Prediction of plant species occurrence as affected by nitrogen deposition and climate change on a European scale.

Plant species occurrence in Europe is affected by changes in nitrogen deposition and climate. Insight into potential future effects of those changes can be derived by a model approach based on field-based empirical evidence on a continental scale. In this paper, we present a newly developed empirical model PROPS, predicting the occurrence probabilities of plant species in response to a combination of climatic factors, nitrogen deposition and soil properties. Parameters included were temperature, precipitation, nitrogen deposition, soil pH and soil C/N ratio. The PROPS model was fitted to plant species occurrence data of about 800,000 European relevés with estimated values for pH and soil C/N ratio and interpolated climate and modelled N deposition data obtained from the Ensemble meteo data set and EMEP model results, respectively. The model was validated on an independent data set. The test of ten species against field data gave an average Pearson's r-value of 0.79. PROPS was applied to a grassland and a heathland site to evaluate the effect of scenarios for nitrogen deposition and climate change on the Habitat Suitability Index (HSI), being the average of the relative probabilities, compared to the maximum probability, of all target species in a habitat. Results for the period 1930-2050 showed that an initial increase and later decrease in nitrogen deposition led to a pronounced decrease in HSI, and with dropping nitrogen deposition to an increase of the HSI. The effect of climate change appeared to be limited, resulting in a slight increase in HSI.

Development of a reactor for the in situ monitoring of 2D materials growth on liquid metal catalysts, using synchrotron x-ray scattering, Raman spectroscopy, and optical microscopy.

Liquid metal catalysts (LMCats) (e.g., molten copper) can provide a new mass-production method for two-dimensional materials (2DMs) (e.g., graphene) with significantly higher quality and speed and lower energy and material consumption. To reach such technological excellence, the physicochemical properties of LMCats and the growth mechanisms of 2DMs on LMCats should be investigated. Here, we report the development of a chemical vapor deposition (CVD) reactor which allows the investigation of ongoing chemical reactions on the surface of a molten metal at elevated temperatures and under reactive conditions. The surface of the molten metal is monitored simultaneously using synchrotron x-ray scattering, Raman spectroscopy, and optical microscopy, thereby providing complementary information about the atomic structure and chemical state of the surface. To enable in situ characterization on a molten substrate at high temperatures (e.g., ∼1370 K for copper), the optical and x-ray windows need to be protected from the evaporating LMCat, reaction products, and intense heat. This has been achieved by creating specific gas-flow patterns inside the reactor. The optimized design of the reactor has been achieved using multiphysics COMSOL simulations, which take into account the heat transfer, fluid dynamics, and transport of LMCat vapor inside the reactor. The setup has been successfully tested and is currently used to investigate the CVD growth of graphene on the surface of molten copper under pressures ranging from medium vacuum up to atmospheric pressure.

Fast and reliable pre-approach for scanning probe microscopes based on tip-sample capacitance.

Within the last three decades Scanning Probe Microscopy has been developed to a powerful tool for measuring surfaces and their properties on an atomic scale such that users can be found nowadays not only in academia but also in industry. This development is still pushed further by researchers, who continuously exploit new possibilities of this technique, as well as companies that focus mainly on the usability. However, although imaging has become significantly easier, the time required for a safe approach (without unwanted tip-sample contact) can be very time consuming, especially if the microscope is not equipped or suited for the observation of the tip-sample distance with an additional optical microscope. Here we show that the measurement of the absolute tip-sample capacitance provides an ideal solution for a fast and reliable pre-approach. The absolute tip-sample capacitance shows a generic behavior as a function of the distance, even though we measured it on several completely different setups. Insight into this behavior is gained via an analytical and computational analysis, from which two additional advantages arise: the capacitance measurement can be applied for observing, analyzing, and fine-tuning of the approach motor, as well as for the determination of the (effective) tip radius. The latter provides important information about the sharpness of the measured tip and can be used not only to characterize new (freshly etched) tips but also for the determination of the degradation after a tip-sample contact/crash.

Dissipation and resonance frequency shift of a resonator magnetically coupled to a semiclassical spin.

