EEG electrode T3 T4 role in olfactory perception and memory retrieval

… The odour of chocolate was associated with significantly less theta activity than was … theta reflect shifts in attention or cognitive load during olfactory perception, with a reduction in theta …

… Because olfactory input is widely distributed in the amygdala … increased theta, we considered the possibility that the theta … , but initially decreased it in 01, O2, T4 and T6. In the case of …

… In the present study, olfactory stimulation analysis with the inhalation of (+)-limonene and terpinolene at a constant concentration of 10% was evaluated. The EEG power spectrum …

… Through the olfactory system, the olfactory bulb receives the fragrance signals and provides … In the present study, theta waves remarkably decreased in 7 out of 8 regions (except T3) …

… patients respond to olfactory stimulation with an increase in temporal lobe slow electrical activity (theta EEG power), … The theta EEG power increase during olfactory stimulation in HIV-in- …

… in theta waves reflect shifts in attention or cognitive load during olfactory perception, with reduced theta … However, no study has assessed EEGs during intravenous olfactory stimulation …

… EEG bands theta, alpha, and beta, and the olfactory EEG … EEG-based analysis of the effects of olfactory stimulation by … at six of the eight electrode sites (F3, T3, T4, P3, P4, and O2) (…

Objectives The objective of the present study was to investigate the usefulness of time-frequency analysis (TFA) of olfactory-induced EEG change with a low-cost, portable olfactometer in the clinical investigation of smell function. Materials & methods A total of 78 volunteers participated. The study was composed of three parts where olfactory stimuli were presented using a custom-built olfactometer. Part I was designed to optimize the stimulus as well as the recording conditions. In part II EEG-power changes after olfactory/trigeminal stimulation were compared between healthy participants and patients with olfactory impairment. In Part III the test-retest reliability of the method was evaluated in healthy subjects. Results Part I indicated that the most effective paradigm for stimulus presentation was cued stimulus, with an interstimulus interval of 18-20s at a stimulus duration of 1000ms with each stimulus quality presented 60 times in blocks of 20 stimuli each. In Part II we found that central processing of olfactory stimuli analyzed by TFA differed significantly between healthy controls and patients even when controlling for age. It was possible to reliably distinguish patients with olfactory impairment from healthy individuals at a high degree of accuracy (healthy controls vs anosmic patients: sensitivity 75%; specificity 89%). In addition we could show a good test-retest reliability of TFA of chemosensory induced EEG-power changes in Part III. Conclusions Central processing of olfactory stimuli analyzed by TFA reliably distinguishes patients with olfactory impairment from healthy individuals at a high degree of accuracy. Importantly this can be achieved with a simple olfactometer.

… EEG recordings from rare patients with medically resistant epilepsy, we find that theta … effects were specific to olfactory stimulation, we compared PPC-AH theta phase locking in the …

… Therefore, we excluded the theta and beta 1 bands from analysis. … coherence increase in the temporal regions examined in this study could be cortical correlates of human olfaction. …

It has been demonstrated that odors could affect humans at the psychophysiological level. Significant research has been done on odor perception and physiological mechanisms; however, this research was mainly performed in highly controlled conditions in order to highlight the perceptive phenomena and the correlated physiological responses in the time frame of milliseconds. The present study explored how human physiological activity evolves in response to different odor conditions during an ecological olfactory experience on a broader time scale (from 1 to 90 s). Two odors, vanilla and menthol, together with a control condition (blank) were employed as stimuli. Electroencephalographic (EEG) activity in four frequency bands of interest, theta, alpha, low beta, and high beta, and the electrodermal activity (EDA) of the skin conductance level and response (SCL and SCR) were investigated at five time points taken during: (i) the first ten seconds of exposure (short-term analysis) and (ii) throughout the entire exposure to each odor (90 s, long-term analysis). The results revealed significant interactions between the odor conditions and the time periods in the short-term analysis for the overall frontal activity in the theta (p = 0.03), alpha (p = 0.005), and low beta (p = 0.0067) bands, the frontal midline activity in the alpha (p = 0.015) and low beta (p = 0.02) bands, and the SCR component (p = 0.024). For the long-term effects, instead, only one EEG parameter, frontal alpha asymmetry, was significantly sensitive to the considered dimensions (p = 0.037). In conclusion, the present research determined the physiological response to different odor conditions, also demonstrating the sensitivity of the employed parameters in characterizing the dynamic of such response during the time. As an exploratory study, this work points out the relevance of considering the effects of continuous exposure instead of short stimulation when evaluating the human olfactory experience, providing insights for future studies in the field.

