1
|
Chong MHY, Worthy KH, Rosa MGP, Atapour N. Neuronal density and expression of calcium-binding proteins across the layers of the superior colliculus in the common marmoset (Callithrix jacchus). J Comp Neurol 2022; 530:2966-2976. [PMID: 35833512 PMCID: PMC9796076 DOI: 10.1002/cne.25388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Revised: 06/17/2022] [Accepted: 06/29/2022] [Indexed: 12/30/2022]
Abstract
The superior colliculus (SC) is a layered midbrain structure with functions that include polysensory and sensorimotor integration. Here, we describe the distribution of different immunohistochemically identified classes of neurons in the SC of adult marmoset monkeys (Callithrix jacchus). Neuronal nuclei (NeuN) staining was used to determine the overall neuronal density in the different SC layers. In addition, we studied the distribution of neurons expressing different calcium-binding proteins (calbindin [CB], parvalbumin [PV] and calretinin [CR]). Our results indicate that neuronal density in the SC decreases from superficial to deep layers. Although the neuronal density within the same layer varies little across the mediolateral axis, it tends to be lower at rostral levels, compared to caudal levels. Cells expressing different calcium-binding proteins display differential gradients of density according to depth. Both CB- and CR-expressing neurons show markedly higher densities in the stratum griseum superficiale (SGS), compared to the stratum opticum and intermediate and deep layers. However, CR-expressing neurons are twice as common as CB-expressing neurons outside the SGS. The distribution of PV-expressing cells follows a shallow density gradient from superficial to deep layers. When normalized relative to total neuronal density, the proportion of CR-expressing neurons increases between the superficial and intermediate layers, whereas that of CB-expressing neurons declines toward the deep layers. The proportion of PV-expressing neurons remains constant across layers. Our data provide layer-specific and accurate estimates of neuronal density, which may be important for the generation of biophysical models of how the primate SC transforms sensory inputs into motor signals.
Collapse
Affiliation(s)
- Melissa H. Y. Chong
- Department of Physiology and Neuroscience ProgramBiomedicine Discovery InstituteMonash UniversityMelbourneAustralia
| | - Katrina H. Worthy
- Department of Physiology and Neuroscience ProgramBiomedicine Discovery InstituteMonash UniversityMelbourneAustralia
| | - Marcello G. P. Rosa
- Department of Physiology and Neuroscience ProgramBiomedicine Discovery InstituteMonash UniversityMelbourneAustralia
| | - Nafiseh Atapour
- Department of Physiology and Neuroscience ProgramBiomedicine Discovery InstituteMonash UniversityMelbourneAustralia
| |
Collapse
|
2
|
Villalobos CA, Wu Q, Lee PH, May PJ, Basso MA. Parvalbumin and GABA Microcircuits in the Mouse Superior Colliculus. Front Neural Circuits 2018; 12:35. [PMID: 29780307 PMCID: PMC5946669 DOI: 10.3389/fncir.2018.00035] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Accepted: 04/16/2018] [Indexed: 11/13/2022] Open
Abstract
The mammalian superior colliculus (SC) is a sensorimotor midbrain structure responsible for orienting behaviors. Although many SC features are known, details of its intrinsic microcircuits are lacking. We used transgenic mice expressing reporter genes in parvalbumin-positive (PV+) and gamma aminobutyric acid-positive (GABA+) neurons to test the hypothesis that PV+ neurons co-localize GABA and form inhibitory circuits within the SC. We found more PV+ neurons in the superficial compared to the intermediate SC, although a larger percentage of PV+ neurons co-expressed GABA in the latter. Unlike PV+ neurons, PV+/GABA+ neurons showed predominantly rapidly inactivating spiking patterns. Optogenetic activation of PV+ neurons revealed direct and feedforward GABAergic inhibitory synaptic responses, as well as excitatory glutamatergic synapses. We propose that PV+ neurons in the SC may be specialized for a variety of circuit functions within the SC rather than forming a homogeneous, GABAergic neuronal subtype as they appear to in other regions of the brain.
