Ken Lukowiak - Academia.edu (original) (raw)

Papers by Ken Lukowiak

PLoS genetics, 2016

The human face is a complex assemblage of highly variable yet clearly heritable anatomic structur... more The human face is a complex assemblage of highly variable yet clearly heritable anatomic structures that together make each of us unique, distinguishable, and recognizable. Relatively little is known about the genetic underpinnings of normal human facial variation. To address this, we carried out a large genomewide association study and two independent replication studies of Bantu African children and adolescents from Mwanza, Tanzania, a region that is both genetically and environmentally relatively homogeneous. We tested for genetic association of facial shape and size phenotypes derived from 3D imaging and automated landmarking of standard facial morphometric points. SNPs within genes SCHIP1 and PDE8A were associated with measures of facial size in both the GWAS and replication cohorts and passed a stringent genomewide significance threshold adjusted for multiple testing of 34 correlated traits. For both SCHIP1 and PDE8A, we demonstrated clear expression in the developing mouse fa...

Biological Psychiatry, Aug 15, 2006

Many accounts of memory suggest that an initial learning experience initiates a cascade of cellul... more Many accounts of memory suggest that an initial learning experience initiates a cascade of cellular and molecular events that are required for the consolidation of memory from a labile into a more permanent state. Studies of memory in many species have routinely found that altered gene activity and new protein synthesis are the critical components of this memory consolidation process. During extinction, when organisms learn that previously established relations between stimuli have been severed, new memories are formed and consolidated. However, the nature of the learning that underlies extinction remains unclear and there are many processes that may contribute to the weakening of behavior that occurs during extinction. In this review, we suggest that the molecular mechanisms that underlie extinction may differ depending on the learning process that is engaged by extinction. We review evidence that extinction, like initial learning, requires transcription and translation, as well as evidence that extinction occurs when protein synthesis is inhibited. We suggest that extinction occurs through the interaction of multiple behavioral and molecular mechanisms.

The Journal of Experimental Biology, Apr 1, 1994

Dopamine elicits alternating bursts of activity in the respiratory interneurones of the snail Lym... more Dopamine elicits alternating bursts of activity in the respiratory interneurones of the snail Lymnaea stagnalis. One of the neurones (VD4) was isolated in culture, and the effects of dopamine on both membrane voltage and current were studied utilising the whole-cell tight-seal recording technique. Dopamine had little effect on resting potentials near Ϫ60 mV, nor did it affect spike threshold or input resistance measured near Ϫ60 mV. However, it did alter the excitability of the cell, changing the response to current injection from one of repetitive spiking to one of rapid accommodation. Under voltage-clamp, VD4 responded to dopamine (EC50=92 nmol l Ϫ1 ) with increased net outward current at all potentials more positive than Ϫ60 mV. This was due primarily to an increase in voltage-gated potassium current and a decrease in calcium current. A reduction of Cd 2+ -sensitive outward current, possibly calcium-gated potassium current, was also evident at potentials more positive than +60 mV. The physiological actions of dopamine on these cells in vivo are consistent with the inhibitory mechanisms presented in this study.

Neth J Zool, 1993

ABSTRACT The distribution of putative nitric oxide synthase- (NOS) containing neurons in the CNS ... more ABSTRACT The distribution of putative nitric oxide synthase- (NOS) containing neurons in the CNS and peripheral tissues of the freshwater pulmonate molluscs, Lymnaea stagnalis, Helisoma trivolvis and Biomphalaria sp. was investigated using NADPH-diaphorase (NADPH-d) histochemistry and NOS-immunolabelling. NADPH-d-positive cells were found in most of the central ganglia but their distribution was different from that of other ncurotransmitters. Comparison of NADPH-d-positive neurons in the CNS of Lymnaea, Helisoma and Biomphalaria showed that bulinid snails contained more NADPH-d positive neurons in the CNS, especially in the cerebral ganglia, compared to Lymnaea. Some of previously identified neurons were found to be NADPH-d-positive (e.g. a buccal gut motoneuron B2 in Lymnaea and its homologues B5 in the bulinids). In addition, the right parietal light yellow' cluster cells (LYC) were also weakly stained in Lymnaea both with NOS antibodies and NADPH-d. Neurons B2 and LYC were isolated and maintained in culture under conditions that support neurite outgrowth. In culture, both B2 and LYC were stained by NADPH-d similar to that observed in whole mount preparations. In addition to cell somata, intense NADPH-d positive staining was observed in the growth cone and at the tips of filopodia of B2 neurons. We suggest that NO (or related substances) is involved in neuronal signalling in molluscan species.

