Michael V.L. Bennett

With sadness, the MBL shares the passing of Michael V.L. Bennett, a pioneer of the field of neuroscience, on November 16, 2023. A Trustee of the Marine Biological Laboratory (MBL) from 1970-1978, co-founder of the MBL Neurobiology course, and a prolific member of the MBL scientific community for more than 70 years, Bennett was Distinguished Professor Emeritus in the Dominick P. Purpura Department of Neuroscience at Albert Einstein College of Medicine in Bronx, N.Y. The MBL flag will be lowered in his memory.

Bennett first came to the MBL while he was an undergraduate at Yale University, where he was mentored by embryologist John Trinkaus and received his B.S. in Zoology in 1952. He attended the MBL’s Invertebrate Zoology course in 1951 and the Physiology course the following summer, returning in 1958 as a Grass Fellow. He joined the MBL Society in 1960 and remained a member until his passing.

A pioneering researcher of intercellular communication in the nervous system, Bennett ran a summer lab in the MBL’s Whitman Center for decades. He was elected to the National Academy of Sciences in 1981.

In 1970, Bennett and John Dowling co-founded the MBL Neurobiology course, which is offered to this day. As Dowling recalled, “Neurobiology was still in its infancy at that time and there were few formal neurobiology courses taught. A training program in neurobiological techniques had been started at the MBL by Steve Kuffler and his Harvard colleagues in the late 1950s, but this program ended in 1966.” With start-up funding and equipment from the Grass Foundation, Bennett and Dowling launched the Neurobiology course, engaging two other faculty and training eight students that first year. They focused the course on molecular and cellular neurobiology, which remains its focus today.

Bennett co-directed the Neurobiology course until 1974 and remained involved as a course lecturer as recently as 2007. He also served on the faculty of the MBL Neural Systems and Behavior course (1979-1981) and lectured on occasion in the Summer Program in Neuroscience, Excellence and Success (SPINES) and in the History of Biology Seminar at MBL.

Bennett was a familiar face in Woods Hole as a member of the “Falmouth Five,” a group of scientists/friends who competed in the Falmouth Road Race every year since its founding in 1973. He last ran the race in 2021, when he was 90 years old.

Bennett is survived by his wife, Dr. R. Suzanne Zukin; his son and daughter, Nicholas Bennett and Elena Bennett; their mother, Dr. Ruth Bennett, his stepdaughter, Heather Zukin and her family; as well as his sister, Dr. Heather (Bonnie) Bennett McCabe, and many nieces, nephews, cousins, and beloved friends. He was predeceased by his stepdaughter, Valerie Zukin.  He is fondly remembered and cherished by generations of his colleagues, trainees — and their trainees — throughout the United States and internationally.

Below is a memorial notice summarizing Bennett’s distinguished research career written by his faculty colleagues in neuroscience at Albert Einstein College of Medicine and/or at the MBL, Alberto Pereda, Pablo Castillo, Brian Salzberg, and David C. Spray. In addition, a notice by his colleagues is published here.

*****

Michael Vander Laan Bennett (Jan. 7, 1931 – Nov. 16, 2023) was a world-renowned authority in the field of intercellular communication in the nervous system. His studies showed that electrical synapses play critical roles in connecting neurons, and are especially important in synchronizing inhibitory interneurons in the mammalian brain.

Bennett received his undergraduate degree in Zoology from Yale University, where he was a competitive gymnast and was mentored by the eminent embryologist John Trinkaus, who continued to impact Bennett’s research at the Marine Biological Laboratory (MBL) many years later.  He was awarded a Rhodes Scholarship at Oxford University, where he obtained his D.Phil. degree from Balliol College in 1957. His doctoral dissertation focused on the functional organization of the mammalian cortex, and he was proud of his Oxford education, noting that both Sherrington and Eccles had studied there.

Bennett then joined Harry Grundfest’s lab at Columbia, attracted by Grundfest’s personality and intellect, and by the opportunity to use sharp intracellular electrodes to record from neurons and effector cells in a vast assortment of exotic invertebrates and fish species that had nervous systems specialized for activities requiring synchronized or rapid transmission.

Bennett’s initial studies focused on electroplaques that generated the shocks for which electric fish are named. However, he quickly became intrigued by the question of how the animals generate synchronized discharge and later studied how weak electric fields are sensed though their specialized receptors, the ampullae of Lorenzini. His interest in electric fish led to his participation in an expedition with Ted Bullock on the research vessel the Alpha Helix on the Amazon River and even studies on mummified Egyptian sacred fish together with an Egyptologist and running buddy, Bob Brier.