Collapse
Affiliation(s)
- Claudio A Villalobos
- Fuster Laboratory of Cognitive Neuroscience, Department of Psychiatry and Biobehavioral Sciences - Department of Neurobiology, Semel Institute for Neuroscience and Human Behavior - Brain Research Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, United States
| | - Qiong Wu
- Fuster Laboratory of Cognitive Neuroscience, Department of Psychiatry and Biobehavioral Sciences - Department of Neurobiology, Semel Institute for Neuroscience and Human Behavior - Brain Research Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, United States
| | - Psyche H Lee
- Fuster Laboratory of Cognitive Neuroscience, Department of Psychiatry and Biobehavioral Sciences - Department of Neurobiology, Semel Institute for Neuroscience and Human Behavior - Brain Research Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, United States
| | - Paul J May
- Department of Neurobiology and Anatomical Sciences, University of Mississippi Medical Center, Jackson, MS, United States
| | - Michele A Basso
- Fuster Laboratory of Cognitive Neuroscience, Department of Psychiatry and Biobehavioral Sciences - Department of Neurobiology, Semel Institute for Neuroscience and Human Behavior - Brain Research Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, United States
| |
Collapse
|
3
|
Loureiro JR, Himmelbach M, Ethofer T, Pohmann R, Martin P, Bause J, Grodd W, Scheffler K, Hagberg GE. In-vivo quantitative structural imaging of the human midbrain and the superior colliculus at 9.4T. Neuroimage 2018; 177:117-128. [PMID: 29729391 DOI: 10.1016/j.neuroimage.2018.04.071] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Revised: 03/29/2018] [Accepted: 04/30/2018] [Indexed: 01/24/2023] Open
Abstract
We explored anatomical details of the superior colliculus (SC) by in vivo magnetic resonance imaging (MRI) at 9.4T. The high signal-to-noise ratio allowed the acquisition of high resolution, multi-modal images with voxel sizes ranging between 176 × 132 × 600 μm and (800)3μm. Quantitative mapping of the longitudinal relaxation rate R1, the effective transverse relaxation rate R2*, and the magnetic susceptibility QSM was performed in 14 healthy volunteers. The images were analyzed in native space as well as after normalization to a common brain space (MNI). The coefficient-of-variation (CoV) across subjects was evaluated in prominent regions of the midbrain, reaching the best reproducibility (CoV of 5%) in the R2* maps of the SC in MNI space, while the CoV in the QSM maps remained high regardless of brain-space. To investigate whether more complex neurobiological architectural features could be detected, depth profiles through the SC layers towards the red nucleus (RN) were evaluated at different levels of the SC along the rostro-caudal axis. This analysis revealed alterations of the quantitative MRI parameters concordant with previous post mortem histology studies of the cyto- and myeloarchitecture of the SC. In general, the R1 maps were hyperintense in areas characterized by the presence of abundant myelinated fibers, and likely enabled detection of the deep white layer VII of the SC adjacent to the periaqueductal gray. While R1 maps failed to reveal finer details, possibly due to the relatively coarse spatial sampling used for this modality, these could be recovered in R2* maps and in QSM. In the central part of the SC along its rostro-caudal axis, increased R2* values and decreased susceptibility values were observed 2 mm below the SC surface, likely reflecting the myelinated fibers in the superficial optic layer (layer III). Towards the deeper layers, a second increase in R2* was paralleled by a paramagnetic shift in QSM suggesting the presence of an iron-rich layer about 3 mm below the surface of the SC, attributed to the intermediate gray layer (IV) composed of multipolar neurons. These results dovetail observations in histological specimens and animal studies and demonstrate that high-resolution multi-modal MRI at 9.4T can reveal several microstructural features of the SC in vivo.
Collapse
Affiliation(s)
- Joana R Loureiro
- High Field Magnetic Resonance Max Planck Institute for Biological Cybernetics, Tübingen, Germany; Institute for Biomedical Magnetic Resonance, Eberhard Karl's University, Tübingen and University Hospital Tübingen, Germany; Division of Neuropsychology, Centre for Neurology, Hertie-Institute for Clinical Brain Research, Germany; Centre for Integrative Neurosciences, Eberhard Karl's University, Tübingen, Germany
| | - Marc Himmelbach
- Division of Neuropsychology, Centre for Neurology, Hertie-Institute for Clinical Brain Research, Germany
| | - Thomas Ethofer
- Institute for Biomedical Magnetic Resonance, Eberhard Karl's University, Tübingen and University Hospital Tübingen, Germany; Department of General Psychiatry and Psychotherapy, Eberhard Karl's University, Tübingen and University Hospital Tübingen, Germany; Centre for Integrative Neurosciences, Eberhard Karl's University, Tübingen, Germany
| | - Rolf Pohmann
- High Field Magnetic Resonance Max Planck Institute for Biological Cybernetics, Tübingen, Germany
| | - Pascal Martin
- Department of General Psychiatry and Psychotherapy, Eberhard Karl's University, Tübingen and University Hospital Tübingen, Germany
| | - Jonas Bause
- High Field Magnetic Resonance Max Planck Institute for Biological Cybernetics, Tübingen, Germany
| | - Wolfgang Grodd
- High Field Magnetic Resonance Max Planck Institute for Biological Cybernetics, Tübingen, Germany
| | - Klaus Scheffler
- High Field Magnetic Resonance Max Planck Institute for Biological Cybernetics, Tübingen, Germany; Institute for Biomedical Magnetic Resonance, Eberhard Karl's University, Tübingen and University Hospital Tübingen, Germany; Centre for Integrative Neurosciences, Eberhard Karl's University, Tübingen, Germany
| | - Gisela E Hagberg
- High Field Magnetic Resonance Max Planck Institute for Biological Cybernetics, Tübingen, Germany; Institute for Biomedical Magnetic Resonance, Eberhard Karl's University, Tübingen and University Hospital Tübingen, Germany.
