Papers by Adrienne Fairhall
The biophysics of adaptive neural coding
Spike Coding
The MIT Press eBooks, Dec 22, 2006
Feed-forward correction of neural timing errors through fluctuating scalar input
Bulletin of the American Physical Society, Mar 17, 2021
Frontiers in Systems Neuroscience, Sep 9, 2020
Single neurons can dynamically change the gain of their spiking responses to take into account sh... more Single neurons can dynamically change the gain of their spiking responses to take into account shifts in stimulus variance. Moreover, gain adaptation can occur across multiple timescales. Here, we examine the ability of a simple statistical model of spike trains, the generalized linear model (GLM), to account for these adaptive effects. The GLM describes spiking as a Poisson process whose rate depends on a linear combination of the stimulus and recent spike history. The GLM successfully replicates gain scaling observed in Hodgkin-Huxley simulations of cortical neurons that occurs when the ratio of spike-generating potassium and sodium conductances approaches one. Gain scaling in the GLM depends on the length and shape of the spike history filter. Additionally, the GLM captures adaptation that occurs over multiple timescales as a fractional derivative of the stimulus envelope, which has been observed in neurons that include long timescale afterhyperpolarization conductances. Fractional differentiation in GLMs requires long spike history that span several seconds. Together, these results demonstrate that the GLM provides a tractable statistical approach for examining single-neuron adaptive computations in response to changes in stimulus variance.
eLife, May 13, 2019
Cognitive flexibility likely depends on modulation of the dynamics underlying how biological neur... more Cognitive flexibility likely depends on modulation of the dynamics underlying how biological neural networks process information. While dynamics can be reshaped by gradually modifying connectivity, less is known about mechanisms operating on faster timescales. A compelling entrypoint to this problem is the observation that exploratory behaviors can rapidly cause selective hippocampal sequences to 'replay' during rest. Using a spiking network model, we asked whether simplified replay could arise from three biological components: fixed recurrent connectivity; stochastic 'gating' inputs; and rapid gating input scaling via long-term potentiation of intrinsic excitability (LTP-IE). Indeed, these enabled both forward and reverse replay of recent sensorimotor-evoked sequences, despite unchanged recurrent weights. LTP-IE 'tags' specific neurons with increased spiking probability under gating input, and ordering is reconstructed from recurrent connectivity. We further show how LTP-IE can implement temporary stimulus-response mappings. This elucidates a novel combination of mechanisms that might play a role in rapid cognitive flexibility.
Decision making strategies in the face of conflicting or uncertain sensory input have been succes... more Decision making strategies in the face of conflicting or uncertain sensory input have been successfully described by a drift diffusion to bound model (DDM) in many different species. Here we analyze large behavioral datasets of larval zebrafish engaged in a ‘coherent dot’ optomotor assay and compare DDM performance with trial-to-trial variation in our experimental results. We find a clear discrepancy in the low-level structure of modeled and experimental data, which compels us to implement a critical extension to the classic DDM. To correct for the discrepancy, we propose to add an extra variable that explicitly controls the transition between an engaged and a disengaged state. This addition not only accurately captures the lower-level structure in our data, but also provides a framework to explain general behavioral switches between different tasks and contextual priorities. We use these insights to define two behavioral performance metrics for the zebrafish, labeled ‘focus’ and ‘c...
Author response: Fast and flexible sequence induction in spiking neural networks via rapid excitability changes
Current Opinion in Neurobiology, Oct 1, 2017
Measuring the activity of neuronal populations with calcium imaging can capture emergent function... more Measuring the activity of neuronal populations with calcium imaging can capture emergent functional properties of neuronal circuits with single cell resolution. However, the motion of freely behaving animals, together with the intermittent detectability of calcium sensors, can hinder automatic long-term monitoring of the
Next-generation brain observatories
Neuron, Nov 1, 2022
Acknowledging female voices
Nature Neuroscience, Jun 26, 2020
Citation count has become one of the most important methods to evaluate a scientist’s contributio... more Citation count has become one of the most important methods to evaluate a scientist’s contributions. In an extensive analysis of citations from a number of leading neuroscience journals, Dworkin and colleagues find evidence of gender bias in citation practices that can have an adverse impact on women’s careers.
