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Line 6: − + − + − + − [[ExperimentDefinitionFile|Experiment Definition File]] = 'sentences.edt';+ − [[OutFolder|Out Folder]] = '../output/sentences/';+ − [[MatlabPathFnc|Matlab Path Fnc]] = [];+ − [[MatlabPathAdd|Matlab Path Add]] = {fullfile(bs_folder('BLOCK'),'..','common_functions'),bs_folder('BLOCK')};+ − + − + − + − [[StimSequence|Stim Sequence]] = {'Making BCIs','is really fun!'}; + + − + Line 45:
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BrainStreamExampleSentences (view source)
Revision as of 14:50, 26 September 2018
, 14:50, 26 September 2018no edit summary
This is an example of a very simple 'experiment' in which letters will appear on the screen one by one to form sentences. In this experiment, adding a new character to a string is called an ''epoch''. A series of epochs that results in a complete sentence is called a ''sequence''. Subjects can press a button when they are ready for the next sentence (sequence). A flowchart of the experiment is shown below:
This is an example of a very simple 'experiment' in which letters will appear on the screen one by one to form sentences. In this experiment, adding a new character to a string is called an ''epoch''. A series of epochs that results in a complete sentence is called a ''sequence''. Subjects can press a button when they are ready for the next sentence (sequence). A flowchart of the experiment is shown below:
[[File:DocsSectionsExampleSentences.Flowchart.png]]
[[File:DocsSectionsExampleSentences_Flowchart.png|841px|235x]]
''Figure 1: Flowchart of the Sentences example experiment''
''Figure 1: Flowchart of the Sentences example experiment''
== Building the experiment ==
== Building the experiment ==
As described in the [.DocsSectionsBuildingExperiments Building Experiments] section, a number of files are needed to define an experiment. In the following, we will show how to create each of these files. If you want to have a look at the final result before reading this tutorial, the experiment file (.exp) for this example can be found in <tt>/brainstream_mds/examples/blocks/sentences/sentences.exp</tt>.
As described in the [[BrainStreamBuildingExperiments|Building Experiments]] section, a number of files are needed to define an experiment. In the following, we will show how to create each of these files. If you want to have a look at the final result before reading this tutorial, the experiment file (.exp) for this example can be found in <tt>/brainstream_mds/examples/blocks/sentences/sentences.exp</tt>.
<div id="BrainStream.[[DocsSectionsBlockFile]]"></div>
<div id="BrainStream.[[DocsSectionsBlockFile]]"></div>
=== Creating the block file ===
=== Creating the block file ===
This experiment consists of only one block (sentences.blk). A number of settings are specified in the [.DocsSectionsBuildingExperiments#SecBlock block file]:
This experiment consists of only one block (sentences.blk). A number of settings are specified in the [[BrainStreamBuildingExperiments#SecBlock|block file]]:
<pre>[DataSources]
<pre>[DataSources]
eeg = 'simulate:biosemi_active2';
eeg = 'simulate:biosemi_active2';
[Files]
[Files]
ExperimentDefinitionFile = 'sentences.edt';
OutFolder = '../output/sentences/';
[Experiment]
[Experiment]
Block = 'sentences';
Block = 'sentences';
MatlabPathFnc|Matlab Path Fnc = [];
MatlabPathAdd|Matlab Path Add = {fullfile(bs_folder('BLOCK'),'..','common_functions'),bs_folder('BLOCK')};
</pre>
</pre>
You can look up the meaning of the topic and key combinations [.DocsSectionsBlockFile here].
You can look up the meaning of the topic and key combinations [[BrainStreamBlockFile|here]].
Note that for the keys that specify folders, such as OutFolder and MatlabPathAdd, relative path names are specified. For more information about relative path names, click [.DocsSectionsPathsFolders#RelativePath here].
Note that for the keys that specify folders, such as OutFolder and MatlabPathAdd, relative path names are specified. For more information about relative path names, click [[BrainStreamPathsFolders#RelativePath|here]].
