Neuronal Activity Topography Research Articles

Neuronal Activity Topography Reveals Neuronal Change in Comatose Patients Treated by tDCS.

BACKGROUND: In our hospital, transcranial direct current stimulation (tDCS) is applied in combination with occupational therapy (OT) for patients with persistent consciousness disorders. There have been reports from some research groups on Left dorsolateral prefrontal area (F3) anodal stimulation as wells as Frontal pole (Fpz) anodal stimulation under different conditions. We chose either anodal stimulation site depending on the patient's condition. CASES: Nine patients underwent tDCS with Fpz or F3 anodal stimulation for 10 days, followed by a 2-day break, after which the stimulation sites were switched, and the patients were stimulated for another 10 days. Their Electroencephalography changes were evaluated by using visual images of neuronal activity topography (NAT). The asymmetry index (AI) was also calculated to compare lateral differences in neuronal changes in the frontal lobe. Seven out of nine cases started with Fpz anode, and two with F3 anode. In the former setting, six cases improved, two aggravated and one remained unchanged. In the latter, one case unchanged and one remained aggravated. After applying tDCS, NAT and AI of the improved cases showed a tendency to approximate the normal control group. Discussion: Among these cases, all but one showed improvement in CRS-R scores, especially in Fpz stimulation. Additionally, changes in the scores indicated that most cases showed improvements in responses to visual and auditory stimulation. Furthermore, the NAT system allows for the rapid and minimally invasive assessment of changes in neuronal activity. Consequently, it is suggested that this system may be valuable for evaluating the therapeutic effects of tDCS and identifying effective stimulation sites.

Neuronal activity topography (NAT) analysis of EEG can predict neurocognitive deterioration earlier than FDG‐PET

AbstractBackgroundWe recently reported that FDG‐PET can predict neurocognitive deterioration three years earlier than cognition in our aging cohort. This study examined whether EEG detects the deterioration as early as FDG‐PET.MethodTwo groups of subjects’ data‐set with normal PET/cognition were selected from our cognitively normal (CN) elderly cohort who participated in the same‐day EEG and FDG‐PET annually. The NLC group (n = 41, age = 75.2±4.7y, MMSE = 29.3±1.1) consists of those whose PET findings remain normal for more than three successive years. NL2 group (n = 22, age = 75.1±4.9y, MMSE = 29.0±1.5) consists of those whose PET findings deteriorate within three years. Each PET image was classified into five ranks (A/A‐/B/B‐/C) by visual and statistical analysis and A/A‐ were regarded as normal. The results of neuropsychological tests (MMSE, HDS‐R, MoCA) and Neuronal Activity Topography (NAT) analysis indices derived from five minutes EEG record at rest with eyes closed were compared between the two groups.ResultThe average value of the two groups is significantly different in (1) the index sNAT value based on the power spectrum of the EEG, (2) the index vNAT value based on the power ratio of the sNAT values of adjacent frequency subbands, and (3) the mean power frequency of the occipital region (sNATNLC = ‐0.077±0.071, sNATNL2 = ‐0.022±0.103, p = 0.03* ; vNATNLC = ‐0.080±0.076, vNATNL2 = ‐0.038±0.059, p = 0.03* ; MPFNLC = 9.29±0.48Hz, MPFNL2 = 8.97±0.55Hz, p = 0.02*). In the NL2 group, a significant negative correlation was found between vNAT value and MMSE, and MoCA (CORvNAT‐MMSE = ‐0.43, p = 0.05* ; CORvNAT‐MoCA = ‐0.59, p < 0.01**. Above findings suggest that the signs of cognitive deterioration in near future is detectable using NAT analysis.ConclusionIn cognitively normal subjects whose PET findings start to deteriorate in the next following years, signs of deterioration are already detectable with NAT analysis of EEG. This suggests that the alteration of neuro‐electrical activity may precede the decline of cerebral glucose metabolism. Further study with larger groups is necessary.

Post-fracture Rehabilitation Effects on Brain Function in Older People

Deterioration of cognitive function is an underlying cause of older people's fractures. The purpose of this study was to evaluate electroencephalogram and cognitive function in patients hospitalized with fractures, both at admission (before intervention) and at the time of discharge (after intervention), to investigate the effects of rehabilitation on brain function. A total of 24 patients hospitalized with fracture due to a fall were enrolled in this study. All the subjects received 140 minutes of rehabilitation every day during hospitalization. Touch Panel-type Dementia Assessment Scale (TDAS) was used to test their cognitive function. In electroencephalography (EEG), the Neuronal Activity Topography (NAT) system was used to calculate the "Alzheimer's disease (AD) - normal controls (NLc) differential similarity" in sNAT, ie, a numerical index to show the proximity to AD or normal NLc. There was no significant difference in the total TDAS score among subjects who were examined before and after intervention, but 12 subjects who were observed with deterioration of cognitive functionat atbefore intervention had a significant improvement in "word-recognition," a sub-item in TDAS (P < 0.05). In addition, the NAT analysis findings showed that the differential similarity in sNAT significantly approached the NLc pattern (P < 0.05). EEGs in patients with fractures resulting from a fall became more similar to NL patterns at the time of discharge. In addition, recent-memory function of patients who had decline in cognitive function improved.