Bennett’s studies of synchronous firing among supramedullary neurons in pufferfish at the MBL in 1958 were the first evidence of electrical coupling in the vertebrate brain, which led to a lifelong interest in this form of synaptic communication. His later studies of the Mauthner cell-to-motoneuron synapse in hatchetfish and of toadfish oculomotor neuron coupling were fundamental in exposing elements of precise timing and synchrony in coupled neuron circuits.

By the mid-1960s, Bennett had risen through assistant and associate faculty ranks in Neurology at Columbia University and been recruited to the Albert Einstein College of Medicine as professor of Anatomy by Dominick P. Purpura, who created the Department of Neuroscience in 1974 which would later bear his name.

Bennett served as chair of the Dominick P. Purpura Department of Neuroscience from 1982 to 1996. He became the Sylvia and Robert S. Olnick Professor of Neuroscience in 1986 and was named Distinguished Professor in 2005. His laboratory and Department were regarded as the preeminent center for research on gap junction physiology and biophysics, and for leading studies into their biochemistry, molecular biology, ultrastructure and cell biology.

In addition to his appointments at Columbia and Einstein, Bennett was affiliated with the MBL in Woods Hole, Mass., where he maintained a laboratory every summer that facilitated access to marine invertebrates as well as fish and their early embryos. At the MBL, he actively contributed to the ‘Monday Night Fights,’ a weekly seminar for resident biophysicists and neuroscientists that became known for the contentious nature of its scientific exchanges. Together with John Dowling, Bennett was instrumental in creating the MBL Neurobiology course, arguably one of the best neuroscience courses in the world.

Distinguished Research Contributions

By 1970, by performing structure and functional correlations, Bennett and his collaborators, George Pappas and Yasuko and Shigehiro Nakajima, had demonstrated not only that electrical coupling was a common mode of synaptic connection among premotor electric fish neurons, but also had found evidence for the anatomical correlate, cell-cell junctions later known as “gap junctions.”  

By this time, Bennett had published numerous reviews establishing the co-existence of electrical and chemical synapses and had championed the advantages of electrical transmission for speed and synchrony in brains of lower vertebrates. He was celebratory when examples of electrical synaptic transmission began to be discovered in the mammalian brain. Thus, these seminal observations defined this field of research, in which he unequivocally became the world’s expert.

What still made electrical synapses less appealing to the neuroscience community than traditional chemical synaptic transmission was the concept that electrical transmission lacked the flexibility that characterized chemical synapses, and the related perception that its structural correlate, the gap junction, was a static cell-cell contact.

In the following decades, this concept would change, first by appreciating that conductance changes due to chemical synapses can shunt current, thereby reducing electrical synapse strength. Then came the discovery that the channels mediating the electrical synapses were gated, by voltage and by intracellular pH, and modified by phosphorylation, thereby providing evidence that the electrical synapse was formed by proteins with similar biochemical properties as those of chemical synapses. The final evidence came with the cloning of the connexin family of proteins that form the gap junction channels in vertebrates and whose mutation can lead to a plethora of human diseases of the nervous system and other tissues. For the gating studies, the preparation of pairs of huge cells from killifish embryos, taught to Bennett by his Yale mentor Trinkaus, and of axolotl embryos from his Einstein colleague, Pat Model, were fundamental.

Based on his discoveries dealing with electrical transmission and gap junctions, Bennett was elected to membership in the National Academy of Sciences in 1981. Major findings from his laboratory in this area continued until the past year.  His recent research interests included studies of unpaired gap junction hemichannels and their role in CNS pathology, gap junction plasticity in the vertebrate brain, and structure-function analysis through connexin mutagenesis.

Beyond these studies dealing with gap junctions and electrical synapses, Bennett also contributed significantly to our understanding of the biophysical properties, regulatory mechanisms, and functional relevance of two distinct ionotropic receptors activated by glutamate, an excitatory neurotransmitter. With Suzanne Zukin, they identified molecular mechanisms by which NMDA receptor trafficking and function (i.e., gating and calcium permeability) are controlled by protein kinases, such as PKC and PKA. Their findings, independently reproduced by several other groups, provided a key mechanism whereby neuromodulatory systems targeting these kinases can regulate synaptic function and fine-tune neuronal circuits. They also found evidence in support of the so-called “GluR2 hypothesis,” establishing that calcium-permeable AMPA receptors that lack the GluR2 subunit contribute significantly to the delayed degeneration that follows global ischemia and experimental epilepsy. Their findings opened the door to novel strategies for treating these neurological insults by manipulating the expression and functional properties of GluR2-lacking AMPA receptors.

Bennett’s brilliant intellect and critical appraisal of scientific results and concepts are legendary.  Even more impactful for his trainees was his wide foundational knowledge, and his exceptional appreciation of how general physiological principles could be understood through using organisms specialized for specific functions. He was a true biologist and one-of-a-kind, and we will dearly miss him.

---- Alberto Pereda, Pablo Castillo, Brian Salzberg, and David C. Spray