Ronald Baisden - Academia.edu (original) (raw)

Papers by Ronald Baisden

Psychonomic Science, 1972

Beginning about 10 days after birth, infant rabbits were tested for spontaneous alternation while... more Beginning about 10 days after birth, infant rabbits were tested for spontaneous alternation while under single dosages of physostigmine and dl-amphetamine, as weil as after saline injections or without any injection. Only under physostigmine did the animals alternate at levels which were above chance and which approximated levels found in normal adult animals of other species. This indicates that the capacity for spontaneous alternation exists in the infant rabbit, even though it is normally not expressed in behavior.

WOODRUFF, M. L. AND R. H. BAISDEN. Exposure to trimethyltin significantly enhances acetylcholines... more WOODRUFF, M. L. AND R. H. BAISDEN. Exposure to trimethyltin significantly enhances acetylcholinesterase staining in the rat dentate gyrus. NEUROTOXICOL TERATOL 12(1) 33-39, 1990.-Trimethyltin (TMT) is known to produce substantial damage to the hippocampal formation. It also destroys neurons within the entorhinal cortex, thereby causing degeneration of perforant path afferents that terminate in the outer molecular layer (OML) of the dentate gyms. Surgical destruction of the entorhinal cortex also causes the perforant path to degenerate. This leads to reactive synpatogenesis (axonal sprouting) of septal afferents to the dentate gyms. The purpose of the present study was to determine whether administration of 6 mg/kg of TMT by gavage to rats would cause axonal sprouting within the septodentate projection. A histochemical stain for acetycholinesterase (ACHE) was used. Compared to control subjects rats given TMT exhibited significantly denser AChE staining in the dentate OML. This is putative indication of reactive synaptogenesis within the cholinergic projection to this layer of the dentate and is somewhat surprising because other neurotoxins, such as lead and ethanol, that affect neurons within the hippocampal formation reduce the capacity for reactive synaptogenesis in response to lesions of the entorhinal cortex. Axonal sprouting Reactive synaptogenesis Hippocampus Dentate gyrus Acetylcholinesterase Cholinergic Entorhinal cortex Trimethyltin Neurotoxin Rat SURGICAL destruction of the entorhinal cortex enhances his-tochemical staining for acetylcholinesterase (ACHE) in the outer molecular layer of the dentate gyrus and this phenomenon is attributed to reactive synaptogenesis of septodentato cholinergic afferents that occupy the area previously receiving axon terminals of the destroyed entorhinal cortex (12, 13, 15). In addition to its well-known effects on the hippocampal formation (Ammon's horn, the dentate gyrus, and subiculum), the neurotoxin trimeth-yltin (TMT) also produces significant cell loss in all divisions of the entorhinal cortex of rats (3,19). Consequently, degeneration of the perforant pathway is appreciable by four days after systemic exposure to TMT (3) and continues for at least 100 days (18). However, neurons within the diagonal band of Broca are spared (3) and, compared to the entorhinal cortex and subfield CA3c of the hippocampus, relatively little cell loss is apparent in the medial septal nucleus (3). This pattern of cell loss and fiber degeneration prompted the hypothesis that systemic exposure to TMT might lead to a pattern of AChE staining within the dentate gyrus similar to that reported to occur following surgical destruction of the entorhinal cortex. The present experiment was conducted to test this hypothesis. METHOD Animals and Treatment Seventeen male Long-Evans (hooded) rats served as subjects. These rats ranged in weight from 256 to 298 g at the beginning of the experiment. They were individually housed in a temperature controlled room and subjected to a 12 hr on/12 hr off light/dark cycle. Food and water were available ad lib. Nine of the rats were lightly anesthetized with ether and orally gavaged with TMT chloride dissolved in distilled water at a dose of 7.69 mg/kg (6.0 mg/kg of the TMT free base). Four rats were lightly anesthetized with ether and orally gavaged with an equivalent volume of distilled water. The four remaining rats served as untreated controls. Tissue Processing and Data Analysis One hundred twenty to 130 days following gavage each rat was overdosed with sodium pentobarbital and transcardially perfused with 300 ml of a 0.9% saline solution followed by 400 ml of 1% glutaraldehyde/1.25% paraformaldehyde in 0.1 M phosphate buffer.