| |
Collapse
|
4
|
Functional Organization and Dynamic Activity in the Superior Colliculus of the Echolocating Bat, Eptesicus fuscus. J Neurosci 2018; 38:245-256. [PMID: 29180610 DOI: 10.1523/jneurosci.1775-17.2017] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2017] [Revised: 10/16/2017] [Accepted: 11/03/2017] [Indexed: 12/11/2022] Open
Abstract
Sensory-guided behaviors require the transformation of sensory information into task-specific motor commands. Prior research on sensorimotor integration has emphasized visuomotor processes in the context of simplified orienting movements in controlled laboratory tasks rather than an animal's more complete, natural behavioral repertoire. Here, we conducted a series of neural recording experiments in the midbrain superior colliculus (SC) of echolocating bats engaged in a sonar target-tracking task that invoked dynamic active sensing behaviors. We hypothesized that SC activity in freely behaving animals would reveal dynamic shifts in neural firing patterns within and across sensory, sensorimotor, and premotor layers. We recorded neural activity in the SC of freely echolocating bats (three females and one male) and replicated the general trends reported in other species with sensory responses in the dorsal divisions and premotor activity in ventral divisions of the SC. However, within this coarse functional organization, we discovered that sensory and motor neurons are comingled within layers throughout the volume of the bat SC. In addition, as the bat increased pulse rate adaptively to increase resolution of the target location with closing distance, the activity of sensory and vocal premotor neurons changed such that auditory response times decreased, and vocal premotor lead times shortened. This finding demonstrates that SC activity can be modified dynamically in concert with adaptive behaviors and suggests that an integrated functional organization within SC laminae supports rapid and local integration of sensory and motor signals for natural, adaptive behaviors.SIGNIFICANCE STATEMENT Natural sensory-guided behaviors involve the rapid integration of information from the environment to direct flexible motor actions. The vast majority of research on sensorimotor integration has used artificial stimuli and simplified behaviors, leaving open questions about nervous system function in the context of natural tasks. Our work investigated mechanisms of dynamic sensorimotor feedback control by analyzing patterns of neural activity in the midbrain superior colliculus (SC) of an echolocating bat tracking and intercepting moving prey. Recordings revealed that sensory and motor neurons comingle within laminae of the SC to support rapid sensorimotor integration. Further, we discovered that neural activity in the bat SC changes with dynamic adaptations in the animal's echolocation behavior.
Collapse
|
5
|
Veale R, Hafed ZM, Yoshida M. How is visual salience computed in the brain? Insights from behaviour, neurobiology and modelling. Philos Trans R Soc Lond B Biol Sci 2017; 372:20160113. [PMID: 28044023 PMCID: PMC5206280 DOI: 10.1098/rstb.2016.0113] [Citation(s) in RCA: 86] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/07/2016] [Indexed: 01/07/2023] Open
Abstract
Inherent in visual scene analysis is a bottleneck associated with the need to sequentially sample locations with foveating eye movements. The concept of a 'saliency map' topographically encoding stimulus conspicuity over the visual scene has proven to be an efficient predictor of eye movements. Our work reviews insights into the neurobiological implementation of visual salience computation. We start by summarizing the role that different visual brain areas play in salience computation, whether at the level of feature analysis for bottom-up salience or at the level of goal-directed priority maps for output behaviour. We then delve into how a subcortical structure, the superior colliculus (SC), participates in salience computation. The SC represents a visual saliency map via a centre-surround inhibition mechanism in the superficial layers, which feeds into priority selection mechanisms in the deeper layers, thereby affecting saccadic and microsaccadic eye movements. Lateral interactions in the local SC circuit are particularly important for controlling active populations of neurons. This, in turn, might help explain long-range effects, such as those of peripheral cues on tiny microsaccades. Finally, we show how a combination of in vitro neurophysiology and large-scale computational modelling is able to clarify how salience computation is implemented in the local circuit of the SC.This article is part of the themed issue 'Auditory and visual scene analysis'.
Collapse
Affiliation(s)
- Richard Veale
- Department of System Neuroscience, National Institute for Physiological Sciences, Okazaki, Japan
| | - Ziad M Hafed
- Physiology of Active Vision Laboratory, Werner Reichardt Centre for Integrative Neuroscience, University of Tuebingen, Tuebingen, Germany
| | - Masatoshi Yoshida
- Department of System Neuroscience, National Institute for Physiological Sciences, Okazaki, Japan
- School of Life Science, The Graduate University for Advanced Studies, Hayama, Japan
| |
Collapse
|
6
|
Aparicio MA, Saldaña E. The dorsal tectal longitudinal column (TLCd): a second longitudinal column in the paramedian region of the midbrain tectum. Brain Struct Funct 2013; 219:607-30. [PMID: 23468089 PMCID: PMC3933748 DOI: 10.1007/s00429-013-0522-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2012] [Accepted: 02/08/2013] [Indexed: 11/03/2022]
Abstract
The tectal longitudinal column (TLC) is a longitudinally oriented, long and narrow nucleus that spans the paramedian region of the midbrain tectum of a large variety of mammals (Saldaña et al. in J Neurosci 27:13108–13116, 2007). Recent analysis of the organization of this region revealed another novel nucleus located immediately dorsal, and parallel, to the TLC. Because the name “tectal longitudinal column” also seems appropriate for this novel nucleus, we suggest the TLC described in 2007 be renamed the “ventral tectal longitudinal column (TLCv)”, and the newly discovered nucleus termed the “dorsal tectal longitudinal column (TLCd)”. This work represents the first characterization of the rat TLCd. A constellation of anatomical techniques was used to demonstrate that the TLCd differs from its surrounding structures (TLCv and superior colliculus) cytoarchitecturally, myeloarchitecturally, neurochemically and hodologically. The distinct expression of vesicular amino acid transporters suggests that TLCd neurons are GABAergic. The TLCd receives major projections from various areas of the cerebral cortex (secondary visual mediomedial area, and granular and dysgranular retrosplenial cortices) and from the medial pretectal nucleus. It densely innervates the ipsilateral lateral posterior and laterodorsal nuclei of the thalamus. Thus, the TLCd is connected with vision-related neural centers. The TLCd may be unique as it constitutes the only known nucleus made of GABAergic neurons dedicated to providing massive inhibition to higher order thalamic nuclei of a specific sensory modality.
