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A radial map of multi-whisker correlation selectivity in the rat barrel cortex

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ABSTRACT

In the barrel cortex, several features of single-whisker stimuli are organized in functional maps. The barrel cortex also encodes spatio-temporal correlation patterns of multi-whisker inputs, but so far the cortical mapping of neurons tuned to such input statistics is unknown. Here we report that layer 2/3 of the rat barrel cortex contains an additional functional map based on neuronal tuning to correlated versus uncorrelated multi-whisker stimuli: neuron responses to uncorrelated multi-whisker stimulation are strongest above barrel centres, whereas neuron responses to correlated and anti-correlated multi-whisker stimulation peak above the barrel–septal borders, forming rings of multi-whisker synchrony-preferring cells.

No MeSH data available.


Nonlinearity of neuronal responses to correlated multi-whisker stimulations.(a) Three examples of neurons' functional responses to PW stimulation (left), sum of the response to PW and two closest adjacent whiskers (middle), and to correlated stimulation (right). (b) Distribution of the NL index. Sixty-eight per cent of neurons are supra-linear. (c) Radial distribution of NL for significantly supra-linear neurons (that is, bootstrap-derived response P<0.05). (d) The radial distribution (517 neurons per bin) of the proportion of supra-linear neurons (NL>1), among all responsive neurons, shows a significant peak. *Mann–Whitney P=1.4E-2. ***P=9.0E-5.
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f3: Nonlinearity of neuronal responses to correlated multi-whisker stimulations.(a) Three examples of neurons' functional responses to PW stimulation (left), sum of the response to PW and two closest adjacent whiskers (middle), and to correlated stimulation (right). (b) Distribution of the NL index. Sixty-eight per cent of neurons are supra-linear. (c) Radial distribution of NL for significantly supra-linear neurons (that is, bootstrap-derived response P<0.05). (d) The radial distribution (517 neurons per bin) of the proportion of supra-linear neurons (NL>1), among all responsive neurons, shows a significant peak. *Mann–Whitney P=1.4E-2. ***P=9.0E-5.

Mentions: Receptive fields are often quantified in the barrel cortex by counting the number of whiskers that evoke a response in a particular neuron, using stimulation of one whisker at a time. Neurons above a barrel predominantly respond to the corresponding whisker, whereas neurons above septa often respond to several adjacent whiskers. Receptive fields are therefore expected to increase along the barrel-to-septum axis9. Does the large amount of correlation-preferring neurons that we observed merely reflect an increase of the receptive fields size above the barrel to septa border, or does it correspond to an increase of supra-linear integration of multi-whisker inputs at this position? We computed the nonlinearity (NL) index of each neuron by comparing the sum of its responses to individual whiskers during uncorrelated stimulation, with its response to correlated stimulation (see Methods and three example neurons in Fig. 3a). A majority of layer 2/3 neurons behaved as nonlinear integrators, with a tendency to supra-linearity (Fig. 3b, NL index >1 for 76% of correlation-preferring neurons). Supra-linearity was not distributed uniformly across layer 2/3. The radial distribution of NL index for supra-linear neurons exhibited an increase from barrel centre to border, with a maximum above the barrel–septum border (Fig. 3c), similar to the radial profile of responses to correlated stimuli (Fig. 2d). Finally, the proportion of supra-linear neurons increased from barrel centre to septum, with a peak at the border (Fig. 3d), similar to the radial distribution of the proportion of cells preferring correlated stimulation (Fig. 2f). The origin of the map for correlation-preferring neurons is therefore likely to reside in the uneven distribution of supra-linear integration properties of layer 2/3 neurons.


A radial map of multi-whisker correlation selectivity in the rat barrel cortex
Nonlinearity of neuronal responses to correlated multi-whisker stimulations.(a) Three examples of neurons' functional responses to PW stimulation (left), sum of the response to PW and two closest adjacent whiskers (middle), and to correlated stimulation (right). (b) Distribution of the NL index. Sixty-eight per cent of neurons are supra-linear. (c) Radial distribution of NL for significantly supra-linear neurons (that is, bootstrap-derived response P<0.05). (d) The radial distribution (517 neurons per bin) of the proportion of supra-linear neurons (NL>1), among all responsive neurons, shows a significant peak. *Mann–Whitney P=1.4E-2. ***P=9.0E-5.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5121329&req=5

f3: Nonlinearity of neuronal responses to correlated multi-whisker stimulations.(a) Three examples of neurons' functional responses to PW stimulation (left), sum of the response to PW and two closest adjacent whiskers (middle), and to correlated stimulation (right). (b) Distribution of the NL index. Sixty-eight per cent of neurons are supra-linear. (c) Radial distribution of NL for significantly supra-linear neurons (that is, bootstrap-derived response P<0.05). (d) The radial distribution (517 neurons per bin) of the proportion of supra-linear neurons (NL>1), among all responsive neurons, shows a significant peak. *Mann–Whitney P=1.4E-2. ***P=9.0E-5.
Mentions: Receptive fields are often quantified in the barrel cortex by counting the number of whiskers that evoke a response in a particular neuron, using stimulation of one whisker at a time. Neurons above a barrel predominantly respond to the corresponding whisker, whereas neurons above septa often respond to several adjacent whiskers. Receptive fields are therefore expected to increase along the barrel-to-septum axis9. Does the large amount of correlation-preferring neurons that we observed merely reflect an increase of the receptive fields size above the barrel to septa border, or does it correspond to an increase of supra-linear integration of multi-whisker inputs at this position? We computed the nonlinearity (NL) index of each neuron by comparing the sum of its responses to individual whiskers during uncorrelated stimulation, with its response to correlated stimulation (see Methods and three example neurons in Fig. 3a). A majority of layer 2/3 neurons behaved as nonlinear integrators, with a tendency to supra-linearity (Fig. 3b, NL index >1 for 76% of correlation-preferring neurons). Supra-linearity was not distributed uniformly across layer 2/3. The radial distribution of NL index for supra-linear neurons exhibited an increase from barrel centre to border, with a maximum above the barrel–septum border (Fig. 3c), similar to the radial profile of responses to correlated stimuli (Fig. 2d). Finally, the proportion of supra-linear neurons increased from barrel centre to septum, with a peak at the border (Fig. 3d), similar to the radial distribution of the proportion of cells preferring correlated stimulation (Fig. 2f). The origin of the map for correlation-preferring neurons is therefore likely to reside in the uneven distribution of supra-linear integration properties of layer 2/3 neurons.

View Article: PubMed Central - PubMed

ABSTRACT

In the barrel cortex, several features of single-whisker stimuli are organized in functional maps. The barrel cortex also encodes spatio-temporal correlation patterns of multi-whisker inputs, but so far the cortical mapping of neurons tuned to such input statistics is unknown. Here we report that layer 2/3 of the rat barrel cortex contains an additional functional map based on neuronal tuning to correlated versus uncorrelated multi-whisker stimuli: neuron responses to uncorrelated multi-whisker stimulation are strongest above barrel centres, whereas neuron responses to correlated and anti-correlated multi-whisker stimulation peak above the barrel&ndash;septal borders, forming rings of multi-whisker synchrony-preferring cells.

No MeSH data available.