We calculate the change of the properties of a resonator, when coupled to a semiclassical spin by means of the magnetic field. Starting with the Lagrangian of the complete system, we provide an analytical expression for the linear response function for the motion in the case of a mechanical resonator and the current for the case of an electromagnetic resonator, thereby considering the influence of the resonator on the spin and vice versa. This analysis shows that the resonance frequency and effective dissipation factor can change significantly due to the relaxation times of the spin. We first derive this for a system consisting of a spin and mechanical resonator and thereafter apply the same calculations to an electromagnetic resonator. Moreover, the applicability of the method is generalized to a resonator coupled to two-level systems and more, providing a key to understand some of the problems of two-level systems in quantum devices.

A note on the definition and the development of cerebellar Purkinje cell zones.

The definition of Purkinje cell zones by their white matter compartments, their physiological properties, and their molecular identity and the birthdate of their Purkinje cells will be reviewed.

Cerebellum: history.

This paper will outline the history of study of the cerebellum from its beginnings to relatively recent times. Although there is no unanimous agreement about what the cerebellum does or how it does it, some principles of its structure and function are well understood. The historical approach can help to identify remaining questions and point the way to future progress. We make no effort to separate anatomical, physiological and clinical studies; rather, we hope to emphasize their interrelation. The cerebellum has always been seen as a distinct subdivision of the brain. Over the years there was an increasingly accurate description of its gross appearance and major subdivisions. By the beginning of the 19th century, the classical descriptive anatomical work was completed, and experimental study of the functions of the cerebellum began. Lesions were made in the cerebellum of experimental animals, and the behavioral deficits that were caused by the lesion were studied and described. These early animal studies powerfully influenced clinical interpretation of the symptoms seen in patients with cerebellar disease. Several questions are implicit in the anatomical and clinical studies of the nineteenth and early twentieth centuries, some of which remain incompletely answered. Many of these are addressed in other chapters in this volume. 1. Do different parts of the cerebellum do different things? The uniformity of the neuronal architecture of the cerebellar cortex suggests that each small region must operate in a similar way, but it is also clear that different regions control different functions. Is there a systematic sensory and/or body representation? 2. What are the functions of the cerebellar hemispheres? Massive in humans and very large in primates, their functions remain in dispute. Because the size of the cerebellar hemispheres parallels the development of the cerebral cortex, some have suggested that the hemispheres in humans and the higher primates may play a role in cognitive functions. 3. If one part of the cerebellum is damaged, can another part take over? A related question is whether normal motor function is possible in cases of complete or near-complete agenesis of the cerebellum. 4. What are the functions of the two distinctly different afferent systems to the cerebellum; the climbing and mossy fibers?

Equilibrium spherically curved two-dimensional Lennard-Jones systems.

To learn about the basic aspects of nanoscale spherical molecular shells during their formation, spherically curved two-dimensional N-particle Lennard-Jones systems are simulated, studying curvature evolution paths at zero temperature. For many N values (N<800) equilibrium configurations are traced as a function of the curvature radius R. Sharp jumps for tiny changes in R between trajectories with major differences in topological structure correspond to avalanche-like transitions. For a typical case, N=25, equilibrium configurations fall on smooth trajectories in state space which can be traced in the E-R plane. The trajectories show up with local energy minima, from which growth in N at steady curvature can develop.

Concurrent validity of a weight-bearing activity questionnaire in prepubertal and pubertal girls and boys.

OBJECTIVE: The purpose of this study was to evaluate the current validity of an interviewer-administered physical activity questionnaire against measurement of physical activity from vertical body accelerometer movements in prepubertal and pubertal children. METHODS: The Weight Bearing Activity Questionnaire for Kids (WBAQK) is an interviewer-administered questionnaire with a recall over 7 days and developed to assess weight-bearing activity in pre-pubertal and pubertal children. The Caltrac(TM) accelerometer was worn for 4-5 days (including 1 weekend day). Thirty-seven schoolgirls and 35 schoolboys participated, with a mean age of 11.2 0.3 years and 12.1 0.2 years, respectively. RESULTS: Weight-Bearing Score (WBS) and Metabolic Score (MS) derived from the WBAQK were significantly and positively related to the score of the Caltrac(TM). Weight-Bearing Score showed higher correlations in both boys (0.59) and girls (0.53) and slightly better compared to MS (0.54 and 0.35). The classification of boys and girls into high and low activity groups resulted also in a better agreement of WBS (71-72%) than of MS (60-67%) with Caltrac(TM). CONCLUSIONS: We conclude that the amount of weight-bearing activity can be estimated with the interviewer-administered WBAQK in boys and girls between 8 and 14 years of age.

