Ultrastructure and distribution of axon terminals from the reticular thalamic nucleus to the anteroventral thalamic nucleus of the rat

The Bard Atherectomy Catheter is a new rotational atherectomy device that consists of a flexible, hollow, thin-walled cutting catheter that, while rotated at 1,500 revolutions per minute, is advanced across the lesion over a special spiral guidewire system. We report the initial clinical experience with this device in 20 peripheral lesions in ten patients. The majority of patients were treated for limb salvage. All lesions were successfully intervened on by atherectomy followed by adjunctive balloon angioplasty. A reduction to less than 50% stenosis was achieved in 13 of the 20 lesions (65%) after atherectomy but in all 20 lesions (100%) after adjunctive angioplasty for all lesions and stenting for dissections in two. Baseline minimal lesion lumen diameter was 0.8 +/- 0.7 mm with a reference vessel diameter of 4.2 +/- 1.7 mm (75 +/- 21% stenosis). The lumen improved to 2.0 +/- 0.8 mm (45 +/- 19% stenosis) (P < 0.001) following atherectomy and to 3.9 +/- 1.9 mm (13 +/- 16% stenosis) (P < 0.001) after adjunctive angioplasty. The average weight of removed atheroma was 45 +/- 58 mg. All ten patients had initial improvement in symptoms. At 6 months follow-up there was persistent improvement in eight patients and two subjects had undergone amputations. Our early clinical experience with this low profile, flexible atherectomy device, that enables extraction of a large amount of atheroma, suggests that it will become a valuable addition to current atherectomy technologies in small- and medium-sized vessels. The value of this device in coronary vessels is under investigation.     

Human behavior and the behavior of other animals.

The full understanding of the behavior of any species must include biology, but at present there is no agreement on how comparisons between our species and others should be made. To a remarkable extent, people believe what they want to believe, as exemplified by the history of the interpretation of the behaviors of the great apes. When comparing human behavior to that of other animals, it is necessary to start with what is known about human beings and then to proceed to comparisons and evolution. Alternative procedures inevitably lead to reductionism and the loss of the very behaviors that make human beings unique. Language (speech and cognition) separates human behavior from that of any other animal and forms the biological base for the social sciences and the singularly human history of the last few thousand years. With the advent of speech, learning takes on wholly new dimensions, and the relation between biology (nature) and learning (nurture) in human beings is quite different from that in any other animal. (58 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Neural firing in ventrolateral thalamic nucleus during conditioned vocal behavior in cats

The ventrolateral (VL) thalamus in mammals is a site well-situated to show vocalization-related neural activity if there is general or classical motor system involvement in vocal production. It receives input from both the basal ganglia and cerebellum, and forms reciprocal connections with motor cortical areas. The current study examined the activity in cat VL thalamus neurons during instrumentally conditioned vocalization. Units in our sample showed irregular spontaneous firing which could be modulated by slowly occurring fluctuations in intensity of vocalization task performance. Two main types of behavioral events were associated with changes in neural firing rate. The first of these was the ingestion of food reward. More than half of all recordings showed phasic bursting patterns during licking; a similar number had increases in firing preparatory to this phasic activity. The second behavioral event modulating unit responses was vocalization. Approximately 60% of recordings showed activity changes time-locked to vocalization. These responses were almost always excitatory, and often involved changes in firing that preceded vocalization onset. No spatial organization of differences in firing pattern between neurons could be distinguished. Our results suggest that VL thalamus may well be involved in mediating vocal behavior, although its functional role remains an object of speculation. Results are compared with previous studies of vocalization-related activity and of VL thalamus activity.     

The propensity for nonregulatory ingestive behavior is related to differences in dopamine systems: Behavioral and biochemical evidence.