Transplants of fetal neural tissue survive and develop in lesion cavities produced in adult rats.... more Transplants of fetal neural tissue survive and develop in lesion cavities produced in adult rats. The present experiment tested the effect of grafting fetal hippocampal or brainstem tissue on the ability of rats with hippocampal lesions to perform on a differential reinforcement of low response rate (DRL) operant schedule. The DRL interval was 20 s. Eighty-six percent of the hippocampal grafts and 69% of the brainstem grafts developed to maturity. Inspection of sections stained using a silver technique for axis cylinders or taken from rats in which the mature transplant had been injected with Fast blue, indicated that these grafts formed connections with the host brain. Consistent with previous reports, rats with hippocampal lesions were impaired in performance of the DRL task. Rats given fetal grafts of hippocampal tissue into the hippocampal lesion site on the day of lesion production were significantly better in performance of the DRL requirement than were lesion-only rats or rats receiving grafts of fetal brainstem tissue. The results of this study confirm that grafts of fetal brain tissue can both develop in a lesion site in an adult brain and ameliorate lesion-induced behavioral deficits.

Molecular and Chemical Neuropathology, Sep 1, 1994

Trimethyltin (TMT) destroys specific subfields of the hippocampus in the rat. TMT also increases ... more Trimethyltin (TMT) destroys specific subfields of the hippocampus in the rat. TMT also increases choline acetyltransferase (CHAT) activity in CA1 of Ammon's horn and the outer molecular layer of the dentate gyrus. This observation suggests that axonal sprouting occurs in the cholinergic septohippocampal system in response to TMT. However, neither does-response nor time course data are available for the effects of TMT on this enzyme. The effects of three dose levels of TMT on ChAT activity in CA1 and the dentate gyrus were determined in Experiment 1 and ChAT activity in these two areas was measured at six time points following exposure to TMT in Experiment 2. Only the highest dose of TMT (6 mg/kg) significantly increased ChAT activity. ChAT activity in the dentate gyrus increased significantly by 3 d after administration and continued to increase until 21 d after exposure. A significant increase was not observed in CA1 until 7 d after exposure to TMT. Asymptotic levels were still reached at d 21. These results indicate a steep dose-response curve for TMT-induced changes in 28 Cannon et al. ChAT activity in the hippocampal formation and that this marker of cholinergic activity is more sensitive to perturbation by TMT in the dentate gyrus than Ammon's horn.

Brain Research, Jan 2, 1984

The existence of a massive cholinergic projection from cells in the medial septal nucleus (MS) an... more The existence of a massive cholinergic projection from cells in the medial septal nucleus (MS) and nucleus of the diagonal band (DB) to the hippocampal formation has been recognized for some time. However, the actual percentages of cholinergic and non-cholinergic neurons in the MS and DB which project to the hippocampus have not been reported. A procedure which combines horseradish peroxidase (HRP) and acetylcholinesterase (ACHE) histochemistry in the same tissue was used to determine these percentages in the rabbit. Less than 50% of the neurons in the MS and DB which were labeled with reaction product following an HRP injection into the dorsal hippocampus also stained for ACHE. Moreover, 70% of all neurons containing HRP reaction product were located in the DB, but neurons in the DB could not be differentiated from those in the MS on the basis of size or morphology. These data are taken to indicate that much of the MS-DB hippocampal projection is not cholinergic. Substance P is suggested as another possible transmitter within this anatomical system.

Progress in Brain Research, Feb 1, 1990

Behav Res Methods, 1980

A circuit for inexpensive automation of a hydraulic microdrive is described. The circuit uses two... more A circuit for inexpensive automation of a hydraulic microdrive is described. The circuit uses two integrated timing circuits with output periods defined by resistance-capacitance circuits. The output of this circuit operates a relay that controls a small electric motor that runs the microdrive. This system can operate in either a continuous mode for long-term infusion of solutions or in a stepwise fashion for lowering electrodes. When attached to an appropriate microdrive, the circuit can be employed in experiments in which brain-behavior relationships are investigated within anatomical, pharmacological, or electrophysiological paradigms.

