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The spectro-temporal receptive field or spatio-temporal receptive field (STRF) of a
/ref> * a first stage of temporal receptive fields corresponding to an idealized cochlea model modeled as window Fourier transform with either Gabor functions in the case of non-causal time or Gammatone functions alternatively generalized Gammatone functions for a truly time-causal model in which the future cannot be accessed, * a second layer of spectra-temporal receptive fields modeled as Gaussian functions over the log-spectral domain and either Gaussian kernels over time in the case of non-causal time or first-order integrators (truncated exponential kernels) coupled in cascade in the case of truly time-causal operations. These shapes of the receptive field functions in these models can be determined by necessity from structural properties of the environment combined with requirements about the internal structure of the auditory system to enable theoretically well-founded processing of sound signals at different temporal and log-spectral scales.
neuron
A neuron, neurone, or nerve cell is an electrically excitable cell that communicates with other cells via specialized connections called synapses. The neuron is the main component of nervous tissue in all animals except sponges and placozoa. ...
represents which types of stimuli excite or inhibit that neuron. "Spectro-temporal" refers most commonly to audition, where the neuron's response depends on frequency versus time, while "spatio-temporal" refers to vision, where the neuron's response depends on spatial location versus time. Thus they are not exactly the same concept, but both are referred to as STRF and serve a similar role in the analysis of neural responses.
If linearity
Linearity is the property of a mathematical relationship ('' function'') that can be graphically represented as a straight line. Linearity is closely related to '' proportionality''. Examples in physics include rectilinear motion, the linear ...
is assumed, the neuron can be modeled as having a time-varying firing rate equal to the convolution
In mathematics (in particular, functional analysis), convolution is a mathematical operation on two functions ( and ) that produces a third function (f*g) that expresses how the shape of one is modified by the other. The term ''convolution'' ...
of the stimulus with the STRF.
Auditory STRFs
The example STRF here is for an auditory neuron from the area CM (caudal medial) of a malezebra finch
The zebra finches are two species of estrildid finch in the genus ''Taeniopygia'' found in Australia and Indonesia. They are seed-eaters that travel in large flocks.
The species are:
Previously, both species were classified as a single specie ...
, when played conspecific
Biological specificity is the tendency of a characteristic such as a behavior or a biochemical variation to occur in a particular species.
Biochemist Linus Pauling stated that "Biological specificity is the set of characteristics of living organis ...
birdsong. The colour of this plot shows the effect of sound on this neuron: this neuron tends to be excited by sound from about 2.5 kHz to 7 kHz heard by the animal 12 ms ago, but it is inhibited by sound in the same frequency range from about 18 ms ago.
Visual STRFs
See * Dario L. Ringach Receptive Fields in Macaque Primary Visual Cortex Spatial Structure and Symmetry of Simple-Cell (2002) * J. H. van Hateren and D. L. Ruderman Independent component analysis of natural image sequences yields spatio-temporal filters similar to simple cells in primary visual cortex (2002)Idealized computational models for auditory receptive fields
A computational theory for early auditory receptive fields can be expressed from normative physical, mathematical and perceptual arguments, permitting axiomatic derivation of auditory receptive fields in two stages:Lindeberg, T. and Friberg, A. Idealized computational models of auditory receptive fields, PLOS ONE, 10(3): e0119032, pages 1-58, 2015/ref> * a first stage of temporal receptive fields corresponding to an idealized cochlea model modeled as window Fourier transform with either Gabor functions in the case of non-causal time or Gammatone functions alternatively generalized Gammatone functions for a truly time-causal model in which the future cannot be accessed, * a second layer of spectra-temporal receptive fields modeled as Gaussian functions over the log-spectral domain and either Gaussian kernels over time in the case of non-causal time or first-order integrators (truncated exponential kernels) coupled in cascade in the case of truly time-causal operations. These shapes of the receptive field functions in these models can be determined by necessity from structural properties of the environment combined with requirements about the internal structure of the auditory system to enable theoretically well-founded processing of sound signals at different temporal and log-spectral scales.
References