Organization of projections from the inferior olive to the cerebellar nuclei in the rat.

The detailed organization of projections from the inferior olive to the cerebellar nuclei of the rat was studied by using anterograde tracing. The presence of a collateral projection to the cerebellar nuclei could be confirmed, and a detailed organization was recognized at the nuclear and subnuclear level. Olivary projections to the different parts of the medial cerebellar nucleus arise from various parts of the caudal half of the medial accessory olivary nucleus. The interstitial cell groups receive olivary afferents from the intermediate part of the medial accessory olive and from the dorsomedial cell column. A mediolateral topography was noted in the projections from the rostral half of the medial accessory olive to the posterior interposed nucleus. Olivary projections to the lateral cerebellar nucleus are derived from the principal olive according to basically inversed rostrocaudal topography. Projections from the dorsomedial group of the principal olive to the dorsolateral hump were found to follow a basically rostrocaudal topography. The anterior interposed nucleus receives olivary afferents from the dorsal accessory olive. Its rostromedial parts are directed to the lateral part of the anterior interposed nucleus and its caudolateral part reach the medial anterior interposed nucleus. No terminal arborizations in the cerebellar nuclei were found to originate from (1) the dorsal fold of the dorsal accessory olive, which resulted in projections to the lateral vestibular nucleus and (2) the dorsal cap of Kooy. It was noted that the olivary projection to the cerebellar nuclei is strictly reciprocal to the nucleo-olivary projection as described by Ruigrok and Voogd (1990). Moreover, it is suggested that the olivonuclear projection adheres to the organization of the climbing fiber projection to the cerebellar cortex and to the corticonuclear projection, thus, establishing and extending the detailed micromodular organization of the connections between inferior olive and cerebellum.

Topography of cerebellar nuclear projections to the brain stem in the rat.

The organization of the cerebellum is characterized by a number of parallel and parasagittally ordered olivocorticonuclear modules; as such, the cerebellar nuclei basically function as output system of these modules. The present study provides a comprehensive and detailed description of the organization of the connections from the cerebellar nuclei to the brain stem in the rat. Thirteen small injections with the anterograde tracer Phaseolus vulgaris leucoagglutinin or biotinylated dextran amine which were centered on various aspects of the cerebellar nuclear complex are described and are illustrated with serial plots detailing the distribution of labeled varicosities throughout the brain stem. In every case at least 1,000 an up to 36,000 varicosities were plotted. All injections resulted in some or heavy labeling concentrated within specific regions of the contralateral inferior olivary complex and, usually, in some labeling of the contralateral ventrolateral thalamus. However, apart from these two areas it is shown that the cerebellar projections are generally very widespread and may be found throughout the entire brain stem. Below, only a survey of main projection areas will be given. Terminal arborizations originating from the rostral part of the medial cerebellar nucleus are mostly found in the caudal half of the brain stem with emphasis on the vestibular nuclear complex, whereas its caudal part rather connects to midbrain areas. Terminals that originate from the dorsolateral protuberance of the medial cerebellar nucleus are distributed more evenly throughout the brain stem and are mostly confined to reticular areas. The interstitial cell groups, interspersed between the medial and both interposed cerebellar nuclei, provide major projections to the ipsilateral vestibular nuclear complex and contralateral mesodiencephalic regions. However, reticular areas are also targeted over a large rostrocaudal range. The medial part of the posterior interposed nucleus sends most projections to the caudomedial red nucleus, prerubral regions and parvicellular reticular formation, all contralateral to the injection site. Projections that originate from more laterally placed injections are directed, apart from the inferior olivary complex, to the rostral half of the contralateral brain stem, where most labeled varicosities are found in the superior colliculus and zona incerta. The anterior interposed nucleus specifically targets the inferior olive, the red nucleus, the pontine reticulotegmental nucleus, the prectectum and the ventrolateral thalamic nucleus. More laterally placed injections also project to the ipsilateral parvicellular reticular formation and deep layers of the spinal trigeminal complex. The latter areas are more specifically targeted by the dorsolateral hump. In addition, its projections are found in the red nucleus and pretectum but do not seem to reach the ventrolateral thalamus. Projections from the lateral cerebellar nucleus are all characterized by a widespread distribution of terminals. Especially, the caudal aspect of the nucleus sends, apart from projections to the deep mesencephalic nucleus, red nucleus, periaquaductal gray, pretectum, prerubral area, and several thalamic regions, prominent projections to the caudal brain stem which terminate in the inferior olive and gigantocellular reticular formation. Projections from the ventral, parvicellular part of the nucleus are mostly, but not exclusively, directed to the rostral half of the brain stem and mainly terminate in the pararubral area, accessory oculomotor nuclei, pretectal areas, zona incerta, and in the parafascicular and ventrolateral thalamic nuclei. We conclude that the impact of the cerebellar nuclei on the brain stem is widespread; projections from different regions of the same cerebellar nucleus may show important differences in distribution of labeled terminals. On the other hand, injections placed in different cerebellar nuclei may result in a simila