Collapse
Affiliation(s)
- M-Auxiliadora Aparicio
- Department of Cell Biology and Pathology, Medical School, University of Salamanca, 37007, Salamanca, Spain
| | | |
Collapse
|
7
|
Abstract
AbstractThe superior colliculus exerts its most direct influence over orienting movements, and saccades in particular, via its descending projections to the brain stem and spinal cord. However, while there is detailed physiological data concerning the generation of saccade-related activity in the primate superior colliculus, there is relatively little data on the detailed connectivity of this structure in primates. Consequently, retrograde transport techniques were utilized to determine the locations of the cells of origin of these descending pathways in macaque monkeys. Tectal cells that projected to the ipsilateral pontine reticular formation were mainly found in the deep gray layer and occasionally in the intermediate gray layer. Tectal cells that projected to the contralateral pontine reticular formation were predominantly located in the intermediate gray layer. The contralaterally projecting population could be subdivided into two groups. The cells in upper sublamina of the intermediate gray layer project primarily to the saccade-related regions of the paramedian reticular formation. Cells in the lower sublamina project primarily to more lateral regions of the pontine reticular formation and to the spinal cord. We conclude that the primate colliculus is provided with at least three descending output channels, which are likely to differ in their connections and functions. Specifically, it seems likely that the lower portion of the intermediate gray layer may be specialized to subserve combined head and eye orienting movements, while the upper sublamina subserves saccades.
Collapse
Affiliation(s)
- P J May
- Department of Anatomy, University of Mississippi Medical Center, Jackson 39216-4505
| | | |
Collapse
|
8
|
May PJ, McHaffie JG, Stanford TR, Jiang H, Costello MG, Coizet V, Hayes LM, Haber SN, Redgrave P. Tectonigral projections in the primate: a pathway for pre-attentive sensory input to midbrain dopaminergic neurons. Eur J Neurosci 2009; 29:575-87. [PMID: 19175405 DOI: 10.1111/j.1460-9568.2008.06596.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Much of the evidence linking the short-latency phasic signaling of midbrain dopaminergic neurons with reward-prediction errors used in learning and habit formation comes from recording the visual responses of monkey dopaminergic neurons. However, the information encoded by dopaminergic neuron activity is constrained by the qualities of the afferent visual signals made available to these cells. Recent evidence from rats and cats indicates the primary source of this visual input originates subcortically, via a direct tectonigral projection. The present anatomical study sought to establish whether a direct tectonigral projection is a significant feature of the primate brain. Injections of anterograde tracers into the superior colliculus of macaque monkeys labelled terminal arbors throughout the substantia nigra, with the densest terminations in the dorsal tier. Labelled boutons were found in close association (possibly indicative of synaptic contact) with ventral midbrain neurons staining positively for the dopaminergic marker tyrosine hydroxylase. Injections of retrograde tracer confined to the macaque substantia nigra retrogradely labelled small- to medium-sized neurons in the intermediate and deep layers of the superior colliculus. Together, these data indicate that a direct tectonigral projection is also a feature of the monkey brain, and therefore likely to have been conserved throughout mammalian evolution. Insofar as the superior colliculus is configured to detect unpredicted, biologically salient, sensory events, it may be safer to regard the phasic responses of midbrain dopaminergic neurons as 'sensory prediction errors' rather than 'reward prediction errors', in which case dopamine-based theories of reinforcement learning will require revision.
Collapse
Affiliation(s)
- Paul J May
- Department of Anatomy, Ophthalmology & Neurology, University of Mississippi Medical Center, Jackson, MS, USA.
