پاورپوینت توضیح کلی در مورد EEG (pptx) 18 اسلاید
دسته بندی : پاورپوینت
نوع فایل : PowerPoint (.pptx) ( قابل ویرایش و آماده پرینت )
تعداد اسلاید: 18 اسلاید
قسمتی از متن PowerPoint (.pptx) :
General explaining about
EEG
تاريخچه: در سال 1924 براي اولين بار توسط فيزيولوژيست آلماني «هانس برگر» ثبت و نام‌گذاري شد.
Why neocortex ?
First, the activity of one neuron is too small to be recorded. To be visible on the scalp, electrical activity must involve thousands of neurons acting synchronously. The neocortex has a high density of neurons, which facilitates their synchronous activation.
Second, it is not enough to act synchronously. Electrical activity is visible only if the activity of the underlying neurons adds up. To add up the activity must be generated by parallel neurons. The neocortex is composed of pyramidal cells aligned in parallel.
Third, the electric and magnetic field decrease with the distance from the source. The neocortex is closer to recording sensors.
the 10-20 international system
It is based on anatomical location and on percentage of distance among these points giving the 10 or 20% in the system name. The original 10-20 system has only nineteen electrodes but has been extended to accommodate more than 200 electrodes.
128 channels
In this system the electrodes' locations are related to specific brain areas. For example, electrodes C3 and C4 are above the motor cortex
F (frontal), C (central), T (temporal), P (posterior), and O (occipital).
Each EEG signal can therefore be correlated to an underlying brain area.
A better correlation can be obtained by registering the electrode's locations with MRI of the subject's head.
Electrical Recording with Differential Amplifiers :
Reference and “ Active ” Electrodes Bipolar and “ Monopolar ” Montages Bias of the Average Reference
B. اندازه‌گيري تک‌قطبي (Unipolar) A. اندازه‌گيري دوقطبي (Bipolar)
Characterization of EEG Activity
General EEG frequencies :
eta: 13-30 Hz (desynchronized)
alpha: 8-12 Hz (synchronized)
theta: 3.5-7.5 Hz (synchronized)
delta: < 3.5 Hz (synchronized)
Lower frequencies are usually higher amplitude (“synchronized”) activity
فرکانس‌هاي مختلف : DELTA
0.5 تا 3 هرتز
خواب بسيار عميق
در شيرخوارگان کمتر از 6 ماه موج غالب است
هنگام حل مسائل دشوار
دلتاي با دامنه‌ي زياد:
ناتوانايي‌هاي يادگيري
صدمات مغزي
