Gregory Jefferis

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Gregory Stephen Xavier Edward Jefferis is a British neuroscientist known for his work on the circuit basis of olfactory perception in the vinegar fly, Drosophila melanogaster. He is a tenured Programme Leader at the MRC Laboratory of Molecular Biology in Cambridge (UK) and associated with the Department of Zoology at the University of Cambridge. [1] [2]

Contents

Education

Jefferis studied Natural Sciences at the University of Cambridge, graduating with a BA from St John's College, Cambridge in 1998. He was awarded a PhD in Neurosciences for his work on the 'Wiring specificity in the olfactory system of Drosophila' in 2003, supervised by Liqun Luo at Stanford University. He became a Fellow of St John's College in 2004.

Career and contributions to science

Jefferis has made significant contributions to our understanding of how neural circuits process sensory information and transform it into behavior. His PhD uncovered principles of brain development using the olfactory system of the vinegar fly, Drosophila melanogaster. He found that central neurons in the brain are pre-specified to form connections with specific incoming sensory neurons. [3] Surprisingly, central dendrites can target independently of incoming sensory axons, suggesting a principle of independent coarse maps refined by contact-mediated matching. [4] Returning to Cambridge in 2004 as a Wellcome research fellow, Jefferis combined genetic single cell labelling and image registration to build a 3D atlas of higher olfactory centers in Drosophila, showing that odors of different behavioral significance are spatially segregated. [5]

Jefferis joined the Neurobiology Division at the MRC Laboratory of Molecular Biology as a tenure-track Programme Leader in 2008 and was awarded tenure in 2014. His group, in collaboration with Barry Dickson, generated the first comprehensive description of circuit-level sex differences in the fly brain, overturning the prevailing view that sex-specific behaviors originated from largely isomorphic circuitry. [6] [7] His group subsequently showed that higher-order olfactory neurons form a bidirectional switch that sex-specifically routes pheromone signals. [8]

Jefferis' group has also made significant efforts in the development of experimental and computational tools for circuit mapping. [9] [10] He is also a principal investigator of the Virtual Fly Brain online resource. [11]

In 2016, he was the lead applicant of a Wellcome Trust Collaborative Award that is using EM connectomics to study the neural circuit basis of memory storage and retrieval; this established the Drosophila Connectomics group at the Department of Zoology, University of Cambridge. He has also received Starting and Consolidator grants from the European Research Council. [12] [13]

Awards and honors

Jefferis has received numerous awards through his career. For his PhD work, Jefferis received a Harold M. Weintraub Graduate Student Award of the Fred Hutchinson Cancer Research Center in 2003 and was selected to deliver the Elkins Memorial lecture at the Neurobiology of Drosophila Meeting in Cold Spring Harbor. In 2012, Jefferis was appointed to the EMBO Young Investigator Programme, and in 2016 was elected to the FENS Kavli Network of Excellence. In 2018, he was announced as the winner of the Royal Society's Francis Crick Medal and Lecture "for his fundamental discoveries concerning the development and functional logic of sensory information processing". [14] [15]

Related Research Articles

<span class="mw-page-title-main">Vomeronasal organ</span> Smell sense organ above the roof of the mouth

The vomeronasal organ (VNO), or Jacobson's organ, is the paired auxiliary olfactory (smell) sense organ located in the soft tissue of the nasal septum, in the nasal cavity just above the roof of the mouth in various tetrapods. The name is derived from the fact that it lies adjacent to the unpaired vomer bone in the nasal septum. It is present and functional in all snakes and lizards, and in many mammals, including cats, dogs, cattle, pigs, and some primates. Some humans may have physical remnants of a VNO, but it is vestigial and non-functional.

<span class="mw-page-title-main">Olfactory bulb</span> Neural structure

The olfactory bulb is a neural structure of the vertebrate forebrain involved in olfaction, the sense of smell. It sends olfactory information to be further processed in the amygdala, the orbitofrontal cortex (OFC) and the hippocampus where it plays a role in emotion, memory and learning. The bulb is divided into two distinct structures: the main olfactory bulb and the accessory olfactory bulb. The main olfactory bulb connects to the amygdala via the piriform cortex of the primary olfactory cortex and directly projects from the main olfactory bulb to specific amygdala areas. The accessory olfactory bulb resides on the dorsal-posterior region of the main olfactory bulb and forms a parallel pathway. Destruction of the olfactory bulb results in ipsilateral anosmia, while irritative lesions of the uncus can result in olfactory and gustatory hallucinations.

<span class="mw-page-title-main">Mushroom bodies</span> Pair of structures in the brains of some arthropods and annelids

The mushroom bodies or corpora pedunculata are a pair of structures in the brain of arthropods, including insects and crustaceans, and some annelids. They are known to play a role in olfactory learning and memory. In most insects, the mushroom bodies and the lateral horn are the two higher brain regions that receive olfactory information from the antennal lobe via projection neurons. They were first identified and described by French biologist Félix Dujardin in 1850.

