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DirectDirectedTransferFunction

Estimate the Direct Directed Transfer Function ( dDTF) or short-time dDTF (sdDTF) measure from a previously computed MVAR model.

Like the other nodes computing dynamical measures, this node accepts as input a multi-variate auto-regressive ( MVAR) model, or, more commonly, a time series of such models. Such models are typically estimated using a model-fitting node such as the Group LASSO MVAR node, the output of which can be directly used by this node (see documentation of that node for proper usage). The output of this node is a square matrix that quantifies connectivity between pairs of brain sources for each frequency bin of interest, and possibly for each time point if the input data were a time series (then yielding a 4-way tensor as output). The desired frequencies can be selected via a parameter. In addition to dDTF, this node can also compute the short-time dDTF (sdDTF) using the normalization parameter. More Info... Version 1.0.0

Ports/Properties

data

Data to process.

verbose name
Data
default value
None
port type
DataPort
value type
Packet (can be None)
data direction
INOUT

frequencies

Frequencies over which to compute the measure, in Hz. This is a list of frequencies (e.g., [1,2,3,4]), or a range expression such as 1...4, or a half-open Python-style range such as 1:5. The node will output one connectivity matrix for each frequency, formatted as a tensor.

verbose name
Frequencies
default value
1...15
port type
Port
value type
object (can be None)

temporal_normalization

Calculate short-time dDTF (sdDTF). This is enabled using short-time temporal normalization.

verbose name
Calc Short-Time Ddtf
default value
False
port type
BoolPort
value type
bool (can be None)

absolute_value_squared

Compute squared magnitude of complex values. If disabled the raw complex values will be returned, i.e., including some phase information.

verbose name
Absolute Value Squared
default value
True
port type
BoolPort
value type
bool (can be None)

include_feature_axis

Include a feature axis. If enabled, a one-element (dummy) feature axis will be appended that has the name of this measure set as the name of the feature. This way, the output of multiple dynamical-measure nodes can be concatenated along the feature axis, and the resulting tensor will retain the names of the measures in its resulting (multi-element) feature axis.

verbose name
Include Feature Axis
default value
False
port type
BoolPort
value type
bool (can be None)

remove_auto_connections

Set auto-connectivity estimates to zero.

verbose name
Mask Auto Connections
default value
False
port type
BoolPort
value type
bool (can be None)

denominator_epsilon

Small value to add to denominators to avoid division by zero.

verbose name
Denominator Epsilon
default value
0
port type
FloatPort
value type
float (can be None)

regularization

Regularization parameter to add to matrices that need to be inverted.

verbose name
Regularization
default value
0
port type
FloatPort
value type
float (can be None)

set_breakpoint

Set a breakpoint on this node. If this is enabled, your debugger (if one is attached) will trigger a breakpoint.

verbose name
Set Breakpoint (Debug Only)
default value
False
port type
BoolPort
value type
bool (can be None)

metadata

User-definable meta-data associated with the node. Usually reserved for technical purposes.

verbose name
Metadata
default value
{}
port type
DictPort
value type
dict (can be None)