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Brainwave
Brainwaves are any form of electrical activity of the brain which are associated with different states of consciousness and brain activity. It is like the electrical signals that are produced by your brain. They can be measured using a device called an EEG and various other types of brainwaves are linked to different states of consciousness and brain activity.
Types of Brain Waves
EEG (electroencephalography) : EEG is a non-invasive method of measuring the electrical activity of the brain. It uses electrodes placed on the scalp to detect and record the brain's electrical activity, which can then be analyzed to understand the various types of brain waves and the different states of brain activity
iEEG (intracranial EEG) : iEEG involves the placement of electrodes directly into the brain (i.e Invasive Technology), either through a surgical procedure or through a device that is implanted for long-term monitoring. This method allows for a more direct and localized recording of brain activity, and can provide a higher resolution and more accurate measurement of brain activity compared to surface EEG.
ECoG(electrocorticography) : ECoG involves the placement of electrodes on the surface of the brain (i.e Invasive Technology). This method can provide a higher spatial resolution than scalp EEG and is useful for studying brain activity associated with specific cognitive or motor tasks.
fNIRS(functional Near-Infrared Spectroscopy) : fNIRS is based on the absorption of near-infrared light by oxygenated and deoxygenated hemoglobin in the brain. fNIRS can provide a non-invasive measurement of brain activity and it has been used in many different settings, including research studies and in some clinical applications. (NOTE : fNIRS is able to provide information about the changes in brain activity in a specific region of the brain, but it's not able to record the rhythmic patterns of electrical activity associated with brain waves as in EEG)
EEG Electrode Placement
< 10/20 System Positioning >
Image Source : 10/20 System Positioning / Trans Cranial Technologies
< 10/10 System Positioning >
Image Source : 10/20 System Positioning / Trans Cranial Technologies
EEG Wave Types
NOTE : You would notice that Alpha wave and Mu Waves has overlapping frequency (almost same range of frequency). Then how we can differentiate between them from EEG plot ?. There are some hints for differentiating them.
Following illustration of typical waveform of each of the type. As you would notice, the brain wave type is classified largely by frequency and amplitude pattern.
Image Source : A Deep Dive Into Brainwaves: Brainwave Frequencies Explained
iEEG Wave Types
iEEG (intracranial electroencephalography) is a method of measuring electrical activity in the brain using electrodes that are surgically implanted directly into the brain tissue. This method allows for a higher temporal and spatial resolution of brain activity compared to non-invasive methods such as scalp EEG. It is often used in research on epilepsy, brain tumors, and other conditions that affect the brain. It is also used for the study of normal brain function and for the development of brain-computer interfaces.
NOTE : the key difference between iEEG and EEG is that iEEG provides a more localized and higher-resolution recording of brain activity, which allows for a more detailed analysis of brain activity
ECoG Wave Types
ECoG (electrocorticography) is a method of measuring electrical activity in the brain that is similar to intracranial EEG (iEEG). Instead of electrodes being implanted directly into the brain tissue, ECoG electrodes are placed on the surface of the brain, typically under the skull but over the brain's surface. This method provides a higher spatial resolution than scalp EEG, and a lower temporal resolution than iEEG. ECoG is often used in research on brain function and for the development of brain-computer interfaces. It also used in the study of epilepsy, brain tumors, and other conditions that affect the brain, as well as in neurosurgery for the localization of eloquent brain regions (areas responsible for language, motor, and other functions).
NOTE : The main difference between ECoG and EEG or iEEG is that ECoG is more invasive than EEG and less invasive than iEEG and it provides a higher spatial resolution than scalp EEG NOTE : What is the difference between iEEG and ECoG ? They sound pretty similar to me. iEEG and ECoG are similar in that they both involve measuring electrical activity in the brain, but there are some key differences between the two methods.
What is ERP (Event Related Potential) ?
Event-related potential (ERP) is a technique used in cognitive neuroscience and psychophysiology to study the neural responses to specific events or stimuli. It involves measuring the electrical activity of the brain (via electroencephalography, or EEG) in response to a specific event or stimulus, such as a visual or auditory cue. The resulting EEG data is then analyzed to identify specific patterns of electrical activity, known as "components," that are thought to correspond to different cognitive processes. These components can be used to study a wide range of cognitive processes, including attention, perception, memory, and decision-making.
