs. These findings reveal previously unknown directional interactions in the primate social brain and highlight distinct causal architectures underlying the bidirectional dynamics of social attention.

neuroscience↗

bioRxiv2024

Development of a Marmoset Apparatus for Automated Pulling (MarmoAAP) to Study Cooperative Behaviors

In recent years, the field of neuroscience has increasingly recognized the importance of studying animal behaviors in naturalistic environments to gain deeper insights into ethologically relevant behavioral processes and neural mechanisms. The common marmoset (Callithrix jacchus), due to its small size, prosocial nature, and genetic proximity to humans, has emerged as a pivotal model toward this effort. However, traditional research methodologies often fail to fully capture the nuances of marmoset social interactions and cooperative behaviors. To address this critical gap, we developed the Marmoset Apparatus for Automated Pulling (MarmoAAP), a novel behavioral apparatus designed for studying cooperative behaviors in common marmosets. MarmoAAP addresses the limitations of traditional behavioral research methods by enabling high-throughput, detailed behavior outputs that can be integrated with video and audio recordings, allowing for more nuanced and comprehensive analyses even in a naturalistic setting. We also highlight the flexibility of MarmoAAP in task parameter manipulation which accommodates a wide range of behaviors and individual animal capabilities. Furthermore, MarmoAAP provides a platform to perform investigations of neural activity underlying naturalistic social behaviors. MarmoAAP is a versatile and robust tool for advancing our understanding of primate behavior and related cognitive processes. This new apparatus bridges the gap between ethologically relevant animal behavior studies and neural investigations, paving the way for future research in cognitive and social neuroscience using marmosets as a model organism.

neuroscience↗

bioRxiv2023

Focal vs Diffuse: Mechanisms of attention mediated performance enhancement in a hierarchical model of the visual system

Spatial attention is an essential cognitive process for visual perception, especially in complex scenes with poor luminance. Attentional modulation of neural activity has been documented across the visual cortex. However, how these changes in neural response lead to better behavioral performance on challenging tasks remain unknown. In our study, we implemented spatial attention in a deep convolutional neural network model of the ventral visual hierarchy and measured its impact on categorization performance on cluttered images with varying contrast levels. We applied attention to network units in three ways: enhancement in attended region (EAR), suppression in unattended region (SUAR) or both. When focally applied to a single convolutional layer, SUAR is more effective in boosting performance than EAR, especially in the presence of high contrast distractors. SUAR is also effective in recovering degraded performance due to low contrast targets, whereas EAR fails to recover. These results predict a novel mechanism of suppression of neural activity corresponding to the unattended parts of visual space. Intriguingly, EAR in our model achieves the same performance as SUAR when attention is diffusely applied to stacks of successive convolutional layers, irrespective of target contrast. This suggests an alternate mechanism of attention wherein enhancement of attended neural activity alone, when applied to successive cortical encoding stages, is an effective strategy for boosting performance in challenging object recognition tasks. Our results indicate that the two alternative attentional mechanisms are functionally equivalent in tackling challenging object recognition tasks.

neuroscience↗

bioRxiv2021

Demands of visual processing hierarchy shape laminar compartmentalization of attention modulation of luminance contrast in area V4

Contrast is a key feature of the visual scene that aids object recognition. Attention has been shown to selectively enhance the responses to low contrast stimuli in visual area V4, a critical hub that sends projections both up and down the visual hierarchy. Veridical encoding of contrast information is a key computation in early visual areas, while later stages encode higher level features that benefit from improved sensitivity to low contrast. How area V4 meets these distinct information processing demands in the attentive state is not known. We found that attentional modulation of contrast responses in area V4 is cortical layer and cell-class specific. Putative excitatory neurons in the superficial output layers that project to higher areas show enhanced boosting of low contrast information. On the other hand, putative excitatory neurons of deep output layers that project to early visual areas exhibit contrast-independent scaling. Computational modeling revealed that such layer-wise differences may result from variations in spatial integration extent of inhibitory neurons. These findings reveal that the nature of interactions between attention and contrast in V4 is highly compartmentalized, in alignment with the demands of the visual processing hierarchy.

neuroscience↗

bioRxiv2021

Cortical Mechanisms of Saccadic Suppression

Saccades are a ubiquitous and crucial component of our visual system, allowing for the efficient deployment of the fovea and its accompanying neural resources. Initiation of a saccade is known to cause saccadic suppression, a temporary reduction in visual sensitivity1, 2 and visual cortical firing rates3-6. While saccadic suppression has been well characterized at the level of perception and single neurons, relatively little is known about the visual cortical networks governing this phenomenon. Here we examine the effects of saccadic suppression on distinct neural subpopulations within visual area V4. We find cortical layer- and cell type-specific differences in the magnitude and timing of peri-saccadic modulation. Neurons in the input layer show changes in firing rate and inter-neuronal correlations prior to saccade onset, indicating that this layer receives information about impending saccades. Putative inhibitory interneurons in the input layer elevate their firing rate during saccades, suggesting they play a role in suppressing the activity of other cortical subpopulations. A computational model of this circuit recapitulates our empirical observations and demonstrates that an input layer-targeting pathway can initiate saccadic suppression by enhancing local inhibitory activity. Collectively, our results provide a mechanistic understanding of how eye movement signaling interacts with cortical circuitry to enforce visual stability.

neuroscience↗

bioRxiv2020

Tonic GABAergic activity facilitates dendritic calcium signaling and short-term plasticity

Brain activity is highly regulated by GABAergic activity, which acts via GABAARs to suppress somatic spike generation as well as dendritic synaptic integration and calcium signaling. Tonic GABAergic conductances mediated by distinct receptor subtypes can also inhibit neuronal excitability and spike output, though the consequences for dendritic calcium signaling are unclear. Here, we use 2-photon calcium imaging in cortical pyramidal neurons and computational modeling to show that low affinity GABAARs containing an 5 subunit mediate a tonic hyperpolarization of the dendritic membrane potential, resulting in deinactivation of voltage-gated calcium channels and a paradoxical boosting of action potential-evoked calcium influx. We also find that GABAergic enhancement of calcium signaling modulates short-term synaptic plasticity, augmenting depolarization-induced suppression of inhibition. These results demonstrate a novel role for GABA in the control of dendritic activity and suggest a mechanism for differential modulation of electrical and biochemical signaling.

neuroscience↗