Investigated the relation between properties of dopaminergic neural systems and the predisposition to exhibit nonregulatory ingestive behavior in 54 male Long-Evans rats. It was found that Ss that ate and drank during electrical stimulation of the lateral hypothalamus (ESLH) showed greater behavioral sensitization to a series of amphetamine injections (3 mg/kg) than those that did not exhibit ingestive behavior during ESLH. In addition, footshock stress produced a greater increase in forebrain dopamine utilization in Ss that engaged in nonregulatory ingestive behavior. This evidence is consistent with the hypothesis that there are individual differences in the responsiveness of forebrain dopamine systems that are related to the behavioral predisposition to exhibit nonregulatory ingestive behavior. (51 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Trigeminal deafferentation and ingestive behavior in rats.

For studying the role of orosensory input in the control of ingestive behavior, 46 male albino Wistar rats were subjected to varying degrees of trigeminal deafferentation in 2 experiments. Somatosensory branches that convey touch, temperature, and pain from the oral cavity were sectioned selectively, and muscles of mastication and taste afferents were left intact. Severe intake deficits were produced, including aphagia, adipsia, and prolonged hypophagia, accompanied by a corresponding decrease in body weight. The deficits were proportional to the extent of deafferentation and were most severe when upper and lower portions of the mouth were affected. Although somatosensory impairment affected the organization of the consummatory response, all Ss could bite, chew, and lick. Analysis of feeding patterns showed that minimally (mandibular) deafferented Ss compensated for the consummatory inefficiency by increasing meal duration but failed to initiate meals at the normal rate, thus keeping food intake below normal levels. Results suggest that oral somatosensory input is critical for the mechanisms that regulate ingestive behavior. (45 ref)) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Gustation and ingestive behavior in the rat.

Studied the contribution of taste to the quantitative control of intake and body weight in 15 male Wistar rats. Gustatory deafferentation was produced by combined bilateral section of the chorda tympani and glossopharyngeal nerves and the pharyngeal branch of the vagus nerve. The procedure did not affect the condition of the mouth, impair orientation to sensory stimuli, or severely disrupt the consummatory sequence. Nevertheless, deafferented Ss showed reduced responsiveness to food and water, elevated quinine HCl aversion thresholds, and impaired feeding efficiency. Food and water intake and body weight remained below control levels for at least 40–50 days postoperatively. Food intake deficits were not observed when Ss were offered ad lib pablum, a result suggesting that increased palatability could compensate for decreased gustatory input. The order of recovery of food intake through different diet types suggests a heightened responsiveness to taste stimuli. The effects of gustatory deafferentation are compared with those seen after section of trigeminal orosensory nerves, and the differential contributions of oral taste and oral touch are discussed. (42 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Trigeminal orosensation and ingestive behavior in the rat.

Used a deafferentation procedure with male Wistar rats to examine the contributions of trigeminal orosensation to control of ingestive behavior. The procedure removed somatosensory input from the mouth while sparing olfaction, lingual taste, vibrissae inputs, and proprioceptive afferents from and efferents to the jaw muscles. Ss with sections of tongue or jaw muscle efferents served as controls. Bilateral trigeminal orosensory deafferentation was followed by effects on ingestive behavior, the magnitudes of which were proportional to the extent of the deafferentation. The trigeminal syndrome includes aphagia and adipsia, impairments in the sensorimotor control of eating and drinking, decreased responsiveness to food and water, and a reduction in the level of body weight regulation. Trigeminal deafferentation spared elementary ingestive movement patterns (biting, licking, and chewing) but disrupted their control by the perioral stimuli. Deficits in food intake varied with the sensory properties of the diet. Recovery of intake took place along a palatability gradient, and recovery of water intake paralleled that of dry food. The chronically reduced body weight was caused by persistent hypophagia and reflected reduced responsiveness to food. Findings suggest a considerable degree of overlap in the neural mechanisms mediating the sensorimotor and motivational control of intake in the rat. (76 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Projections from the lateral mammillary nucleus to the anterodorsal thalamic nucleus in the rat

