Biology subjects

Cushing, C.

Publications and source records attributed to Cushing, C..

4 recordsLinked to original sources

bioRxiv2023

Modulating Subjective Pain Perception with Decoded MNI-space Neurofeedback

Pain is a complex emotional experience that still remains challenging to manage. Previous functional magnetic resonance imaging (fMRI) studies have associated pain with distributed patterns of brain activity (i.e., brain decoders), but it is still unclear whether these observations reflect causal mechanisms. To address this question, we devised a new neurofeedback approach leveraging real-time decoding of fMRI data to test if modulating pain-related multivoxel fMRI patterns could lead to changes in subjective pain experience. We first showed that subjective pain ratings can indeed be accurately predicted using a real-time decoding approach based on the stimulus intensity independent pain signature (SIIPS) and the neurologic pain signature (NPS). Next, we trained participants in a double-blinded decoded fMRI neurofeedback experiment to up- or down-regulate the SIIPS. Our results indicate that participants can learn to down-regulate the expression of SIIPS independently from NPS expression. Importantly, the success of this neurofeedback training was associated with the perceived intensity of painful stimulation following the intervention. Taken together, these results indicate that closed-loop brain imaging can be efficiently conducted using a priori fMRI decoders of pain, potentially opening up a new range of applications for decoded neurofeedback, both for clinical and basic science purposes.

neuroscience↗

bioRxiv2023

Interaction Between the Prefrontal and Visual Cortices Supports Subjective Fear

It has been reported that threatening and non-threatening visual stimuli can be distinguished based on the multi-voxel patterns of hemodynamic activity in the human ventral visual stream. Do these findings mean that there may be evolutionarily hardwired mechanisms within early perception, for the fast and automatic detection of threat, and maybe even for the generation of the subjective experience of fear? In this human neuroimaging study, we presented participants (Fear group: N=30; No Fear group: N = 30) with 2700 images of animals that could trigger subjective fear or not as a function of individuals idiosyncratic "fear profiles" (i.e., fear ratings of animals reported by a given participant). We provide evidence that the ventral visual stream may represent affectively neutral visual features that are statistically associated with fear ratings of participants, without representing the subjective experience of fear itself. More specifically, we show that patterns of hemodynamic activity predictive of a specific "fear profile" can be observed in the ventral visual stream whether a participant reports being afraid of the stimuli or not. Further, we found that the multivariate information synchronization between ventral visual areas and prefrontal regions distinguished participants who reported being subjectively afraid of the stimuli from those who did not. Together, these findings support the view that the subjective experience of fear may depend on the relevant visual information triggering implicit metacognitive mechanisms in the prefrontal cortex.

neuroscience↗

bioRxiv2017

Neurodynamics and connectivity during facial fear perception: The role of threat exposure and signal congruity

Fearful faces convey threat cues whose meaning is contextualized by eye gaze: While averted gaze is congruent with facial fear (both signal avoidance), direct gaze is incongruent with it, as direct gaze signals approach. We have previously shown using fMRI that the amygdala is engaged more strongly by fear with averted gaze, which has been found to be processed more efficiently, during brief exposures. However, the amygdala also responds more to fear with direct gaze during longer exposures. Here we examined previously unexplored brain oscillatory responses to characterize the neurodynamics and connectivity during brief ([~]250 ms) and longer ([~]883 ms) exposures of fearful faces with direct or averted eye gaze. We replicated the exposure time by gaze direction interaction in fMRI (N=23), and observed greater early phase locking to averted-gaze fear (congruent threat signal) with MEG (N=60) in a network of face processing regions, with both brief and longer exposures. Phase locking to direct-gaze fear (incongruent threat signal) then increased significantly for brief exposures at [~]350 ms, and at [~]700 ms for longer exposures. Our results characterize the stages of congruent and incongruent facial threat signal processing and show that stimulus exposure strongly affects the onset and duration of these stages.

neuroscience↗

bioRxiv2017

Differential hemispheric and visual stream involvement in ensemble coding of emotion in facial crowds

The visual system takes advantage of redundancies in the scene by extracting summary statistics from a set of items. Similarly, in many social situations where scrutinizing each individuals expression is inefficient, human observers make snap judgments of crowds of people by reading \"crowd emotion\" to avoid danger (e.g., mass panic or violent mobs) or to seek help. However, how the brain accomplishes this feat remains unaddressed. Here we report a set of behavioral and fMRI studies in which participants made avoidance or approach decisions by choosing between two facial crowds presented in the left and right visual fields (LVF/RVF). Participants were most accurate for crowds containing task-relevant cues: avoiding angry crowds and approaching happy crowds. This effect was amplified by sex-linked facial cues (angry male/happy female crowds) and highly lateralized, with better recognition of the task-congruent facial crowd when presented in LVF. fMRI results showed that the dorsal visual stream was preferentially activated in crowd emotion processing, with intraparietal sulcus and superior frontal gyrus predicting behavioral crowd emotion efficiency, whereas the ventral visual stream showed greater involvement in individual face emotion processing, with fusiform cortex activity predicting the accuracy of decisions about individual face emotion. Our results shed new light on the distinction between global vs. local processing of face stimuli, revealing differential involvement of the left and right hemispheres and the dorsal and ventral pathways in reading crowd vs. individual emotion.

neuroscience↗