NOTE : The number in Stimuls-Response Delay is just a ball-park figure. Do not take this as a strict value. You may see a little bit different number from different source.
P1 is a component of the event-related potential (ERP) that is observed in the EEG signal in response to visual stimuli, typically around 100-150 milliseconds after the stimulus. It is thought to reflect the early stages of visual processing, particularly in the primary visual cortex.
The P1 component is a positive-going potential that is observed in the EEG signal in response to visual stimuli, such as simple geometric shapes, gratings, and checkerboards. It is thought to reflect the early stages of visual processing, particularly in the primary visual cortex, where the visual information is encoded in terms of simple features such as brightness, color, and contrast. The amplitude of the P1 component is often larger for stimuli that are presented at the center of the visual field than for stimuli that are presented at the periphery of the visual field, reflecting the fact that the primary visual cortex has a higher spatial resolution in the fovea than in the periphery.
It is widely used in the research on visual perception, particularly in the study of the neural correlates of early visual processing, attention allocation, and working memory in healthy individuals and in patients with visual and neurological disorders.
P2 is a component of the event-related potential (ERP) that is observed in the EEG signal in response to visual stimuli, typically around 150-250 milliseconds after the stimulus. It is thought to reflect the early stages of visual processing, attention allocation, and working memory.
The P2 component is a positive-going potential that is observed in the EEG signal in response to visual stimuli, such as simple geometric shapes, gratings, and checkerboards. It is thought to reflect the early stages of visual processing, particularly in the primary visual cortex, where the visual information is encoded in terms of simple features such as brightness, color, and contrast. The amplitude of the P2 component is often larger for stimuli that are presented at the center of the visual field than for stimuli that are presented at the periphery of the visual field, reflecting the fact that the primary visual cortex has a higher spatial resolution in the fovea than in the periphery.
P2 is often considered as a reflection of the allocation of attentional resources to the stimulus, as well as the early stages of working memory. It has been found that the amplitude of the P2 component is modulated by task demands, such as the attentional load and the memory load of a task.
It is widely used in the research on visual perception, particularly in the study of the neural correlates of early visual processing, attention allocation, and working memory in healthy individuals and in patients with visual and neurological disorders.
P3a is a component of the event-related potential (ERP) that is observed in the EEG signal in response to visual and auditory stimuli, typically around 300-350 milliseconds after the stimulus. It is thought to reflect early stages of attention allocation, target detection and decision making.
The P3a component is a positive-going potential that is observed in the EEG signal in response to a variety of stimuli, such as simple geometric shapes, gratings, checkerboards, and sounds. It is thought to reflect the early stages of attention allocation, target detection and decision making. The amplitude of the P3a component is often larger for stimuli that are considered to be targets or relevant for a task, as compared to stimuli that are considered to be non-targets or irrelevant.
It is observed in both the visual and auditory modalities and it is thought to be related to the orienting of attention to new or rare stimuli. It has been found that the amplitude of the P3a component is modulated by task demands, such as the attentional load, the memory load and the difficulty of a task.
It is widely used in the research on cognitive and attention processing, particularly in the study of the neural correlates of attention allocation, target detection, and decision making in healthy individuals and in patients with cognitive and neurological disorders
This component is typically observed around 50 milliseconds after the presentation of a stimulus. It is often associated with the processing of auditory stimuli, and is thought to reflect the initial activation of the primary auditory cortex.
The P50 component is a specific type of "sensory gating" which refers to the ability of the brain to selectively filter out redundant or irrelevant information. The P50 component is thought to reflect the neural process of suppressing or "gating out" stimuli that are not relevant to the task at hand.
P50 is often used as an index of "gating deficit" in certain psychiatric disorders such as schizophrenia, where the suppression of irrelevant stimuli is impaired, leading to increased sensitivity to auditory stimuli.
This component is typically observed around 200 milliseconds after the presentation of a stimulus. It is often associated with the processing of auditory and somatosensory stimuli, and is thought to reflect the initial processing of the stimuli in the primary sensory cortices.
P200 is often considered as an index of sensory discrimination and early attentional processing. It's amplitude is modulated by factors such as the similarity of the stimuli, the relevance of the stimuli to the task, and the attentional focus of the participant.
P200 is also often used as an index of cognitive and attentional function in a variety of clinical populations, such as individuals with attention-deficit/hyperactivity disorder (ADHD) or schizophrenia.