<span class="mw-page-title-main">Olfactory system</span> Sensory system used for smelling

The olfactory system or sense of smell is the sensory system used for smelling (olfaction). Olfaction is one of the special senses, that have directly associated specific organs. Most mammals and reptiles have a main olfactory system and an accessory olfactory system. The main olfactory system detects airborne substances, while the accessory system senses fluid-phase stimuli.

<span class="mw-page-title-main">Interneuron</span> Neurons that are not motor or sensory

Interneurons are neurons that connect to brain regions, i.e. not direct motor neurons or sensory neurons. Interneurons are the central nodes of neural circuits, enabling communication between sensory or motor neurons and the central nervous system (CNS). They play vital roles in reflexes, neuronal oscillations, and neurogenesis in the adult mammalian brain.

The antennal lobe is the primary olfactory brain area in insects. The antennal lobe is a sphere-shaped deutocerebral neuropil in the brain that receives input from the olfactory sensory neurons in the antennae and mouthparts. Functionally, it shares some similarities with the olfactory bulb in vertebrates. The anatomy and physiology function of the insect brain can be studied by dissecting open the insect brain and imaging or carrying out in vivo electrophysiological recordings from it.

The fruitless gene (fru) is a Drosophila melanogaster gene that encodes several variants of a putative transcription factor protein. Normal fruitless function is required for proper development of several anatomical structures necessary for courtship, including motor neurons which innervate muscles needed for fly sexual behaviors. The gene does not have an obvious mammalian homolog, but appears to function in sex determination in species as distant as the mosquito Anopheles gambiae.

Optogenetics is a biological technique to control the activity of neurons or other cell types with light. This is achieved by expression of light-sensitive ion channels, pumps or enzymes specifically in the target cells. On the level of individual cells, light-activated enzymes and transcription factors allow precise control of biochemical signaling pathways. In systems neuroscience, the ability to control the activity of a genetically defined set of neurons has been used to understand their contribution to decision making, learning, fear memory, mating, addiction, feeding, and locomotion. In a first medical application of optogenetic technology, vision was partially restored in a blind patient with Retinitis pigmentosa.

<span class="mw-page-title-main">Connectome</span> Comprehensive map of neural connections in the brain

A connectome is a comprehensive map of neural connections in the brain, and may be thought of as its "wiring diagram". An organism's nervous system is made up of neurons which communicate through synapses. A connectome is constructed by tracing the neuron in a nervous system and mapping where neurons are connected through synapses.

Connectomics is the production and study of connectomes: comprehensive maps of connections within an organism's nervous system. More generally, it can be thought of as the study of neuronal wiring diagrams with a focus on how structural connectivity, individual synapses, cellular morphology, and cellular ultrastructure contribute to the make up of a network. The nervous system is a network made of billions of connections and these connections are responsible for our thoughts, emotions, actions, memories, function and dysfunction. Therefore, the study of connectomics aims to advance our understanding of mental health and cognition by understanding how cells in the nervous system are connected and communicate. Because these structures are extremely complex, methods within this field use a high-throughput application of functional and structural neural imaging, most commonly magnetic resonance imaging (MRI), electron microscopy, and histological techniques in order to increase the speed, efficiency, and resolution of these nervous system maps. To date, tens of large scale datasets have been collected spanning the nervous system including the various areas of cortex, cerebellum, the retina, the peripheral nervous system and neuromuscular junctions.

<span class="mw-page-title-main">Sense of smell</span> Sense that detects smells

The sense of smell, or olfaction, is the special sense through which smells are perceived. The sense of smell has many functions, including detecting desirable foods, hazards, and pheromones, and plays a role in taste.

Mosaic analysis with a repressible cell marker, or MARCM, is a genetics technique for creating individually labeled homozygous cells in an otherwise heterozygous Drosophila melanogaster. It has been a crucial tool in studying the development of the Drosophila nervous system. This technique relies on recombination during mitosis mediated by FLP-FRT recombination. As one copy of a gene, provided by the balancer chromosome, is often enough to rescue a mutant phenotype, MARCM clones can be used to study a mutant phenotype in an otherwise wildtype animal.

The lateral horn is one of the two areas of the insect brain where projection neurons of the antennal lobe send their axons. The other area is the mushroom body. Several morphological classes of neurons in the lateral horn receive olfactory information through the projection neurons.

A Drosophila connectome is a list of neurons in the Drosophila melanogaster nervous system, and the chemical synapses between them. The fly's nervous system consists of the brain plus the ventral nerve cord, and both are known to differ considerably between male and female. Dense connectomes have been completed for the female adult brain, the male nerve cord, and the female larval stage. The available connectomes show only chemical synapses - other forms of inter-neuron communication such as gap junctions or neuromodulators are not represented. Drosophila is the most complex creature with a connectome, which had only been previously obtained for three other simpler organisms, first C. elegans. The connectomes have been obtained by the methods of neural circuit reconstruction, which over the course of many years worked up through various subsets of the fly brain to the almost full connectomes that exist today.