There has been an abundance of research on the connections of the mammillary bodies but the projections from the lateral mammillary nucleus to the anterodorsal thalamic nucleus has remained a gray area due to a dearth of material which directly addresses the details of this pathway. This study seeks to further define the nature of this particular nerve connection within the mammillothalmic tract. The technique employed is fluorescent nerve tract tracing using two fluorescent tracers implanted separately into each anterodorsal thalamic nucleus then followed retrogradely to the soma of the neurons in the lateral mammillary nucleus. Fluorescent photomicrography allowed us to document the single and double labeled cells of the lateral mammillary nucleus. The single labeled cells can be categorized into ipsilaterally projecting neurons and contralaterally projecting neurons. About half of all labeled cells were bilaterally projecting double-labeled, a third was ipsilaterally projecting single-labeled and the remainder were contralaterally projecting single labeled-cells. There were no labeled cells traced to the medial mamillary nucleus. The mammillary bodies play an important role in the limbic circuitry and a part of the so-called "Papez Circuit". The pathway by which the mammillary body projects to the other structures of the limbic system and the way it connects the limbic system to other parts of the brain like the tegmentum is not fully understood. This clarification of the connection between the lateral mammilary nucleus and the anterodorsal thalamic nucleus is but one of the contemplated pathways.     

Trigeminal reflexes and ingestive behavior in the rat.

Used photographic, eletrophysiological, and neurobehavioral analyses in 3 experiments with 21 Wistar rats to examine the contribution of trigeminally mediated jaw-opening reflexes to the control of ingestive behavior. During eating and drinking, jaw opening was always preceded by a period of perioral contact with the food or water source (Exp I). Electrical and mechanical stimulation of perioral areas in Ss that were anesthetized with chlorprothixene (0.3 ml) and either ketamine HCl (0.05 ml/100 g) or chloralose (80 mg/kg) elicited jaw-opening reflexes (recorded from the mylohyoid nerve trunk) at short latencies and low stimulus intensities (Exp II). Trigeminal orosensory deafferentation (sparing jaw muscle afferents and efferents, taste, vision, and olfaction) abolished or significantly reduced mouth opening during eating or drinking (Exp III). It is concluded that motivational processes operate through trigeminal reflexes to generate eating in rats. (37 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Relative contributions of thalamic reticular nucleus neurons and intrinsic interneurons to inhibition of thalamic neurons projecting to the motor cortex

1. Intracellular responses to stimulation of the cerebral cortex (Cx) and cerebellum were analyzed in thalamocortical neurons (TCNs) in the ventroanterior-ventrolateral (VA-VL) complex of the thalamus and neurons in the thalamic reticular nuclei (RNs) of anesthetized cats, and the contribution of reticular nucleus neurons (RNNs) and thalamic interneurons (TINs) to cerebral and cerebellar inhibition of TCNs was determined. 2. Single TCNs projecting to area 4 or 6 received convergent monosynaptic excitatory and disynaptic inhibitory inputs from both the dentate nucleus (DN) and the interpositus nucleus (IN). These TCNs also received monosynaptic excitatory postsynaptic potentials (EPSPs) and disynaptic inhibitory postsynaptic potentials (IPSPs) from the pericruciate cortex (areas 4 and 6). Each TCN received the strongest excitatory and inhibitory inputs from the cortical area to which that TCN projected, and weaker inhibitory inputs from adjacent cortical areas. 3. RNNs were identified morphologically by intracellular injection of horseradish peroxidase (HRP). Stimulation of the brachium conjunctivum (BC) evoked disynaptic EPSPs with a long decay phase in RNNs in the anterior ventrolateral part of the RN. Single RNNs received convergent disynaptic excitatory inputs from both the DNA and the IN. Stimulation of the Cx produced monosynaptic long-lasting EPSPs with two different latencies in these RNNs: early EPSPs with latencies of 0.9-2.1 ms and late EPSPs with latencies of 1.8-3.5 ms. Collision experiments with BC- and Cx-evoked EPSPs in RNNs indicated that BC-evoked disynaptic EPSPs and Cx-evoked early EPSPs were produced by axon collaterals of TCNs to RNNs. The latencies of the Cx-evoked late EPSPs in RNNs were almost identical to those of Cx-evoked monosynaptic EPSPs in TCNs, indicating that corticothalamic neurons (CTNs) exert monosynaptic excitatory effects on RNNs and TCNs. 4. Stimulation of the Cx produced IPSPs in TCNs with short latencies of 1.8-2.7 ms and longer latencies of > or = 2.8 ms. The Cx-evoked early IPSPs with latencies of 1.8-2.7 ms were mediated by RNNs. The origin of Cx-evoked late IPSPs with latencies of > or = 2.8 ms in TCNs was twofold, Cx-induced early IPSPs in TCNs were facilitated by conditioning cortical stimulation that induced late IPSPs in the TCNs. The same conditioning cortical stimulation also facilitated BC-evoked disynaptic IPSPs. The time course of this facilitatation indicated that CTNs produce long-lasting excitation in TINs. These results indicated that Cx-evoked IPSPs with latencies of > 2.7 ms were mediated at least in part by RNNs and inhibitory TINs in the VA-VL complex.(ABSTRACT TRUNCATED AT 400 WORDS)     