In addition to the standard topics and keys, we can specify our own settings in the block file. In this example, it would be useful to specify in the block file which sentences we want to show. We could for example define a key StimSequence under topic Experiment:
In addition to the standard topics and keys, we can specify our own settings in the block file. In this example, it would be useful to specify in the block file which sentences we want to show. We could for example define a key StimSequence under topic Experiment:
<pre>[Experiment]
<pre>
[Experiment]
StimSequence = {'Making BCIs','is really fun!'};
</pre>
</pre>
The information specified in the block file can be retrieved during the experiment using the [.DocsSectionsProgrmmersGuide#GetBlockVal bs_get_blockvalue] function. In the next section we will show exactly how this works. The advantage of specifying the sentences in the block file is that we can use the same Actions table for displaying any sentence.
The information specified in the block file can be retrieved during the experiment using the [[BrainStreamProgrmmersGuide#GetBlockVal|bs_get_blockvalue]] function. In the next section we will show exactly how this works. The advantage of specifying the sentences in the block file is that we can use the same Actions table for displaying any sentence.
=== Creating the Actions Table ===
=== Creating the Actions Table ===
# before each sequence, decide whether to start a new sequence or end the experiment
# before each sequence, decide whether to start a new sequence or end the experiment
# before each epoch, decide whether to start a new epoch or end the sequence
# before each epoch, decide whether to start a new epoch or end the sequence
We will write [.DocsSectionsBuildingExperiments#SecUserFun user defined functions] for making these decisions.
We will write [[BrainStreamBuildingExperiments#SecUserFun|user defined functions]] for making these decisions.
In order to be able to make each decision, we also need to:
In order to be able to make each decision, we also need to:
# within each sequence, keep track of how many epochs we have shown so far
# within each sequence, keep track of how many epochs we have shown so far
We will make use of [.DocsSectionsBuildingExperiments#SecUserFun user defined variables] for these tasks.
We will make use of [[BrainStreamBuildingExperiments#SecUserFun|user defined variables]] for these tasks.
The [.DocsSectionsBuildingExperiments#SecActions Actions table] has three standard columns ''marker, time'' and ''function''. In addition, we will add three columns for our user defined variables. The first user variable, ''stimsequence'', will contain the sequences that we want to show. The second user variable,<em> sequence_count</em>, will keep track of the number of sequences that have been shown already. The third user variable, ''epoch_count'', will keep track how many epochs of a sequence have been shown already. These are the columns of the Actions table:
The [[BrainStreamBuildingExperiments#SecActions|Actions table]] has three standard columns ''marker, time'' and ''function''. In addition, we will add three columns for our user defined variables. The first user variable, ''stimsequence'', will contain the sequences that we want to show. The second user variable,<em> sequence_count</em>, will keep track of the number of sequences that have been shown already. The third user variable, ''epoch_count'', will keep track how many epochs of a sequence have been shown already. These are the columns of the Actions table:
{| border="1"
{| class="wikitable"
|-
|-
| '''marker''' || '''time''' || '''function''' || '''stimsequence''' || '''sequence_count''' || '''epoch_count'''
| '''marker''' || '''time''' || '''function''' || '''stimsequence''' || '''sequence_count''' || '''epoch_count'''
|-
|-
| || | || | ||
| || || || || ||
|}
|}
We will initialize these variables at the beginning of the experiment. It is usually good to define the initialization actions at the BS_INIT marker, as this is always the first marker to arrive within an experiment. At the beginning of the experiment, the sequence counter will be set to 0. The epoch counter is initialized as empty and will be set to 0 at the beginning of each new sequence. The variable ''stimsequence'' must contain the sentences that will be shown. We will initialize it as empty and retrieve its content from the block file in the next step.
We will initialize these variables at the beginning of the experiment. It is usually good to define the initialization actions at the BS_INIT marker, as this is always the first marker to arrive within an experiment. At the beginning of the experiment, the sequence counter will be set to 0. The epoch counter is initialized as empty and will be set to 0 at the beginning of each new sequence. The variable ''stimsequence'' must contain the sentences that will be shown. We will initialize it as empty and retrieve its content from the block file in the next step.