The Journal of Neuroscience : The Official Journal of the Society for Neuroscience

The Canadian journal of neurological sciences. Le journal canadien des sciences neurologiques

Journal of Experimental Biology

Acta Biologica Hungarica

ABSTRACT

Advances in experimental medicine and biology, 2001

This Workshop addressed emerging issues of central integration of chemoreceptor inputs during cha... more This Workshop addressed emerging issues of central integration of chemoreceptor inputs during challenges such as hypoxia, hypercapnia and exercise. Classical chemoreflex models assume that respiratory output increases in direct proportion to the sum of chemoreceptor inputs via a hard-wired neural controller, with additive interactions between afferent and efferent pathways (Figure lA). While this structure has proved satisfactory in explaining the

The Journal of neuroscience : the official journal of the Society for Neuroscience, 1984

In Aplysia californica, multiple regulatory mechanisms are involved in the actions of neurotransm... more In Aplysia californica, multiple regulatory mechanisms are involved in the actions of neurotransmitters on the gill. Neurotransmitter receptors and adenylate cyclase were examined in a particulate fraction of gill homogenates. The neuropeptide FMRF-amide stimulated enzyme activity 7- to 8-fold (EC50, 1 microM) via receptors that were pharmacologically distinct from those for dopamine and serotonin. FMRF-amide augmented cyclic AMP levels in slices of gill tissue with a time course similar to that for adenylate cyclase activation. Increases in cyclic AMP levels produced by the neuropeptide were potentiated by the phosphodiesterase inhibitor theophylline. Physiological responses to neuropeptides and cyclic AMP analogues were examined in a perfused, isolated gill preparation. Phasic contractions evoked by FMRF-amide (EC50, 0.1 microM) were mimicked by membrane-permeable analogues of cyclic AMP. Comparison of FMRF-amide effects on adenylate cyclase and gill behavior suggests an associati...

The Journal of Physiology, 2002

NeuroReport, 1994

The presence and distribution of nitric oxide synthase (NOS) in the CNS and peripheral organs (bu... more The presence and distribution of nitric oxide synthase (NOS) in the CNS and peripheral organs (buccal muscles, oesophagus, salivary glands, foot, mantle and pneumostome) of the pulmonate mollusc, Lymnaea stagnalis were studied using an antiserum developed against rat cerebellar NOS. NOS-immunopositive neurones in Lymnaea were localized predominantly in the buccal ganglia as well as in distinct areas of the cerebral and suboesophageal ganglia. NOS-immunoreactive terminals were also found on the somata of some central neurones. In the periphery, NOS-immunostaining was detected only in a few neurones in the pneumostome area and in the osphradial ganglion. In addition, approximately 100 NOS-immunopositive cells have been found in the salivary glands. Our data supports other recent reports indicating that NO may be a signal molecule in the CNS of molluscs.

Journal of Experimental Biology, 2005

Journal of Experimental Biology, 2009

We found strain differences in the ability of wild Alberta Lymnaea stagnalis to form long-term me... more We found strain differences in the ability of wild Alberta Lymnaea stagnalis to form long-term memory (LTM) following operant conditioning when L. stagnalis were collected from the wild and trained in the laboratory. Lymnaea stagnalis obtained from the Belly River watershed had an enhanced ability to form LTM compared with those from an isolated pond (referred to as Jackson snails). We therefore asked whether the differences in cognitive ability were an epiphenomenon as a result of training in the laboratory. To answer this question we trained each specific strain (Belly and Jackson) in both the laboratory and the field (i.e. in their home pond and in the pond where the other strain resided -referred to as the visitor pond). We found that within each strain there was no difference in the LTM phenotype whether they were trained in the lab or in either their home or visitor pond. That is, the strain differences in the ability to form LTM were still present. Interestingly, we found no strain differences in the ability to learn or the ability to form intermediate-term memory (ITM).

Journal of Experimental Biology, 2008

The rationale behind this selection of topics was to provide interested readers with a very catho... more The rationale behind this selection of topics was to provide interested readers with a very catholic view of neurosensation, ranging from some of the first sensory cells that emerge in a developing organism to the molecular evolution of ion channels that are used to transduce signals in ...

Synapse, 2002

Precise neuronal connectivity during development is subservient to all nervous system functions i... more Precise neuronal connectivity during development is subservient to all nervous system functions in adult animals. However, the cellular mechanisms that mastermind this neuronal connectivity remain largely unknown. This lack of fundamental knowledge regarding nervous system development is due in part to the immense complexity of mammalian brain, as cell-cell interactions between defined sets of pre- and postsynaptic partners are often difficult to investigate directly. In this study, we developed a novel model system which has allowed us to reconstruct synapses between identified motor neurons and their target heart muscle cell in a soma-muscle configuration. Utilizing this soma-myocardial cell synapse model, we demonstrate that synapses between somata and heart muscle cells can be reconstructed in cell culture. The soma-myocardial cell synapses required 12-24 h to develop and thus differed temporally from conventional neuromuscular synapses (seconds to a few minutes). We also demonstrate that the synapses are target cell-type-specific and are most likely independent of transmitter phenotypic characteristics of presynaptic neurons.

Journal of Neurophysiology, 2004