Biology subjects

Perlmutter, S.

Publications and source records attributed to Perlmutter, S..

3 recordsLinked to original sources

bioRxiv2026

Reducing the Foreign Body Reaction to Neuronal Implants in the Central Nervous System with Porous Precision-templated, Mechanically Compliant Hydrogel Scaffolds

Central nervous system diseases and injuries might be treated by implanted devices, tissue regenerative scaffolds, or drug delivery platforms. However, inflammatory CNS responses limit these interventions and may worsen outcomes following damage to the CNS. Via the foreign body reaction, macrophages and glial cells trigger a "glial scar" around implants, reducing device performance, scaffold regenerative ability, or drug delivery potential. Previous studies have shown that stiffness of CNS implants significantly affects glial encapsulation, but few studies have investigated materials that truly match brain tissue stiffness. Porous precision-templated scaffolds with uniform, interconnected, 40 {micro}m spherical pores have shown favorable healing outcomes and a reduced FBR in numerous soft and hard tissue applications. To quantify the effects of both hydrogel compliance (stiffness) and pore size on glial encapsulation, we implanted poly(2-hydroxyethyl methacrylate-co-glycerol methacrylate) (pHEMA/GMA) scaffolds of varying stiffness and pore size for 4 weeks in rat brain. We observed reduced astrocyte encapsulation around PTS compared to solid hydrogel rods, reduced pro-inflammatory macrophage polarization for softer hydrogels versus stiffer hydrogels, and the presence of new blood vessels, neuronal markers and neurogenesis within the pores. Utilizing soft, precision-porous hydrogels could provide a strategy for mitigating glial scarring and improving regeneration in implant-based CNS treatments.

bioengineering↗

bioRxiv2023

Expansion-assisted selective plane illumination microscopy for nanoscale imaging ofcentimeter-scale tissues

Recent advances in tissue processing, labeling, and fluorescence microscopy are providing unprecedented views of the structure of cells and tissues at sub-diffraction resolutions and near single molecule sensitivity, driving discoveries in diverse fields of biology, including neuroscience. Biological tissue is organized over scales of nanometers to centimeters. Harnessing molecular imaging across intact, three-dimensional samples on this scale requires new types of microscopes with larger fields of view and working distance, as well as higher throughput. We present a new expansion-assisted selective plane illumination microscope (ExA-SPIM) with aberration-free 1.5 {micro}mx1.5 {micro}mx3 {micro}m optical resolution over a large field of view (10.6x8.0 mm2) and working distance (35 mm) at speeds up to 946 megavoxels/sec. Combined with new tissue clearing and expansion methods, the microscope allows imaging centimeter-scale samples with 375 nm lateral and 750 nm axial resolution (4x expansion), including entire mouse brains, with high contrast and without sectioning. We illustrate ExA-SPIM by reconstructing individual neurons across the mouse brain, imaging cortico-spinal neurons in the macaque motor cortex, and visualizing axons in human white matter.

neuroscience↗

bioRxiv2021

Cortical responses to vagus nerve stimulation are modulated by ongoing oscillatory activity associated with different brain states in non-human primates

Vagus nerve stimulation (VNS) has been tested as therapy for several brain disorders and as a means to modulate cortical excitability and brain plasticity. Cortical effects of VNS, manifesting as vagal-evoked potentials (VEPs), are thought to arise from activation of ascending cholinergic and noradrenergic systems. However, it is unknown whether those effects are modulated by brain state at the time of stimulation. In 2 freely behaving macaque monkeys, we delivered trains of left cervical VNS at different frequencies (5-300 Hz) while recording local field potentials (LFPs) from sites in contralateral prefrontal, sensorimotor and parietal cortical areas. Brain states were inferred from spectral components of LFPs and the presence of overt movement: active awake, resting awake, REM sleep and NREM sleep. VNS elicited VEPs comprising early (<70 ms), intermediate (70-250 ms) and late (>250 ms) components in all sampled cortical areas. The magnitude of only the intermediate and late components was modulated by brain state and pulsing frequency. These findings have implications for the role of ongoing cortical activity and brain state in shaping cortical responses to peripheral stimuli, for the modulation of vagal interoceptive signaling by cortical states, and for the calibration of VNS therapies.

neuroscience↗