dorsal/arxiv
View SchemaTemporal Symmetry in Primary Auditory Cortex: Implications for Cortical Connectivity
| Authors | Jonathan Z. Simon, Didier A. Depireux, David J. Klein, Jonathan B. Fritz, Shihab A. Shamma |
|---|---|
| Categories | |
| ArXiv ID | q-bio/0608027 |
| URL | https://arxiv.org/abs/q-bio/0608027 |
Abstract
Neurons in primary auditory cortex (AI) in the ferret (Mustela putorius) that are well described by their spectro-temporal response field (STRF), are found also to have a distinctive property that we call temporal symmetry. For temporally symmetric neurons, every temporal cross-section of the STRF (impulse response) is given by the same function of time, except for a scaling and a "Hilbert rotation". This property held in 85% of neurons (123 out of 145) recorded from awake animals, and in 96% of neurons (70 out of 73) recorded from anesthetized animals. This property of temporal symmetry is highly constraining for possible models of functional neural connectivity within and into AI. We find that the simplest models of functional thalamic input, from the ventral Medial Geniculate Body (MGB), into the entry layers of AI are ruled out because they are incompatible with the constraints of the observed temporal symmetry. This is also the case for the simplest models of functional intracortical connectivity. Plausible models that do generate temporal symmetry, both from thalamic and intracortical inputs, are presented. In particular, we propose that two specific characteristics of the thalamo-cortical interface may be responsible. The first is a temporal mismatch between the fast dynamics of the thalamus and the slow responses of the cortex. The second is that all thalamic inputs into a cortical module (or a cluster of cells) must be restricted to one point of entry (or one cell in the cluster). This latter property implies a lack of correlated horizontal interactions across cortical modules during the STRF measurements. The implications of these insights in the auditory system, and comparisons with similar properties in the visual system, are explored.
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"abstract": "Neurons in primary auditory cortex (AI) in the ferret (Mustela putorius) that\nare well described by their spectro-temporal response field (STRF), are found\nalso to have a distinctive property that we call temporal symmetry. For\ntemporally symmetric neurons, every temporal cross-section of the STRF (impulse\nresponse) is given by the same function of time, except for a scaling and a\n\"Hilbert rotation\". This property held in 85% of neurons (123 out of 145)\nrecorded from awake animals, and in 96% of neurons (70 out of 73) recorded from\nanesthetized animals. This property of temporal symmetry is highly constraining\nfor possible models of functional neural connectivity within and into AI. We\nfind that the simplest models of functional thalamic input, from the ventral\nMedial Geniculate Body (MGB), into the entry layers of AI are ruled out because\nthey are incompatible with the constraints of the observed temporal symmetry.\nThis is also the case for the simplest models of functional intracortical\nconnectivity. Plausible models that do generate temporal symmetry, both from\nthalamic and intracortical inputs, are presented. In particular, we propose\nthat two specific characteristics of the thalamo-cortical interface may be\nresponsible. The first is a temporal mismatch between the fast dynamics of the\nthalamus and the slow responses of the cortex. The second is that all thalamic\ninputs into a cortical module (or a cluster of cells) must be restricted to one\npoint of entry (or one cell in the cluster). This latter property implies a\nlack of correlated horizontal interactions across cortical modules during the\nSTRF measurements. The implications of these insights in the auditory system,\nand comparisons with similar properties in the visual system, are explored.",
"arxiv_id": "q-bio/0608027",
"authors": [
"Jonathan Z. Simon",
"Didier A. Depireux",
"David J. Klein",
"Jonathan B. Fritz",
"Shihab A. Shamma"
],
"categories": [
"q-bio.NC",
"q-bio.QM"
],
"title": "Temporal Symmetry in Primary Auditory Cortex: Implications for Cortical Connectivity",
"url": "https://arxiv.org/abs/q-bio/0608027"
},
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