On November 16, 2008 the Cajal Club presented the Cortical Discoverer award to Dr Yasuo Kawaguchi, the Cortical Explorer award to Dr Lee A. Shapiro, and the Cortical Scholar Award to Dr Kenneth Y.-C. Kwan. The site of this year's awards was the annual Cajal Club Social at the Society for Neuroscience meeting, which was in Washington, DC. The Krieg Cortical Kudos Awards Committee consisted of Edward G. Jones (President), Pasko Rakic, Jon H. Kaas, Gordon M. Shepherd, Larry W. Swanson, and Charles E. Ribak. The Cortical Kudos winners, along with Harvey J. Karten, the winner of the Sanford L. Palay Award in Structural Neuroscience sponsored by the publisher of The Journal of Comparative Neurology, John Wiley & Sons, and presented at the Cajal Club Social, were honored later that night at a dinner hosted by the Cajal Club Board at Jaleo, a local Spanish restaurant (Figure 1).

The Cortical Discoverer Award

The highest-level award, the Cortical Discoverer prize ($5000), is given to a senior scientist who has contributed significantly to our understanding of the cerebral cortex. In 2008, the Award was presented to Dr Yasuo Kawaguchi, who has demonstrated a lifetime of major contributions to the understanding of cortical circuitry, especially at the level of interneuron structure and function.

Yasuo Kawaguchi is an internationally recognized neuroscientist who has made numerous important contributions to our understanding of cerebral cortical functional architecture. His research has had a major impact on the field in part because he developed methodology to perform intracellular labeling of individual, physiologically characterized neurons. Based on this approach he was the first to identify different spiking capacities of interneurons that were characterized by their differential expression of calcium binding proteins. This was a fundamental observation that revolutionized the way intrinsic cortical circuitry is now examined. By combining this with a variety of other methods, including immunocytochemistry, he has been able to examine particular aspects of neuronal circuits in great detail, and his results have led to substantial advances in the field. The main conclusion that has been drawn from these studies is that interneurons can be readily recognized by their unique morphological, neurochemical, and physiological characteristics. For example, by combining the physiological and chemical properties of morphologically diverse interneurons, Dr Kawaguchi has been able to divide them into several interesting groups. Each of these subtypes displays a characteristic firing pattern, a particular spatial distribution of axonal collaterals, and a specific tendency to form differentiable postsynaptic elements.

Since 1999, Dr Kawaguchi has been a Professor in the Division of Cerebral Circuitry at the National Institute for Physiological Sciences in Myodaiji, Okazaki, Japan. He received his M.D. degree from Tokyo University in 1980 and then earned a Ph.D. in Physiology from the same institution, working under the guidance of Masao Ito. He then moved to the University of Tennessee, where he was a Research Associate with Charles Wilson. After several years there, he moved back to Japan to work as a Researcher in Edward G. Jones’ Laboratory for Neural Systems at the Frontier Research Program, RIKEN. Then, from 1993 to 2001 he was Head of the Laboratory for Neural Circuits, Bio-Mimetic Control Research Center, RIKEN, during which time he also assumed his current position. Dr Kawaguchi's early research was on neural mechanisms related to cerebellar circuitry. He then moved on to examine the neurophysiology of interneurons in the hippocampus of rats, where he first combined intracellular recording with histochemical staining for the calcium binding protein parvalbumin. Next, he explored the rat caudoputamen, where he ended up characterizing 3 classes of interneurons based on a combination of physiological, morphological, and histochemical criteria. And finally, while continuing his groundbreaking research on the basal ganglia, he took up the work for which he is honored here: the characterization of neurotransmitter-specific classes of isocortical interneurons, especially in the frontal cortex of rats.

The Cortical Explorer Award

The Cortical Explorer prize ($3000) is usually awarded to a scientist at an intermediate stage of their career for achievements within 6 years of receiving an advanced professional degree (Ph.D. or M.D.). This year the award was presented to Lee Shapiro, who was recognized for his groundbreaking work on the dendritic development and connections of newly generated granule neurons in the adult rat hippocampal formation.

As detailed in the nominating letter from his mentor, Charles Ribak, Dr Shapiro examined these newborn neurons using electron microscopy and immunocytochemistry for the growth cone-associated protein, doublecortin. He found that there is a one-to-one relationship between a radial glial cell (putative progenitor cell) and a doublecortin-labeled cell body, prior to the formation of its dendrites. Using serial sections to reconstruct this pair of cells, he was the first to demonstrate that nonradial processes of the radial glial cell in the adult dentate gyrus subgranular zone form a basket that cradles the cell body of the newly generated neuron. His analysis then focused on the growth of dendrites from these newly generated doublecortin-labeled cells, and he showed the dendrites grow upon the radial process of the radial glial cell and proposed that the former acts as a guide for the dendrite to grow through the densely packed granule cell layer. These seminal discoveries were later confirmed and cited by other investigators, including Gerd Kempermann, Rusty Gage, Arturo Alvarez-Buylla, and Tatsunori Seki.

Dr Shapiro continued his studies by analyzing the temporal pattern of apical dendrite development using combined BrdU and doublecortin immunocytochemistry, examining in a straightforward way the time it took for a newly generated granule cell to grow its apical dendrite into the molecular layer. He was able to calculate the rate of dendritic growth for a newly generated neuron in the adult dentate gyrus and showed that it was about 15 μm/day for the first 3 days, and then a doubling in length occurred at 4 and 5 days. In addition, electron microscopy of doublecortin-labeled apical dendrites showed that they had developing synapses on them in the molecular layer but not in the granule cell layer. Using these data as a baseline he then went on to examine newly born adult granule cells in epileptic rats and adduce evidence that their basal dendrites contribute to recurrent excitatory circuits that may influence spontaneous seizures. Finally, he has extended this work in a highly innovative, unexpected direction—providing evidence that adult neurogenesis contributes to the olfactory piriform cortex, in much the same way as has been extensively documented in the olfactory bulb.