Significance To elucidate when and where in the brain different aspects of odor perception emerge, we decoded odors from an electroencephalogram and associated the results with perception and source activities. The odor information was decoded 100 ms after odor onset at the earliest, with its signal sources estimated in and around the olfactory areas. The neural representation of odor unpleasantness emerged 300 ms after odor onset, followed by pleasantness and perceived quality at 500 ms. During this time, brain regions representing odor information spread rapidly from the olfactory areas to regions associated with emotional, semantic, and memory processing. The results suggested that odor perception emerges through computations in these areas, with different perceptual aspects having different spatiotemporal dynamics.

… induced similar EEG signals during 50–100, 150–200, and 350–400 ms at the theta frequency… We found that theta and gamma activities were related to olfactory-associated brain areas …

Brain activity may manifest itself as oscillations which are repetitive rhythms of neuronal firing. These local field potentials can be measured via intracranial electroencephalography (iEEG). This review focuses on iEEG used to map human brain structures involved in olfaction. After presenting the methodology of the review, a summary of the brain structures involved in olfaction is given, followed by a review of the literature on human olfactory oscillations in different contexts. A single case is provided as an illustration of the olfactory oscillations. Overall, the timing and sequence of oscillations found in the different structures of the olfactory system seem to play an important role for olfactory perception.

… In this work, we developed a pipeline of analysis for the study of EEG-based brain connectivity during hedonic olfactory stimulation. In particular, we propose a framework that allows to …

Olfaction is crucial to our dietary choices and significantly influences our emotional and cognitive landscapes. Understanding the underlying neural mechanisms is pivotal, especially through the use of electroencephalography (EEG). This technology has strong temporal resolution, allowing it to capture the dynamics of neural responses to odors, bypassing the need for subjective interpretations. The application of EEG in food flavor research is still relatively new, but it has great potential. This review begins with an examination of general scent stimulation, charts the advances in using EEG to understand odor perception, and explores its future in food flavor science. By analyzing EEG's ability to detect distinct patterns and strengths in brain activity, we can elucidate the perceptual, affective, and cognitive frameworks associated with food odors. Event-related potentials and oscillatory activities, markers of central olfactory processing, provide insights into the neural architecture of olfaction. These markers are instrumental in assessing the influence of food odors on health, emotions, and decision-making processes. We argue that EEG's application in olfaction research holds considerable promise for the food industry to innovate products that are not only healthier but also more appealing, thereby promoting human well-being.

… in the EEG signal after the supply of olfactory stimuli during simultaneous EEG/fMRI olfactory … Additionally mint has a significant increase in theta band in temporal and parietal areas. …

The human sense of smell is important for many vital functions, but with the current state of the art, there is a lack of objective and non-invasive methods for smell disorder diagnostics. In recent years, increasing attention is being paid to olfactory event-related potentials (OERPs) of the brain, as a viable tool for the objective assessment of olfactory dysfunctions. The aim of this review is to describe the main features of OERPs signals, the most widely used recording and processing techniques, and the scientific progress and relevance in the use of OERPs in many important application fields. In particular, the innovative role of OERPs is exploited in olfactory disorders that can influence emotions and personality or can be potential indicators of the onset or progression of neurological disorders. For all these reasons, this review presents and analyzes the latest scientific results and future challenges in the use of OERPs signals as an attractive solution for the objective monitoring technique of olfactory disorders.

