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Behavioral states may be associated with distinct spatial patterns in electrocorticogram.

Panagiotides H, Freeman WJ, Holmes MD, Pantazis D - Cogn Neurodyn (2010)

Bottom Line: Moments of maximal spatial variance are shown to cluster by behavior.Comparisons between conditions using a permutation test reveal significantly different spatial patterns for each behavior.We conclude that ECoG recordings obtained on the cortical surface with optimal high spatial frequency resolution reveal distinct local spatial patterns that reflect different behavioral states, and we predict that similar patterns will be found in many if not most cortical areas on which a microgrid is placed.

View Article: PubMed Central - PubMed

ABSTRACT
To determine if behavioral states are associated with unique spatial electrocorticographic (ECoG) patterns, we obtained recordings with a microgrid electrode array applied to the cortical surface of a human subject. The array was constructed with the intent of extracting maximal spatial information by optimizing interelectrode distances. A 34-year-old patient with intractable epilepsy underwent intracranial ECoG monitoring after standard methods failed to reveal localization of seizures. During the 8-day period of invasive recording, in addition to standard clinical electrodes a square 1 × 1 cm microgrid array with 64 electrodes (1.25 mm separation) was placed on the right inferior temporal gyrus. Careful review of video recordings identified four extended naturalistic behaviors: reading, conversing on the telephone, looking at photographs, and face-to-face interactions. ECoG activity recorded with the microgrid that corresponded to these behaviors was collected and ECoG spatial patterns were analyzed. During periods of ECoG selected for analysis, no electrographic seizures or epileptiform patterns were present. Moments of maximal spatial variance are shown to cluster by behavior. Comparisons between conditions using a permutation test reveal significantly different spatial patterns for each behavior. We conclude that ECoG recordings obtained on the cortical surface with optimal high spatial frequency resolution reveal distinct local spatial patterns that reflect different behavioral states, and we predict that similar patterns will be found in many if not most cortical areas on which a microgrid is placed.

No MeSH data available.


Related in: MedlinePlus

Sample segments excluded from analysis due to artifacts
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Fig2: Sample segments excluded from analysis due to artifacts

Mentions: Only the microgrid physiological record during the aforementioned behaviors was considered for analysis. The record during those time periods was seizure-free. Unlike conventional EEG recordings, corticographic recordings are less susceptible to muscle artifacts, such as eye blinks, body, head and tongue movement, than conventional EEG recordings. The main artifact that may be seen with intracranial EEG is pulse signals, if the electrode is near a vessel. Other artifacts include the electrode wire being grossly pulled from the outside, which is a rare occurrence because the subdural electrodes are securely anchored (Spencer et al. 2008). In this study, the physiological record for each condition was visually inspected and motion and other artifacts were identified and demarcated. Artifacts were characterized by their amplitude and overall morphology. The most common artifact was signals sharply deviating from the overall norm in one or more electrodes. Figure 2 shows examples of such artifact segments. Overall, the percentage of the data that were excluded from analysis was: 24.65% for the face condition, 24.8% for the pictures condition, 0.3% for the reading condition, and 14.7% for the phone condition. All artifact-free segments of each specific behavior were entered into subsequent analysis.Fig. 2


Behavioral states may be associated with distinct spatial patterns in electrocorticogram.

Panagiotides H, Freeman WJ, Holmes MD, Pantazis D - Cogn Neurodyn (2010)

Sample segments excluded from analysis due to artifacts
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3045495&req=5

Fig2: Sample segments excluded from analysis due to artifacts
Mentions: Only the microgrid physiological record during the aforementioned behaviors was considered for analysis. The record during those time periods was seizure-free. Unlike conventional EEG recordings, corticographic recordings are less susceptible to muscle artifacts, such as eye blinks, body, head and tongue movement, than conventional EEG recordings. The main artifact that may be seen with intracranial EEG is pulse signals, if the electrode is near a vessel. Other artifacts include the electrode wire being grossly pulled from the outside, which is a rare occurrence because the subdural electrodes are securely anchored (Spencer et al. 2008). In this study, the physiological record for each condition was visually inspected and motion and other artifacts were identified and demarcated. Artifacts were characterized by their amplitude and overall morphology. The most common artifact was signals sharply deviating from the overall norm in one or more electrodes. Figure 2 shows examples of such artifact segments. Overall, the percentage of the data that were excluded from analysis was: 24.65% for the face condition, 24.8% for the pictures condition, 0.3% for the reading condition, and 14.7% for the phone condition. All artifact-free segments of each specific behavior were entered into subsequent analysis.Fig. 2

Bottom Line: Moments of maximal spatial variance are shown to cluster by behavior.Comparisons between conditions using a permutation test reveal significantly different spatial patterns for each behavior.We conclude that ECoG recordings obtained on the cortical surface with optimal high spatial frequency resolution reveal distinct local spatial patterns that reflect different behavioral states, and we predict that similar patterns will be found in many if not most cortical areas on which a microgrid is placed.

View Article: PubMed Central - PubMed

ABSTRACT
To determine if behavioral states are associated with unique spatial electrocorticographic (ECoG) patterns, we obtained recordings with a microgrid electrode array applied to the cortical surface of a human subject. The array was constructed with the intent of extracting maximal spatial information by optimizing interelectrode distances. A 34-year-old patient with intractable epilepsy underwent intracranial ECoG monitoring after standard methods failed to reveal localization of seizures. During the 8-day period of invasive recording, in addition to standard clinical electrodes a square 1 × 1 cm microgrid array with 64 electrodes (1.25 mm separation) was placed on the right inferior temporal gyrus. Careful review of video recordings identified four extended naturalistic behaviors: reading, conversing on the telephone, looking at photographs, and face-to-face interactions. ECoG activity recorded with the microgrid that corresponded to these behaviors was collected and ECoG spatial patterns were analyzed. During periods of ECoG selected for analysis, no electrographic seizures or epileptiform patterns were present. Moments of maximal spatial variance are shown to cluster by behavior. Comparisons between conditions using a permutation test reveal significantly different spatial patterns for each behavior. We conclude that ECoG recordings obtained on the cortical surface with optimal high spatial frequency resolution reveal distinct local spatial patterns that reflect different behavioral states, and we predict that similar patterns will be found in many if not most cortical areas on which a microgrid is placed.

No MeSH data available.


Related in: MedlinePlus