Sucharit Katyal

University College London | UCL · Institute of Neurology

Meditation training is proposed to enhance mental well-being by modulating neural activity, particularly alpha and theta brain oscillations , and autonomic activity. Although such enhancement also depends on the quality of meditation, little is known about how these neural and physiological changes relate to meditation quality. One model characteri...

Ambiguous sensory stimuli provide insight into the dynamics of the human mind. When viewing substantially different images in the two eyes (i.e., binocular rivalry (BR)), perception spontaneously fluctuates between the two images along with patch‐like mixtures of the two, with limited ability to control such fluctuations. Previous studies have show...

When ambiguous visual stimuli have multiple interpretations, human perception can alternate between them, producing perceptual multistability. There is a large variation between individuals in how long stable percepts endure, on average, between switches, but the underlying neural basis of this individual difference in perceptual dynamics remains o...

Neural suppression plays an important role in cortical function, including sensory, memory, and motor systems. It remains, however, relatively poorly understood. A paradigmatic case arises when conflicting images are presented to the two eyes. These images can compete for awareness, and one is usually strongly suppressed. The mechanisms that resolv...

Human superior colliculus (SC) responds in a retinotopically selective manner when attention is deployed on a high-contrast visual stimulus using a discrimination task. To further elucidate the role of SC in endogenous visual attention, high-resolution fMRI was used to demonstrate that SC also exhibits a retinotopically selective response for cover...

During binocular rivalry, conflicting images are presented one to each eye and perception alternates stochastically between them. Despite stable percepts between alternations, modeling suggests that neural signals representing the two images change gradually, and that the duration of stable percepts are determined by the time required for these sig...

While most current accounts of consciousness identify it with mental contents, certain meditation practices—like open monitoring (OM)—are said to enable a unique conscious state where meditators can experience mental content from a meta or a de-reified perspective as “ongoing phenomena.” Phenomenologically, such a state is considered as suspension...

This is an editorial piece for a special issue (SI) in Frontiers of Psychology on 'The Varieties of Contemplative Experiences and Practices'. While diverse contemplative techniques are employed across a plethora of traditions around the world, contemplative research over the years has not reflected this variety. Despite exponential growth in contem...

Individuals with anxiety and depression (AD) exhibit chronic metacognitive biases such as underconfidence. The origin of such biases is unknown. Here we quantified the impact of feedback on confidence in two large general population samples (N=230 and N=278). We studied metacognition both locally, as confidence in individual task instances, and glo...

Format: Case Studies/Individual Presentations Abstract: With contributions from 9 postdoctoral researchers at UCL Queen Square Institute of Neurology, we redesigned the Critical Appraisal component of our Research Methods module (Postgraduate Taught), prompted by the return to face-to-face teaching after nearly 2 years of teaching online during th...

Foundational work in the psychology of metacognition identified a distinction between metacognitive knowledge (stable beliefs about one’s capacities) and metacognitive experiences (local evaluations of performance). More recently, the field has focused on the latter half of the construct in the form of confidence estimates, developing tasks and met...

According to many first-person accounts, consciousness comprises a subject-object structure involving a mental action or attitude starting from the “subjective pole” upon an object of experience. In recent years, many paradigms have been developed to manipulate and empirically investigate the object of consciousness. However, well-controlled invest...

Metacognition refers to an ability to access and evaluate one’s own cognitive processes. A common measure of metacognition is the extent to which trial-by-trial confidence ratings track performance, indexed by metrics of metacognitive efficiency such as Mratio (meta-d’/d’). Recent studies disagree over whether metacognitive efficiency can be improv...

Traditional spiritual literature contains rich anecdotal reports of spontaneously arising experiences occurring during meditation practice, but formal investigation of such experiences is limited. Previous work has sometimes related spontaneous experiences to the Indian traditional contemplative concept of kundalini. Historically, descriptions of k...

According to many first-person accounts, consciousness comprises a subject-object structure involving a mental action or attitude starting from the “subjective pole” upon an object of experience. In recent years, many paradigms have been developed to manipulate and empirically investigate the object of consciousness. However, well-controlled invest...

We frequently associate ourselves with certain affective attributes (e.g., I am joyful, I am lazy, etc.) and not others. However, little is understood about how such self-associations come about. Interoceptive predictive theories propose that a sense of self, especially in an affective context, results from the brain making inferences about interna...

Background: Meditation training is thought to enhance mental wellbeing by modulating neural activity, notably alpha and theta oscillations, and autonomic activity. However, considering that the enhancement of mental wellbeing also depends on the quality or “depth” of meditation, little is known about how these neural and physiological changes relat...