{| border="1"
{| class="wikitable"
|-
|-
| '''<strong>marker</strong>''' || '''<strong>time</strong>''' || '''<strong>function</strong>''' || '''<strong>stimsequence</strong>''' || '''<strong>sequence_count</strong>''' || '''<strong>epoch_count</strong>'''
| '''<strong>marker</strong>''' || '''<strong>time</strong>''' || '''<strong>function</strong>''' || '''<strong>stimsequence</strong>''' || '''<strong>sequence_count</strong>''' || '''<strong>epoch_count</strong>'''
|-
|-
| BS_INIT || EVENT || | [] || 0 || []
| BS_INIT || EVENT || || [] || 0 || []
|}
|}
Information specified in the block file can be retrieved during the experiment using the [.DocsSectionsProgrmmersGuide#GetBlockVal bs_get_blockvalue] function. At the BS_INIT marker, we will insert the marker init_sequence. As this marker does not need to be accurately synchronized with the data, we insert this marker [.DocsSectionsMarkerHandling#BufferMarker via the !FieldTrip buffer]. When the init_sequence marker arrives, we will execute a user defined function <tt>initSequence</tt> to retrieve the content of ''stimsequence'' from the block file and place it in the [.DocsSectionsImportantConcepts#SecVariables global variables].
Information specified in the block file can be retrieved during the experiment using the [[BrainStreamProgrmmersGuide#GetBlockVal|bs_get_blockvalue]] function. At the BS_INIT marker, we will insert the marker init_sequence. As this marker does not need to be accurately synchronized with the data, we insert this marker [[BrainStreamMarkerHandling#BufferMarker|via the FieldTrip buffer]]. When the init_sequence marker arrives, we will execute a user defined function <tt>initSequence</tt> to retrieve the content of ''stimsequence'' from the block file and place it in the [[BrainStreamImportantConcepts#SecVariables|global variables]].
{| border="1"
{| class="wikitable"
|-
|-
| '''<strong>marker</strong>''' || '''<strong>time</strong>''' || '''<strong>function</strong>''' || '''<strong>stimsequence</strong>''' || '''<strong>sequence_count</strong>''' || '''<strong>epoch_count</strong>'''
| '''<strong>marker</strong>''' || '''<strong>time</strong>''' || '''<strong>function</strong>''' || '''<strong>stimsequence</strong>''' || '''<strong>sequence_count</strong>''' || '''<strong>epoch_count</strong>'''
| BS_INIT || EVENT || <strong>bs_send_buffer_marker('init_sequence','eeg',0,'now')<br /></strong> || [] || 0 || []
| BS_INIT || EVENT || <strong>bs_send_buffer_marker('init_sequence','eeg',0,'now')<br /></strong> || [] || 0 || []
|-
|-
| <strong>init_sequence <br /></strong> || <strong>EVENT <br /></strong> || <strong>initSequence <br /></strong> || <strong>put </strong> || |
| <strong>init_sequence <br /></strong> || <strong>EVENT <br /></strong> || <strong>initSequence <br /></strong> || <strong>put </strong> || ||
|}
|}
Now we can proceed to the next step in the flowchart, the point where we need to decide whether to start a new sequence. Using the bs_send_buffer_marker function, we will insert a marker next_sequence to begin this next stage of the experiment. When this marker comes in, first the sequence counter must be increased by 1:
Now we can proceed to the next step in the flowchart, the point where we need to decide whether to start a new sequence. Using the bs_send_buffer_marker function, we will insert a marker next_sequence to begin this next stage of the experiment. When this marker comes in, first the sequence counter must be increased by 1:
{| border="1"
{| class="wikitable"
|-
|-
| '''<strong>marker</strong>''' || '''<strong>time</strong>''' || '''<strong>function</strong>''' || '''<strong>stimsequence</strong>''' || '''<strong>sequence_count</strong>''' || '''<strong>epoch_count</strong>'''
| '''<strong>marker</strong>''' || '''<strong>time</strong>''' || '''<strong>function</strong>''' || '''<strong>stimsequence</strong>''' || '''<strong>sequence_count</strong>''' || '''<strong>epoch_count</strong>'''
| BS_INIT || EVENT || bs_send_buffer_marker('init_sequence','eeg',0,'now') || [] || 0 || []
| BS_INIT || EVENT || bs_send_buffer_marker('init_sequence','eeg',0,'now') || [] || 0 || []
|-
|-
| init_sequence || EVENT || initSequence || put || |
| init_sequence || EVENT || initSequence || put || ||
|-
|-
| || | <strong>bs_send_buffer_marker('next_sequence','eeg',0,'now')</strong> || | ||
| || || <strong>bs_send_buffer_marker('next_sequence','eeg',0,'now')</strong> || || ||
|-
|-
| <strong>next_sequence</strong> || <strong>EVENT</strong> || | || <strong>$self+1</strong> ||
| <strong>next_sequence</strong> || <strong>EVENT</strong> || || || <strong>$self+1</strong> ||
|}
|}
Subsequently, we need to write a function that uses the content of ''stimsequence'' and the current value of ''sequence_count'' to decide whether to start a new sequence. We will call this function <tt>nextSequence</tt>. Because the function needs the content of two of our variables as input, we must specify get statements for these variables.
