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Stretch induced hyperexcitability of mice callosal pathway.

Fan A, Stebbings KA, Llano DA, Saif T - Front Cell Neurosci (2015)

Bottom Line: Memory and learning are thought to result from changes in synaptic strength.FA amplitude and activation rate decrease as excitability increases in stretch cases but not in electrically enhanced cases.These results collectively demonstrate that a small stretch in physiological range can modulate neural activities significantly, suggesting that mechanical events can be employed as a novel tool for the modulation of neural plasticity.

View Article: PubMed Central - PubMed

Affiliation: Department of Mechanical Science and Engineering, University of Illinois Urbana, IL, USA.

ABSTRACT
Memory and learning are thought to result from changes in synaptic strength. Previous studies on synaptic physiology in brain slices have traditionally been focused on biochemical processes. Here, we demonstrate with experiments on mouse brain slices that central nervous system plasticity is also sensitive to mechanical stretch. This is important, given the host of clinical conditions involving changes in mechanical tension on the brain, and the normal role that mechanical tension plays in brain development. A novel platform is developed to investigate neural responses to mechanical stretching. Flavoprotein autofluoresence (FA) imaging was employed for measuring neural activity. We observed that synaptic excitability substantially increases after a small (2.5%) stretch was held for 10 min and released. The increase is accumulative, i.e., multiple stretch cycles further increase the excitability. We also developed analytical tools to quantify the spatial spread and response strength. Results show that the spatial spread is less stable in slices undergoing the stretch-unstretch cycle. FA amplitude and activation rate decrease as excitability increases in stretch cases but not in electrically enhanced cases. These results collectively demonstrate that a small stretch in physiological range can modulate neural activities significantly, suggesting that mechanical events can be employed as a novel tool for the modulation of neural plasticity.

No MeSH data available.


Related in: MedlinePlus

Enhanced excitability of callosal pathway by stretch alone and the 2 control schemes. (A) Normalized probability of response of stretched group and control group. The stretched data set here is individually normalized to the average probability of the first baseline. This serves to show the variation in the starting probability of response, as given in the error bar. All subsequent column plots are normalized to the first baseline probability within individual experimental data set, leading to an error bar magnitude of 0. Subfigure includes a schematic of the paradigm. (B) The slopes of excitability vs. baseline # in each independent data set are averaged and reported here. This serves to compare the increase in excitability of the stretched and control groups. All error bars in SD. P-value obtained from 2-tail t-test with unequal variance.
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Figure 2: Enhanced excitability of callosal pathway by stretch alone and the 2 control schemes. (A) Normalized probability of response of stretched group and control group. The stretched data set here is individually normalized to the average probability of the first baseline. This serves to show the variation in the starting probability of response, as given in the error bar. All subsequent column plots are normalized to the first baseline probability within individual experimental data set, leading to an error bar magnitude of 0. Subfigure includes a schematic of the paradigm. (B) The slopes of excitability vs. baseline # in each independent data set are averaged and reported here. This serves to compare the increase in excitability of the stretched and control groups. All error bars in SD. P-value obtained from 2-tail t-test with unequal variance.

Mentions: Excitability here is defined as the ratio of number of times the slice responds (detected using FA) to the number it is electrically stimulated. Thus, excitability gives the probability of FA response. We found that in all slices undergoing the stretch-baseline-cycle (n = 4), excitability increases after every cycle to ultimately 3 times of the original probability (Figure 2A). It thus seems that the slice “remembers” its past history of stretch, and its current excitability results from a cumulative effect of its past stretches. Normalized baseline measurements from the control group (n = 3) are plotted next to stretched group. We fit a linear regression to each experiment individually, and the averaged slope is reported in Figure 2B comparing the slope in stretched and control slices. We found that the stretched slices showed a significant increase in excitability compared to control slices (p = 0.013).


Stretch induced hyperexcitability of mice callosal pathway.

Fan A, Stebbings KA, Llano DA, Saif T - Front Cell Neurosci (2015)

Enhanced excitability of callosal pathway by stretch alone and the 2 control schemes. (A) Normalized probability of response of stretched group and control group. The stretched data set here is individually normalized to the average probability of the first baseline. This serves to show the variation in the starting probability of response, as given in the error bar. All subsequent column plots are normalized to the first baseline probability within individual experimental data set, leading to an error bar magnitude of 0. Subfigure includes a schematic of the paradigm. (B) The slopes of excitability vs. baseline # in each independent data set are averaged and reported here. This serves to compare the increase in excitability of the stretched and control groups. All error bars in SD. P-value obtained from 2-tail t-test with unequal variance.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4525056&req=5

Figure 2: Enhanced excitability of callosal pathway by stretch alone and the 2 control schemes. (A) Normalized probability of response of stretched group and control group. The stretched data set here is individually normalized to the average probability of the first baseline. This serves to show the variation in the starting probability of response, as given in the error bar. All subsequent column plots are normalized to the first baseline probability within individual experimental data set, leading to an error bar magnitude of 0. Subfigure includes a schematic of the paradigm. (B) The slopes of excitability vs. baseline # in each independent data set are averaged and reported here. This serves to compare the increase in excitability of the stretched and control groups. All error bars in SD. P-value obtained from 2-tail t-test with unequal variance.
Mentions: Excitability here is defined as the ratio of number of times the slice responds (detected using FA) to the number it is electrically stimulated. Thus, excitability gives the probability of FA response. We found that in all slices undergoing the stretch-baseline-cycle (n = 4), excitability increases after every cycle to ultimately 3 times of the original probability (Figure 2A). It thus seems that the slice “remembers” its past history of stretch, and its current excitability results from a cumulative effect of its past stretches. Normalized baseline measurements from the control group (n = 3) are plotted next to stretched group. We fit a linear regression to each experiment individually, and the averaged slope is reported in Figure 2B comparing the slope in stretched and control slices. We found that the stretched slices showed a significant increase in excitability compared to control slices (p = 0.013).

Bottom Line: Memory and learning are thought to result from changes in synaptic strength.FA amplitude and activation rate decrease as excitability increases in stretch cases but not in electrically enhanced cases.These results collectively demonstrate that a small stretch in physiological range can modulate neural activities significantly, suggesting that mechanical events can be employed as a novel tool for the modulation of neural plasticity.

View Article: PubMed Central - PubMed

Affiliation: Department of Mechanical Science and Engineering, University of Illinois Urbana, IL, USA.

ABSTRACT
Memory and learning are thought to result from changes in synaptic strength. Previous studies on synaptic physiology in brain slices have traditionally been focused on biochemical processes. Here, we demonstrate with experiments on mouse brain slices that central nervous system plasticity is also sensitive to mechanical stretch. This is important, given the host of clinical conditions involving changes in mechanical tension on the brain, and the normal role that mechanical tension plays in brain development. A novel platform is developed to investigate neural responses to mechanical stretching. Flavoprotein autofluoresence (FA) imaging was employed for measuring neural activity. We observed that synaptic excitability substantially increases after a small (2.5%) stretch was held for 10 min and released. The increase is accumulative, i.e., multiple stretch cycles further increase the excitability. We also developed analytical tools to quantify the spatial spread and response strength. Results show that the spatial spread is less stable in slices undergoing the stretch-unstretch cycle. FA amplitude and activation rate decrease as excitability increases in stretch cases but not in electrically enhanced cases. These results collectively demonstrate that a small stretch in physiological range can modulate neural activities significantly, suggesting that mechanical events can be employed as a novel tool for the modulation of neural plasticity.

No MeSH data available.


Related in: MedlinePlus