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Neurons in the barrel cortex turn into processing whisker and odor signals: a cellular mechanism for the storage and retrieval of associative signals.

Wang D, Zhao J, Gao Z, Chen N, Wen B, Lu W, Lei Z, Chen C, Liu Y, Feng J, Wang JH - Front Cell Neurosci (2015)

Bottom Line: How the neurons are recruited as associative memory cells to encode multiple input signals for their associated storage and distinguishable retrieval remains unclear.After associative learning, the neurons and astrocytes in the sensory cortices are able to store the newly learnt signal (cross-modal memory) besides the innate signal (native-modal memory).Such associative memory cells distinguish the differences of these signals by programming different codes and signify the historical associations of these signals by similar codes in information retrievals.

View Article: PubMed Central - PubMed

Affiliation: State Key Lab of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences Beijing, China.

ABSTRACT
Associative learning and memory are essential to logical thinking and cognition. How the neurons are recruited as associative memory cells to encode multiple input signals for their associated storage and distinguishable retrieval remains unclear. We studied this issue in the barrel cortex by in vivo two-photon calcium imaging, electrophysiology, and neural tracing in our mouse model that the simultaneous whisker and olfaction stimulations led to odorant-induced whisker motion. After this cross-modal reflex arose, the barrel and piriform cortices connected. More than 40% of barrel cortical neurons became to encode odor signal alongside whisker signal. Some of these neurons expressed distinct activity patterns in response to acquired odor signal and innate whisker signal, and others encoded similar pattern in response to these signals. In the meantime, certain barrel cortical astrocytes encoded odorant and whisker signals. After associative learning, the neurons and astrocytes in the sensory cortices are able to store the newly learnt signal (cross-modal memory) besides the innate signal (native-modal memory). Such associative memory cells distinguish the differences of these signals by programming different codes and signify the historical associations of these signals by similar codes in information retrievals.

No MeSH data available.


Related in: MedlinePlus

Odorant-induced whisker motion is identified by seeing a similarity of whisker motion patterns induced by whisker and odor stimuli. (A) Shows the pattern of whisker motion induced by odor stimulus in CR-formation mice. (B) Shows the pattern of whisker motion induced by whisker stimulus naturally in NCG mice. The patterns of whisker motions are similar in response to odor signal in CR-formation mice and in response to whisker signal in NCG mice. (C–E) Illustrates the comparisons of whisker retraction duration, whisking frequency and whisking angle induced by WS to NCG mice (blue bar) and by OS to CR-formation mice (red bar).
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Figure 2: Odorant-induced whisker motion is identified by seeing a similarity of whisker motion patterns induced by whisker and odor stimuli. (A) Shows the pattern of whisker motion induced by odor stimulus in CR-formation mice. (B) Shows the pattern of whisker motion induced by whisker stimulus naturally in NCG mice. The patterns of whisker motions are similar in response to odor signal in CR-formation mice and in response to whisker signal in NCG mice. (C–E) Illustrates the comparisons of whisker retraction duration, whisking frequency and whisking angle induced by WS to NCG mice (blue bar) and by OS to CR-formation mice (red bar).

Mentions: Strain C57 mice including males and females in postnatal day 20 were divided into three groups that received different treatments (Figure 1) in whisker stimulus (WS, 5 Hz mechanical stimulation) and odor stimulus (OS, butyl acetate). The trainings included a simultaneous pairing of conditioned OS with unconditioned WS (paired-stimulus group, PSG), WS/OS-unpairing (unpaired-stimulus group, UPSG; the interval between WS and OS about 2–5 min), and neither OS nor WS (naïve control group, NCG). WS and OS were given by the digital multiple sensory modal stimulator (MSMS) made in our laboratory. The OS was given by switching on butyl acetate-contained tube and generating a small liquid drop in front of the mouse noses (Video one in Supplementary Material). The intensity of butyl acetate odor was enough to induce the responses of olfactory bulb neurons detected by two-photon imaging (Figure S1). The WS to mouse assigned whiskers was given to the contralateral side of the barrel cortices that were studied in two-photon imaging and electrophysiology (Video one in Supplementary Material). The WS intensity suitably triggered whisker fluctuation (whisker-induced whisker motion, Figure 2). The parameters to train each mouse in PSG and UPSG by WS and OS were 20 s each training and five times per day in intervals of 2 h for 10 days (Figure 1). This training period was based on a fact that the onset of odorant-induced whisker motion reached the plateau level about 10 training days (Figure 4D). The stimulation intensity, duration and frequency were precisely controlled by MSMS, which were fixed for each trial and each mouse. During the training, each of the mice was placed in a home-made cage, in which their running and motion were restricted, but their body and arms freely extended. There are no circadian disturbance and stress conditions, such as noise, light, unusual odors, and motions from the experimenters. The mice were placed into the cage for 10 min every day about 1 week to have them habituated to experiment condition before the training, and placed into the cages about 5 min prior to each training for their quiet adaptation during the training. Care was also used in the odor-test procedure (please see below). It is noteworthy that the mice in NCG were placed in these home-made cages, but did not receive WS and OS.


