Hafeez Ullah Amin

Brain activation during cognitive tasks: An overview of EEG and fMRI studies

Brain controls all body functions that enable us to perform daily life events dynamically. Memory is an important part of brain that controls and processes our present and past information and interconnects with future plans to assist corresponding dynamic activities of whole body. In cognitive psychology, human memory processes are functionally divided into three categories namely encoding, retention, and recalling. This paper provides an overview of memory processes and brain regions that are activated during these processes using electroencephalography (EEG) and functional magnetic resonance imaging (fMRI). We discussed issues related to cognitive tasks design that may be helpful in future memory research to conduct experiment with EEG and fMRI in a better way.

Brain Behavior in Learning and Memory Recall Process: A High-Resolution EEG Analysis

Learning is a cognitive process, which leads to create new memory. Today, multimedia contents are commonly used in classroom for learning. This study investigated brain physiological behavior during learning and memory process using multimedia contents and Electroencephalogram (EEG) method. Fifteen healthy subjects voluntarily participated and performed three experimental tasks: i) Intelligence task, ii) learning task, and iii) recall task. EEG was recorded duration learning and memory recall task using 128 channels Hydro Cel Geodesic Net system (EGI Inc., USA) with recommended specifications. EEG source localization showed that deep brain medial temporal region was highly activated during learning task. EEG theta band in frontal and parietal regions and gamma band at left posterior temporal and frontal regions differentiated successful memory recall. This study provide additional understanding of successful memory recall that complements earlier brain mapping studies.

EEG based evaluation of stereoscopic 3D displays for viewer discomfort

BackgroundConsumer preference is rapidly changing from 2D to 3D movies due to the sensational effects of 3D scenes, like those in Avatar and The Hobbit. Two 3D viewing technologies are available: active shutter glasses and passive polarized glasses. However, there are consistent reports of discomfort while viewing in 3D mode where the discomfort may refer to dizziness, headaches, nausea or simply not being able to see in 3D continuously.MethodsIn this paper, we propose a theory that 3D technology which projects the two images (required for 3D perception) alternatively, cannot provide true 3D visual experience while the 3D technology projecting the two images simultaneously is closest to the human visual system for depth perception. Then we validate our theory by conducting experiments with 40 subjects and analyzing the EEG results of viewing 3D movie clips with passive polarized glasses while the images are projected simultaneously compared to 2D viewing. In addition, subjective feedback of the subjects was also collected and analyzed.ResultsA higher theta and alpha band absolute power is observed across various areas including the occipital lobe for 3D viewing. We also found that the complexity of the signal, e.g. variations in EEG samples over time, increases in 3D as compared to 2D. Various results conclude that working memory, as well as, attention is increased in 3D viewing because of the processing of more data in 3D as compared to 2D. From subjective feedback analysis, 75% of subjects felt comfortable with 3D passive polarized while 25% preferred 3D active shutter technology.ConclusionsWe conclude that 3D passive polarized technology provides more comfortable visualization than 3D active shutter technology. Overall, 3D viewing is more attractive than 2D due to stereopsis which may cause of high attention and involvement of working memory manipulations.

Dynamics of Scalp Potential and Autonomic Nerve Activity during Intelligence Test

The main objective of this study was to examine the changes in autonomic nervous system (ANS) and scalp potential during intelligence test (IQ). Electroencephalogram (EEG) and Electrocardiogram (ECG) signals were recorded simultaneously from eight healthy participants during IQ and resting states (eyes–closed and eyes-open). Heart rate (HR) and heart rate variability (HRV) were derived from ECG signal. EEG mean power was computed for five frequency bands (delta, theta, alpha, beta, and gamma) and analyzed in 12 regions across the scalp. The EEG frequency bands showed significant (p<0.025) changes between IQ test and rest states. Delta and theta at frontal (PF, AF, F) and temporal regions (FT, T, TP) and alpha activity at parietal (P), parieto-occipital (PO) and occipital (O) regions were significant. In beta and gamma bands, highly reduced mean power was found at P, PO, and O regions as compared to PF, AF, and F regions in IQ test. HR and low frequency in normalized unit (LFnu) were increased significantly (p<0.05 and p<0.025, respectively) in IQ test. Further, high frequency in normalized unit (HFnu) was decreased (p<0.11). Results showed parallel changes in scalp potential and automatic nervous activity during IQ test compared to rest conditions.