Subsequently, we need to write a function that uses the content of ''stimsequence'' and the current value of ''sequence_count'' to decide whether to start a new sequence. We will call this function <tt>nextSequence</tt>. Because the function needs the content of two of our variables as input, we must specify get statements for these variables.
{| border="1"
{| class="wikitable"
|-
|-
| '''<strong>marker</strong>''' || '''<strong>time</strong>''' || '''<strong>function</strong>''' || '''<strong>stimsequence</strong>''' || '''<strong>sequence_count</strong>''' || '''<strong>epoch_count</strong>'''
| '''<strong>marker</strong>''' || '''<strong>time</strong>''' || '''<strong>function</strong>''' || '''<strong>stimsequence</strong>''' || '''<strong>sequence_count</strong>''' || '''<strong>epoch_count</strong>'''
| BS_INIT || EVENT || bs_send_buffer_marker('init_sequence','eeg',0,'now') || [] || 0 || []
| BS_INIT || EVENT || bs_send_buffer_marker('init_sequence','eeg',0,'now') || [] || 0 || []
|-
|-
| init_sequence || EVENT || initSequence || put || |
| init_sequence || EVENT || initSequence || put || ||
|-
|-
| || | bs_send_buffer_marker('next_sequence','eeg',0,'now') || | ||
| || || bs_send_buffer_marker('next_sequence','eeg',0,'now') || || ||
|-
|-
| next_sequence || EVENT || <strong>nextSequence</strong> || <strong>get</strong> || $self+1, <strong>get</strong> ||
| next_sequence || EVENT || <strong>nextSequence</strong> || <strong>get</strong> || $self+1, <strong>get</strong> ||
If the outcome of the decision is that another sequence should be displayed, the marker start_sequence will be inserted. At the start of a new sequence, the variable <em>epoch_count </em>must be set to 0. Then BrainStream must wait for a button press from the participant, which is achieved by specifying timepoint 'button_1' for this event. The displaying of the characters is handled by the function displayString. This function will not be discussed in detail, but it is important to know that it requires the content of the variables <em>stimsequence </em>and<em> sequence_count.</em> Therefore, get statements must be specified for these variables. Now we have reached the next decision point in the experiment flowchart, where we need to decide whether to start a new epoch or end the sequence. We will insert marker ''next_epoch'' to trigger this decision making step.
If the outcome of the decision is that another sequence should be displayed, the marker start_sequence will be inserted. At the start of a new sequence, the variable <em>epoch_count </em>must be set to 0. Then BrainStream must wait for a button press from the participant, which is achieved by specifying timepoint 'button_1' for this event. The displaying of the characters is handled by the function displayString. This function will not be discussed in detail, but it is important to know that it requires the content of the variables <em>stimsequence </em>and<em> sequence_count.</em> Therefore, get statements must be specified for these variables. Now we have reached the next decision point in the experiment flowchart, where we need to decide whether to start a new epoch or end the sequence. We will insert marker ''next_epoch'' to trigger this decision making step.