… , ie, olfactory stimulation. At rest with eyes closed, delta-1 and alpha-2 power differences were evident in OCD patients as compared with normal controls. During olfactory … lobe EEG …

… alpa density, and the lack of objective data on Antarctic olfactory … in EEG and electrodermal reponses for real and suggested … T3 and involved all EEG sites, the third was dominated by T4…

Odor habituation is a phenomenon that after repeated exposure to an odor, is characterized by decreased responses to it. The central nervous system is involved in odor habituation. To study odor habituation in humans, measurement of event-related potentials (ERPs) has been widely used in the olfactory system and other sensory systems, because of their high temporal resolution. Most previous odor habituation studies have measured the olfactory ERPs of (200–800) ms. However, several studies have shown that the odor signal is processed in the central nervous system earlier than at 200 ms. For these reasons, we studied whether when odors were habituated, olfactory ERP within 200 ms of odors could change. To this end, we performed an odor habituation behavior test and electroencephalogram experiments. In the behavior test, under habituation conditions, odor intensity was significantly decreased. We found significant differences in the negative and positive potentials within 200 ms across the conditions, which correlated significantly with the results of the behavior test. We also observed that ERP latency depended on the conditions. Our study suggests that odor habituation can involve the olfactory ERP of odors within 200 ms in the brain.

… to spontaneous EEG cortical activity in response to olfactory … and the immediate cortical EEG activity evoked by an odour. … increasing response for electrodes T3, F4, FTC1 and FZ. …

… There was no significant difference for P300 amplitudes between T3 (0) reference) and T4 (0… High-hypnotizable subjects emitted EEG-P300evoked potentials of greater amplitude in …

Quantitative evaluation of the sense of smell is done by the olfactory event-related potential (OERP) test. OERP consists of N1, P1, N2, P2, and P3, of which N1 and P1 latency are known to be affected by the concentration of odor stimuli associated with the pre-sensory phase and P2 and P3 are the stages at which odors are perceived and are known to change by subjective evaluation of the stimulus. The purpose of this study was to clarify the correlation between the expression of OERP and the subjective evaluation of the object on the fragrance stimulus using various fragrances. Therefore, the study examined the relative waveform power ratio, preference for each scent stimulus, and finally the amplitude and latency change of the components of OERP, N1 and P2. In contrast, it was found that the late P2 response waveform was an effective aroma stimulus recognition waveform in OERP compared to the initial response waveforms.

… of odor memories across multiple timescales of the theta … judgments on a final probe odor (retrieval): an identity match … with the temporal pattern of theta, as well as of both theta and …

… subjects on components of the olfactory eventrelated potentials (OERP). The subjects were … , and the OERP were then established. The latencies of the OERP were not affected by the …

… We assessed the olfactory function by using Sniffin’ sticks test and olfactory event-related potentials (OERPs). The findings of unilateral deficit of identification associated with parosmia …

3M syndrome is a rare disorder that involves the gene cullin-7 (CUL7). CUL7 modulates odour detection, conditions the olfactory response (OR) and plays a role in the development of the olfactory system. Despite this involvement, there are no direct studies on olfactory functional effects in 3M syndrome. The purpose of the present work was to analyse the cortical OR through chemosensory event-related potentials (CSERPs) and power spectra calculated by electroencephalogram (EEG) signals recorded in 3M infants: two twins (3M-N) and an additional subject (3M-O). The results suggest that olfactory processing is diversified. Comparison of N1 and Late Positive Component (LPC) indicated substantial differences in 3M syndrome that may be a consequence of a modified olfactory processing pattern. Moreover, the presence of delta rhythms in 3M-O and 3M-N clearly indicates their involvement with OR, since the delta rhythm is closely connected to chemosensory perception, in particular to olfactory perception.

… olfaction event-related potential (OERP) [2-3]. These researches have a problem that OERP is not enough features for olfaction … ) and the temporal lobe (T3, T4) to acquire EEG signals …

Introduction. Olfactory dysfunction is considered to be an early and relatively important marker of Parkinson's disease (PD). Olfactory studies using objective neurophysiological methods may become one of the diagnostic tests to identify individuals with a high risk of developing PD. The aim of the study was to assess the spectral and topographic characteristics of bioelectrical brain activity in patients with PD during directional perception of olfactory stimuli. Materials and methods. This study included 30 patients with PD (mean age was 66.5 6.5 years). The control group consisted of 20 people without PD (mean age was 65.3 8.5 years). Lavender oil, clove oil, camphor oil and -mercaptoethanol solution (an aversive stimulus) were used for olfactory stimulation, while distilled water was used as a control test. The test subject sat with their eyes closed and inhaled the presented smell for 30 seconds, while an EEG recording was made during this time. Study results. Olfactory stimulation in patients with PD showed increased synchronicity of the 3 rhythm in the right hemisphere, as well as the rhythm in the parieto-occipital regions of both hemispheres. These changes indicate significant activation of internal (endogenous) attention, increased overall, non-specific readiness potential, as well as the involvement of the limbic-reticular complex in olfactory perception. Olfactory perception in the control group was accompanied by reduction in the 1 rhythm amplitude in the parieto-occipital regions bilaterally, which may indicate moderate activation of external (exogenous) attention and the posterior attention system responsible for simple perception processes. Conclusion. Increased 3 rhythm amplitude in the right hemisphere and increased rhythm amplitude, observed during directional olfactory perception, may indicate olfactory dysfunction and should be viewed as an additional indicator when establishing a diagnosis of Parkinsons disease.

