Summary:
Scientists at Gladstone Institutes have uncovered how parvalbumin (PV) interneurons produce gamma oscillations—fast brain waves crucial for attention, memory, and cognition—by firing in tightly timed, successive waves rather than all at once. In mouse models of Alzheimer’s disease, this coordinated turn-taking collapses into pathological hypersynchrony. Restoring the sodium channel Nav1.1 in PV cells reestablished normal timing, strengthened gamma rhythms, suppressed epileptic-like spikes, reduced amyloid plaque load, and rescued cognitive performance.
Key Facts:
- Dynamic turn-taking generates gamma waves: Using simultaneous in vivo two-photon calcium imaging and electrical recordings in behaving mice, researchers showed that PV interneurons create 30–90 Hz gamma rhythms through a sequential relay: early responders fire strongly, later cohorts fire progressively less, and nearly one-third of the population remains inactive during each cycle.
- Timing collapses in Alzheimer’s disease: In Alzheimer’s mouse models, this organized relay breaks down: early responders slow, late responders become overactive, and previously silent cells fail to remain quiet, producing widespread hypersynchrony and weakened gamma power.
- Nav1.1 restores rhythm and cognition: Targeted overexpression of the voltage-gated sodium channel Nav1.1 in PV interneurons reinstated normal sequential firing, increased gamma oscillation strength, reduced seizure-like network spikes, decreased amyloid plaque burden, and improved lifespan and memory in treated mice.
Source: Gladstone Institutes
Why this matters: Gamma oscillations—rapid electrical cycles between 30 and 90 Hz—coordinate distant brain regions and support high-level functions such as focused attention, skill learning, and recall of memories. Disruption of these rhythms is a consistent feature in Alzheimer’s disease, but the cellular mechanisms that generate gamma and how they fail in disease were not fully understood.
The Gladstone-led team, in collaboration with the Allen Institute and UTHealth Houston, used novel experimental approaches to observe individual PV interneurons in awake, behaving animals and to track how their activity forms gamma rhythms.
Their results, published in Neuron, reveal that PV interneurons do not fire as a homogeneous group. Instead, they participate in brief, staggered contributions that together create each gamma cycle. This nuanced cellular choreography explains why simply increasing overall inhibitory activity does not necessarily improve oscillatory power or cognitive function.
Imaging interneurons during natural behavior
Previous studies often used optogenetics to activate all PV interneurons simultaneously, demonstrating that these cells can drive gamma frequencies but masking how they naturally coordinate. To capture physiological dynamics, the researchers combined high-speed electrocorticography with calcium imaging that marked individual PV cell spikes with fluorescent signals in mice running on a treadmill—an activity that engages attention circuits and naturally generates gamma activity.
The recordings showed that during each gamma burst, PV cells fire in a precise sequence: an early subset produces strong activity, following subsets contribute progressively weaker signals, and a substantial fraction remains silent within that cycle. This sequential recruitment and transient inactivation repeat rapidly to form coherent gamma oscillations across the network.
“Instead of all cells contributing at once, each PV interneuron contributes briefly and in turn, and those staggered moments combine to produce the global rhythm,” said lead author Keran Ma, PhD. Senior author Jorge J. Palop, PhD, likened the pattern to a flock of birds whose individual turns create an organized collective motion rather than a rigid, simultaneous march.
How timing breaks down in Alzheimer’s models
In mice engineered to model Alzheimer’s disease, the team observed a collapse of this temporal structure. Early-firing PV cells became delayed and weaker, late cohorts became overactive, and the normally silent group failed to remain quiet. The loss of temporal segregation shifted the network into hypersynchrony—cells firing together instead of sequentially—which paradoxically reduced gamma power and destabilized circuit function.
This dysfunctional pattern offers a circuit-level explanation for clinical observations: a substantial subset of people with Alzheimer’s disease shows subclinical epileptic activity. In the animal models, epileptic-like spikes emerged following abrupt declines in PV interneuron activity, linking disrupted inhibitory timing to episodes of network hyperexcitability.
Repairing timing with Nav1.1
The investigators tested whether boosting PV interneuron excitability could restore proper timing. Nav1.1, a voltage-gated sodium channel critical for rapid spiking in PV cells, is known to be reduced in Alzheimer’s models and patient tissue. Using viral tools to overexpress Nav1.1 selectively in PV interneurons, the researchers found dramatic improvements:
- Restored cellular dynamics: PV cell recruitment returned to normal sequential waves, and gamma oscillation power increased.
- Reduced hyperexcitability: Epileptic-like network spikes were largely abolished.
- Pathological and behavioral benefit: Treated mice exhibited lower amyloid plaque burden, better memory task performance, and extended lifespan relative to untreated controls.
These findings suggest that restoring interneuron timing can reverse multiple downstream consequences of Alzheimer’s-related circuit dysfunction.
The authors emphasize that it remains unclear why interneuron dysfunction appears early in Alzheimer’s disease progression, but their work supports the view that disrupted PV cell dynamics and weakened gamma oscillations are central contributors to cognitive decline. The team is advancing small-molecule approaches to enhance Nav1.1 function as a potential therapeutic strategy to reinforce interneuron firing fidelity and protect against neurodegeneration.
Funding: This research was supported by the Ray and Dagmar Dolby Family Fund, the Cure Alzheimer’s Fund, the Simon Family Trust, the Alzheimer’s Association (24AARG-1247332), the Texas Alzheimer’s Research and Care Consortium (1271368), and the National Institutes of Health (AG094667, AG092683, AG082147, AG062629, AG073082, UG3/UH3 MH120095, R35 NS097976, R35 NS143067, RF1AG064926, K99/R00AG062776).
Editorial Notes:
- This article was edited by a Neuroscience News editor.
- The original journal paper was reviewed in full.
- Additional explanatory context was added by editorial staff.
About this Alzheimer’s disease research:
- Media Contact: Julie Langelier
- Source: Gladstone Institutes
- Image Credit: Image credited to Neuroscience News
- Original Research (Open Access): Neuron (Oct 1, 2026). “Parvalbumin cell state dynamics regulate gamma oscillations and are disrupted in Alzheimer’s disease.” Authors: Keran Ma, Kyerl Park, Patrick S. Honma, Yutong Zhang, Erica Brady, Yuechen Qiu, Ximena Opitz-Araya, Jonathan T. Ting, Boaz P. Levi, Katerina Akassoglou, and Jorge J. Palop.
- DOI: 10.1016/j.neuron.2026.09.025
Abstract
Parvalbumin cell state dynamics regulate gamma oscillations and are disrupted in Alzheimer’s disease
Gamma oscillations are essential for cognitive processing, yet the precise cellular and circuit dynamics that generate them have been unclear. By establishing a method for simultaneous calcium imaging and electrocorticography in awake mice, the study demonstrates that spontaneous gamma is accompanied by rapid transitions among parvalbumin (PV) interneuron states.
PV interneurons do not act as a uniformly synchronized population; they show sequential recruitment, transient inactivation, and frequent transitions between activity states, forming dynamic functional networks that organize gamma rhythms.
In J20 Alzheimer’s model mice, these state transitions became dysregulated, producing abnormal PV recruitment, impaired coupling between PV activity and gamma oscillations, and network hyperexcitability. Enhancing interneuron excitability through expression of the Nav1.1 sodium channel restored PV dynamics, strengthened gamma oscillations, and stabilized network function.
These results identify dynamic PV cell states as a core organizing feature of gamma oscillations and point to their disruption as a circuit mechanism underlying network dysfunction in Alzheimer’s disease.