| | | | | | | | | | | | | | | | | |
Collapse
|
9
|
Fuentes-Santamaria V, Alvarado JC, Stein BE, McHaffie JG. Cortex contacts both output neurons and nitrergic interneurons in the superior colliculus: direct and indirect routes for multisensory integration. Cereb Cortex 2007; 18:1640-52. [PMID: 18003596 DOI: 10.1093/cercor/bhm192] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The ability of cat superior colliculus (SC) neurons to integrate information from different senses is thought to depend on direct projections from regions along the anterior ectosylvian sulcus (AES). However, electrical stimulation of AES also activates SC output neurons polysynaptically. In the present study, we found that nitric oxide (NO)-containing (nitrergic) interneurons are a target of AES projections, forming a component of this cortico-SC circuitry. The dendritic and axonal processes of these corticorecipient nitrergic interneurons apposed the soma and dendrites of presumptive SC output neurons. Often, an individual cortical fiber targeted both an output neuron and a neighboring nitrergic interneuron that, in turn, contacted the output neuron. Many (46%) nitrergic neurons also colocalized with gamma-aminobutyric acid (GABA), suggesting that a substantial subset have the potential for inhibiting output neurons. These observations suggest that nitrergic interneurons are positioned to convey cortical influences onto SC output neurons disynaptically via nitrergic mechanisms as well as conventional neurotransmitter systems utilizing GABA and other, possibly excitatory, neurotransmitters. In addition, because NO also acts as a retrograde messenger, cortically mediated NO release from the postsynaptic elements of nitrergic interneurons could influence presynaptic cortico-SC terminals that directly contact output neurons.
Collapse
Affiliation(s)
- Veronica Fuentes-Santamaria
- Department of Neurobiology and Anatomy, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA.
| | | | | | | |
Collapse
|
10
|
Lindsey JD, Scadeng M, Dubowitz DJ, Crowston JG, Weinreb RN. Magnetic resonance imaging of the visual system in vivo: Transsynaptic illumination of V1 and V2 visual cortex. Neuroimage 2007; 34:1619-26. [PMID: 17204432 DOI: 10.1016/j.neuroimage.2006.07.048] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2005] [Revised: 07/12/2006] [Accepted: 07/12/2006] [Indexed: 10/23/2022] Open
Abstract
Brain nuclei directly receiving retinal projections are readily labeled in magnetic resonance images following intraocular injection of manganese (Mn). To assess whether Mn in retinal ganglion cell axons can be transsynaptically delivered to visual cortex, mice that had previously received intraocular Mn injection were anesthetized with isoflurane, and T1-weighted data sets were acquired of the eyes and brain using a 7-T magnetic resonance imaging machine. Image intensity within contralateral brain structures was evaluated by assessing 1) signal-to-noise ratios, 2) mean image intensity, and 3) mean image intensity normalized to facial muscle intensity. Image intensity was increased throughout the visual pathway including within contralateral visual cortex areas V1 and V2L. Mean normalized image intensity was greater by 53% in the ipsilateral optic nerve and by 31% and 28% in the contralateral lateral geniculate nucleus and superior colliculus, respectively (N=5, P<0.02, paired t test). In contralateral visual cortex areas V1 and V2L, image intensity was increased by 7.5% and 6.8%, respectively (P<0.02 for both, paired t test). Power analysis of the different evaluation methods yielded evidence of superior sensitivity using the normalization method. Reconstruction of the visual system based upon threshold analysis allowed simultaneous visualization of all portions of the major retinal projections to the brain. These results support use of high magnetic field MRI imaging and data normalization for in vivo quantitative analysis of the mouse brain visual system including visual cortex.
Collapse
Affiliation(s)
- James D Lindsey
- Sophie and Arthur Brody Optic Nerve Laboratory, Hamilton Glaucoma Center, Department of Ophthalmology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0946, USA.
| | | | | | | | | |
Collapse
|
11
|
Lee JY, Choi JS, Ahn CH, Kim IS, Ha JH, Jeon CJ. Calcium-binding protein calretinin immunoreactivity in the dog superior colliculus. Acta Histochem Cytochem 2006; 39:125-38. [PMID: 17327899 PMCID: PMC1698867 DOI: 10.1267/ahc.06008] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2006] [Accepted: 08/04/2006] [Indexed: 01/01/2023] Open
Abstract
We studied calretinin-immunoreactive (IR) fibers and cells in the canine superior colliculus (SC) and studied the distribution and effect of enucleation on the distribution of this protein. Localization of calretinin was immunocytochemically observed. A dense plexus of anti-calretinin-IR fibers was found within the upper part of the superficial gray layer (SGL). Almost all of the labeled fibers were small in diameter with few varicosities. The intermediate and deep layers contained many calretinin-IR neurons. Labeled neurons within the intermediate gray layer (IGL) formed clusters in many sections. By contrast, labeled neurons in the deep gray layer (DGL) did not form clusters. Calretinin-IR neurons in the IGL and DGL varied in morphology and included round/oval, vertical fusiform, stellate, and horizontal neurons. Neurons with varicose dendrites were also labeled in the IGL. Most of the labeled neurons were small to medium in size. Monocular enucleation produced an almost complete reduction of calretinin-IR fibers in the SC contralateral to the enucleation. However, many calretinin-IR cells appeared in the contralateral superficial SC. Enucleation appeared to have no effect on the distribution of calretinin-IR neurons in the contralateral intermediate and deep layers of the SC. The calretinin-IR neurons in the superficial dog SC were heterogeneous small- to medium-sized neurons including round/oval, vertical fusiform, stellate, pyriform, and horizontal in shape. Two-color immunofluorescence revealed that no cells in the dog SC expressed both calretinin and GABA. Many horseradish peroxidase (HRP)-labeled retinal ganglion cells were seen after injections into the superficial layers. The vast majority of the double-labeled cells (HRP and calretinin) were small cells. The present results indicate that antibody to calretinin labels subpopulations of neurons in the dog SC, which do not express GABA. The results also suggest that the calretinin-IR afferents in the superficial layers of the dog SC originate from small class retinal ganglion cells. The expression of calretinin might be changed by the cellular activity of selective superficial collicular neurons. These results are valuable in delineating the basic neurochemical architecture of the dog visual system.
