About

Kevin M. Franks is an Associate Professor of Neurobiology at Duke University. He is a faculty member of the Duke Institute for Brain Sciences and is based in the Bryan Research Building in Durham, North Carolina. His research focuses on neurobiology, and he is involved in the department's various educational and research programs. As a member of the faculty, he contributes to the academic and scientific community through his teaching, research, and participation in departmental activities.

Research topics

• Computer Science
• Neuroscience
• Biology
• Immunology
• Medicine
• Psychology

Selected publications

• Distinct Neural Representations of Hunger and Thirst in Neonatal Mice Before the Emergence of Food- and Water-Seeking Behavior

  SSRN Electronic Journal · 2025-01-01 · 1 citations

  preprintOpen access
  PublisherDOI

• Distinct neural representations of hunger and thirst in neonatal mice before the emergence of food- and water-seeking behaviors

  Current Biology · 2025-06-11

  articleOpen access

  Hunger and thirst are two fundamental drives for maintaining homeostasis and elicit distinct food- and water-seeking behaviors essential for survival. For neonatal mammals, however, both hunger and thirst are sated by consuming milk from their dams. While distinct neural circuits underlying hunger and thirst drives in the adult brain have been characterized, it is unclear when these distinctions emerge in neonates and what processes may affect their development. Here, we show that hypothalamic hunger and thirst regions already exhibit specific responses to starvation and dehydration well before a neonatal mouse can seek food and water separately. At this early age, hunger neurons drive feeding behaviors more than thirst neurons do. In vivo Neuropixels recordings revealed that maternal presentation leads to a relative increase in activity in dehydrated and starved neonatal mice, which is suppressed by feeding on short timescales, particularly in hypothalamic and thalamic neurons. Activity changes become more heterogeneous on longer timescales. Lastly, within neonatal regions that respond to both hunger and thirst, subpopulations of neurons respond distinctly to one or the other need. Combining food and water into a liquid diet throughout the animal's life does not alter the distinct representations of hunger and thirst in the adult brain. Thus, neural representations of hunger and thirst in mice become distinct before food- and water-seeking behaviors mature and are robust to environmental changes in food and water sources.

  PublisherOA PDFDOI

• Embryonically Active Piriform Cortex Neurons Promote Intracortical Recurrent Connectivity during Development

  bioRxiv (Cold Spring Harbor Laboratory) · 2024-05-09 · 3 citations

  preprintOpen accessCorresponding

  SUMMARY Neuronal activity plays a critical role in the maturation of circuits that propagate sensory information into the brain. How widely does early activity regulate circuit maturation across the developing brain? Here, we used Targeted Recombination in Active Populations (TRAP) to perform a brain-wide survey for prenatally active neurons in mice and identified the piriform cortex as an abundantly TRAPed region. Whole-cell recordings in neonatal slices revealed preferential interconnectivity within embryonically TRAPed piriform neurons and their enhanced synaptic connectivity with other piriform neurons. In vivo Neuropixels recordings in neonates demonstrated that embryonically TRAPed piriform neurons exhibit broad functional connectivity within piriform and lead spontaneous synchronized population activity during a transient neonatal period, when recurrent connectivity is strengthening. Selectively activating or silencing of these neurons in neonates enhanced or suppressed recurrent synaptic strength, respectively. Thus, embryonically TRAPed piriform neurons represent an interconnected hub-like population whose activity promotes recurrent connectivity in early development.

  PublisherOA PDFDOI

• The spiking output of the mouse olfactory bulb encodes large-scale temporal features of natural odor environments

  bioRxiv (Cold Spring Harbor Laboratory) · 2024-03-05 · 6 citations

  preprintOpen access

  In natural odor environments, odor travels in plumes. Odor concentration dynamics change in characteristic ways across the width and length of a plume. Thus, spatiotemporal dynamics of plumes have informative features for animals navigating to an odor source. Population activity in the olfactory bulb (OB) has been shown to follow odor concentration across plumes to a moderate degree (Lewis et al., 2021). However, it is unknown whether the ability to follow plume dynamics is driven by individual cells or whether it emerges at the population level. Previous research has explored the responses of individual OB cells to isolated features of plumes, but it is difficult to adequately sample the full feature space of plumes as it is still undetermined which features navigating mice employ during olfactory guided search. Here we released odor from an upwind odor source and simultaneously recorded both odor concentration dynamics and cellular response dynamics in awake, head-fixed mice. We found that longer timescale features of odor concentration dynamics were encoded at both the cellular and population level. At the cellular level, responses were elicited at the beginning of the plume for each trial, signaling plume onset. Plumes with high odor concentration elicited responses at the end of the plume, signaling plume offset. Although cellular level tracking of plume dynamics was observed to be weak, we found that at the population level, OB activity distinguished whiffs and blanks (accurately detected odor presence versus absence) throughout the duration of a plume. Even ~20 OB cells were enough to accurately discern odor presence throughout a plume. Our findings indicate that the full range of odor concentration dynamics and high frequency fluctuations are not encoded by OB spiking activity. Instead, relatively lower-frequency temporal features of plumes, such as plume onset, plume offset, whiffs, and blanks, are represented in the OB.