{| border="1"
{| class="wikitable"
|-
|-
| '''<strong>marker</strong>''' || '''<strong>time</strong>''' || '''<strong>function</strong>''' || '''<strong>stimsequence</strong>''' || '''<strong>sequence_count</strong>''' || '''<strong>epoch_count</strong>'''
| '''<strong>marker</strong>''' || '''<strong>time</strong>''' || '''<strong>function</strong>''' || '''<strong>stimsequence</strong>''' || '''<strong>sequence_count</strong>''' || '''<strong>epoch_count</strong>'''
| init_sequence || EVENT || initSequence || put || |
| init_sequence || EVENT || initSequence || put || |
|-
|-
| || | bs_send_buffer_marker('next_sequence','eeg',0,'now') || | ||
| || || bs_send_buffer_marker('next_sequence','eeg',0,'now') || || ||
|-
|-
| next_sequence || EVENT || nextSequence || get || $self+1, get ||
| next_sequence || EVENT || nextSequence || get || $self+1, get ||
| <strong>start_sequence</strong> || <strong>button_1</strong> || <strong>displayString('')</strong> || <strong>get</strong> || <strong>get</strong> || <strong>0</strong>
| <strong>start_sequence</strong> || <strong>button_1</strong> || <strong>displayString('')</strong> || <strong>get</strong> || <strong>get</strong> || <strong>0</strong>
|-
|-
| || | <strong>bs_send_buffer_marker('next_epoch','eeg',0,'now')</strong> || | ||
| || || <strong>bs_send_buffer_marker('next_epoch','eeg',0,'now')</strong> || || ||
|}
|}
When the next_epoch marker comes in, first the epoch counter must be increased by 1. Subsequently, we need to write a function that uses the content of ''stimsequence'' and the current values of ''sequence_count'' and ''epoch_count'' to decide whether to start a new epoch. We will call this function <tt>nextEpoch</tt>. Because the function needs the content of all our variables as input, we must specify get statements for these variables. The Actions table now looks like this:
When the next_epoch marker comes in, first the epoch counter must be increased by 1. Subsequently, we need to write a function that uses the content of ''stimsequence'' and the current values of ''sequence_count'' and ''epoch_count'' to decide whether to start a new epoch. We will call this function <tt>nextEpoch</tt>. Because the function needs the content of all our variables as input, we must specify get statements for these variables. The Actions table now looks like this:
{| border="1"
{| class="wikitable"
|-
|-
| '''<strong>marker</strong>''' || '''<strong>time</strong>''' || '''<strong>function</strong>''' || '''<strong>stimsequence</strong>''' || '''<strong>sequence_count</strong>''' || '''<strong>epoch_count</strong>'''
| '''<strong>marker</strong>''' || '''<strong>time</strong>''' || '''<strong>function</strong>''' || '''<strong>stimsequence</strong>''' || '''<strong>sequence_count</strong>''' || '''<strong>epoch_count</strong>'''
| init_sequence || EVENT || initSequence || put || |
| init_sequence || EVENT || initSequence || put || |
|-
|-
| || | bs_send_buffer_marker('next_sequence','eeg',0,'now') || | ||
| || || bs_send_buffer_marker('next_sequence','eeg',0,'now') || || ||
|-
|-
| next_sequence || EVENT || nextSequence || get || $self+1, get ||
| next_sequence || EVENT || nextSequence || get || $self+1, get ||
| start_sequence || button_1 || displayString('') || get || get || 0
| start_sequence || button_1 || displayString('') || get || get || 0
|-
|-
| || | bs_send_buffer_marker('next_epoch','eeg',0,'now') || | ||
| || || bs_send_buffer_marker('next_epoch','eeg',0,'now') || | ||
|-
|-
| <strong>next_epoch</strong> || <strong>EVENT</strong> || <strong>nextEpoch</strong> || <strong>get</strong> || <strong>get</strong> || <strong>$self+1, get</strong>
| <strong>next_epoch</strong> || <strong>EVENT</strong> || <strong>nextEpoch</strong> || <strong>get</strong> || <strong>get</strong> || <strong>$self+1, get</strong>
event = bs_send_buffer_marker(event,'end_sequence','eeg',0,'now'); % end the sequence
event = bs_send_buffer_marker(event,'end_sequence','eeg',0,'now'); % end the sequence
end
end
</pre>If the outcome of the decision is that another character should be displayed, the marker proc_epoch will be inserted. As we want to use this marker for data selection (see [.DocsSectionsExampleSentences#DataSelection next section]), accurate synchronization between marker and data is required. Therefore, we will insert this marker [.DocsSectionsMarkerHandling#HardwareMarker via the hardware]. When this marker arrives, the displayString function will be used to show the current character. After this has been done, we insert the next_epoch marker and thereby return to the question whether to start another epoch. The next_epoch marker is inserted 0.25 seconds after the bs_send_buffer_marker function is called. As a result, there is a pause of approximately 0.25 seconds between the appearance of each character on the screen.