The anatomy of the cerebellum.

Vertebrate cerebella occupy a position in the rostral roof of the 4th ventricle and share a common pattern in the structure of their cortex. They differ greatly in their external form, the disposition of the neurones of the cerebellar cortex and in the prominence of their afferent, intrinsic and efferent connections.

Single Purkinje cell can innervate multiple classes of projection neurons in the cerebellar nuclei of the rat: a light microscopic and ultrastructural triple-tracer study in the rat.

Two different populations of projection neurons are intermingled in the cerebellar nuclei. One group consists of small, gamma-aminobutyric acid-containing (GABAergic) neurons that project to the inferior olive, and the other group consists of larger, non-GABAergic neurons that provide an input to one or more, usually premotor, centers in the brainstem, such as the red nucleus, the thalamus, and the superior colliculus. All cerebellar nuclear neurons are innervated by GABAergic Purkinje cells. In this study, we investigated whether individual Purkinje cells of the C1 zone of the paramedian lobe of the rat innervate both groups of projection neurons in the anterior interposed nucleus. Two different, retrogradely transported tracers, either cholera toxin beta subunit (CTb) or wheat germ agglutinin coupled to horseradish peroxidase (WGA-HRP) and a gold lectin tracer were injected into the red nucleus and the inferior olive, respectively, whereas Purkinje cell axons were anterogradely labeled with biotinylated dextran amine (BDA) injected into the paramedian lobule. Cerebellar nuclear sections studied with the light microscope demonstrated a close relation of varicosities from BDA-labeled Purkinje cell axons with both gold lectin- and CTb-labeled neurons. Branches of individual axons could be traced to both retrogradely labeled cell populations. At the ultrastructural level, synapses of labeled Purkinje cell terminals with profiles of WGA-HRP-labeled projection neurons predominated over contacts with gold lectin-containing neurons. Nine out of 367 investigated BDA-labeled terminals were observed to be presynaptic to a WGA-HRP-labeled profile as well as to a gold lectin-labeled profile. This indicates that nuclear cells that project to the inferior olive as well as those that project to premotor centers are under the influence of the same Purkinje cells. Such an arrangement would suggest an in-phase cortical modulation of the activation patterns of the inhibitory cells that project to the inferior olive and excitatory cells that project to premotor nuclei, which could explain why olivary neurons, especially those of the rostral part of the dorsal accessory olive, appear to be unresponsive to stimuli generated during active movement.

The anatomy of the cerebellum.

Vertebrate cerebella occupy a position in the rostral roof of the 4th ventricle and share a common pattern in the structure of their cortex. They differ greatly in their external form, the disposition of the neurons of the cerebellar cortex and in the prominence of their afferent, intrinsic and efferent connections.

Cholinergic innervation and receptors in the cerebellum.

