Survival and Axonal Outgrowth of the Mauthner Cell Following Spinal Cord Crush Does Not Drive Post-injury Startle Responses.

A pair of Mauthner cells (M-cells) can be found in the hindbrain of most teleost fish, as well as amphibians and lamprey. The axons of these reticulospinal neurons cross the midline and synapse on interneurons and motoneurons as they descend the length of the spinal cord. The M-cell initiates fast C-type startle responses (fast C-starts) in goldfish and zebrafish triggered by abrupt acoustic/vibratory stimuli.

Invasion of microglia/macrophages and granulocytes into the Mauthner axon myelin sheath following spinal cord injury of the adult goldfish, Carassius auratus.

Rapid activation of resident glia occurs after spinal cord injury. Somewhat later, innate and adaptive immune responses occur with the invasion of peripheral immune cells into the wound site. The activation of resident and peripheral immune cells has been postulated to play harmful as well as beneficial roles in the regenerative process.

Hypoxia Has a Lasting Effect on Fast-Startle Behavior of the Tropical Fish .

Anthropogenic activities and climate change have resulted in an increase of hypoxic conditions in nearshore ecosystems worldwide. Depending on the persistence of a hypoxic event, the survival of aquatic animals can be compromised. Temperate fish exposed to hypoxia display a reduction in the probability of eliciting startle responses thought to be important for escape from predation.

Mary Jane Hogue (1883-1962): A pioneer in human brain tissue culture.

The ability to maintain human brain explants in tissue culture was a critical step in the use of these cells for the study of central nervous system disorders. Ross G. Harrison (1870-1959) was the first to successfully maintain frog medullary tissue in culture in 1907, but it took another 38 years before successful culture of human brain tissue was accomplished.

The Marine Biological Laboratory (Woods Hole) and the scientific advancement of women in the early 20th century: the example of Mary Jane Hogue (1883-1962).

The Marine Biological Laboratory (MBL) in Woods Hole, MA provided opportunities for women to conduct research in the late 19th and early 20th century at a time when many barriers existed to their pursuit of a scientific career. One woman who benefited from the welcoming environment at the MBL was Mary Jane Hogue. Her remarkable career as an experimental biologist spanned over 55 years.

A hindbrain segmental scaffold specifying neuronal location in the adult goldfish, Carassius auratus.

The vertebrate hindbrain develops as a series of well-defined neuroepithelial segments or rhombomeres. While rhombomeres are visible in all vertebrate embryos, generally there is not any visible segmental anatomy in the brains of adults. Teleost fish are exceptional in retaining a rhombomeric pattern of reticulospinal neurons through embryonic, larval, and adult periods.

On the training of future neuroscientists: insights from the Grass laboratory.

The understanding of nature is a continuous process that requires the transference of current knowledge to future generations. In this NeuroView, we address the critical issue of training of future scientists, an essential aspect of scientific progress. As an example of the impact training programs can have on shaping future scientists, we focus on the experience of the Grass Laboratory, which provides early career investigators the opportunity to embark on independent research experiences.

How the early voltage clamp studies of José del Castillo inform "modern" neuroscience.

The description of ionic currents that flow across the membrane of the squid giant axon during an action potential sparked an interest in determining whether there were similar currents in vertebrates. The preparation of choice was the node of Ranvier in single myelinated fibers in frog. José del Castillo spent 3 years on the United States mainland from 1956 to 1959.

Regeneration in the era of functional genomics and gene network analysis.

What gives an organism the ability to regrow tissues and to recover function where another organism fails is the central problem of regenerative biology. The challenge is to describe the mechanisms of regeneration at the molecular level, delivering detailed insights into the many components that are cross-regulated. In other words, a broad, yet deep dissection of the system-wide network of molecular interactions is needed.

Axon cap morphology of the sea robin (Prionotus carolinus): Mauthner cell is correlated with the presence of "signature" field potentials and a C-type startle response.

Studies on the Mauthner cell (M-cell) of goldfish, Carassius auratus, have facilitated our understanding of how sensory information is integrated in the hindbrain to initiate C-type fast startle responses (C-starts). The goldfish M-cell initial segment/axon hillock is surrounded by a composite axon cap consisting of a central core and a peripheral zone covered by a glial cell layer. The high resistivity of the axon cap results in "signature" field potentials recorded on activation of the M-cell, allowing unequivocal physiological identification of the M-cell and of its feedback and reciprocal inhibitory networks that are crucial in ensuring that only one M-cell is active and that it fires only once.

Distinct startle responses are associated with neuroanatomical differences in pufferfishes.