Human respiratory muscles: sensations, reflexes and fatiguability

1. Given the importance of the ventilatory 'pump' muscles, it would not be surprising if they were endowed with both sensory and motor specializations. The present review focuses on some unexpected properties of the respiratory muscle system in human subjects. 2. Although changes in blood gas tension were long held not to influence sensation directly, studies in subjects who are completely paralysed show that increases in arterial CO2 levels elicit strong sensations of respiratory discomfort. 3. Stretch reflexes in human limb muscles contain a monosynaptic spinal excitation and a long-latency excitation. However, inspiratory muscles show an initial inhibition when tested with brief airway occlusions during inspiration. This inhibition does not depend critically on input from pulmonary or upper airway receptors. 4. Human inspiratory muscles (including the diaphragm) have been considered to fatigue during inspiratory resistive loading. However, recent studies using phrenic nerve stimulation to test the force produced by the diaphragm show that carbon dioxide retention (hypoventilation) and voluntary cessation of loading occur before the muscles become overtly fatigued.     

Influence of multiple models on the behavior of institutionalized retarded children: increased generalization to other models and other behaviors

After being pretested to determine base levels of imitation, 32 9-14 yr old retarded children were reinforced for imitating a model in 9 training sessions. Ss in a single model condition were reinforced by the same model across all sessions, whereas Ss in a multiple model condition were reinforced by 3 different models (3 sessions per model). A posttest to assess levels of imitation was then conducted by a model with whom the Ss had not had contact and who demonstrated a new set of behaviors. Results during training sessions show that (a) Ss learned to imitate, and this learning was not inhibited by multiple models; and (b) Ss generalized and imitated nonreinforced behaviors, and this response generalization was facilitated by multiple models. Most importantly, pre-posttest comparisons indicated that generalized use of the new response class (imitation) with new models was 8 times greater for Ss trained with multiple as opposed to single models. Implications for the maintenance and generalized effectiveness of social intervention programs are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Gustatory functions, sodium appetite, and conditioned taste aversion survive excitotoxic lesions of the thalamic taste area

Rats with bilateral, electrophysiologically guided, ibotenic acid lesions of the gustatory thalamus (THLX) were tested for their ability to perform a variety of taste-guided behaviors. First, in daily 30-min sessions, the rats were given repeated 10-s access periods to a range of concentrations of sucrose, NaCl, or QHCl, plus water. Both the control and the THLX rats exhibited similar concentration-response functions, regardless of hydrational state. Next, on 3 trials, the rats were given 15 min access to 0.3 M l-alanine and then injected with LiCl (0.15 M, 1.33 ml/100 g body weight ip). All rats learned a taste aversion following 1 pairing with LiCl. Finally, on 3 separate occasions, the rats were injected with furosemide, and Na(+)-appetite was evaluated 24 hr later. All rats expressed an equivalent sodium appetite after the first furosemide injection, but only the control rats increased intake of 0.51 M NaCl with repeated sodium depletions. These observations reinforce prior data implying that an intact gustatory thalamus is not necessary for the expression of some taste-guided behaviors.     