Context-dependent representations of movement in Drosophila dopaminergic reinforcement pathways
Nature Neuroscience, Oct 25, 2021
Dopamine plays a central role in motivating and modifying behavior, serving to invigorate current... more Dopamine plays a central role in motivating and modifying behavior, serving to invigorate current behavioral performance and guide future actions through learning. Here we examine how this single neuromodulator can contribute to such diverse forms of behavioral modulation. By recording from the dopaminergic reinforcement pathways of the Drosophila mushroom body during active odor navigation, we reveal how their ongoing motor-associated activity relates to goal-directed behavior. We find that dopaminergic neurons correlate with different behavioral variables depending on the specific navigational strategy of an animal, such that the activity of these neurons preferentially reflects the actions most relevant to odor pursuit. Furthermore, we show that these motor correlates are translated to ongoing dopamine release and acutely perturbing dopaminergic signaling alters the strength of odor tracking. Context-dependent representations of movement and reinforcement cues are thus multiplexed within the mushroom body dopaminergic pathways, enabling them to coordinately influence both ongoing and future behavior.
bioRxiv (Cold Spring Harbor Laboratory), May 18, 2023
Maintaining motor skills is crucial for an animal's survival, enabling it to endure diverse pertu... more Maintaining motor skills is crucial for an animal's survival, enabling it to endure diverse perturbations throughout its lifespan, such as trauma, disease, and aging. What mechanisms orchestrate brain circuit reorganization and recovery to preserve the stability of behavior despite the continued presence of a disturbance? To investigate this question, we chronically silenced a fraction of inhibitory neurons in a pre-motor circuit necessary for singing in zebra finches. This manipulation altered brain activity and severely perturbed their song, a complex learned behavior, for around two months, after which it was precisely restored. Electrophysiology recordings revealed abnormal offline dynamics resulting from chronic inhibition loss, while subsequent recovery of the behavior occurred despite partial normalization of brain activity. Single-cell RNA sequencing revealed that chronic silencing of interneurons leads to elevated levels of microglia and MHC I. These experiments demonstrate that the adult brain can overcome extended periods of drastic abnormal activity. The reactivation of mechanisms employed during learning, including offline neuronal dynamics and upregulation of MHC I and microglia, could facilitate the recovery process following perturbation of the adult brain. These findings indicate that some forms of brain plasticity may persist in a dormant state in the adult brain until they are recruited for circuit restoration.
Spike Coding
The MIT Press eBooks, Dec 22, 2006
All metal vibration isolator for use in cryogenic and vacuum environments
ENeuro, Mar 1, 2021
Everyone agrees that we do not yet understand how brains work, neither well enough to satisfactor... more Everyone agrees that we do not yet understand how brains work, neither well enough to satisfactorily explain basic functions such as memory nor to design effective interventions to restore mental health. This is one of the great scientific challenges of our era, with huge implications not only for human health but for insight into all animal life and for the development of future technologies. How should resources be invested to foster the necessary leap toward understanding? Given the pressing societal need and the very high public expectations of neuroscience, stoked by TED talks, New York Times articles, and sci fi, the pressures riding on choices of funding targets are enormous. Against this background, 2013 was a banner year for the brain: both the European Union and the United States agreed to devote unprecedented support specifically to neuroscience. The European Union funded the billion-dollar Human Brain Project (HBP; Amunts et al, 2016), whose centerpiece was a team science effort to develop neuroinformatics infrastructure and to expand the Blue Brain Project (Markram, 2006), a high-fidelity biophysically realistic computational model of brain tissue. In the United States, the BRAIN Initiative launched with an initial commitment of $100 million and the appointment of a panel of respected scientists who met over months to identify major gaps and promising directions in neuroscience (Jorgenson et al., 2015). Government agencies then formulated funding opportunities that supported individual labs or small teams to develop new technologies to record, stimulate, analyze, and interpret neural activity. These efforts stimulated brain initiatives in several other
Neuron, Nov 1, 2016
Neuroscience research is becoming increasingly more collaborative and interdisciplinary with part... more Neuroscience research is becoming increasingly more collaborative and interdisciplinary with partnerships between industry and academia and insights from fields beyond neuroscience. In the age of institutional initiatives and multi-investigator collaborations, scientists from around the world shared their perspectives on the effectiveness of large-scale collaborations versus single-lab, hypothesis-driven science.
Behaviour of a vibration isolator suitable for use in cryogenic or vacuum environments
Measurement Science and Technology, Sep 1, 1991
The design of an all-metal spring-mass vibration isolation system for use in gravitational wave d... more The design of an all-metal spring-mass vibration isolation system for use in gravitational wave detection instruments such as the resonant bar antenna and the laser interferometer is described. The vibration transfer characteristics of the system are investigated in view of the requirements of seismic isolation for this application. The transfer function of the isolation system considered has resonant modes with frequencies less than 300 Hz and a steep roll off with no internal modes in the domain of interest of the detector. The prototype model examined was designed with a relatively high corner frequency as an initial test of the concept but the design should allow this to be lowered to less than 50 Hz. The advantages of this design include its suitability for use under vacuum environments and its mechanical simplicity.
Uploads
Papers by Adrienne Fairhall