Cell and Tissue Research, Sep 1, 1976

The synaptic organization of the pars lateralis portion of the ventral lateral geniculate nucleus... more The synaptic organization of the pars lateralis portion of the ventral lateral geniculate nucleus is similar to that of other thalamic nuclei. There are four types of synaptic knobs (RL, RS, F 1, F2). RL knobs are large and irregularly shaped, contain round synaptic vesicles and make multiple asymmetrical junctions. They are found primarily in "synaptic islands" making contact with gemmules, spines, small dendrites, and other synaptic profiles containing pleiomorphic synaptic vesicles (F2). Smaller RS knobs contain round vesicles and make asymmetrical junctions with the same type of elements as RL knobs, with the exception of the F2 profiles, but are seldom found in synaptic islands. F1 knobs contain flattened synaptic vesicles and form symmetrical junctions with F2 knobs, gemmules, spines, and small-medium dendrites in synaptic islands, throughout the neuropil, and on the proximal dendrites and soma of the largest type of neuron. F2 knobs are irregularly shaped, contain pleiomorphic synaptic vesicles and make symmetrical junctions primarily with gemmules and spines in synaptic islands. They are postsynaptic to RL and F 1 knobs. Occipital decortication indicates that cortical terminals are of the RS type. Bilateral enucleation indicates that retinal terminals are of both the RL and RS type. The large amount of geographic overlap of retinal and cortical terminals on gemmules, spines, and small dendrites found in the neuropil outside of synaptic islands logically would maximize axonal sprouting between these two sources.

Biotech Histochem, 1980

A simple method for staining nerve cells and fibers of the salamander central nervous system is d... more A simple method for staining nerve cells and fibers of the salamander central nervous system is described. The procedure employs Carnoy's fixation followed by Protargol inpregnation and Nissl staining. This technique permits the simultaneous observation of intracellular neurofibrils, neuronal processes and basophilic components of the neuron. In addition, it eliminates the need to stain alternate sections with separate procedures to view the various components of the urodele central nervous system.

Neurotoxicology, Feb 1, 1991

The effect of transplants of either fetal hippocampal or dorsal ventricular ridge (DVR) tissue in... more The effect of transplants of either fetal hippocampal or dorsal ventricular ridge (DVR) tissue into the brains of adult male rats exposed to TMT was determined for two behavioral tasks. Administration of TMT produced deficits in acquisition and performance of an operant differential reinforcement of low response rates (DRL) schedule and learning in the Morris water maze. The fetal transplants developed well within the TMT-damaged brains of the adult rats and numerous axons could be shown to cross the host-transplant interface. The transplants significantly reduced the DRL deficit produced by exposure to TMT. However, the TMT-induced deficit in water maze acquisition was made significantly worse by the hippocampal transplants. The improvement in DRL performance is attributed to the effect on the host brain of an unidentified trophic substance produced by the transplants. However, this positive effect may not protect the brain sufficiently to produce recovery in tasks demanding more complex neural computations than are required to withhold lever-press responses. The transplant-induced deficit observed in some aspects of water maze acquisition and performance may be attributable to either a tumor-like deleterious effect of the mass of the transplant or to abnormal neuronal activity transmitted from the transplant to the host brain. The results of the present study, and those from other similar studies, suggest that transplants of fetal tissue may be useful in producing changes in the brain of an animal exposed to an environmental neurotoxin, but that research should be focused upon development of transplant methodology that will minimize adverse effects of the grafts.

Progress in Brain Research, 1990

APA PsycNET Our Apologies! - The following features are not available with your current Browser c... more APA PsycNET Our Apologies! - The following features are not available with your current Browser configuration. - alerts user that their session is about to expire - display, print, save, export, and email selected records - get My ...