Contribution of the rat's neocortex to ingestive control: I. Latent learning for the taste of sodium chloride.

Conducted 3 experiments with 13 decorticate and 12 control male Sprague-Dawley rats to investigate whether some permanent ingestive control deficit would be revealed in a latent learning paradigm for salt taste. The ability of Ss to associate how they obtained the taste of NaCl when Na-replete was assessed by examining barpresses during extinction when Na-depleted. Intact Ss exposed to 4–6 hrs of NaCl taste training retained the association after decortication; decorticate Ss exposed to the same training acquired the association. Decorticate Ss exposed to as little as 2 min of NaCl taste training demonstrated the ability to associate barpressing with NaCl by their resistance to extinction. This association was specific to NaCl training. It is concluded that subcortical structures are adequate for latent learning involving NaCl taste. Conversely, previous research has shown that the neocortex is required for the retention of taste-aversion learning for the same taste. (43 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The roles of thalamic nucleus submedius in nociception and pain modulation

Recent studies on the roles of thalamic nucleus submedius (Sm) in nociception and pain modulation were reviewed in this article in combination with own our works. Results of these studies showed that Sm may be involved in effective-motivational aspects of pain, and that Sm-VLO-PAG may constitute a pathway of nociceptive modulation which may depress the nociceptive inputs at the spinal cord level via the brain-stem descending inhibitory system, thereby mediate a negative feedback regulation of pain.     

Morphology of rats AV thalamic nucleus in light and electron microscopy

The structure of the rat's antero-ventral thalamic (AVTh) nucleus has been investigated in order to provide background information for the accompanying study in which an attempt was made to identify the synaptic terminals of the different afferent fiber systems to this nucleus by means of both EM autoradiography and the EM degeneration techniques. Nissl stained sections showed that the rat's AVTh nucleus contains mainly relatively light staining neurons which in Golgi material were found to possess tufted dendrites. In EM material three types of synaptic terminals were found which showed a topical distribution over the neuronal surface. Soma and stem dendrites carry a limited number of terminal with symmetrical synapses and flattened vesiclesmproximal dendrites carry mainly large asymmetrical synaptic terminals while distal dendrites are crowded with small asymmetrical synaptic terminals.     

Contralateral cortical projection to the mediodorsal thalamic nucleus: origin and synaptic organization in the rat

The origin of the corticothalamic projections to the contralateral mediodorsal nucleus, the collateralization of cortical fibers and their synaptic organization in the ipsi- and contralateral mediodorsal nuclei were investigated in adult rats with double retrograde fluorescent and anterograde tracing. After tracer injections in the mediodorsal nuclei on either side, neurons were retrogradely labeled in all the areas of the contralateral prefrontal cortex in which ipsilateral labeling was also observed. Contralateral corticothalamic cells accounted for 15% of the labeled neurons in the orbital and agranular insular areas, while their proportion was lower (3%) in the anterior cingulate cortex. Up to 70% of the contralateral cortical neurons were double labeled by bilateral injections in the mediodorsal nuclei. At the electron microscopic level, unilateral injections of biotinylated dextran-amine in the orbitofrontal cortex resulted in anterograde labeling of small terminals and a few large boutons in the ipsilateral mediodorsal nucleus, while only small boutons were identified contralaterally. The diameter of postsynaptic dendritic profiles contacted by labeled small cortical endings was significantly larger in the ipsilateral mediodorsal nucleus than contralaterally. These findings demonstrate that dense contralateral cortical projections to the mediodorsal nucleus derive from the orbital and agranular insular areas, and that crossed corticothalamic afferents are mostly formed by collaterals of the ipsilateral connections. Our observations also point out the heterogeneity of corticothalamic boutons in the rat mediodorsal nucleus and morphological differences in the synaptic organization of prefrontal fibers innervating the two sides, indicating that ipsilateral cortical afferents may be more proximally distributed than crossed cortical fibers on dendrites of mediodorsal neurons.     

