Abstract
Purpose: To provide experimental support to the hypothesis of a possible disruption in the physiological thalamic regulation of cortico-cortical synchronisation - thalamocortical dysrhythmia (TCD) - in the pathophysiology of photosensitive epilepsy (PSE).
Method: 16 subjects, 8 with PSE and 8 healthy volunteers (CTR) with no history of neurological disorders entered the study. Data was acquired with a 128-channel dense array EEG and a 306 sensor MEG. Horizontal stationary sinusoidal gratings with spatial frequency of 3 cycles per degree (cpd) were presented for a 4 sec ‘‘on’’ period, followed by a 4 sec ‘‘off’’ period during which a full field equiluminant screen was shown. Independent Component Analysis (ICA) and time-frequency analysis of the extracted components were carried out, followed by cluster analysis on the components map.
Result: Clusters of components with clear dipolar pattern in the occipital region exhibited the following features: 1- evoked and induced gamma band (25–60 Hz) in PSE and CTR groups, without statistically significant differences between the two groups; 2- sustained desynchronisation in the alpha- beta bands (8–20 Hz) only in the CTR group; 3- statistically significant phase locked and sustained synchronisation (power increase) in the theta band (4–8 Hz) in the PSE group.
Conclusion: Abnormal theta synchronisation can be interpreted as the electrophysiological correlate of disordered connection between thalamus and occipital cortex in PSE, in line with TCD model. TCD rather than a syndrome, as proposed in several studies, could be a shared mechanism in a number of pathological conditions including PSE.
Method: 16 subjects, 8 with PSE and 8 healthy volunteers (CTR) with no history of neurological disorders entered the study. Data was acquired with a 128-channel dense array EEG and a 306 sensor MEG. Horizontal stationary sinusoidal gratings with spatial frequency of 3 cycles per degree (cpd) were presented for a 4 sec ‘‘on’’ period, followed by a 4 sec ‘‘off’’ period during which a full field equiluminant screen was shown. Independent Component Analysis (ICA) and time-frequency analysis of the extracted components were carried out, followed by cluster analysis on the components map.
Result: Clusters of components with clear dipolar pattern in the occipital region exhibited the following features: 1- evoked and induced gamma band (25–60 Hz) in PSE and CTR groups, without statistically significant differences between the two groups; 2- sustained desynchronisation in the alpha- beta bands (8–20 Hz) only in the CTR group; 3- statistically significant phase locked and sustained synchronisation (power increase) in the theta band (4–8 Hz) in the PSE group.
Conclusion: Abnormal theta synchronisation can be interpreted as the electrophysiological correlate of disordered connection between thalamus and occipital cortex in PSE, in line with TCD model. TCD rather than a syndrome, as proposed in several studies, could be a shared mechanism in a number of pathological conditions including PSE.
| Original language | English |
|---|---|
| Article number | p432 |
| Pages (from-to) | 127 |
| Number of pages | 1 |
| Journal | Epilepsia |
| Volume | 53 |
| Issue number | s5 |
| DOIs | |
| Publication status | Published - 11 Sep 2012 |
| Event | 10th European Congress on Epileptology - London, United Kingdom Duration: 30 Sep 2012 → 4 Oct 2012 |