Boundary EEG Asymmetry Is Associated to Linguistic Competence in Vascular Cognitive Impairments.

Background and Purpose: We recently noted a gradual change in the boundary electroencephalography (EEG) oscillation of 7.8 Hz between theta (θ) and alpha (α) bands in response to increased atherosclerosis levels in the elderly. The aim of this study was to investigate the role of boundary EEG oscillations of θ-α bands on cognitive functions in vascular cognitive impairments (VCI) patients.Materials and Methods: We examined 55 patients with VCI in carotid stenosis, and underwent EEG in a resting state with closed eyes for 5 min. The asymmetry index (AI) along homologous channel pairs (e.g., F7-8) was assessed using neuronal activity topography (NAT). AI referring to 10 frequency components ranging from 4 to 20 Hz and neuropsychological assessments including linguistic competence were analyzed.Results: The main findings was that the language score had a positive association with AI in 7.8 Hz at F7-8 and a negative association with AI in 6.3 Hz at C3-4 and 14.1 Hz at F3-4.Conclusion: EEG asymmetry in a boundary range might have a special role in linguistic competence, suggesting the application of neural oscillation on the cognitive function evaluation and neurorehabilition induced by a frequency-specific transcranial alternating current stimulation.

Altered Neuronal Activity Topography Markers in the Elderly with Increased Atherosclerosis.

Background: Previously, we reported on vascular cognitive impairment (VCI) templates, consisting of patients with VCI associated with carotid stenosis (>60%) using a quantitative electroencephalographic (EEG) technique called neuronal activity topography (NAT). Here using the VCI templates, we investigated the hypothesis that internal carotid artery–intima-media thickness (ICA–IMT) is associated with EEG spectrum intensity (sNAT) and spectrum steepness (vNAT).Methods: A total of 221 community-dwelling elderly subjects were recruited. Four groups were classified according to quartiles of ICA–IMT as assessed by ultrasonography: control group A, normal (≤0.9 mm); group B, mild atherosclerosis (1−1.1 mm); group C, moderate atherosclerosis (1.2−1.8 mm); and group D, severe atherosclerosis (≥1.9 mm). EEG markers of power ratio index (PRI), and the binary likelihood of being in the VCI group vs. the that of being in control group A (sLx:VCI−A, vLx:VCI−A) were assessed, respectively. Differences in mean total scores for PRI, sLx:VCI−A, vLx:VCI−A, between control group A and the other groups were compared using Dunnett's test, respectively.Results: The mean total scores of the PRI were 3.25, 3.00, 2.77, and 2.26 for groups A, B, C, and D, respectively. There was a significant decrease in the PRI in group D compared with group A (P = 0.0066). The mean total scores of the sLx:VCI−A were −0.14, −0.11, −0.1, and −0.03 for groups A, B, C, and D, respectively. The sLx:VCI−A in group D was significantly higher compared to that in group A (P < 0.0001). The mean total scores of the vLx:VCI−A were −0.04,−0.01, 0.01, and 0.06 for group A, B, C, and D, respectively. The vLx:VCI−A in group D and group C was significantly higher compared to that in group A, respectively (P < 0.0001, P = 0.02).Conclusion: Community-dwelling elderly subjects in the increased carotid atherosclerosis of ICA–IMT (≥1.9 mm) were at greatest risk of an EEG change as assessed by NAT.

Neuronal Activity Topography Parameters as a Marker for Differentiating Vascular Cognitive Impairment in Carotid Stenosis

Previously, we reported on the differentiation between patients with Alzheimer disease and normal controls using a quantitative electroencephalographic technique called neuronal activity topography (NAT). In this technique, cerebral neuronal activities are characterized by the signal intensity and coherence (sNAT and vNAT, respectively). In the present study, we examined 47 patients with vascular cognitive impairment in carotid stenosis and 52 normal controls. All subjects underwent electroencephalography in a resting state with closed eyes for 5 minutes. Electroencephalographic markers of the differential likelihood, that is, the sensitivity-versus-specificity characteristics, sL(x:VCI-NLc) and vL(x:VCI-NLc), were assessed with neuronal activity topography and were compared between the 2 groups. sL(x:VCI-NLc) and vL(x:VCI-NLc) crossed each other at a cutoff value of the differential likelihood. Separation of the patients and controls was made with a sensitivity of 92% and 88%, as well as a false-positive rate of 8% and 12% for sL(x:VCI-NLc) and vL(x:VCI-NLc), respectively. Using sNAT, we accurately differentiated 92% patients with vascular cognitive impairment. We recommend that sNAT, rather than vNAT, should be used in detecting vascular cognitive impaired patients.

