Biology subjects

Thomas, E. R.

Publications and source records attributed to Thomas, E. R..

3 recordsLinked to original sources

bioRxiv2024

Bidirectional modulation of negative emotional states by parallel genetically-distinct basolateral amygdala pathways to ventral striatum subregions

Distinct basolateral amygdala (BLA) cell populations influence emotional responses in manners thought important for anxiety and anxiety disorders. The BLA contains numerous cell types which can broadcast information into structures that may elicit changes in emotional states and behaviors. BLA excitatory neurons can be divided into two main classes, one of which expresses Ppp1r1b (encoding protein phosphatase 1 regulatory inhibitor subunit 1B) which is downstream of the genes encoding the D1 and D2 dopamine receptors (drd1 and drd2 respectively). The role of drd1+ or drd2+ BLA neurons in learned and unlearned emotional responses is unknown. Here, we identified that the drd1+ and drd2+ BLA neuron populations form two parallel pathways for communication with the ventral striatum. These neurons arise from the basal nucleus of the BLA, innervate the entire space of the ventral striatum, and are capable of exciting ventral striatum neurons. Further, through three separate behavioral assays, we found that the drd1+ and drd2+ parallel pathways bidirectionally influence both learned and unlearned emotional states when they are activated or suppressed, and do so depending upon where they synapse in the ventral striatum - with unique contributions of drd1+ and drd2+ circuitry on negative emotional states. Overall, these results contribute to a model whereby parallel, genetically-distinct BLA to ventral striatum circuits inform emotional states in a projection-specific manner.

neuroscience↗

bioRxiv2023

Predictions and errors are distinctly represented across V1 layers

Predictive processing frameworks of cortical functioning propose that neural populations in different cortical layers serve distinct roles in representing the world. There are distinct testable theories within this framework that we examined with a 7T fMRI study, where we contrasted responses in primary visual cortex (V1) to expected (75% likely) and unexpected (25%) Gabor orientations. Multivariate decoding analyses revealed an interaction between expectation and layer, such that expected events could be decoded with comparable accuracy across layers, while unexpected events could only be decoded in superficial laminae. These results are in line with predictive processing accounts where expected virtual input is injected into deep layers, while superficial layers process the error with respect to expected signals. While this account of cortical processing has been popular for decades, such distinctions have not previously been demonstrated in the human sensory brain. We discuss how both prediction and error processes may operate together to shape our unitary perceptual experiences.

neuroscience↗

bioRxiv2020

Action enhances predicted touch

It is widely believed that predicted tactile action outcomes are perceptually attenuated. The present experiments determined whether predictive mechanisms always generate attenuation, or instead can enhance perception - as typically observed in sensory cognition domains outside of action. We manipulated probabilistic expectations in a paradigm often used to demonstrate tactile attenuation. Participants produced actions and subsequently rated the intensity of forces on a passive finger. Experiment 1 confirmed previous findings that action outcomes are perceived less intensely than passive stimulation, but demonstrated more intense perception when active finger stimulation was removed. Experiments 2 and 3 manipulated prediction explicitly and found that expected touch during action is perceived more intensely than unexpected touch. Computational modelling suggested that expectations increase the gain afforded to expected tactile signals. These findings challenge a central tenet of prominent motor control theories and demonstrate that sensorimotor predictions do not exhibit a qualitatively distinct influence on tactile perception. Statement of RelevancePerception of expected action outcomes is thought to be attenuated. Such a mechanism may be adaptive because surprising inputs are more useful - e.g., signalling the need to take new courses of action - and is thought to explain why we cannot tickle ourselves and unusual aspects of action and awareness in clinical populations. However, theories outside of action purport that predicted events are perceptually facilitated, allowing us to generate largely accurate representations of our noisy sensory world. We do not know whether action predictions really alter perception differently from other predictions because different manipulations have been performed. Here we perform similar manipulations and demonstrate that action predictions can enhance, rather than attenuate, touch. We thereby demonstrate that action predictions may not have a qualitatively distinct influence on perception, such that we must re-examine theories concerning how predictions influence perception across domains and clinical theories based upon their assumptions.

neuroscience↗