We have studied the source and ultrastructural characteristics of ChAT-immunoreactive fibers in the cerebellum of the rat, and the distribution of muscarinic and nicotinic receptors in the cerebellum of the rat, rabbit, cat and monkey, in order to define which of the cerebellar afferents may use ACh as a neurotransmitter, what target structures are they, and which cholinergic receptor mediate the actions of these pathways. Our data confirm and extend previous observations that cholinergic markers occur at relatively low density in the cerebellum and show not only interspecies variability, but also heterogeneity between cerebellar lobules in the same species. As previously demonstrated by Barmack et al. (1992a,b), the predominant fiber system in the cerebellum that might use ACh as a transmitter or a co-transmitter is formed by mossy fibers originating in the vestibular nuclei and innervating the nodulus and ventral uvula. Our results show that these fibers innervate both granule cells and unipolar brush cells, and that the presumed cholinergic action of these fibers most likely is mediated by nicotinic receptors. In addition to cholinergic mossy fibers, the rat cerebellum is innervated by beaded ChAT-immunoreactive fibers. We have demonstrated that these fibers originate in the pedunculopontine tegmental nucleus (PPTg), the lateral paragigantocellular nucleus (LPGi), and to a lesser extent in various raphe nuclei. In both the cerebellar cortex and the cerebellar nuclei these fibers make asymmetric synaptic junctions with small and medium-sized dendritic profiles. Both muscarinic and nicotinic receptor could mediate the action of these diffuse beaded fibers. In the cerebellar nuclei the beaded cholinergic fibers form a moderately dense network, and could in principle have a significant effect on neuronal activity. For instance, the cholinergic fibers arising in the PPTg may modulate the excitability of the cerebellonuclear neurons in relation to sleep and arousal (e.g. McCormick, 1989). Studies on the distribution of cholinergic markers in the cerebellum have proven valuable besides the issue whether cholinergic mechanism play a role in the cerebellar circuitry, because they illustrate a complexity of the cerebellar anatomy that extends beyond its regular trilaminar and foliar arrangement. For instance, AChE histochemistry has been shown to preferentially stain the borders of white matter compartments (the 'raphes', Voogd, 1967), and therefore is useful in topographical analysis of the cortico-nuclear and olivocerebellar projections (Hess and Voogd, 1986; Tan et al., 1995; Voogd et al., 1996; see Voogd and Ruigrok, 1997, this Volume). ChAT-immunoreactivity, at least in rat, appears to be a good marker to outline the morphological heterogeneity of mossy fibers, and m2-immunocytochemistry could be used to label (subpopulations of) Golgi cells, subsets of mossy fibers and, in the rabbit, a specific subset of Purkinje cells (Jaarsma et al., 1995).

Structure and serotonin 5-HT2C receptor activity of ortho- and meta-substituted phenylpiperazines.

The structural characteristics of ortho- and meta-substituted phenylpiperazines have been investigated in order to understand their actions at the serotonin 5-HT2C receptor. The crystal structures of the 4-methylated analogues of two phenylpiperazines that are already known as 5-HT2C ligands, 1-(1-naphthyl)-4-methylpiperazine (1NMP) and 1-[(3-trifluoromethyl)phenyl]-4-methylpiperazine (TFMPMP), and those of two novel 5-HT2C ligands, 1-(2-methoxyphenyl)piperazine (oMPP) and 1-(3-methoxyphenyl)piperazine (mMPP), are determined. Molecular mechanics calculations are performed to calculate the energy profiles of six phenylpiperazines for rotation about the central phenyl-nitrogen bond. The activities of several phenylpiperazines, in combination with their crystal structures and conformational characteristics, lead to the hypothesis that the conformation for which the piperazine ring and the phenyl ring are approximately co-planar should be the 5-HT2C receptor 'activating' conformation. This hypothesis is then used to predict the activities of the two novel 5-HT2C ligands oMPP and mMPP. oMPP is predicted to be an antagonist at this receptor, whereas mMPP is predicted to be an agonist. As this prediction was confirmed by in vitro and in vivo tests, the proposed conformation is very likely to be responsible for the activation of the 5-HT2C receptor.

White matter of the cerebellum of the chicken (Gallus domesticus): a quantitative light and electron microscopic analysis of myelinated fibers and fiber compartments.