GABAergic and pallidal terminals in the thalamic reticular nucleus of squirrel monkeys

The ultrastructure of synaptic terminals from the external segment of the globus pallidus and of other synaptic terminals positive for gamma-aminobutyric acid (GABA) was examined in the thalamic reticular nucleus (TRN) of squirrel monkeys. Two GABA-positive terminals types were commonly encountered within the TRN neuropil. The most common type of GABAergic terminals (F terminals) are filled with dispersed pleomorphic synaptic vesicles and clusters of mitochondria. These terminals establish multiple symmetric synapses upon the somata and dendrites of TRN neurons. The external pallidal terminals, labeled with WGA-HRP, arise from thinly myelinated axons and correspond to the medium to large F terminals. A less prevalent population of smaller GABAergic synaptic profiles was also identified. The synaptic profiles in this second group contain considerably fewer pleomorphic synaptic vesicles in small irregular clusters and fewer mitochondria, establish symmetric synapses, are postsynaptic to other axonal terminals, are presynaptic to dendrites and soma, and are unlabeled following pallidal injections of WGA-HRP.     

Limited access to a dietary fat option affects ingestive behavior but not body composition in male rats

Survival, recoverability and sublethal injury of two strains of Listeria monocytogenes, Scott A and an environmental strain KM, on exposure to sea water at 12.8 or 20.8 degrees C was determined using in situ diffusion chambers. Plate counts were used to assess recoverability and injury while 5-cyano-2,3-ditolyl tetrazolium chloride (CTC) reduction was used to determine respiratory activity. T90 values (times for 10-fold decreases in numbers of recoverable cells) on non-selective medium (trypticase soya agar with 0.6% yeast extract) at 12.8 and 20.8 degrees C were 61.7 and 69.2 h for L. monocytogenes Scott A, and 103.0 and 67.0 h for L. monocytogenes KM, respectively. On selective medium (Oxford agar), T90 values at 12.8 and 20.8 degrees C were 60.6 and 56.9 h for L. monocytogenes Scott A, and 83.0 and 65.9 h for L. monocytogenes KM, respectively. With Scott A, the percentage of sublethally injured cells at 12.8 and 20.8 degrees C was 1.7 and 17.7%, respectively, while for KM the values were 19.0 and 1.6%, respectively. The fraction of cells reducing CTC but which were not recoverable on plating progressively increased on exposure to sea water. Listeria monocytogenes KM challenged at 58 degrees C showed an apparent increase in heat resistance after exposure to sea water at 20.8 degrees C for 7 d (D58 = 2.64 min) compared with before exposure (D58 = 1.24). This increase in thermal resistance was not apparent at temperatures greater than 63 degrees C, and analysis of the best-fit regression lines fitted to the thermal data obtained from the two cell populations indicated that their thermal resistance was not significantly different (P > 0.05) over the temperature range tested (58-62 degrees C).     

Neurons in the human thalamic somatosensory nucleus (Ventralis caudalis) respond to innocuous cool and mechanical stimuli

A population of neurons in the principal somatosensory nucleus of human thalamus (ventralis caudalis, Vc) had a significant tonic, graded response to cool stimuli and also responded to innocuous mechanical stimuli (mechanical-cool neurons). These neurons were clustered at the dorsal aspect of medial Vc. Stimulation at the sites where these neurons were recorded evoked tingling sensations in the part of the body including or adjacent to the receptive field of these neurons. These neurons may contribute to the mechanism that mediates the perception of cold in man.