In the SERCOM Tone Pips routine, a series of pure tones is generated during an optional visual stimulus. At the same time, neuronal response data from the animal is collected and displayed. As soon as the Tone Pips option is specified (hitting 'p' from the SERCOM program), the tone pips menu will come on the screen. It is here that the various stimulus parameters are specified. Below is a sample of this menu.
Low Freq = 1000 Hz
High Freq = 4000 Hz
Frequency Scale (linear=0, log=1) : 0
Speaker selection (0 - 15) = 9
Speaker attenuation = 20.00 dB
Led selection (0 - 15) = 7
Led intensity (1 - 8) = 4
Give reward (0=no, 1=yes) = 1
Led duration = 4000.00 msec
Spotting time = 1000.00 msec
Led off-time = 1500.00 msec
Stimulus Duration = 500.00 msec
Repetition Time = 700.00 msec
Stimulus Delay = 50.00 msec
Number of Frequencies (linear) = 7
Steps per Octave (log) = 2
p=^P=Pause, e=^Z=Exit, r=Retrieve, s=Store
g=^G=Go, w=Dset(newname), u=Dset(inc unit#), x=Dset(inc seq#), d=t=Screen Dump
After the parameters are all specified, the user types the letter 'g' or 'G'
to start things off. The visual stimulus (Led selection)
will turn on. After a brief Spotting time, a series
of tone pips will start. Each successive tone pip will be of a different
frequency, starting with the Low Frequency and going up to
the High Frequency.
The third parameter in the menu, Frequency Scale,
determines whether the frequency steps between successive tones will be
linear or logarithmic. The size of the steps is determined by the
Number of Frequencies parameter (linear case)
or the Steps per Octave parameter (log case).
In this example, there
will be 7 tone pips presented at linear frequency intervals (every
500 Hz) between 1000 Hz and 4000 Hz. There will be 1 tone pip presented
every 700 msec (Repetition Time). Within this repetition
time, there will be a Stimulus Delay of 50 msec, then
the tone pip will start and continue for a Stimulus Duration
of 500 msec. The stimulus delay allows for collecting neuronal data before
each auditory stimulus starts.
The visual stimulus remains on for the entire Led duration period. It then turns off and will remain off during the specified Led off-time period. At this point the program will repeat the visual stimulus, along with the "off-time", over and over again.
Meanwhile, the successive tone pips will be generated, but only during the led duration time period, not during the "off-time" of the visual stimulus. If the led duration time is only long enough for part of the tone pips of the series to be done, then the remaining tone pips will be generated during the next led duration period. After an entire series of tone pips is completed (Low Freq to High Freq), the program waits until the end of the current visual stimulus and subsequent off-time, and repeats the entire process all over again, starting with the lowest frequency tone pip of the series, and a new led duration time.
Note that the visual stimulus is optional -- it can be omitted by setting the Led selection parameter to 0. However, the parameters Led duration, Spotting time, and Led off-time must still be specified. One can use a very long Led duration time to accomodate a long series of tone pips.
The following figure illustrates the timing of the tone pips with respect to the visual stimulus. The tone pip labeled f1 stands for Low Freq and f7 stands for High Freq.
If the parameter Give reward is set to 1, then the animal will receive a reward at the end of each led duration (even if the led selection is set to 0).
The output display of the Tone Pips routine has two parts. There is a plot of the accumulation of spikes generated after every series of tones, plus a dot raster display of the spike times during each repetition interval.
The arrow keys are used to move around in the menu. There are also several single-character commands available to the user at all times, while in the Tone Pips menu. They are listed here, and described in more detail below.
g, G, or ^G Start or restart stimulus p, P, or ^P Stop stimulus, stay in Tone Pips menu e, E, or ^Z Stop stimulus, return to SER main menu d or D Dump next spike display to printer t or T Dump next spike display to printer s or S Store current menu params to special block r or R Retrieve menu params stored by 's' w or W Save current data, specify data set name u or U Save current data, increment unit # x or X Save current data, increment sequence #
After setting the parameters to the desired values, the series of Tone Pips is started by typing CTRL-G. At the end of each series of pips, the neuronal response display will be updated and the tones will be generated again. This continues until the user stops the stimulus. The command 'e' is used to exit, and 'p' pauses the stimulus (until the next 'g' command). Any individual parameter can be changed at any time -- type the new value, then hit 'Return' or one of the arrow keys to move the cursor. Then, stimulus will stop and restart with the new parameter values. Note that it can be faster to change a number of parameters by first typing 'p' to stop the stimulus, then modifying the parameters, then hitting 'g' to restart.
With the Tone Pips stimulus there is the special feature of a private storage block for the menu parameters. To store the current set of menu parameters into this storage block, type 's' or 'S'. Then, continue to run the stimulus, changing any parameter to a new value. To retrieve the set of parameters stored by the S command, type 'r' or 'R'.
There is now a hard copy feature, specified with the 'D' or 'T' option. Simply type D or T and the program will send to the printer a copy of the spike curve and dot raster at the end of the current series of tone pips. (The display is only updated at the end of each series of pips, and so both the 'd' and 't' options have been designed to do the same thing, that is, to send a hard copy dump of the next update of the display.)
Invalid parameter settings sometimes cause the stimulus to stop. The user must change the appropriate parameter(s), then type 'g' or CTRL-G to restart the stimulus.
To store the response data from the current series of tone pips, the user can type 'w', 'u', or 'x'. Each of these commands stores the data for the entire series of tones. The only difference between the 3 commands is how the name for the new data set is chosen. Each command displays the name of the most recently stored data set. The 'w' command prompts the user to type in a new name for the data set to be stored. The 'u' or the 'x' command will try to automatically create a new data set ID name. They look at the previous name, which is understood to have the format 'unit#-sequence#', preceded by an optional string of characters. For example, a valid name would be abc100-12, where the unit number is 100 and the sequence number is 12. The 'u' command will increment the unit number, and the 'x' command will increment the sequence number. If the previous data set name is not in this format, then each of the commands will prompt the user to type in a new data set id name.
The data for a series of tone pips are stored with the data set type name SCPP, which will distinguish it from data collected during one of the other stimulus options. The schema name for each data set is SCH019.
See also the general description of the
SERCOM program.
See also the descriptions of the other stimulus options:
Clicks,
Noise,
jane@neurophys.wisc.edu