</pre>If the outcome of the decision is that another character should be displayed, the marker proc_epoch will be inserted. As we want to use this marker for data selection (see [[BrainStreamExampleSentences#DataSelection|next section]), accurate synchronization between marker and data is required. Therefore, we will insert this marker [[BrainStreamMarkerHandling#HardwareMarker|via the hardware]. When this marker arrives, the displayString function will be used to show the current character. After this has been done, we insert the next_epoch marker and thereby return to the question whether to start another epoch. The next_epoch marker is inserted 0.25 seconds after the bs_send_buffer_marker function is called. As a result, there is a pause of approximately 0.25 seconds between the appearance of each character on the screen.
{| border="1"
{| class="wikitable"
|-
|-
| '''<strong>marker</strong>''' || '''<strong>time</strong>''' || '''<strong>function</strong>''' || '''<strong>stimsequence</strong>''' || '''<strong>sequence_count</strong>''' || '''<strong>epoch_count</strong>'''
| '''<strong>marker</strong>''' || '''<strong>time</strong>''' || '''<strong>function</strong>''' || '''<strong>stimsequence</strong>''' || '''<strong>sequence_count</strong>''' || '''<strong>epoch_count</strong>'''
| init_sequence || EVENT || initSequence || put || |
| init_sequence || EVENT || initSequence || put || |
|-
|-
| || | bs_send_buffer_marker('next_sequence','eeg',0,'now') || | ||
| || || bs_send_buffer_marker('next_sequence','eeg',0,'now') || || ||
|-
|-
| next_sequence || EVENT || nextSequence || get || $self+1, get ||
| next_sequence || EVENT || nextSequence || get || $self+1, get ||
| start_sequence || button_1 || displayString('') || get || get || 0
| start_sequence || button_1 || displayString('') || get || get || 0
|-
|-
| || | bs_send_buffer_marker('next_epoch','eeg',0,'now') || | ||
| || || bs_send_buffer_marker('next_epoch','eeg',0,'now') || || ||
|-
|-
| next_epoch || EVENT || nextEpoch || get || get || $self+1, get
| next_epoch || EVENT || nextEpoch || get || get || $self+1, get
|-
|-
| <strong>proc_epoch</strong> || <strong>EVENT</strong> || <strong>displayString()</strong> || | ||
| <strong>proc_epoch</strong> || <strong>EVENT</strong> || <strong>displayString()</strong> || || ||
|-
|-
| || | <strong>bs_send_buffer_marker('next_epoch','eeg',0.25,'now')</strong> || | ||
| || || <strong>bs_send_buffer_marker('next_epoch','eeg',0.25,'now')</strong> || || ||
|}
|}
When all epochs of a sequence have been processed, the <tt>nextEpoch</tt> function will insert the end_sequence marker. When this marker arrives, we immediately insert the next_sequence marker, thereby returning to the question whether to start another sequence. The next_sequence marker is inserted 1 second after the bs_send_buffer_marker function is called. As a result, there is a pause of approximately 1 second between each sequence. The Actions table now contains all the necessary steps of the experiment.
When all epochs of a sequence have been processed, the <tt>nextEpoch</tt> function will insert the end_sequence marker. When this marker arrives, we immediately insert the next_sequence marker, thereby returning to the question whether to start another sequence. The next_sequence marker is inserted 1 second after the bs_send_buffer_marker function is called. As a result, there is a pause of approximately 1 second between each sequence. The Actions table now contains all the necessary steps of the experiment.
