282 research outputs found

    Odor pleasantness modulates functional connectivity in the olfactory hedonic processing network

    Get PDF
    Olfactory hedonic evaluation is the primary dimension of olfactory perception and thus central to our sense of smell. It involves complex interactions between brain regions associated with sensory, affective and reward processing. Despite a recent increase in interest, several aspects of olfactory hedonic evaluation remain ambiguous: uncertainty surrounds the communication between, and interaction among, brain areas during hedonic evaluation of olfactory stimuli with different levels of pleasantness, as well as the corresponding supporting oscillatory mechanisms. In our study we investigated changes in functional interactions among brain areas in response to odor stimuli using electroencephalography (EEG). To this goal, functional connectivity networks were estimated based on phase synchronization between EEG signals using the weighted phase lag index (wPLI). Graph theoretic metrics were subsequently used to quantify the resulting changes in functional connectivity of relevant brain regions involved in olfactory hedonic evaluation. Our results indicate that odor stimuli of different hedonic values evoke significantly different interaction patterns among brain regions within the olfactory cortex, as well as in the anterior cingulate and orbitofrontal cortices. Furthermore, significant hemispheric laterality effects have been observed in the prefrontal and anterior cingulate cortices, specifically in the beta ((13–30) Hz) and gamma ((30–40) Hz) frequency band

    Disturbed resting state EEG synchronization in bipolar disorder: A graph-theoretic analysis

    Get PDF
    AbstractDisruption of functional connectivity may be a key feature of bipolar disorder (BD) which reflects disturbances of synchronization and oscillations within brain networks. We investigated whether the resting electroencephalogram (EEG) in patients with BD showed altered synchronization or network properties. Resting-state EEG was recorded in 57 BD type-I patients and 87 healthy control subjects. Functional connectivity between pairs of EEG channels was measured using synchronization likelihood (SL) for 5 frequency bands (δ, θ, α, β, and γ). Graph-theoretic analysis was applied to SL over the electrode array to assess network properties. BD patients showed a decrease of mean synchronization in the alpha band, and the decreases were greatest in fronto-central and centro-parietal connections. In addition, the clustering coefficient and global efficiency were decreased in BD patients, whereas the characteristic path length increased. We also found that the normalized characteristic path length and small-worldness were significantly correlated with depression scores in BD patients. These results suggest that BD patients show impaired neural synchronization at rest and a disruption of resting-state functional connectivity

    An information theoretic approach to assess perceived audio quality using eeg with reduced number of electrodes

    Get PDF
    Electroencephalograph(EEG) is a process mainly used in medical and research fields to study the electrical activities in a brain. In this technique, 128 or 256 electrodes are attached to the scalp and the electrical activities of the human brain is recorded with the help of a software. In the global scenario, the EEG responses are studied and analysed to acknowledge any disorders in the brain, such as epilepsy or head injury. Recent studies performed by researchers, have focused on analysing these electrical activities to access perceived audio quality from users by using information theoretic approaches, such as mutual information. Experiments were conducted by using a total of 128 electrodes, comprised in 8 regions of interests. In the research, each region is considered to have 9 electrodes each. The aim of this thesis was to build on previous research, and to reduce the use of the number of electrodes, so as to reduce the cost and complexity of the setup. In order to achieve this, first both the good and the bad quality audios were analyzed, and a receiver operating characteristic curve is plotted to draw a classification. Furthermore, a combination of different regions were taken and their mutual information were calculated, in order to check which group of regions give us the best result. This test is undertaken for each available combination of 2 or 3 regions. The classification accuracy was obtained by a variance detector approach and the accuracy was verified by computing z scores

    Neuromarketing: a review of research and implications for marketing

    Get PDF
    In this research, we reviewed existing studies which used neuromarketing techniques in various fields of research. The results revealed that most attempts in neuromarketing have been made for business research. This research provides important results on the use of neuromarketing techniques, their limitations and implications for marketing research. We hope that this research will provide useful information about the neuromarketing techniques, their applications and help the researchers in conducting the research on neuromarketing with insight into the state-of-the-art of development methods
    • …
    corecore