char_01

Characterization of tuning curves, including spline fit, peak detection, width at half-height, and orientation and direction selectivity indices.

Options:

• plot - plot the tuning curve, and write the following parameters to the statfile:
  1. name - filename without the path
  2. pname - name of the principle parameter
  3. modx - modulation index: F1/(DC-DC_0)
  4. dirx - OPTIONAL directionality index: 1.0 - n/p, where n,p=DC-DC_0, -1.0 default (Maunsell and Van Essen, 1983). Or, orientation index: 1-orth/pref.

  5. v_max - varied parameter's value at the maximum spike rate
  6. v_left - varied parameter's value at the left fractional rise point
  7. v_right - varied parameter's value at the right fractional rise point
  8. width - a measure of the width from v_left to v_right

     Note, if v_left (v_right) is not defined, it is set to -1. This causes 'width' to be undefined, and it is then also set to -1.
     

  9. sr_max - spike rate at the maximum.
  10. snr - signal to noise ratio, mean/sdev at max response.
  11. sr0 - firing rate for the baseline condition (spikes/s)
• min_max_sdev -

Parameter definitions:

• pname1 - Varying parameter to act as independent variable.
• frac_height - fractional value for picking the width of the peak.
• force_fit - [-1] 0-fit DC, 1-fit F1
• y_scale - [0.0] multiply y-values (before any offset)
• y_offset - [0.0] add to y-values (after any scale)
• circ_flag - set to 1 if "pname1" values fall on a circle.
• circ_value - the circumference of the circle, e.g., 360.0. Note, "scale_factor" is not applied to this value. Note, this value is used as end-point for interpolation.
• width_logbase - set to "2", "10" or "e" for log. width computation.
• invert_flag - invert the values of "pname1" before output.
• scale_factor - multiply the values of "pname1" by this float value.
• scale_by_param - multiply the values of "pname1" by this value.
• invert_sbp_flag - if 1, scale by the inverse of "scale_by_param".
• stat_filename - append statistics to this file.
• interp_factor - multiply data points by this to get spline points.
• dir_index_flag - if 1, compute and report a direction index: 1-n/p, where 'n' is the response at 180 deg from max.
• ori_index_flag - if 1, compute and report an orientation index: 1-n/p, where 'n' is the average response at 90 deg from max.
• mod_index_flag - if 1, compute and report a modulation index: 1-n/p, where 'n' is the minimum response.
• control_param - name of param to use for baseline rate computation, defaults to "ampl" if not set.
• control_max - maximum value of control param on background trials.

Example:

#
#  Designed for files where 'direction' varies over 180 degrees
#
char_01
group 0
plot

chan ex_8_8

pname1 direction           # Name of principle parameter that varies
ori_index_flag 1           # Compute and orientation selectivity index
frac_height 0.5            # Compute width at this fraction of peak height
circ_flag 1                # Is the axis circular?
circ_value 180.0           # Use 360 for a full direction tuning curve
control_param contrast     # Parameter for computing baseline response
stat_filename zzz_direction.stat  # Statistics will be written here
interp_factor 10.0         # For creating points along the spline fit

condition
param_range contrast 1 100