Collapse
Affiliation(s)
- Jea-Young Lee
- Department of Biology, College of Natural Sciences, Kyungpook National University
| | - Jae-Sik Choi
- Department of Biology, College of Natural Sciences, Kyungpook National University
| | - Chang-Hyun Ahn
- Department of Biology, College of Natural Sciences, Kyungpook National University
| | - In-Suk Kim
- Department of Ophthalmic Optics, Chodang University
| | - Ji-Hong Ha
- Department of Genetic Engineering, College of Natural Sciences, Kyungpook National University
| | - Chang-Jin Jeon
- Department of Biology, College of Natural Sciences, Kyungpook National University
- Correspondence to: Prof. Chang-Jin Jeon, Ph.D., Department of Biology, College of Natural Sciences, Kyungpook National University, 1370 Sankyuk-dong, Daegu, 702–701, S. Korea. E-mail:
| |
Collapse
|
12
|
May PJ. The mammalian superior colliculus: laminar structure and connections. PROGRESS IN BRAIN RESEARCH 2006; 151:321-78. [PMID: 16221594 DOI: 10.1016/s0079-6123(05)51011-2] [Citation(s) in RCA: 452] [Impact Index Per Article: 25.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The superior colliculus is a laminated midbrain structure that acts as one of the centers organizing gaze movements. This review will concentrate on sensory and motor inputs to the superior colliculus, on its internal circuitry, and on its connections with other brainstem gaze centers, as well as its extensive outputs to those structures with which it is reciprocally connected. This will be done in the context of its laminar arrangement. Specifically, the superficial layers receive direct retinal input, and are primarily visual sensory in nature. They project upon the visual thalamus and pretectum to influence visual perception. These visual layers also project upon the deeper layers, which are both multimodal, and premotor in nature. Thus, the deep layers receive input from both somatosensory and auditory sources, as well as from the basal ganglia and cerebellum. Sensory, association, and motor areas of cerebral cortex provide another major source of collicular input, particularly in more encephalized species. For example, visual sensory cortex terminates superficially, while the eye fields target the deeper layers. The deeper layers are themselves the source of a major projection by way of the predorsal bundle which contributes collicular target information to the brainstem structures containing gaze-related burst neurons, and the spinal cord and medullary reticular formation regions that produce head turning.
Collapse
Affiliation(s)
- Paul J May
- Department of Anatomy, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS 39216, USA.
| |
Collapse
|
13
|
Sooksawate T, Saito Y, Isa T. Electrophysiological and morphological properties of identified crossed tecto-reticular neurons in the rat superior colliculus. Neurosci Res 2005; 52:174-84. [PMID: 15893578 DOI: 10.1016/j.neures.2005.03.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2004] [Revised: 03/05/2005] [Accepted: 03/10/2005] [Indexed: 11/22/2022]
Abstract
Previously we classified randomly sampled neurons in the intermediate layer (SI) of the rat superior colliculus (SC) into six subclasses according to their firing responses to depolarizing current pulses and five subclasses based on their morphological properties in slice preparations. In the present study, we investigated properties of a major output cell group of the rat SC (PND 17-24), crossed tecto-reticular neurons (cTRNs), which project to the contralateral medial pontine reticular formation. The cTRNs were identified by retrograde labeling with a fluorescent tracer (n=112). We compared their properties with those of presumed interneurons (n=127). We found that a majority of cTRNs were regular spiking neurons with moderate firing frequency (73%) and were multipolar-shaped (66%). The cTRNs had larger membrane capacitance, larger soma size and lower input impedance than presumed interneurons. Electrical stimulation of the superficial gray layer induced oligosynaptic EPSPs in the cTRNs. When bicuculline was added to the extracellular solution, the EPSPs were markedly enhanced and bursting spike responses were induced. The bursting responses were suppressed by applying D-2-amino-5-phosphonovalerate. These results suggest that the cTRNs exhibit NMDA receptor-dependent bursting responses to visual inputs. These observations give insights into the neuronal mechanism of generating burst activity in cTRNs, which triggers orienting behaviors.