{| border="1"
{| class="wikitable"
|-
|-
| '''<strong>marker</strong>''' || '''<strong>time</strong>''' || '''<strong>function</strong>''' || '''<strong>stimsequence</strong>''' || '''<strong>sequence_count</strong>''' || '''<strong>epoch_count</strong>'''
| '''<strong>marker</strong>''' || '''<strong>time</strong>''' || '''<strong>function</strong>''' || '''<strong>stimsequence</strong>''' || '''<strong>sequence_count</strong>''' || '''<strong>epoch_count</strong>'''
| BS_INIT || EVENT || bs_send_buffer_marker('init_sequence','eeg',0,'now') || [] || 0 || []
| BS_INIT || EVENT || bs_send_buffer_marker('init_sequence','eeg',0,'now') || [] || 0 || []
|-
|-
| init_sequence || EVENT || initSequence || put || |
| init_sequence || EVENT || initSequence || put || ||
|-
|-
| || | bs_send_buffer_marker('next_sequence','eeg',0,'now') || | ||
| || || bs_send_buffer_marker('next_sequence','eeg',0,'now') || || ||
|-
|-
| next_sequence || EVENT || nextSequence || get || $self+1, get ||
| next_sequence || EVENT || nextSequence || get || $self+1, get ||
| start_sequence || button_1 || displayString('') || get || get || 0
| start_sequence || button_1 || displayString('') || get || get || 0
|-
|-
| || | bs_send_buffer_marker('next_epoch','eeg',0,'now') || | ||
| || || bs_send_buffer_marker('next_epoch','eeg',0,'now') || || ||
|-
|-
| next_epoch || EVENT || nextEpoch || get || get || $self+1, get
| next_epoch || EVENT || nextEpoch || get || get || $self+1, get
|-
|-
| proc_epoch || EVENT || displayString() || | ||
| proc_epoch || EVENT || displayString() || || ||
|-
|-
| || | bs_send_buffer_marker('next_epoch','eeg',0.25,'now') || | ||
| || || bs_send_buffer_marker('next_epoch','eeg',0.25,'now') || || ||
|-
|-
| <strong>end_sequence</strong> || <strong>EVENT</strong> || <strong>bs_send_buffer_marker('next_sequence','eeg',1,'now')</strong> || | ||
| <strong>end_sequence</strong> || <strong>EVENT</strong> || <strong>bs_send_buffer_marker('next_sequence','eeg',1,'now')</strong> || || ||
|}
|}
<div id="DataSelection"></div>
<div id="DataSelection"></div>
=== Specifying Data Selection ===
=== Specifying Data Selection ===
New epochs are started by the proc_epoch marker. We will therefore use this marker to trigger data selection. For now, we will only print the message 'Process the data' in the Matlab command window every time data is collected. However, instead of showing a simple message you could also write functions to actually process the data. This is the new Actions table:
New epochs are started by the proc_epoch marker. We will therefore use this marker to trigger data selection. For now, we will only print the message 'Process the data' in the Matlab command window every time data is collected. However, instead of showing a simple message you could also write functions to actually process the data. This is the new Actions table:
{| border="1"
{|class="wikitable"
|-
|-
| '''<strong>marker</strong>''' || '''<strong>time</strong>''' || '''<strong>function</strong>''' || '''<strong>stimsequence</strong>''' || '''<strong>sequence_count</strong>''' || '''<strong>epoch_count</strong>'''
| '''<strong>marker</strong>''' || '''<strong>time</strong>''' || '''<strong>function</strong>''' || '''<strong>stimsequence</strong>''' || '''<strong>sequence_count</strong>''' || '''<strong>epoch_count</strong>'''
| BS_INIT || EVENT || bs_send_buffer_marker('init_sequence','eeg',0,'now') || [] || 0 || []
| BS_INIT || EVENT || bs_send_buffer_marker('init_sequence','eeg',0,'now') || [] || 0 || []
|-
|-
| init_sequence || EVENT || initSequence || put || |
| init_sequence || EVENT || initSequence || put || ||
|-
|-
| || | bs_send_buffer_marker('next_sequence','eeg',0,'now') || | ||
| || || bs_send_buffer_marker('next_sequence','eeg',0,'now') || || ||
|-
|-
| next_sequence || EVENT || nextSequence || get || $self+1, get ||
| next_sequence || EVENT || nextSequence || get || $self+1, get ||
| start_sequence || button_1 || displayString('') || get || get || 0
| start_sequence || button_1 || displayString('') || get || get || 0
|-
|-
| || | bs_send_buffer_marker('next_epoch','eeg',0,'now') || | ||
| || || bs_send_buffer_marker('next_epoch','eeg',0,'now') || || ||
|-
|-
| next_epoch || EVENT || nextEpoch || get || get || $self+1, get
| next_epoch || EVENT || nextEpoch || get || get || $self+1, get
|-
|-
| proc_epoch || EVENT || displayString() || | ||
