Dr Joydeep Bhattacharya - Research projects

E-mail j.bhattacharya (@gold.ac.uk)

Neuronal Substrates of Visual Insight

Insight or Eureka - a sudden recognition of a novel pattern by recombining remotely associated elements - is a central component of human intelligence. Insight is mainly studied in the domain of (verbal, mathematical) problem solving, but here we would like to investigate the aspect of visual insight. Typically, we will look for the neural basis of object recognition, corresponding to Eureka moment. Special classes of visual images exist that appear, at first glance, as a jumble of random dots or patterns, and then all on a sudden, a moment of recognition happens when the dots or patterns come together into a coherent entity or object; at this moment, a transition occurs in the brain and we would like to characterize the neuronal substrate of this transition. The project will offer important and novel information about visual search, object recognition, and visual eureka and their neural signatures on dynamical brain responses.

Support System Based on Nonlinear Analysis of Bio-Signals toward Proactive Diagnosis

It is well known that the brain, an inherently nonlinear dynamical system, in which the extensive communication between regions takes place during cognition or even at rest, creates and reshapes continuously complex functional networks of correlated dynamics. And it is increasingly believed that the complexity of the network drastically breaks down in humans with severe neurological and mental disorders. So it is extremely important to understand and identify the changing patterns of the underlying brain network. Further, little is known about the intermediate state when the symptoms are mild or dormant. The nonlinear dynamical characteristics of the brain responses are supposed to offer a better diagnostic support system than standard linear classifier. This project will be in joint collaboration with a premier research centre of Japan where magnetoencephalographic (MEG) signals will be recorded form humans with and without pathology while performing various cognitive tasks. We will adopt a battery of state-of-the art data analysis techniques based on chaos and complexity theory which will apply to the recorded signals for possible early diagnosis.

Neural Correlates of Preference of Contemporary Music

It is known that human adults as well as infants prefer to listen to consonant over dissonant intervals. Neuroscientifically, listening to preferred stimulus are assumed to engage several cortical (and subcortical) structures implicated in evaluating reward-based stimuli. However, there has been no result available on functional connectivity patterns related to musical preference or aesthetical judgement of contemporary music (CoM). The interest in functional connectivity or neuronal synchronization is motivated by the fact that music perception as any high cognitive act demands not only coactivation but also extensive functional cooperation between multiple brain areas Therefore, we will investigate the preference in CoM where the participants will make explicit choices in alternative forced choice paradigm. We will investigate the effects of three different individual variables (pitch, rhythm, and timbre). A further modified paradigm, where the exposure time for each stimulus is decided by the participant, will also be adopted. Brain electrical responses and auxiliary physiological signals will be recorded simultaneously. Typically, the specific aims are as follows: (i) to investigate the functional connectivity patterns between distant brain areas in the different frequency bands associated with choice and non-choice (ii) to investigate the effect of choice and non-choice on psychophysiological measurements, and (c) to investigate the effect of exposure of the musical stimuli on the preference dynamics.

Brain Responses in Aesthetic Preference and Judgement of Visual Art

A longstanding issue in aesthetic theory and research has revolved around the role of emotion in aesthetic experience, and it has been investigated from several perspectives, including subjective/phenomenological, behavioural, and neuroimaging. Contrary to the cognitive stance theory as presumed by Kant, it has been found that active ratings of visual paintings on aesthetic preference did activate those brain regions that have been involved in processing positive or pleasant emotion. However, no information is available about the functional role of cortical network and oscillations in rating visual art objects. Further, earlier study was primarily involved with aesthetic preference not with aesthetic judgement; the former is less about the work of art and more about the personal likes or dislikes. Accordingly we would like to design experimental paradigms where the subjects (non-artists or no training in art) would provide objective aesthetical judgement and also subjective aesthetical preference about presented objects of visual art (belonging to different period).

Transient Oscillation in Human Information Processing

Brain responses are often nonlinear and nonstationary, yet most of the available data analysis techniques are based on the assumptions of linearity and stationarity. The analysis of neural responses during cognitive functioning are constrained by two additional factors: (i) cognitive events are transients, i.e. their durations are short, in the range of hundreds of milliseconds, and (ii) neural responses for different trials are not exactly similar, i.e. significant variations exist from trial to trial. Accordingly, the adopted methods should be able to apply on limited time samples and be adaptive or data-driven. In this project, we will systematically investigate several data driven methods for investigating transient periodicity or oscillations in a time series. Additionally, the neurophysiological significance of the constituent oscillatory modes will be investigated in the context of neuronal coherence. The project promises to offer a novel insight into the local oscillatory properties of the complex neural signals and its outcome can be applied to diverse cognitive and clinical settings.

Tracking Neural Information Pathway of Multisensory Interaction

Our perception relies on integrating information across different senses and this almost automated processing of multisensory integration is essential for successful interaction in real-life environment11. For some special types of sensory integration, the perception of one sensory modality can be qualitatively altered by the occurrence of another sensory modality, thus creating a novel perceptual experience termed as multisensory illusion (MSI). EEG signals will be recorded while participants will perform several multisensory tasks. State of the art data analysis techniques will be applied to track the information flow between multiple brain regions. Studying MSI provides a unique opportunity to investigate the individual sensory contributions as well as their possible interactions/ integrations/ dominance and further predicting the final perceptual outcome by isolating the critical sequence of neural events on a trial-by-trial basis. Further the project will also establish the link between brain and behaviour.