Dr Shapiro obtained his Ph.D. degree in Biopsychology at the State University of New York, Stony Brook under the supervision of Dr Patricia Whitaker-Azmitia. His training with Pat was primarily in immunocytochemical studies of glial cells using S-100B antibodies at the light microscopic level. He then moved to the Ribak laboratory as a postdoctoral fellow in 2003, and in 2008 assumed his current position as Assistant Professor in the Department of Surgery, Division of Neurosurgery, at the Texas A & M University School of Medicine in Temple, Texas. He has given over a dozen invited talks and his research has appeared in distinguished journals including the Journal of Neuroscience, European Journal of Neuroscience, Neuroscience, and Brain Research Reviews.

The Cortical Scholar Award

The Cortical Scholar prize ($1000) is awarded to a predoctoral fellow who is at the end stage of completing a doctoral dissertation or within a year of obtaining the degree. This year's cortical scholar award was presented to Kenneth Kwan, who was recognized for innovative and influential studies of gene regulatory events in cerebral cortical neuron development.

In some of his earliest work as a student in the Interdepartmental Neuroscience Program at Yale University he contributed to a joint project between the State and Sestan laboratories that involved characterizing mutations of the gene SLITRK1 in patients with Tourette's syndrome. Ken independently suggested that a rare variant in the 3′ untranslated region corresponds to a brain-expressed microRNA binding domain, and went on to design experiments evaluating the functional consequences of this variant—demonstrating that the substitution led to increased microRNA binding to the target, with corresponding decreased mRNA expression, in vitro. Then he designed and performed experiments demonstrating that SLITRK1 regulates dendritic arborization in layer 5 pyramidal neurons. This project was published in Science, where Ken was a co-first author.

For his thesis work, Ken examined the transcriptional regulation of cortical pyramidal neuron identity and connectivity, focusing on roles of the transcription factor SOX5 (not previously implicated in isocortical development) in controlling the identity and connectivity of deep cortical plate and subplate neurons. For this he analyzed SOX5 knockout and transgenic reporter mice with a variety of methods. There were 3 major findings, reported in PNAS, that are directly relevant to understanding molecular mechanisms controlling the migration, molecular identity, and connectivity of early born isocortical projection neurons. As described in the nominating letter from his thesis advisor, Nenad Sestan, he first provided experimental evidence for a novel model of neuron identity acquisition via progressive postmigratory refinement of molecular properties requiring SOX5. Second, he used cortical neuron birthdating methods to show that SOX5 is required by deep-layer neurons to migrate past earlier-born neurons. And third, he demonstrated that in SOX5 knockout mice descending projections from layer 5 neurons are significantly reduced, in contrast to those from layer 6 and the subplate, which are completely lost. Thus, well-known aspects of neuronal identity including spatial distribution, molecular identity, and connectivity are not solely or terminally specified at or around the time of their final mitosis. Instead, late postmitotic and postmigratory events like SOX5 expression are also required to refine distinct phenotypes.

Ken received a B.Sc. in biochemistry from the University of Waterloo, Ontario, Canada, in 2002, and then went to Yale University, where he received 2 highly competitive doctoral student awards, and is widely regarded as one of the very best students in the Neuroscience Program over the last decade.

Conclusion

Since 1988, the Cajal Club has honored outstanding neuroscientists for their basic research on the organization of the cerebral cortex—first at its annual meetings associated with the American Association of Anatomists, and beginning in 2004 at the popular Cajal Club Social at the annual meeting of the Society for Neuroscience. These awards are funded by a generous donation from the late Dr Wendell J. Krieg, the first president of the Cajal Club, and his wife Roberta. Wendell was a distinguished neuroanatomist at Northwestern University in Chicago—where he succeeded Stephen Walter Ranson as Director of the renowned Institute of Neurology—and he expressed a deep reverence and respect for the Nobel Prize-winning work of Santiago Ramón y Cajal on the nervous system (Whitlock DG. 2007. The Cajal Club: its origin, originator and benefactor, Wendell J.S. Krieg. Brain Res Rev. 55:450–562). The proceeds of the Krieg's bequest were designated to fund the Krieg Cortical Kudos awards for neuroscientists who have made significant contributions to the understanding of the structural organization, function, and embryonic development of the cerebral cortex. The awards program is unique in that it recognizes research excellence at 3 progressively greater levels of achievement and maturity—named appropriately by Dr Krieg himself Cortical Scholars, Cortical Explorers, and Cortical Discoverers.

Figure 1.

Neuroscientists honored at the Cajal Club's annual Society for Neuroscience Social event in 2008 are, from left to right, Harvey J. Karten, Kenneth Y.-C. Kwan, Lee A. Schapiro, and Yasuo Kawaguchi. Photo courtesy of Larry Swanson.

Figure 1.

Neuroscientists honored at the Cajal Club's annual Society for Neuroscience Social event in 2008 are, from left to right, Harvey J. Karten, Kenneth Y.-C. Kwan, Lee A. Schapiro, and Yasuo Kawaguchi. Photo courtesy of Larry Swanson.