  PublisherOA PDFDOI

• Embryonically active piriform cortex neurons promote intracortical recurrent connectivity during development

  Neuron · 2024-07-03 · 14 citations

  articleOpen accessCorresponding

  Neuronal activity plays a critical role in the maturation of circuits that propagate sensory information into the brain. How widely does early activity regulate circuit maturation across the developing brain? Here, we used targeted recombination in active populations (TRAP) to perform a brain-wide survey for prenatally active neurons in mice and identified the piriform cortex as an abundantly TRAPed region. Whole-cell recordings in neonatal slices revealed preferential interconnectivity within embryonically TRAPed piriform neurons and their enhanced synaptic connectivity with other piriform neurons. In vivo Neuropixels recordings in neonates demonstrated that embryonically TRAPed piriform neurons exhibit broad functional connectivity within piriform and lead spontaneous synchronized population activity during a transient neonatal period, when recurrent connectivity is strengthening. Selectively activating or silencing these neurons in neonates enhanced or suppressed recurrent synaptic strength, respectively. Thus, embryonically TRAPed piriform neurons represent an interconnected hub-like population whose activity promotes recurrent connectivity in early development.

  PublisherOA PDFDOI

• Neuroscience: Seq-ing maps in the olfactory cortex

  Current Biology · 2023-04-01 · 2 citations

  letterOpen accessCorresponding
  PublisherOA PDFDOI

• Electrophysiological Recordings from Identified Cell Types in the Olfactory Cortex of Awake Mice

  Methods in molecular biology · 2023-01-01 · 2 citations

  articleSenior author
  PublisherDOI

• Chronic loss of inhibition in piriform cortex following brief, daily optogenetic stimulation

  Cell Reports · 2021-04-01 · 31 citations

  articleOpen accessSenior authorCorresponding

  It is well established that seizures beget seizures, yet the cellular processes that underlie progressive epileptogenesis remain unclear. Here, we use optogenetics to briefly activate targeted populations of mouse piriform cortex (PCx) principal neurons in vivo. After just 3 or 4 days of stimulation, previously subconvulsive stimuli trigger massive, generalized seizures. Highly recurrent allocortices are especially prone to "optokindling." Optokindling upsets the balance of recurrent excitation and feedback inhibition. To understand how this balance is disrupted, we then selectively reactivate the same neurons in vitro. Surprisingly, we find no evidence of heterosynaptic potentiation; instead, we observe a marked, pathway-specific decrease in feedback inhibition. We find no loss of inhibitory interneurons; rather, decreased GABA synthesis in feedback inhibitory neurons appears to underlie weakened inhibition. Optokindling will allow precise identification of the molecular processes by which brain activity patterns can progressively and pathologically disrupt the balance of cortical excitation and inhibition.

  PublisherDOI

• Author response: Parallel processing by distinct classes of principal neurons in the olfactory cortex

  2021-11-08

  peer-reviewOpen accessSenior author

  In vivo recordings from identified cell classes in the olfactory cortex of a novel transgenic mouse reveal that distinct classes of principal neurons operate largely in parallel and differentially process odor information.

  PublisherDOI

• Parallel processing by distinct classes of principal neurons in the olfactory cortex

  bioRxiv (Cold Spring Harbor Laboratory) · 2021-07-14 · 1 citations

  preprintOpen accessSenior authorCorresponding

  SUMMARY Understanding the specific roles that different neuron types play within a neural circuit is essential for understanding what that circuit does and how it does it. Primary olfactory (piriform, PCx) cortex contains two main types of principal neurons: semilunar (SL) and pyramidal (PYR). SLs and PYRs have different morphologies, connectivity, biophysical properties, and downstream projections, predicting distinct roles in cortical odor processing. The prevailing model is that odor processing in PCx occurs in two stages, where SLs are the primary recipients of olfactory bulb (OB) input, and PYRs receive and transform information from SLs. Here we recorded from opto-genetically-identified SLs and PYRs in awake, head-fixed mice. We found differences in SL and PYR odor-evoked activity that reflect their different connectivity profiles. But SL responses did not precede PYR responses and suppressing SL activity had little effect on PYR odor responses. These results suggest that SLs and PYRs form parallel odor processing channels.

  PublisherOA PDFDOI

Recent grants

• NIH Grant K99DC009839

  NIH · $180k · 2010

• CRCNS: Odor processing by cortical neural circuits

  NIH · $716k · 2017–2022

• Odor Coding in Piriform Cortex

  NIH · $3.5M · 2016–2028

• Synaptic Processes Mediating Cortical Odor Coding

  NIH · $728k · 2012–2016

• Predictive Computational Models of Olfactory Networks

  NIH · $38.9M · 2019–2025

Frequent coauthors

• Terrence J. Sejnowski

  28 shared

• Thomas M. Bartol

  Salk Institute for Biological Studies

  17 shared

• Kevin A. Bolding

  Monell Chemical Senses Center

  17 shared

• Alexander Fleischmann

  Providence College

  9 shared

• Daniel Keller

  Western Kentucky University

  9 shared

• Benjamin Roland

  Inserm

  8 shared

• Dara L. Sosulski

  University College London

  7 shared

• Richard Axel

  Columbia University

  7 shared

Labs

• Franks LabPI