Bistable perceptual tasks such as binocular rivalry demonstrate that human perception continuously fluctuates, with limited ability to control it. Previous behavioural studies have shown that long-term mental training through meditation practice enables a reduction of such fluctuations, thus stabilising perception. Using EEG, we investigated the ne...

Contemplative practices are thought to modify one’s experience of self and fundamentally change self-referential processing. However, few studies have examined the brain correlates of self-referential processing in long-term meditators. Here, we used the self-referential encoding task (SRET) to examine event-related potentials (ERP) during assessme...

Contemplative practices are thought to modify one's experience of self and fundamentally change self-referential processing. However, few studies have examined the effect of long-term meditation training on brain correlates of self-referential processing. Here we used the self-referential encoding task (SRET) to examine event-related potentials (ER...

The superior colliculus (SC) is a layered midbrain structure involved in directing both head and eye movements and coordinating visual attention. Although a retinotopic organization for the mediation of saccadic eye-movements has been shown in monkey SC, in human SC the topography of saccades has not been confirmed. Here, a novel experimental parad...

Short-term training can lead to improvements in behavioral discrimination of auditory and visual stimuli, as well as enhanced EEG responses to those stimuli. In the auditory domain, fluency with tonal languages and musical training has been associated with long-term cortical and subcortical plasticity, but less is known about the effects of shorter...

A model describing absorptive states of meditative consciousness in advanced practitioners within a model of hierarchical cognition and Bayesian inference.

When the two eyes view incompatible images, perception alternates between them. What neural computations underlie this binocular rivalry? Perceptual alternations may simply reflect competition between the sets of monocular neurons that respond to each image, with the stronger driving perception. Here, we test an alternative hypothesis, that the com...

When the two eyes receive different inputs, the visual system either fuses the images into one coherent percept, or engages in binocular rivalry. What neural computations decide between rivalry and fusion? If these computations compare opposing neural signals for fusion and rivalry, and adjusts their weights based on stimulus history, then adapting...

Many perceptual skills improve with training, and research suggests that long- and short-term experiences modify auditory neural structures and function. Long-term cortical and subcortical plasticity has been associated with musical training and fluency in tonal languages, and short-term training effects have been regularly observed in cortical res...

When differing visual inputs reach the two eyes, the visual system in some cases integrates them into a fused percept, while in others produces rivalry, with only one perceived at a time. The process by which the visual system determines whether two images should be fused or should rival remains relatively unstudied. We investigated this process us...

Background / Purpose: A few humans are born without an optic chiasm. In such subjects, both left and right visual hemifields are represented bilaterally in the visual cortex. Here, we investigated the representation of visual space on the superior colliculus (SC) of an achiasmatic subject, and its relationship to the SC representation of somatose...

Background / Purpose: Monkey sub-threshold microstimulation studies in superior colliculus (SC) suggest endogenous attention (1).Monkey single-unit studies find enhancement for visual and visuomotor neurons with only exogenous attention with intermediate layer visuomotor neurons exhibiting a baseline enhancement (2).We test endogenous attention i...

Background / Purpose: Polar angle retinotopic map of visual stimulation and attention have been previously demonstrated in human superior colliculus using fMRI (1). This work continues the effort to map visual stimulation and attention as well as saccades along the eccentricity dimension. Main conclusion: We demonstrated a retinotopic organiza...

Functional MRI (fMRI) is a widely used tool for non-invasively measuring correlates of human brain activity. However, its use has mostly been focused upon measuring activity on the surface of cerebral cortex rather than in subcortical regions such as midbrain and brainstem. Subcortical fMRI must overcome two challenges: spatial resolution and physi...

Functional magnetic resonance imaging (fMRI) has become a popular technique for studies of human brain activity. Typically, fMRI is performed with >3-mm sampling, so that the imaging data can be regarded as two-dimensional samples that average through the 1.5-4-mm thickness of cerebral cortex. The increasing use of higher spatial resolutions, <1.5-...

Background / Purpose: It is well known that neurons within the intermediate layers of macaque superior colliculus (SC) form a retinotopic map of the visual field. Here, we examine the representation of saccades in human SC. Main conclusion: We used two approaches: a single-condition approach to map both eccentricity and polar angle; and a phas...

Experiments were performed to examine the topography of covert visual attention signals in human superior colliculus (SC), both across its surface and in its depth. We measured the retinotopic organization of SC to direct visual stimulation using a 90° wedge of moving dots that slowly rotated around fixation. Subjects (n = 5) were cued to perform a...

Functional magnetic resonance imaging (fMRI) has become an exceedingly popular technique for studies of human brain activity. Typically, fMRI is performed with >3-mm sampling, so that the imaging data can be regarded as two-dimensional samples that roughly average through the typically 1.5—4-mm thickness of cerebral cortex. The use of higher spatia...