EEG Markers for Characterizing Anomalous Activities of Cerebral Neurons in NAT (Neuronal Activity Topography) Method

A pair of markers, sNAT and vNAT, is derived from the electroencephalogram (EEG) power spectra (PS) recorded for 5 min with 21 electrodes (4-20 Hz) arranged according to the 10-20 standard. These markers form a new diagnosis tool "NAT" aiming at characterizing various brain disorders. Each signal sequence is divided into segments of 0.64 s and its discrete PS consists of eleven frequency components from 4.68 (3 × 1.56) Hz through 20.34 (13 × 1.56) Hz. PS is normalized to its mean and the bias of PS components on each frequency component across the 21 signal channels is reset to zero. The marker sNAT consists of ten frequency components on 21 channels, characterizing neuronal hyperactivity or hypoactivity as compared with NLc (normal controls). The marker vNAT consists of ten ratios between adjacent PS components denoting the over- or undersynchrony of collective neuronal activities as compared with NLc. The likelihood of a test subject to a specified brain disease is defined in terms of the normalized distance to the template NAT state of the disease in the NAT space. Separation of MCI-AD patients (developing AD in 12-18 months) from NLc is made with a false alarm rate of 15%. Locations with neuronal hypoactivity and undersynchrony of AD patients agree with locations of rCBF reduction measured by SPECT. The 2-D diagram composed of the binary likelihoods between ADc and NLc in the two representations of sNAT and vNAT enables tracing the NAT state of a test subject approaching the AD area, and the follow-up of the treatment effects.

EEG and Neuronal Activity Topography analysis can predict effectiveness of shunt operation in idiopathic normal pressure hydrocephalus patients

Idiopathic normal pressure hydrocephalus (iNPH) is a neuropsychiatric syndrome characterized by gait disturbance, cognitive impairment and urinary incontinence that affect elderly individuals. These symptoms can potentially be reversed by cerebrospinal fluid (CSF) drainage or shunt operation. Prior to shunt operation, drainage of a small amount of CSF or “CSF tapping” is usually performed to ascertain the effect of the operation. Unfortunately, conventional neuroimaging methods such as single photon emission computed tomography (SPECT) and functional magnetic resonance imaging (fMRI), as well as electroencephalogram (EEG) power analysis seem to have failed to detect the effect of CSF tapping on brain function. In this work, we propose the use of Neuronal Activity Topography (NAT) analysis, which calculates normalized power variance (NPV) of EEG waves, to detect cortical functional changes induced by CSF tapping in iNPH. Based on clinical improvement by CSF tapping and shunt operation, we classified 24 iNPH patients into responders (N = 11) and nonresponders (N = 13), and performed both EEG power analysis and NAT analysis. We also assessed correlations between changes in NPV and changes in functional scores on gait and cognition scales before and after CSF tapping. NAT analysis showed that after CSF tapping there was a significant decrease in alpha NPV at the medial frontal cortex (FC) (Fz) in responders, while nonresponders exhibited an increase in alpha NPV at the right dorsolateral prefrontal cortex (DLPFC) (F8). Furthermore, we found correlations between cortical functional changes and clinical symptoms. In particular, delta and alpha NPV changes in the left-dorsal FC (F3) correlated with changes in gait status, while alpha and beta NPV changes in the right anterior prefrontal cortex (PFC) (Fp2) and left DLPFC (F7) as well as alpha NPV changes in the medial FC (Fz) correlated with changes in gait velocity. In addition, alpha NPV changes in the right DLPFC (F8) correlated with changes in WMS-R Mental Control scores in iNPH patients. An additional analysis combining the changes in values of alpha NPV over the left-dorsal FC (∆alpha-F3-NPV) and the medial FC (∆alpha-Fz-NPV) induced by CSF tapping (cut-off value of ∆alpha-F3-NPV + ∆alpha-Fz-NPV = 0), could correctly identified “shunt responders” and “shunt nonresponders” with a positive predictive value of 100% (10/10) and a negative predictive value of 66% (2/3). In contrast, EEG power spectral analysis showed no function related changes in cortical activity at the frontal cortex before and after CSF tapping. These results indicate that the clinical changes in gait and response suppression induced by CSF tapping in iNPH patients manifest as NPV changes, particularly in the alpha band, rather than as EEG power changes. Our findings suggest that NAT analysis can detect CSF tapping-induced functional changes in cortical activity, in a way that no other neuroimaging methods have been able to do so far, and can predict clinical response to shunt operation in patients with iNPH.

39. Early diagnosis of vascular cognitive impairment with carotid stenosis using Neuronal Activity Topography (NAT)

39. Early diagnosis of vascular cognitive impairment with carotid stenosis using Neuronal Activity Topography (NAT)

P35-1 Application of neuronal activity topography to vascular cognitive impairment with carotid artery stenosis

P35-1 Application of neuronal activity topography to vascular cognitive impairment with carotid artery stenosis

62. New imaging system “Neuronal Activity Topography (NAT)”

62. New imaging system “Neuronal Activity Topography (NAT)”