Collapse
Affiliation(s)
- Thongchai Sooksawate
- Department of Developmental Physiology, National Institute for Physiological Sciences, Myodaiji, Okazaki 444-8585, Japan
| | | | | |
Collapse
|
14
|
Grantyn A, Brandi AM, Dubayle D, Graf W, Ugolini G, Hadjidimitrakis K, Moschovakis A. Density gradients of trans-synaptically labeled collicular neurons after injections of rabies virus in the lateral rectus muscle of the rhesus monkey. J Comp Neurol 2002; 451:346-61. [PMID: 12210129 DOI: 10.1002/cne.10353] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
We evaluated the two-dimensional distribution of superior colliculus (SC) neurons visualized after retrograde transneuronal transport of rabies virus injected into the lateral rectus muscle of rhesus monkeys to test whether the density of projection neurons might play a role in the spatiotemporal transformation and vector decomposition. If this were the case, the number of horizontal eye movement-related SC neurons should increase with their distance from the rostral pole of the SC and decrease with their distance from the representation of the horizontal meridian. Labeled neurons of the intermediate SC layers were counted inside a 1-mm-wide band that matched the horizontal meridian of the collicular motor map. Local areal densities were plotted against distance from the rostral SC pole. At 2.5 days after inoculation, there was no labeling in the SC. At 3 days, moderate labeling appeared on both sides, mostly in the intermediate layers. At 3.5 days, cell numbers substantially increased and the laminar distribution changed as cells appeared in the superficial SC layers. At 3 days, rostrocaudal density profiles were unimodal, with peaks at locations near 50 degrees (contralateral SC) and 25-30 degrees (ipsilateral SC) horizontal eccentricity. At 3.5 days, distributions were bimodal due to the appearance of a second high-density region near the rostral pole of the SC. The distribution of SC neurons influencing the abducens nucleus, thus, was nonuniform. Caudal sites contained more neurons, but the experimentally observed density gradients were shallower than the theoretically predicted ones that would be necessary to fully account for the spatiotemporal transformation. Similarly, we studied the distributions of cell densities in the intermediate SC layers along an isoamplitude line (representing saccades of equal amplitudes but different directions). Consistent with theoretical estimates of the density gradients required for vector decomposition, we found that the concentrations of labeled cells were highest in the vicinity of the horizontal meridian but their decrease toward the periphery of the motor map was steeper than predicted. We conclude that SC cell density gradients cannot fully account for the spatiotemporal transformation and vector decomposition in the absence of an additional mechanism such as the previously demonstrated (Grantyn et al., [1997] Soc. Neurosci. Abstr. 23:1295; Moschovakis et al., [1998] J. Neurosci. 18:10219-10229) locus-dependent weighting of the strength of efferent projections to the saccade generators.
Collapse
Affiliation(s)
- Alexej Grantyn
- Laboratoire de Physiologie de la Perception et de l'Action, CNRS-Collège de France, 75005 Paris, France. alexej.
| | | | | | | | | | | | | |
Collapse
|
15
|
Bressand K, Dematteis M, Ming Gao D, Vercueil L, Louis Benabid A, Benazzouz A. Superior colliculus firing changes after lesion or electrical stimulation of the subthalamic nucleus in the rat. Brain Res 2002; 943:93-100. [PMID: 12088842 DOI: 10.1016/s0006-8993(02)02541-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Recent data have suggested a critical role for the basal ganglia in the remote control of epileptic seizures. In particular, it has been shown that inhibition of either substantia nigra pars reticulata or subthalamic nucleus as well as activation of the superior colliculus suppresses generalized seizures in several animal models. It was previously shown that high frequency stimulation of the subthalamic nucleus, thought to act as functional inhibition, stopped ongoing non-convulsive generalized seizures in rats. In order to determine whether high frequency stimulation of the subthalamic nucleus involved an activation of superior colliculus neurons, we examined the effects of subthalamic nucleus manipulation, by either high frequency stimulation or chemical lesion, on the spontaneous electrical activity of superior colliculus neurons. Acute high frequency stimulation of the subthalamic nucleus (frequency 130 Hz) induced an immediate increase of unitary activity in 70% of responding cells, mainly located within the deep layers, whereas a reduction was observed in the remaining 30%. The latter responses are dependent on the intensity and frequency of the stimulation. Unilateral excitotoxic lesion of the subthalamic nucleus induced a delayed and transient decrease of superior colliculus activity. Our data suggest that high frequency stimulation of the subthalamic nucleus suppresses generalised epileptic seizures through superior colliculus activation.
Collapse
Affiliation(s)
- Karine Bressand
- Laboratoire de Neurobiologie Préclinique, INSERM U318, Centre Hospitalier Universitaire, Grenoble, France.
| | | | | | | | | | | |
Collapse
|
16
|
Isa T, Saito Y. The direct visuo-motor pathway in mammalian superior colliculus; novel perspective on the interlaminar connection. Neurosci Res 2001; 41:107-13. [PMID: 11591438 DOI: 10.1016/s0168-0102(01)00278-4] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The mammalian superior colliculus (SC) is a center controlling the orienting behaviors such as saccadic eye movements. The superficial layers receive visual inputs and the deeper layers send descending motor command to the brainstem and spinal cord. Existence of the interlaminar connection from the superficial to the deeper layers has been an issue of debate during the last two decades. Recent studies have proved the existence of the interlaminar connection by introducing the in vitro slice preparations. When the collicular circuit is disinhibited from gamma-amino butyric acid A (GABA(A)) receptor-mediated inhibition, the signal transmission through the interlaminar connection is enormously facilitated and neurons in the deeper layers exhibit bursting response to stimulation of the superficial layer with non-linear amplification mechanism that depends on the activation of NMDA-type glutamate receptors. In addition, the cholinergic input to the intermediate layer lowers the threshold for the bursting response and facilitates the transmission through the interlaminar connection via activation of nicotinic receptors. The signal transmission through the interlaminar connection may lead to execution of extremely short latency saccades called express saccades.