This component is a positive-going deflection that occurs about 300 milliseconds after a stimulus is presented. It is thought to reflect cognitive processes related to attention and decision-making, such as the allocation of attention to a target stimulus or the evaluation of the relevance of a stimulus.
The amplitude of the P300 is typically larger for "target" stimuli (i.e., stimuli that are infrequent or relevant to the task at hand) compared to "non-target" stimuli.
The P300 is commonly used in BCI research as an indicator of cognitive processing. It has been used in studies of a variety of cognitive and neurological disorders, including Alzheimer's disease, schizophrenia, and attention-deficit/hyperactivity disorder (ADHD). Additionally, P300-based BCIs have been used to develop assistive technology for individuals with motor impairments.
It is also used in lie detection and in the field of neuro-marketing, where it is used to measure the consumer's attention and reaction to different stimuli. Some companies use P300 to measure the consumer's reaction to their ads, package design, and even price changes.
NOTE : It seems that P300 is more often mentioned in the context of brainwave signal processing comparing to other ERP. It may be because it is a robust and reliable measure of cognitive processing and it is relatively easy to elicit and measure
The P600 is a component of the event-related potential (ERP) that is typically observed in response to language-related stimuli. It is a positive deflection in the EEG signal that occurs around 600 milliseconds after the stimulus is presented. The P600 is thought to reflect the neural processes involved in syntactic processing and is often observed in tasks that involve the manipulation of sentence structure. It is considered to be a marker of syntactic integration and reanalysis.
The N1 component of the event-related potential (ERP) is a negative deflection in the EEG signal that typically occurs around 100-200 milliseconds after a stimulus is presented. The N1 is thought to reflect sensory processing, particularly in the primary visual and auditory cortices. It has been observed in response to various types of stimuli, including visual and auditory stimuli, and is often used as an index of early sensory processing and attention. The N1 component is sensitive to the physical characteristics of the stimuli such as its luminance, contrast, and spatial frequency.
The N2 component of the event-related potential (ERP) is a negative deflection in the EEG signal that typically occurs around 200-300 milliseconds after a stimulus is presented. The N2 is thought to reflect cognitive processes such as attention allocation, conflict detection, and response inhibition. It is observed in response to various types of stimuli, including visual, auditory, and somatosensory stimuli. The N2 is typically larger and more prolonged when the task is more demanding or when there is conflict between the stimuli and the response. It has also been observed to be sensitive to the context of the task and the subject's prior expectations. Some studies also found N2 to be related to working memory and semantic processing
This component is a negative-going deflection that occurs around 200 milliseconds after a stimulus is presented. It is thought to reflect cognitive processes related to attention and spatial processing, such as the allocation of attention to a specific location in space.
This component is a negative-going deflection that occurs around 170 milliseconds after a face is presented. It is thought to reflect cognitive processes related to face processing, such as the encoding of facial features.
This component is a negative-going deflection that occurs about 400 milliseconds after a stimulus is presented. It is thought to reflect cognitive processes related to language processing, such as the integration of a word or phrase into the context of a sentence.
MMN (MisMatch Negativity)
MMN is a component of the event-related potential (ERP) that is observed in the EEG signal in response to a change or deviation in a regular pattern of auditory or visual stimuli. The MMN is a negative deflection that occurs in the period following the deviant stimulus, typically around 100-250 milliseconds. It is thought to reflect the neural processes involved in change detection, auditory memory and perception.
MMN is an automatic and implicit measure of the brain's ability to detect changes in the environment, it is not affected by attention, awareness, or decision making. It can be used to study a variety of cognitive and neurological disorders, such as autism, schizophrenia, and dyslexia.
The MMN is widely used in the research on cognitive and auditory processing, particularly in the study of the neural correlates of change detection, auditory memory, and perception in healthy individuals and in patients with cognitive and neurological disorders.
This component is a positive-going deflection that occurs around 100 milliseconds after a visual stimulus is presented. It is thought to reflect cognitive processes related to early visual processing, such as the detection of motion or changes in contrast.
CNV (Contingent Nevative Variation)
This component is a slow negative-going deflection that occurs up to several seconds before a voluntary movement. It is thought to reflect cognitive processes related to motor preparation and planning
LPC (Late Positive Component)
LPC is an ERP component that is observed in the EEG signal in response to a variety of cognitive tasks, typically around 400-600 milliseconds after the stimulus. It is thought to reflect the neural processes involved in semantic processing, context integration, and memory encoding.
