Biology subjects

Macedo-Lima, M.

Publications and source records attributed to Macedo-Lima, M..

4 recordsLinked to original sources

bioRxiv2026

Perceptual training selectively strengthens top-down signaling to sensory cortex

Sensory cortical neurons adjust their responses to enhance the detection and discrimination of behaviorally relevant stimuli. Top-down signals from frontal cortical regions are thought to mediate these changes, and prior work has proposed that these signals may strengthen during perceptual learning. However, this hypothesis has not been tested directly. Here, we asked whether neurons in the orbitofrontal cortex (OFC), a higher-order brain region implicated in top-down control of sensory cortex, alter their activity during auditory perceptual learning and whether learning-related changes are transmitted to sensory cortex. We found that OFC neurons encode both trial outcome and stimulus-related information, and that the strength and sensitivity of these signals increase as animals learn to detect progressively weaker amplitude modulations. Notably, learning-related changes were conveyed to auditory cortex, but not visual cortex, indicating that perceptual learning selectively strengthens signaling within a task-relevant frontal-to-sensory cortical circuit. Together, these findings provide direct evidence that top-down cortical networks are modified during perceptual learning.

neuroscience↗

bioRxiv2023

Orbitofrontal Cortex Modulates Auditory Cortical Sensitivity and Sound Perception

Sensory perception is dynamic, quickly adapting to sudden shifts in environmental or behavioral context. Though decades of work have established that these dynamics are mediated by rapid fluctuations in sensory cortical activity, we have a limited understanding of the brain regions and pathways that orchestrate these changes. Neurons in the orbitofrontal cortex (OFC) encode contextual information, and recent data suggest that some of these signals are transmitted to sensory cortices. Whether and how these signals shape sensory encoding and perceptual sensitivity remains uncertain. Here, we asked whether the OFC mediates context-dependent changes in auditory cortical sensitivity and sound perception by monitoring and manipulating OFC activity in freely moving animals under two behavioral contexts: passive sound exposure and engagement in an amplitude modulation (AM) detection task. We found that the majority of OFC neurons, including the specific subset that innervate the auditory cortex, were strongly modulated by task engagement. Pharmacological inactivation of the OFC prevented rapid context-dependent changes in auditory cortical firing, and significantly impaired behavioral AM detection. Our findings suggest that contextual information from the OFC mediates rapid plasticity in the auditory cortex and facilitates the perception of behaviorally relevant sounds. Significance StatementSensory perception depends on the context in which stimuli are presented. For example, perception is enhanced when stimuli are informative, such as when they are important to solve a task. Perceptual enhancements result from an increase in the sensitivity of sensory cortical neurons; however, we do not fully understand how such changes are initiated in the brain. Here, we tested the role of the orbitofrontal cortex (OFC) in controlling auditory cortical sensitivity and sound perception. We found that OFC neurons change their activity when animals perform a sound detection task. Inactivating OFC impairs sound detection and prevents task-dependent increases in auditory cortical sensitivity. Our findings suggest that the OFC controls contextual modulations of the auditory cortex and sound perception.

neuroscience↗

bioRxiv2020

Genetically-identified cell types in avian pallium mirror core principles of excitatory and inhibitory neurons in mammalian cortex

In vertebrates, advanced cognitive abilities are associated with a highly developed telencephalic pallium. In mammals, the six-layered neocortex of the pallium is composed of excitatory neurons and inhibitory interneurons, organized across layers into microcircuits. These organizational principles are proposed to support efficient, high-level information processing. Comparative perspectives across vertebrates provide a lens to understand what common features of pallium are important for complex cognition. For non-mammalian vertebrates that exhibit complex cognitive abilities, such as birds, the physiology of identified pallial cell types and their circuit organization are largely unresolved. Using viral tools to target excitatory vs. inhibitory neurons in the zebra finch auditory association pallium, we systematically tested predictions derived from mammalian neocortex. We identify two segregated neuronal populations that exhibit profound physiological and computational similarities with mammalian excitatory and inhibitory neocortical cells. Specifically, despite dissimilarities in gross architecture, avian association pallium exhibits neocortex-typical coding principles, and inhibitory-dependent cortical synchrony, gamma oscillations, and local suppression. Our findings suggest parallel evolution of physiological and network roles for pallial cell types in amniotes with substantially divergent pallial organization.

neuroscience↗

bioRxiv2020

Dopamine D1 receptor activation drives plasticity in the songbird auditory pallium

Vocal learning species must form and extensively hone associations between sounds and social contingencies. In songbirds, dopamine signaling guides song motor-production, variability, and motivation, but it is unclear how dopamine regulates fundamental auditory associations for learning new sounds. We hypothesized that dopamine regulates learning in the auditory pallium, in part by interacting with local neuroestradiol signaling. Here, we show that zebra finch auditory neurons frequently coexpress D1 receptor (D1R) protein, neuroestradiol-synthase, GABA, and parvalbumin. Auditory classical conditioning increased neuroplasticity gene induction in D1R-positive neurons. In vitro, D1R pharmacological activation reduced the amplitude of GABAergic and glutamatergic currents, and increased the latters frequency. In vivo, D1R activation reduced the firing of putative interneurons, increased the firing of putative excitatory neurons, and made both neuronal types unable to adapt to novel stimuli. Together, these data support the hypothesis that dopamine acting via D1Rs modulates learning and memory in the songbird sensory cortex.

neuroscience↗