find_frequency_peaks

find_frequency_peaks(spect, stimes, sfreqs, varargin)

PEAK PROMINENCE CALCULATION IN THE FREQUENCY DOMAIN

🔶

function used to calculate the peak prominence of the spectrum at each point in a spectrogram. Works by looking for activity in the designated frequency range. Normalizes the frequency values by dividing by a percentile of the the spectral values. The percentile can be calculated from a full night (artifact/wake-free sleep) or from a local segment with length of X minutes. By default, no normalization is applied since the prominence extraction implicitly takes care of the slow trend in the frequency domain.

Usage: [ fproms, ffreq, fwidth, x_fwidth, normalized_spectrogram ] = find_frequency_peaks(spectrogram,stimes,sfreqs,valid_time_inds,’<flag#1>’,<arg#1>…<flag#n>’,<arg#n>);

##### Declared Inputs: [[[NEEDS UPDATES!!!]]]

The following variables can be generated from the multitaper_spectrogram function:

• scube: The spectrum at each time point. Format( Time X Frequency X Channels);

• stimes: The time step vectors as defined by the mutlitaper

  spectrogram parameters.

• sfreqs: The frequency step vector as defined by the mutlitaper

  spectrogram parameters.

Other Parameters:

• stages: The sleep stages as a vector.

• epochsize: The epochsize at which the stages were scored.

##### Optional Inputs:

• ‘norm_method’: A string specifying what normalization

  method to use. Can be ‘percentile’ (default), ‘detrend’, or ‘none’ default: ‘percentile’

• ‘peak_freq_range’: The range of frequencies to look for

  peak prominence values within. default: [9, 17]

• ‘detrend_freq_range’: The range of frequencies to detrend

  the spectrum between. default: [6, 30]

• ‘plot_on’: Whether to plot the spectrum for

  visulization. Note: will plot at every time step. default : false

• ‘percent_num’: At which percentile to perform the

  normalization at. Will take the percentile at each frequency point. default : 3

• ‘in_db’: Whether to employ findpeaks on spectrum

  at each time slice after converting to dB scale. default: false

• ‘smooth_Hz’: Will complete a smoothing at each time

  slice of the spectrum before finding a peak in the spindle frequence range. Enter the number of Hz. default: 0

• ‘local_norm_minutes’: Whether to perform the normalization of

  a spectrum basecd on the local spectral values versus the default which is the percentile calculated across the entire artifact/wake-free sleep recording. default: 0

• ‘time_range’: Option to calculate only a portion of

  the night. default = [:] (full night)

##### Outputs:

In case of multiple channels, outputs will have multiple columns representing the multiple channel input.

• fproms: The peak prominence values at each time

  point found in the designated frequency range.

• ffreq: The frequency at which the peak was

  detected.

• fwidth: The width of the peak that was detected in

  the spectrum. The width is in units Hz.

• nscube: Normalized spectrogram in the specified

  detrend_freq_range.