Neurons in the barrel cortex turn into processing whisker and odor signals: a cellular mechanism for the storage and retrieval of associative signals.

Wang D, Zhao J, Gao Z, Chen N, Wen B, Lu W, Lei Z, Chen C, Liu Y, Feng J, Wang JH - Front Cell Neurosci (2015)

Odorant-induced whisker motion is identified by seeing a similarity of whisker motion patterns induced by whisker and odor stimuli. (A) Shows the pattern of whisker motion induced by odor stimulus in CR-formation mice. (B) Shows the pattern of whisker motion induced by whisker stimulus naturally in NCG mice. The patterns of whisker motions are similar in response to odor signal in CR-formation mice and in response to whisker signal in NCG mice. (C–E) Illustrates the comparisons of whisker retraction duration, whisking frequency and whisking angle induced by WS to NCG mice (blue bar) and by OS to CR-formation mice (red bar).
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Related In: Results  -  Collection

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Figure 2: Odorant-induced whisker motion is identified by seeing a similarity of whisker motion patterns induced by whisker and odor stimuli. (A) Shows the pattern of whisker motion induced by odor stimulus in CR-formation mice. (B) Shows the pattern of whisker motion induced by whisker stimulus naturally in NCG mice. The patterns of whisker motions are similar in response to odor signal in CR-formation mice and in response to whisker signal in NCG mice. (C–E) Illustrates the comparisons of whisker retraction duration, whisking frequency and whisking angle induced by WS to NCG mice (blue bar) and by OS to CR-formation mice (red bar).
Mentions: Strain C57 mice including males and females in postnatal day 20 were divided into three groups that received different treatments (Figure 1) in whisker stimulus (WS, 5 Hz mechanical stimulation) and odor stimulus (OS, butyl acetate). The trainings included a simultaneous pairing of conditioned OS with unconditioned WS (paired-stimulus group, PSG), WS/OS-unpairing (unpaired-stimulus group, UPSG; the interval between WS and OS about 2–5 min), and neither OS nor WS (naïve control group, NCG). WS and OS were given by the digital multiple sensory modal stimulator (MSMS) made in our laboratory. The OS was given by switching on butyl acetate-contained tube and generating a small liquid drop in front of the mouse noses (Video one in Supplementary Material). The intensity of butyl acetate odor was enough to induce the responses of olfactory bulb neurons detected by two-photon imaging (Figure S1). The WS to mouse assigned whiskers was given to the contralateral side of the barrel cortices that were studied in two-photon imaging and electrophysiology (Video one in Supplementary Material). The WS intensity suitably triggered whisker fluctuation (whisker-induced whisker motion, Figure 2). The parameters to train each mouse in PSG and UPSG by WS and OS were 20 s each training and five times per day in intervals of 2 h for 10 days (Figure 1). This training period was based on a fact that the onset of odorant-induced whisker motion reached the plateau level about 10 training days (Figure 4D). The stimulation intensity, duration and frequency were precisely controlled by MSMS, which were fixed for each trial and each mouse. During the training, each of the mice was placed in a home-made cage, in which their running and motion were restricted, but their body and arms freely extended. There are no circadian disturbance and stress conditions, such as noise, light, unusual odors, and motions from the experimenters. The mice were placed into the cage for 10 min every day about 1 week to have them habituated to experiment condition before the training, and placed into the cages about 5 min prior to each training for their quiet adaptation during the training. Care was also used in the odor-test procedure (please see below). It is noteworthy that the mice in NCG were placed in these home-made cages, but did not receive WS and OS.

Bottom Line: How the neurons are recruited as associative memory cells to encode multiple input signals for their associated storage and distinguishable retrieval remains unclear.After associative learning, the neurons and astrocytes in the sensory cortices are able to store the newly learnt signal (cross-modal memory) besides the innate signal (native-modal memory).Such associative memory cells distinguish the differences of these signals by programming different codes and signify the historical associations of these signals by similar codes in information retrievals.

View Article: PubMed Central - PubMed

Affiliation: State Key Lab of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences Beijing, China.

ABSTRACT
Associative learning and memory are essential to logical thinking and cognition. How the neurons are recruited as associative memory cells to encode multiple input signals for their associated storage and distinguishable retrieval remains unclear. We studied this issue in the barrel cortex by in vivo two-photon calcium imaging, electrophysiology, and neural tracing in our mouse model that the simultaneous whisker and olfaction stimulations led to odorant-induced whisker motion. After this cross-modal reflex arose, the barrel and piriform cortices connected. More than 40% of barrel cortical neurons became to encode odor signal alongside whisker signal. Some of these neurons expressed distinct activity patterns in response to acquired odor signal and innate whisker signal, and others encoded similar pattern in response to these signals. In the meantime, certain barrel cortical astrocytes encoded odorant and whisker signals. After associative learning, the neurons and astrocytes in the sensory cortices are able to store the newly learnt signal (cross-modal memory) besides the innate signal (native-modal memory). Such associative memory cells distinguish the differences of these signals by programming different codes and signify the historical associations of these signals by similar codes in information retrievals.

No MeSH data available.


Related in: MedlinePlus