Psychonomic Science, 1972

Life sciences, Jan 21, 1981

Molecular and chemical neuropathology / sponsored by the International Society for Neurochemistry and the World Federation of Neurology and research groups on neurochemistry and cerebrospinal fluid, 1994

Adult male Long-Evans rats were given 6 mg/kg trimethyltin (TMT). Rats were killed 1, 3, 7, 14, 2... more Adult male Long-Evans rats were given 6 mg/kg trimethyltin (TMT). Rats were killed 1, 3, 7, 14, 21, 35, or 60 d later. An untreated control group was included. Brain sections were processed using film autoradiography to visualize in the hippocampus either total muscarinic receptor binding ([3H]quinuclidinyl benzilate; [3H]QNB), or M1 receptors ([3H]pirenzepine; [3H]PZ), or M2 receptors ([3H]oxotremorine-M; [3H]OXO-M). A reduction in [3H]QNB binding was found in CA1 and CA3c 7 d after TMT, but not in CA3a, b, or the dentate gyrus. [3H]PZ binding was decreased throughout Ammon's horn by 14 d after treatment. [3H]OXO-M binding decreased 1 d after exposure in CA1 and in all subfields of Ammon's horn by d 3. Neither [3H]PZ or [3H]OXO-M binding decreased in the dentate gyrus of TMT-treated rat at any time point. The temporal patterns of receptor loss may be explicable by reference to timing of fiber and cell body degeneration reported in previous studies and the regional differenc...

Trimethyltin (TMT) destroys specific subfields of the hippocampus in the rat. TMT also increases ... more Trimethyltin (TMT) destroys specific subfields of the hippocampus in the rat. TMT also increases choline acetyltransferase (ChAT) activity in CA1 of Ammon's horn and the outer molecular layer of the dentate gyrus. This observation suggests that axonal sprouting occurs in the cholinergic septohippocampal system in response to TMT. However, neither does-response nor time course data are available for the effects of TMT on this enzyme. The effects of three dose levels of TMT on ChAT activity in CA1 and the dentate gyrus were determined in Experiment 1 and ChAT activity in these two areas was measured at six time points following exposure to TMT in Experiment 2. Only the highest dose of TMT (6 mg/kg) significantly increased ChAT activity. ChAT activity in the dentate gyrus increased significantly by 3 d after administration and continued to increase until 21 d after exposure. A significant increase was not observed in CA1 until 7 d after exposure to TMT. Asymptotic levels were still...

American Journal of Anatomy, 1987

The origin of different branches of the facial nerve in the rabbit was determined by using retrog... more The origin of different branches of the facial nerve in the rabbit was determined by using retrograde transport of HRP. Either the proximal stump of specific nerves was exposed to HRP after transection, or an injection of the tracer was made into particular muscles innervated by a branch of the facial nerve. A clear somatotopic pattern was observed. Those branches which innervate the rostral facial musculature arise from cells located in the lateral and intermediate portions of the nuclear complex. Orbital musculature is supplied by neurons in the dorsal portion of the complex, with the more rostral orbital muscles receiving input from more laterally located cells while the caudal orbital region receives innervation from more medial regions of the dorsal facial nucleus. The rostral portion of the ear also receives innervation from cells located in the dorsomedial part of the nucleus, but the caudal aspect of the ear is supplied exclusively by cells located in medial regions. The cervical platysma, the platysma of the lower jaw, and the deep muscles (i.e., digastric and stylohyoid) receive input from cells topographically arranged in the middle and ventral portions of the nuclear complex. It is proposed that the topographic relationship between the facial nucleus and branches of the facial nerve reflects the embryological derivation of the facial muscles. Those muscles that develop from the embryonic sphincter colli profundus layer are innervated by lateral and dorsomedial portions of the nuclear complex. The muscles derived from the embryonic platysma layer, including the deep musculature, receive their input from mid to ventral regions of the nuclear complex.