Neurogenesis is the process by which nervous system cells, the neurons, are produced by neural stem cells (NSCs). In short, it is brain growth in relation to its organization. This occurs in all species of animals except the porifera (sponges) and placozoans. Types of NSCs include neuroepithelial cells (NECs), radial glial cells (RGCs), basal progenitors (BPs), intermediate neuronal precursors (INPs), subventricular zone astrocytes, and subgranular zone radial astrocytes, among others.

<span class="mw-page-title-main">Insect olfaction</span> Function of chemical receptors

Insect olfaction refers to the function of chemical receptors that enable insects to detect and identify volatile compounds for foraging, predator avoidance, finding mating partners and locating oviposition habitats. Thus, it is the most important sensation for insects. Most important insect behaviors must be timed perfectly which is dependent on what they smell and when they smell it. For example, olfaction is essential for locating host plants and hunting prey in many species of insects, such as the moth Deilephila elpenor and the wasp Polybia sericea, respectively.

<span class="mw-page-title-main">Vanessa Ruta</span> American neuroscientist

Vanessa Julia Ruta is an American neuroscientist known for her work on the structure and function of chemosensory circuits underlying innate and learned behaviors in the fly Drosophila melanogaster. She is the Gabrielle H. Reem and Herbert J. Kayden Associate Professor and Head of the Laboratory of Neurophysiology and Behavior at The Rockefeller University and, as of 2021, an Investigator of the Howard Hughes Medical Institute.

Marta Zlatic is a Croatian neuroscientist who is group leader at the MRC Laboratory of Molecular Biology in Cambridge, UK. Her research investigates how neural circuits generate behaviour.

<span class="mw-page-title-main">Reinhard F. Stocker</span> Swiss biologist

Reinhard F. Stocker is a Swiss biologist. He pioneered the analysis of the sense of smell and taste in higher animals, using the fly Drosophila melanogaster as a study case. He provided a detailed account of the anatomy and development of the olfactory system, in particular across metamorphosis, for which he received the Théodore-Ott-Prize of the Swiss Academy of Medical Sciences in 2007, and pioneered the use of larval Drosophila for the brain and behavioural sciences.

A descending neuron is a neuron that conveys signals from the brain to neural circuits in the spinal cord (vertebrates) or ventral nerve cord (invertebrates). As the sole conduits of information between the brain and the body, descending neurons play a key role in behavior. Their activity can initiate, maintain, modulate, and terminate behaviors such as locomotion. Because the number of descending neurons is several orders of magnitude smaller than the number of neurons in either the brain or spinal cord/ventral nerve cord, this class of cells represents a critical bottleneck in the flow of information from sensory systems to motor circuits.

References

  1. ↑ "Gregory Jefferis - MRC Laboratory of Molecular Biology".
  2. ↑ "Gregory Jefferis - Department of Zoology - University of Cambridge".
  3. ↑ Jefferis, GS (2001). "Target neuron prespecification in the olfactory map of Drosophila" (PDF). Nature. 414 (6860): 204–8. Bibcode:2001Natur.414..204J. doi:10.1038/35102574. PMID   11719930. S2CID   4431800.
  4. ↑ Jefferis, GS (2001). "Target neuron prespecification in the olfactory map of Drosophila" (PDF). Nature. 414 (6860): 204–8. Bibcode:2001Natur.414..204J. doi:10.1038/35102574. PMID   11719930. S2CID   4431800.
  5. ↑ Jefferis, GS (2007). "Comprehensive maps of Drosophila higher olfactory centers: spatially segregated fruit and pheromone representation". Cell. 128 (6): 1187–203. doi:10.1016/j.cell.2007.01.040. PMC   1885945 . PMID   17382886.
  6. ↑ Cachero, S (2010). "Sexual dimorphism in the fly brain". Curr. Biol. 18 (20): 1589–601. doi:10.1016/j.cub.2010.07.045. PMC   2957842 . PMID   20832311.
  7. ↑ Yu, YJ (2010). "Cellular organization of the neural circuit that drives Drosophila courtship behavior". Curr. Biol. 18 (20): 1602–14. doi: 10.1016/j.cub.2010.08.025 . PMID   20832315.
  8. ↑ Kohl, J (2013). "A bidirectional circuit switch reroutes pheromone signals in male and female brains". Cell. 155 (7): 1610–23. doi:10.1016/j.cell.2013.11.025. PMC   3898676 . PMID   24360281.
  9. ↑ Costa, M (2016). "NBLAST: Rapid, Sensitive Comparison of Neuronal Structure and Construction of Neuron Family Databases". Neuron. 91 (2): 293–311. doi:10.1016/j.neuron.2016.06.012. PMC   4961245 . PMID   27373836.
  10. ↑ "Jefferis Lab resources".
  11. ↑ "Virtual Fly Brain".
  12. ↑ "Neural Basis of Olfactory Perception in Drosophila".
  13. ↑ "ERC Consolidator Grants 2014" (PDF).
  14. ↑ "The Royal Society - Francis Crick Medal and Lecture".
  15. ↑ "Greg Jefferis awarded Francis Crick Medal and Lecture by the Royal Society". 2018-07-19.
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