Low magnification light microscopic examination of the white matter in appropriately stained avian and mammalian cerebellum reveals a mediolateral succession in which areas of large, heavily myelinated fibers alternate with areas containing nearly exclusively small fibers. A large fiber accumulation (LFA) and its medially adjoining small fiber area (SFA) form a fiber compartment, which, with related parts of cortex and central nuclei, constitutes a so-called cerebellar module. The composition and the apparent mediolateral heterogeneity of cerebellar fiber compartments was quantified in the chicken by morphometrical analysis of myelinated fiber profiles in light (LM) and electron (EM) microscopic micrographs. In LM versus EM, approximately 37% of the myelinated fiber population is neglected. This deficit concerns profiles that are smaller than 1.2 micron2 (diameter < 1.2 microns). EM analysis is therefore considered a prerequisite and forms the main part of this study. The myelinated fiber population has a left-skewed log normal size distribution. Ninety-nine percent of the myelinated fibers fall within the range of 0.1 to 20 microns2 (diameter = 0.4-5.0 microns) and 90% are even smaller than 7 micron2 (diameter < 3.0 microns). Small fibers are abundant in both parts of the compartment. Statistical comparisons provide quantitative confirmation of the LM distinction of LFAs and SFAs. It appears, moreover, that, apart from typical LFAs and SFAs, transitional zones rather than sharp borders can be distinguished between the two. The medial border of the LFA appears to be more sharply defined than its lateral border. Distinct mediolateral fluctuations were found with respect to fiber density (166-243 fibers/1,000 microns2), mean profile area (2.4-4.0 microns2), and interspace (31-47%). These differences reflect the contrast between LFA (lower density, larger mean profile area) and SFA (higher density, smaller mean profile area). The interspace discriminates less well between LFA and SFA but is often smaller in the LFA and larger in the SFA. The presented quantitative characteristics of mediolateral heterogeneity in the cerebellar fiber layer can be used as reference for morphometric studies on the different fiber systems of the cerebellar white matter and the functional organization of the compartments.

Light-microscopic distribution and parasagittal organisation of muscarinic receptors in rabbit cerebellar cortex.

Recent studies on the effects of intrafloccular injections of muscarinic agonists and antagonists on compensatory eye movements in rabbit, indicate that muscarinic receptors may play a modulatory role in the rabbit cerebellar circuitry. It was previously demonstrated by Neustadt et al. (1988), that muscarinic receptors in rabbit cerebellar cortex are distributed into alternating longitudinal zones of very high and very low receptor density. In the present study, the zonal and cellular distribution of muscarinic receptors in the rabbit cerebellar cortex is investigated in detail using in vitro ligand autoradiography with the non-selective high-affinity antagonist [3H]quinuclidinyl benzilate (QNB), and the M2-specific antagonist [3H]AF-DX384, and immunocytochemistry with a monoclonal antibody specific for the cloned m2 muscarinic receptor protein. [3H]QNB and [3H]AF-DX384 binding sites and m2-immunoreactivity had similar overall distributions: dense labeling occurred in the dendritic arbors of a subset of Purkinje cells that are organized into parasagittal bands. A high level of muscarinic receptor labeling was also observed in a thin substratum of the molecular layer immediately above the Purkinje cell layer of the vestibulo-cerebellar lobules, i.e. the nodulus, the ventral uvula and the flocculus. Labeling in this stratum was associated with densely packed fibres, which were putatively identified as parallel fibres. Also Golgi cells, which were localized in part in the molecular layer, and a subset of mossy fibre rosettes, primarily concentrated in lobule VI, were immunoreactive for the m2 receptor. The parasagittal band of labeled Purkinje cell dendrites were most prominent in the anterior lobe (lobules I-V), in crus 1 and 2, in the flocculus, the ventral paraflocculus and the rostral folium of the nodulus. In other lobules, only infrequent Purkinje cells contained muscarinic receptors. The parasagittal organisation of muscarinic receptors differed from that of zebrin I, a Purkinje cell-specific protein which is often used as a marker of parasagittal parcelation of the cerebellar cortex. In the anterior lobe, however, there was a partial correspondence between muscarinic receptor and zebrin I bands. In the flocculus the distribution of muscarinic-receptor-positive Purkinje cells was related to the distinct white matter compartments as revealed with acetylcholinesterase (AChE) histochemistry. Muscarinic receptor-containing Purkinje cells were located primarily in the floccular zone 1, which is implicated in the control of eye movements about a horizontal axis. In order to relate the distribution of muscarinic receptor labeling to that of cholinergic nerve terminals, [3H]QNB binding sites and sodium-dependent [3H]hemicholinium-3 binding were compared. Sodium-dependent [3H]hemicholinium-3 binding sites mainly occurred in the granule cell layer of the vestibulo-cerebellum, which corresponds well with the distribution of the acetylcholine synthesizing enzyme, choline acetyltransferase (ChAT). However, sodium-dependent [3H]hemicholinium binding complemented, rather than co-localized with, muscarinic receptors which were primarily distributed in the molecular layer of the lobules of the vestibulo-cerebellar lobules. Their functional significance is puzzling, since their distribution does not correspond to that of markers of cholinergic innervation.