Despite the key function of the Mauthner cells (M-cells) in initiating escape responses and thereby promoting survival, there are multiple examples of M-cell loss across the teleost phylogeny. Only a few studies have directly considered the behavioral consequences of naturally occurring M-cell variation across species. We chose to examine this issue in pufferfishes, as previous research suggested that there might be variability in M-cell anatomy in this group of fish.

Evolution of the Mauthner axon cap.

Studies of vertebrate brain evolution have focused primarily on patterns of gene expression or changes in size and organization of major brain regions. The Mauthner cell, an important reticulospinal neuron that functions in the startle response of many species, provides an opportunity for evolutionary comparisons at the cellular level. Despite broad interspecific similarities in Mauthner cell morphology, the motor patterns and startle behaviors it initiates vary markedly.

Reticulospinal neurons in anamniotic vertebrates: a celebration of Alberto Stefanelli's contributions to comparative neuroscience.

Over the past 76 years Alberto Stefanelli has successfully used a comparative approach to study the nervous system. His main research focus during that time has been on identifiable reticulospinal neurons including Müller and Mauthner neurons found in anamniotic vertebrates. Born in Venice, Italy in 1908, Professor Stefanelli pursued most of his academic career at the University of Rome, where he retired as Chair of Comparative Anatomy in 1978.

Correlation of C-start behaviors with neural activity recorded from the hindbrain in free-swimming goldfish (Carassius auratus).

Startle behaviors in teleost fishes are well suited for investigations of mechanisms of sensorimotor integration because the behavior is quantifiable and much of the underlying circuitry has been identified. The teleost C-start is triggered by an action potential in one of the two Mauthner (M) cells. To correlate C-start behavior with electrophysiology, extracellular recordings were obtained from the surface of the medulla oblongata in the hindbrain, close to the M-axons, in freely swimming goldfish monitored using high-speed video.

The effects of head and tail stimulation on the withdrawal startle response of the rope fish (Erpetoichthys calabaricus).

While most actinopterygian fishes perform C-start or S-start behaviors as their primary startle responses, many elongate species instead use a withdrawal movement. Studies of withdrawal have focused on the response to head-directed or nonspecific stimuli. During withdrawal, the animal moves its head back from the stimulus, often resulting in several tight bends in the body.

Recovery of C-starts, equilibrium and targeted feeding after whole spinal cord crush in the adult goldfish Carassius auratus.

Central nervous system neurons of many adult teleost fish are capable of regrowth across spinal cord lesions, which may result in behavioral recovery of swimming. Since there have been few, if any, studies that examine the return of behaviors other than swimming, we provide a quantitative analysis of the recovery of C-starts that occur in adult goldfish after spinal cord injury. In addition, we include a qualitative analysis of the return of targeted feeding and equilibrium.

Decrease in occurrence of fast startle responses after selective Mauthner cell ablation in goldfish (Carassius auratus).

A single action potential in one of a pair of reticulospinal neurons, the Mauthner cells, precedes a short-latency electromyographic response of the trunk and tail musculature on the opposite side of the body and a fast startle response in goldfish. It has been postulated that not only the Mauthner cell, but also an array of neurons can trigger or participate in fast startle responses (Eaton et al. 1991).

Comparison of fast startle responses between two elongate bony fish with an anguilliform type of locomotion and the implications for the underlying neuronal basis of escape behavior.

A comparative anatomical and behavioral approach was used to elucidate the role of medullary networks associated with Mauthner cells (M-cells) in determining the type of fast startle responses of elongate bony fish with an anguilliform type of locomotion. The M-cell initiates fast startle responses in goldfish and is thought to initiate such responses in other fish as well [Wilson, 1959; Eaton et al., 1977; Currie and Carlsen, 1987; Currie, 1991].

Comparative studies on the Mauthner cell of teleost fish in relation to sensory input.

Most physiological and behavioral studies of the Mauthner cells have used the goldfish and a few other fish from the superorder Ostariophysi, series Otophysi (= otophysans). We first provide some background and recent findings on the Mauthner cells of otophysan fish and then compare this information to that known about the Mauthner cells in certain non-otophysan fish. These comparisons are meant to provide the impetus for a comparative approach to understanding the role of the Mauthner cells in behavior.

Julia B. Platt (1857-1935): pioneer comparative embryologist and neuroscientist.

Julia Barlow Platt was a comparative embryologist and neurobiologist who was primarily interested in segmentation of the head in vertebrates. She was born on September 14, 1857 in San Francisco, California. Platt grew up in Burlington, Vermont, attended the University of Vermont and began graduate studies at Harvard University.