Abstract Unlike many human senses, multimedia primarily engages the visual and auditory faculties. To broaden the sensory experience influenced by multimedia, it has incorporated olfactory stimulation to enhance the sense of reality. Odors are typically matched with objects in scenes. However, it is impractical to include all odors corresponding to every object in a scene for viewers. Alternatively, researchers propose presenting a singular odor from a category, representative of others within that category. Yet, it remains uncertain whether viewers' reactions to videos featuring multiple odors (e.g., rose, lavender, and lily) from a specific category (e.g., flower) are comparable. Therefore, we investigated whether odors within a given category could exhibit similarity in congruency based on the electroencephalogram (EEG) data's five frequency bands (delta, theta, alpha, beta, and gamma) collected as viewers watched videos. Through questionnaires and EEG experiments, we sought to comprehend the impact of similar odors within categories. It was observed that odors within a specific category were more congruent with videos than those from different odor categories. The delta and theta bands predominantly clustered in EEG data when odors from similar categories were presented to viewers. The theta band, linked to neural signals of odors during olfactory processing, played a significant role. However, despite their association with human emotional responses, the alpha, beta, and gamma bands did not exhibit clustering based on category. Our findings demonstrate the viability of selecting odors based on their categories in multimedia.

… to recognize olfactory stimuli from the EEG response. The study includes recognizing both … stimuli is usually confined in 3–13 Hz, ie, theta (3–7 Hz) and alpha (7–13 Hz) bands [30]–[33…

Classification of olfactory-induced electroencephalogram (EEG) signals has shown great potential in many fields. Since different frequency bands within the EEG signals contain different information, extracting specific frequency bands for classification performance is important. Moreover, due to the large inter-subject variability of the EEG signals, extracting frequency bands with subject-specific information rather than general information is crucial. Considering these, the focus of this letter is to classify the olfactory EEG signals by exploiting the spectral-domain information of specific frequency bands. In this letter, we present an olfactory EEG signal classification network based on frequency band feature extraction. A frequency band generator is first designed to extract frequency bands via the sliding window technique. Then, a frequency band attention mechanism is proposed to optimize frequency bands for a specific subject adaptively. Last, a convolutional neural network (CNN) is constructed to extract the spatio-spectral information and predict the EEG category. Comparison experiment results reveal that the proposed method outperforms a series of baseline methods in terms of both classification quality and inter-subject robustness. Ablation experiment results demonstrate the effectiveness of each component of the proposed method.

Odor sensory evaluation has a broad application in food, clothing, cosmetics, and other fields. Traditional artificial sensory evaluation has poor repeatability, and the machine olfaction represented by the electronic nose (E-nose) is difficult to reflect human feelings. Olfactory electroencephalogram (EEG) contains odor and individual features associated with human olfactory preference, which has unique advantages in odor sensory evaluation. However, the difficulty of cross-subject olfactory EEG recognition greatly limits its application. It is worth noting that E-nose and olfactory EEG are more advantageous in representing odor information and individual emotions, respectively. In this paper, an E-nose and olfactory EEG multimodal learning method is proposed for cross-subject olfactory preference recognition. Firstly, the olfactory EEG and E-nose multimodal data acquisition and preprocessing paradigms are established. Secondly, a complementary multimodal data mining strategy is proposed to effectively mine the common features of multimodal data representing odor information and the individual features in olfactory EEG representing individual emotional information. Finally, the cross-subject olfactory preference recognition is achieved in 24 subjects by fusing the extracted common and individual features, and the recognition effect is superior to the state-of-the-art recognition methods. Furthermore, the advantages of the proposed method in cross-subject olfactory preference recognition indicate its potential for practical odor evaluation applications.