Toxin-Induced Models of Neurological Disorders, 1994

Physiology & Behavior, 1994

III. Effects of trimethyltin on acquisition and reversal of a light-dark discrimination by rats. ... more III. Effects of trimethyltin on acquisition and reversal of a light-dark discrimination by rats. PHYSIOL BEHAV 55(6) 1055 -1061 , 1994 deficits produced by trimethyltin (TMT) are usually attributed to the hippocampal damage caused by this toxicant. The purpose of this experiment was to determine the effects of TMT administration on acquisition and reversal of a discrete trial light-dark discrimination. Acquisition of this task is impaired by hippocampal lesions but the effects of TMT on it are not known. Forty-five days after some of the rats were given one of three doses of TMT, adult, male Long-Evans rats were given 100 trials per day for 20 days to acquire a discrete trial lever press discrimination with lit cue lights located above the correct lever. At the end of this time the contingencies were reversed and the rats were given 30 more days of training. No significant group differences occurred during the first 20 days. A significant group effect was found for the 30 days of reversal training. The rats given the highest dose of TMT (6 mg/kg) obtained significantly more reinforcements during reversal training than the other groups. Because surgical hippocampal lesions generally impair both acquisition and reversal of visual discriminations, these data were unexpected and suggest that other factors than hippocampal damage enter into the behavioral effects of TMT.

Physiology & Behavior, 1993

WOODRUFF, M. L., R. H. BAISDEN AND R. L. CANNON. Transplant-induced working memory deficits in hi... more WOODRUFF, M. L., R. H. BAISDEN AND R. L. CANNON. Transplant-induced working memory deficits in hippocampectomized rats. PHYSIOL BEHAV 54(3) [579][580][581][582][583][584][585][586][587] 1993.--This experiment determined the effects of transplantation of fetal hippocampus on the ability of male rats with hippocampal lesions to acquire versions of a radial ann maze that depended on either extramaze cues or intramaze cues for solution. Rats receiving transplants took significantly more trials than control rats to emit three consecutive errorless trials in the extramaze cue (spatial) variation of the maze. Rats with just hippocampal lesions never differed from any other group. No differences in this measure were found for the intramaze cue condition. Rats receiving transplants made more repeat entries into reinforced arms in both versions of the maze than control rats and more reentries into neverbaited arms in the spatial maze, Rats with hippocampal lesions failed to differ from any other group on this measure in the spatial maze, but were different from normal rats in the intramaze cue maze. These data suggest that in some tasks transplants of fetal tissue lead to greater behavioral impairment than lesions alone.

Psychonomic Science, 1972

Molecular and Chemical Neuropathology, Sep 1, 1994

Brain Research, Jan 2, 1984

Progress in Brain Research, Feb 1, 1990

Behav Res Methods, 1980

Cell and Tissue Research, Sep 1, 1976

Biotech Histochem, 1980

Neurotoxicology, Feb 1, 1991

Progress in Brain Research, 1990

Psychonomic Science, 1972

Life sciences, Jan 21, 1981

Trimethyltin (TMT) destroys specific subfields of the hippocampus in the rat. TMT also increases ... more Trimethyltin (TMT) destroys specific subfields of the hippocampus in the rat. TMT also increases choline acetyltransferase (ChAT) activity in CA1 of Ammon's horn and the outer molecular layer of the dentate gyrus. This observation suggests that axonal sprouting occurs in the cholinergic septohippocampal system in response to TMT. However, neither does-response nor time course data are available for the effects of TMT on this enzyme. The effects of three dose levels of TMT on ChAT activity in CA1 and the dentate gyrus were determined in Experiment 1 and ChAT activity in these two areas was measured at six time points following exposure to TMT in Experiment 2. Only the highest dose of TMT (6 mg/kg) significantly increased ChAT activity. ChAT activity in the dentate gyrus increased significantly by 3 d after administration and continued to increase until 21 d after exposure. A significant increase was not observed in CA1 until 7 d after exposure to TMT. Asymptotic levels were still...

American Journal of Anatomy, 1987

Toxin-Induced Models of Neurological Disorders, 1994

Physiology & Behavior, 1994

Physiology & Behavior, 1993