| proc_epoch || EVENT || displayString() || || ||
|-
|-
| || | bs_send_buffer_marker('next_epoch','eeg',0.25,'now') || | ||
| || || bs_send_buffer_marker('next_epoch','eeg',0.25,'now') || || ||
|-
|-
| || <strong>DATA <br /></strong> || <strong>bs_disp('Process the data')</strong> || | ||
| || <strong>DATA <br /></strong> || <strong>bs_disp('Process the data')</strong> || || ||
|-
|-
| end_sequence || EVENT || bs_send_buffer_marker('next_sequence','eeg',1,'now') || | ||
| end_sequence || EVENT || bs_send_buffer_marker('next_sequence','eeg',1,'now') || || ||
|}
|}
We also need a [.DocsSectionsBuildingExperiments#SecDataSel DataSelection table] to specify the exact time window of data selection. If we want to record one second of data after the onset of each epoch, our DataSelection table looks like this:
We also need a [[BrainStreamBuildingExperiments#SecDataSel|DataSelection table]] to specify the exact time window of data selection. If we want to record one second of data after the onset of each epoch, our DataSelection table looks like this:
{| border="1"
{| class="wikitable"
|-
|-
| '''marker''' || '''begintime''' || '''endtime''' || '''datasource'''
| '''marker''' || '''begintime''' || '''endtime''' || '''datasource'''
|}
|}
In this experiment, the fourth column ''datasource'' is not absolutely necessary. As only one data source (simulated EEG data, see [.DocsSectionsExampleSentences#BrainStream.[[DocsSectionsBlockFile]] blocksettings]) is used, BrainStream will automatically apply all data selection settings to this data source.
In this experiment, the fourth column ''datasource'' is not absolutely necessary. As only one data source (simulated EEG data, see [[BrainStreamExampleSentences#BrainStream|blocksettings]) is used, BrainStream will automatically apply all data selection settings to this data source.
=== Creating the Dictionary table ===
=== Creating the Dictionary table ===
The [.DocsSectionsBuildingExperiments#SecDict Dictionary table] specifies a marker number for each marker that is used in this experiment. The Dictionary table looks like this:
The [[BrainStreamBuildingExperiments#SecDict|Dictionary table]] specifies a marker number for each marker that is used in this experiment. The Dictionary table looks like this:
{| border="1"
{| class="wikitable"
|-
|-
| '''marker''' || '''type''' || '''value''' || '''datasource'''
| '''marker''' || '''type''' || '''value''' || '''datasource'''
|}
|}
In this experiment, the fourth column ''datasource'' is not absolutely necessary. As only one data source (simulated EEG data, see [.DocsSectionsExampleSentences#BrainStream.[[DocsSectionsBlockFile]] blocksettings]) is used, BrainStream will automatically apply all marker settings to this data source.
In this experiment, the fourth column ''datasource'' is not absolutely necessary. As only one data source (simulated EEG data, see [[BrainStreamExampleSentences#BrainStream|blocksettings]) is used, BrainStream will automatically apply all marker settings to this data source.
== Testing the experiment ==
== Testing the experiment ==
The easiest way to create all files that define this experiment is via the [.DocsSectionsBrainStreamEditor BrainStream editor]. You can open the editor by typing <tt>bs_editor</tt> in the Matlab command window (make sure that <tt>brainstream_mds/core</tt> is your current working directory). An experiment file (.exp) has already been created for this example experiment and is located in <tt>/brainstream_mds/examples/blocks/sentences/sentences.exp</tt>. If you open this file in the BrainStream editor, the experiment looks like this:
The easiest way to create all files that define this experiment is via the [.DocsSectionsBrainStreamEditor BrainStream editor]. You can open the editor by typing <tt>bs_editor</tt> in the Matlab command window (make sure that <tt>brainstream_mds/core</tt> is your current working directory). An experiment file (.exp) has already been created for this example experiment and is located in <tt>/brainstream_mds/examples/blocks/sentences/sentences.exp</tt>. If you open this file in the BrainStream editor, the experiment looks like this:
[[File:DocsSectionsExampleSentences.BS_editor.png]]
[[File:DocsSectionsExampleSentences_BS_editor.png|1054px|658x]]
''Figure 2: The Sentences Experiment in the BrainStream Editor''
''Figure 2: The Sentences Experiment in the BrainStream Editor''