Multi-unit Analysis of Homeostatic Plasticity Impairments and FXS Within Mouse Somatosensory Barrels and Septa Pubblico

Huang, Washington (Spring 2024)

Permanent URL: https://etd.library.emory.edu/concern/etds/d217qq96d?locale=it
Published

Abstract

Importance: Autism Spectrum Disorder (ASD) is a prevalent neurodevelopmental condition with no known cure, affecting 1 in 100 individuals worldwide. Fragile X Syndrome (FXS), a common inherited neurodevelopmental disorder, is often co-diagnosed with ASD and is characterized by cognitive, motor, and neural plasticity impairments. This research focuses on understanding the impacts of FXS on neural networks and homeostatic plasticity within the barrels and septa of the mouse somatosensory cortex, areas crucial for processing whisker sensory stimuli and eliciting whisker motor movements.

Objective: This study aims to elucidate the role and functionality of homeostatic plasticity in the septal regions compared to the well-studied barrel regions of the somatosensory cortex in FXS models. Specifically, it investigates the effects of FXS on baseline neural activity and responses following whisker deprivation.

Methods: Multi-unit recording data from extracellular neural recording probes placed in the barrel cortex of wild-type and Fmr1 Knockout (KO) mice were collected under both whisker-deprived and non-deprived conditions at two time points (Postnatal age P16 and P21). Whiskers were stimulated at six different velocities. Histology was performed to determine probe placement in the barrel cortex. Data was analyzed by creating velocity response curves (VRCs) for each condition.  

Main hypothesis: Multi-unit activity within the barrels and septa will have similar homeostatic plasticity responses following whisker deprivation in wild-type subjects, while Fmr1 KO would lead to a larger neural activity decrease in the septa when compared to barrels.

Results: The investigation into homeostatic plasticity within the barrel and septa in FXS models faced significant challenges due to insufficient sample sizes across multiple experimental conditions, preventing statistical significance. Consequently, this limitation hindered the ability to support or reject the main hypothesis.

Conclusion: This study underscores the inherent complexities and limitations of employing multi-unit analysis to explore intricate neurological phenomena such as homeostatic plasticity in the context of FXS. This research journey highlighted the crucial need for larger sample sizes and more refined methodologies when studying homeostatic plasticity and FXS within the somatosensory cortex. Nonetheless, the study represents a novel examination of the septa and paves the way for future studies to unravel the complexity of homeostatic plasticity and FXS.

Table of Contents

01) Introduction

01)          Fragile X Syndrome

02)          Plasticity

04)          Barrel/ Septa Research

07)          Research Direction

08) Methods

08)          Subjects

09)          Extracellular Recording

10)          Histology

11)          Data Analysis

11) Results

12)          P16 VRC Results

13)          P21 VRC Results

14)          Overall Results

15) Discussion

17)          Limitations

20) Future Directions and Conclusion

22) Figures and Graphs

22)          Table 1: P16 Subject Distribution Chart

22)          Table 2: P21 Subject Distribution Chart

23)          Figure 1a: Image of Barrel Cortex and Probe in Barrel

23)          Figure 1b: Image of Barrel Cortex and Probe in Septa

24)          Figure 2: P16 WT Constant Barrel VRC Comparison

25)          Figure 3: P16 WT Constant Septa VRC Comparison

26)          Figure 4: P16 nWD Constant Barrel VRC Comparison

27)          Figure 5: P16 nWD Constant Septa VRC Comparison

28)          Figure 6: P16 WD Constant Barrel VRC Comparison

29)          Figure 7: P21 WT Constant Barrel VRC Comparison

30)          Figure 8: P21 WT Constant Septa VRC Comparison

31)          Figure 9: P21 nWD Constant Barrel VRC Comparison

32)          Figure 10: P21 WD Constant Barrel VRC Comparison

33)          Figure 11: P21 WD Constant Septa VRC Comparison

34) Works Cited

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