The LPC is often observed in the EEG signal in response to tasks that require semantic processing, such as word recognition, sentence comprehension, and memory encoding. It is believed to reflect the neural processes involved in the integration of semantic information, particularly in the context of memory encoding.
The LPC is widely used in the research on cognitive and language processing, particularly in the study of semantic processing, memory encoding, and context integration in healthy individuals and in patients with cognitive and neurological disorders.
SPCN (Sustained Posterior Contralateral Negativity)
SPCN is a component of the event-related potential (ERP) that is observed in the EEG signal in response to a variety of cognitive tasks, typically around 1000-2000 milliseconds after the stimulus. It is thought to reflect the neural processes involved in semantic processing, memory encoding, and decision making.
SPCN is a sustained negativity that is observed over the contralateral posterior scalp regions (usually over the parietal and temporal regions) in response to semantic processing tasks, such as word and picture categorization, semantic decision, and memory encoding. The SPCN is larger for semantically incongruent than for congruent stimuli and is interpreted as reflecting the neural processes involved in semantic processing, memory encoding and decision making.
It is widely used in the research on cognitive and language processing, particularly in the study of semantic processing, memory encoding, and decision making in healthy individuals and in patients with cognitive and neurological disorders.
LPP (Late Positive Potential)
LPP is a component of the event-related potential (ERP) that is observed in the EEG signal in response to a variety of cognitive tasks, typically around 400-800 milliseconds after the stimulus. It is associated with the processing of emotionally and motivationally significant stimuli.
The LPP is often observed in the EEG signal in response to tasks that require emotional processing, such as emotional words, pictures, and faces. It is believed to reflect the neural processes involved in the processing of emotionally and motivationally significant stimuli, particularly in the context of memory encoding.
The LPP is a positive going potential, which is observed in the EEG signal after the presentation of emotionally and motivationally significant stimuli, such as emotionally valenced words, pictures, and faces. The amplitude of the LPP is often larger for stimuli that are considered to be emotionally positive (e.g. happy faces) than for stimuli that are considered to be emotionally negative (e.g. angry faces) or neutral.
It is widely used in the research on cognitive and emotional processing, particularly in the study of emotional processing, memory encoding, and context integration in healthy individuals and in patients with cognitive and neurological disorders.
MRCP (Movement Related Cortical Potential)
The movement-related cortical potential (MRCP) is a component of the event-related potential (ERP) that is observed in the EEG signal in response to voluntary movements. The MRCP is a negative deflection that occurs in the pre-movement period, typically around 100-200 milliseconds before the movement begins. It is thought to reflect the neural processes involved in the preparation and planning of movements, and is often used as an index of motor planning and preparation.
The MRCP is composed of several subcomponents, including the readiness potential (RP), the Bereitschaftspotential (BP), and the negative slope of the lateralized readiness potential (LRP-N). The RP is thought to reflect the neural processes involved in the preparation and planning of movements, while the BP is thought to reflect the neural processes involved in the selection and initiation of movements. The LRP-N is observed in the contralateral hemisphere to the movement and reflects the neural processes involved in the lateralization of motor control.
The MRCP is widely used in the research on motor control, particularly in the study of the neural correlates of movement preparation and execution in healthy individuals and in patients with movement disorders.
PINV (Post-Imperative Negative Variation)
The post-imperative negative variation (PINV) is a component of the event-related potential (ERP) that is observed in the EEG signal in response to imperative stimuli such as "stop" or "go" commands. The PINV is a negative deflection that occurs in the period following the imperative stimulus, typically around 300-500 milliseconds. It is thought to reflect the neural processes involved in response inhibition, specifically the process of stopping an ongoing motor response.
The PINV is observed in the EEG signal when a subject receives a command to stop a response that has been previously prepared. It is believed to reflect the neural processes involved in the inhibition of the prepared response, and is often used as an index of response inhibition and cognitive control.
The PINV has been widely studied in the context of cognitive and motor control, particularly in the study of response inhibition and impulse control in healthy individuals and in patients with movement disorders or neurological conditions such as attention deficit hyperactivity disorder (ADHD) and Parkinson's disease.
NOTE : Positive-going deflection vs Negative-going deflection
Reference
YouTube
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