The Influences of Emotion on Learning and Memory

Emotion has a substantial influence on the cognitive processes in humans, including perception, attention, learning, memory, reasoning, and problem solving. Emotion has a particularly strong influence on attention, especially modulating the selectivity of attention as well as motivating action and behavior. This attentional and executive control is intimately linked to learning processes, as intrinsically limited attentional capacities are better focused on relevant information. Emotion also facilitates encoding and helps retrieval of information efficiently. However, the effects of emotion on learning and memory are not always univalent, as studies have reported that emotion either enhances or impairs learning and long-term memory (LTM) retention, depending on a range of factors. Recent neuroimaging findings have indicated that the amygdala and prefrontal cortex cooperate with the medial temporal lobe in an integrated manner that affords (i) the amygdala modulating memory consolidation; (ii) the prefrontal cortex mediating memory encoding and formation; and (iii) the hippocampus for successful learning and LTM retention. We also review the nested hierarchies of circular emotional control and cognitive regulation (bottom-up and top-down influences) within the brain to achieve optimal integration of emotional and cognitive processing. This review highlights a basic evolutionary approach to emotion to understand the effects of emotion on learning and memory and the functional roles played by various brain regions and their mutual interactions in relation to emotional processing. We also summarize the current state of knowledge on the impact of emotion on memory and map implications for educational settings. In addition to elucidating the memory-enhancing effects of emotion, neuroimaging findings extend our understanding of emotional influences on learning and memory processes; this knowledge may be useful for the design of effective educational curricula to provide a conducive learning environment for both traditional “live” learning in classrooms and “virtual” learning through online-based educational technologies.

Effects of stereoscopic 3D display technology on event-related potentials (ERPs)

The purpose of this study is to explore the effects of stereoscopic 3D (S3D) display technology on event-related brain potentials (ERPs). A sample of thirty-four healthy participants was subjected to an oddball paradigm after being exposed to stereoscopic 3D contents with passive polarized display or traditional 2D display. The participants were randomly assigned to two groups-2D group and S3D group; in such a way that their intelligence ability and age were controlled between the groups. The behavioral and ERP results did not show any significant differences between S3D and 2D groups for either ERP components (amplitude and latency) or accuracy and response time of the target detection. These results suggest that passive polarized S3D display technology may not induce any effects (cognitive or visual fatigue) which may disturb the ERP components.

Evaluation of passive polarized stereoscopic 3D display for visual & mental fatigues.

Visual and mental fatigues induced by active shutter stereoscopic 3D (S3D) display have been reported using event-related brain potentials (ERP). An important question, that is whether such effects (visual & mental fatigues) can be found in passive polarized S3D display, is answered here. Sixty-eight healthy participants are divided into 2D and S3D groups and subjected to an oddball paradigm after being exposed to S3D videos with passive polarized display or 2D display. The age and fluid intelligence ability of the participants are controlled between the groups. ERP results do not show any significant differences between S3D and 2D groups to find the aftereffects of S3D in terms of visual and mental fatigues. Hence, we conclude that passive polarized S3D display technology may not induce visual and/or mental fatigue which may increase the cognitive load and suppress the ERP components.

EEG spectral analysis during complex cognitive task at occipital

Normal oscillations in different frequency bands have an important role in cognitive processing in the frontal region. The key issue is whether frequency oscillations of Electroencephalography (EEG) are related to cognitive task or not in occipital region. All frequency bands delta (δ), theta (θ), alpha (α), beta (β) and gamma (γ) are involved in brain tasks. This study is conducted to investigate the functional relationship between EEG frequency bands and the cognitive task. In various studies theta, alpha and beta bands are discussed for cognitive tasks; however there are few studies which have been focused on delta band for cognitive tasks. In this paper, behavior of θ, α, β and γ is described but the primary focus is on delta (δ) band during cognitive task in occipital region as it had been ignored in the literature. In conclusion, this study explains how different frequencies change during cognitive task as compared to base line (eyes open) in occipital region and the results show that there is an increase in power during the task in delta and theta band.

EEG spectral analysis and functional connectivity during learning of science concepts

This paper aims to analyze the neuronal behavior of the brain during learning of science complex concepts and compare the brain dynamics during learning state with resting state. A sample of 34 healthy participants was recruited and performed two tasks, Ravens Advanced Progressive Matrices (RAPM) intelligence assessment and learning task. Electroencephalography (EEG) signals were recorded during resting state (eyes open) and in learning task. In the learning task, participants study animated contents about human anatomy and physiology for 10 minutes. In the EEG spectral analysis, all six frequency bands showed higher mean power during learning task compared to resting state in the frontal lobe, especially in FP2 and F8 locations. High EEG activity in frontal sites reflects high attention demand and working memory resources for studying the complex science concepts. There is also high connectivity between fronto-temporo-parietal regions indicate that an increase connection network for new memory encoding and it is critical for learning and memory.

A system based on 3D and 2D educational contents for true and false memory prediction using EEG signals

Electroencephalography (EEG) has been widely adopted for investigating brain behavior in different cognitive tasks e.g. learning and memory. In this paper, we propose a pattern recognition system for discriminating the true and false memories in case of short-term memory (STM) for 3D and 2D educational contents by analyzing EEG signals. The EEG signals are converted to scalp-maps (topomaps) and city-block distance is applied to reduce the redundancy and select the most discriminative topomaps. Finally, statistical features are extracted from selected topomaps and passed to Support Vector Machine (SVM) to predict brain states corresponding to true and false memories. A sample of thirty four healthy subjects participated in the experiments, which consist of two tasks: learning and memory recall. In the learning task, half of the participants watched 2D educational contents and half of them watched the same contents in 3D mode. After 30 minutes of retention, they were asked to perform memory recall task, in which EEG signals were recorded. The classification accuracy of 97.5% was achieved for 3D as compared to 96.5% for 2D. The statistical analysis of the results suggest that there is no significant difference between 2D and 3D educational contents on STM in terms of true and false memory assessment.