BrainProducts-Presentation-VEP优质PPT.ppt

1、BrainVision Analyzer Professional,The most advanced and easy to use EEG analysis package!#,Welcome to.,Packed with features to help you make the most out of your data.,VISUALLY EVOKED POTENTIAL DATA,On the next couple of slides we want to demonstrate the ease and power of analyzing visual evoked pot

2、ential data with the help of the sophisticated tools implemented in,BrainVision Analyzer Professional,We will take you through all the necessary steps from data inspection through the full process of data analysis to the building of grand averages and peak detection.,During this process we will perf

3、orm the following steps,Grand average building for all datasets of a category.,Peak detection and export（N1,N2,P2,P3,LPC）.,Average building for all categories.,Segmentation of all significant events into separate branches.,Baseline correction of all segments.,Artefact rejection（amplitude,gradient,ra

4、nge and flat spots）.,Ocular correction of data for VEOG and HEOG artefacts.,Global segmentation for all significant events.,Rereferencing from Cz reference to linked ears.,Inspection of the raw data for artefacts.,Navigating and inspecting your data set.,To navigate within your data set,you can use

5、the navigation bar at the bottom of the BrainVision Analyzer window.,You can step forward and backward within your dataset in increments of the window size or in one second increments.You can also jump to any desired position within your dataset by clicking into the scroll bar or into the marker fie

6、ld at the top of the navigation area.,Navigating and visually inspecting your data set.,As you can easily see from the picture on the left,there are a number of blink artefacts in our dataset.You can also see,that the data was obviously recorded with Cz reference and that channel T7 seems to contain

7、 a lot of noise.Lets have a look.,Navigating and visually inspecting your data set.,Lets have a look at a possible blink in order to show you the great features BrainVision Analyzer supports for the visual inspection of data.Simply mark a time range in your data with your mouse.It will show up highl

8、ighted in light blue.Then release the mouse button to open the context menu.,Navigating and visually inspecting your data set.,As you can see,we have a number of choices of what to do with the marked area.We could choose to perform an FFT for our time range,display a 3D-map or even a CSD-map.We will

9、 choose the map option to display the topographic distribution of the voltages for our time range.,Navigating and visually inspecting your data set.,As could be expected,the voltage distribution shows the typical pattern for a blink artefact with strong and rather symmetrical activity at frontal sit

10、es and with pronounced attenuation of the blink propagation towards posterior sites.Lets have a look at another type of artefact in our data.,Navigating and visually inspecting your data set.,As was said before,channel T7 seems to contain a lot of noise.This could be do to movement artefacts from th

11、e jaws as well as to a badly seated electrode or any number of other reasons.Lets have a look at the frequency distribution within this channel.,Navigating and visually inspecting your data set.,This time we marked the entire visible time range with the mouse and chose the FFT option from the automa

12、tically opened context menu.By releasing the mouse over the FFT entry we open the FFT window to view the frequency distribution of the selected channels.,Navigating and visually inspecting your data set.,As in any other window we can choose the channels to view by marking their names with the mouse

13、and then double-clicking.We chose to view T7 only.Channel T7 contains a lot of activity throughout the available spectrum with the exception of 50 Hertz indicating that a 50 Hz notch filter was used.,Once you are satisfied that you have seen the types of artefacts present in your data,you are ready

14、to correct or reject these artefacts.-But first lets rereference the dataset from the Czto A1A2 reference（linked ears）.,Rereferencing your data set to linked ears.,Just as any other operation you might want to perform that changes the characteristics of your dataset,rereferencing your data is consid

15、ered as a Transformation“within BrainVision Analyzer.Therefore,you can find the rereferencing routine together with the numerous other data modifying operations in the menu main program menu Transformation“.Lets choose it and see what it offers.,Rereferencing your data set to linked ears.,The first

16、window of the New Reference entry form requests the information about which electrodes will form the new reference.-Since we want to rereference to A1A2（linked ears）,we will choose just these two.Obviously,you could also have chosen all electrodes for average reference or any combination you desire.,Rereferencing your data set to linked ears.,In the second window of the entry form you can specify the channels that the new reference should be applied to and whether the remaining channels that are