Linearity of Cortical Receptive Fields Measured with Natural Sounds

Although auditory cortex is thought to play an important role in processing complex natural sounds such as speech and animal vocalizations, the specific functional roles of cortical receptive fields (RFs) remain unclear. Here, we study the relationship between a behaviorally important function: the discrimination of natural sounds and the structure of cortical RFs. We examine this problem in the model system of songbirds, using a computational approach. First, we constructed model neurons based on the spectral temporal RF (STRF), a widely used description of auditory cortical RFs. We focused on delayed inhibitory STRFs, a class of STRFs experimentally observed in primary auditory cortex (ACx) and its analog in songbirds (field L), which consist of an excitatory subregion and a delayed inhibitory subregion cotuned to a characteristic frequency. We quantified the discrimination of birdsongs by model neurons, examining both the dynamics and temporal resolution of discrimination, using a recently proposed spike distance metric (SDM). We found that single model neurons with delayed inhibitory STRFs can discriminate accurately between songs. Discrimination improves dramatically when the temporal structure of the neural response at fine timescales is considered. When we compared discrimination by model neurons with and without the inhibitory subregion, we found that the presence of the inhibitory subregion can improve discrimination. Finally, we modeled a cortical microcircuit with delayed synaptic inhibition, a candidate mechanism underlying delayed inhibitory STRFs, and showed that blocking inhibition in this model circuit degrades discrimination.

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Faculty Opinions recommendation of Task difficulty and performance induce diverse adaptive patterns in gain and shape of primary auditory cortical receptive fields.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1159938.620195 ◽

2009 ◽

Author(s):

Alan Palmer ◽

Christian John Sumner

Keyword(s):

Task Difficulty ◽

Receptive Fields ◽

And Performance ◽

Cortical Receptive Fields

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Role of the Zebra Finch Auditory Thalamus in Generating Complex Representations for Natural Sounds

Journal of Neurophysiology ◽

10.1152/jn.00128.2010 ◽

2010 ◽

Vol 104 (2) ◽

pp. 784-798 ◽

Cited By ~ 15

Author(s):

Noopur Amin ◽

Patrick Gill ◽

Frédéric E. Theunissen

Keyword(s):

Receptive Fields ◽

Neural Representation ◽

Natural Sounds ◽

Auditory Midbrain ◽

Complex Sounds ◽

Auditory Thalamus ◽

Spectrotemporal Receptive Fields ◽

Primary Sensory Cortex ◽

Relay Nucleus ◽

Field L

We estimated the spectrotemporal receptive fields of neurons in the songbird auditory thalamus, nucleus ovoidalis, and compared the neural representation of complex sounds in the auditory thalamus to those found in the upstream auditory midbrain nucleus, mesencephalicus lateralis dorsalis (MLd), and the downstream auditory pallial region, field L. Our data refute the idea that the primary sensory thalamus acts as a simple, relay nucleus: we find that the auditory thalamic receptive fields obtained in response to song are more complex than the ones found in the midbrain. Moreover, we find that linear tuning diversity and complexity in ovoidalis (Ov) are closer to those found in field L than in MLd. We also find prevalent tuning to intermediate spectral and temporal modulations, a feature that is unique to Ov. Thus even a feed-forward model of the sensory processing chain, where neural responses in the sensory thalamus reveals intermediate response properties between those in the sensory periphery and those in the primary sensory cortex, is inadequate in describing the tuning found in Ov. Based on these results, we believe that the auditory thalamic circuitry plays an important role in generating novel complex representations for specific features found in natural sounds.

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Spectral-Temporal Receptive Fields of Nonlinear Auditory Neurons Obtained Using Natural Sounds

Journal of Neuroscience ◽

10.1523/jneurosci.20-06-02315.2000 ◽

2000 ◽

Vol 20 (6) ◽

pp. 2315-2331 ◽

Cited By ~ 312

Author(s):

Frédéric E. Theunissen ◽

Kamal Sen ◽

Allison J. Doupe

Keyword(s):

Receptive Fields ◽

Natural Sounds ◽

Auditory Neurons

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Two-dimensional receptive-field organization in striate cortical neurons of the cat

Visual Neuroscience ◽

10.1017/s0952523800003011 ◽

1994 ◽

Vol 11 (4) ◽

pp. 703-720 ◽

Cited By ~ 10

Author(s):

Ming Sun ◽

A. B. Bonds

Keyword(s):

Receptive Field ◽

Cortical Neurons ◽

Ocular Dominance ◽

Receptive Fields ◽

Field Size ◽

Two Dimensional ◽

Cortical Layers ◽

Field Organization ◽

Receptive Field Organization ◽

Cortical Receptive Fields

AbstractThe two-dimensional organization of receptive fields (RFs) of 44 cells in the cat visual cortex and four cells from the cat LGN was measured by stimulation with either dots or bars of light. The light bars were presented in different positions and orientations centered on the RFs. The RFs found were arbitrarily divided into four general types: Punctate, resembling DOG filters (11%); those resembling Gabor filters (9%); elongate (36%); and multipeaked-type (44%). Elongate RFs, usually found in simple cells, could show more than one excitatory band or bifurcation of excitatory regions. Although regions inhibitory to a given stimulus transition (e.g. ON) often coincided with regions excitatory to the opposite transition (e.g. OFF), this was by no means the rule. Measurements were highly repeatable and stable over periods of at least 1 h. A comparison between measurements made with dots and with bars showed reasonable matches in about 40% of the cases. In general, bar-based measurements revealed larger RFs with more structure, especially with respect to inhibitory regions. Inactivation of lower cortical layers (V-VI) by local GABA injection was found to reduce sharpness of detail and to increase both receptive-field size and noise in upper layer cells, suggesting vertically organized RF mechanisms. Across the population, some cells bore close resemblance to theoretically proposed filters, while others had a complexity that was clearly not generalizable, to the extent that they seemed more suited to detection of specific structures. We would speculate that the broadly varying forms of cat cortical receptive fields result from developmental processes akin to those that form ocular-dominance columns, but on a smaller scale.

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