Collapse
Affiliation(s)
- T Isa
- Department of Integrative Physiology, National Institute for Physiological Sciences, Myodaiji, Okazaki 444-8585, Japan.
| | | |
Collapse
|
17
|
Gandhi NJ, Keller EL. Comparison of saccades perturbed by stimulation of the rostral superior colliculus, the caudal superior colliculus, and the omnipause neuron region. J Neurophysiol 1999; 82:3236-53. [PMID: 10601457 DOI: 10.1152/jn.1999.82.6.3236] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Over the past decade, considerable research efforts have been focused on the role of the rostral superior colliculus (SC) in control of saccades. The most recent theory separates the deeper intermediate layers of the SC into two functional regions: the rostral pole of these layers constitutes a fixation zone and the caudal region comprises the saccade zone. Sustained activity of fixation neurons in the fixation zone is argued to maintain fixation and help prevent saccade generation by exciting the omnipause neurons (OPNs) in the brain stem. This hypothesis is in contrast to the traditional view that the SC contains a topographic representation of the saccade motor map on which the rostral pole of the SC encodes signals for generating small saccades (<2 degrees ) instead of preventing them. There is therefore an unresolved controversy about the specific role on the most rostral region of the SC, and we reexamined its functional contribution by quantifying and comparing spatial and temporal trajectories of 30 degrees saccades perturbed by electrical stimulation of the rostral pole and more caudal regions in the SC and of the OPN region. If the rostral pole serves to preserve fixation, then saccades perturbed by stimulation should closely resemble interrupted saccades produced by stimulation of the OPN region. If it also contributes to saccade generation, then the disrupted movements would better compare with redirected saccades observed after stimulation of the caudal SC. Our experiments revealed two significant findings: 1) the locus of stimulation was the primary factor determining the perturbation effect. If the directions of the target-directed saccade and stimulation-evoked saccade were aligned and if the stimulation was delivered within approximately the rostral 2 mm (<10 degrees amplitude) of SC, the ongoing saccade stopped in midflight but then resumed after stimulation end to reach the original visually specified goal with close to normal accuracy. When stimulation was applied at more caudal sites, the ongoing saccade directly reached the target location without stopping at an intermediate position. If the directions differed considerably, both initial and resumed components were typically observed for all stimulation sites. 2) A quantitative analysis of the saccades perturbed from the fixation zone showed significant deviations from their control spatial trajectories. Thus they resembled redirected saccades induced by caudal SC stimulation and differed significantly from interrupted saccades produced by OPN stimulation. The amplitude of the initial saccade, latency of perturbation, and spatial redirection were greatest for the most caudal sites and decreased gradually for rostral sites. For stimulation sites within the rostral pole of SC, the measures formed a smooth continuation of the trends observed in the saccade zone. As these results argue for the saccade zone concept, we offer reinterpretations of the data used to support the fixation zone model. However, we also discuss scenarios that do not allow an outright rejection of the fixation zone hypothesis.
Collapse
Affiliation(s)
- N J Gandhi
- Graduate Group in Bioengineering, University of California, San Francisco 94143, California, USA
| | | |
Collapse
|
18
|
Saito Y, Isa T. Electrophysiological and morphological properties of neurons in the rat superior colliculus. I. Neurons in the intermediate layer. J Neurophysiol 1999; 82:754-67. [PMID: 10444674 DOI: 10.1152/jn.1999.82.2.754] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
To begin characterizing the neural elements underlying the dynamic properties of local circuits in the mammalian superior colliculus (SC), electrophysiological and morphological properties of individual neurons in the intermediate layer [stratum griseum intermediale (SGI)] were investigated using whole cell patch-clamp recording and intracellular staining with biocytin in slice preparations from young (17-22 days old) and adult rats (7-8 wk old). Voltage responses to depolarizing current pulses of 223 neurons recorded in young rats were classified into six subclasses: regular-spiking neurons (n = 113), interspike intervals during depolarizing current pulses were constant; late-spiking neurons (n = 48), initiation of repetitive firing was delayed markedly from the onset of depolarizing pulses because of a transient hyperpolarization caused by A-like currents; burst-spiking neurons (n = 29), transient burst firing due to low-threshold Ca(2+) channels were observed at the firing threshold level; fast-spiking neurons (n = 19), constant repetitive firings at frequencies >100 Hz were observed for the duration of the depolarizing pulse; neurons with marked spike frequency adaptation (n = 11), interspike intervals more than doubled due to spike frequency adaptation during depolarizing pulses; and neurons with rapid spike inactivation (n = 3), spike amplitude rapidly reduced, width increased during depolarizing pulses, and spiking was terminated after generating a few spikes. In response to hyperpolarizing current pulses, two different types of inward rectification were observed; time-dependent inward rectification by hyperpolarization-activated current (I(h); n = 29) and time-independent inward rectification (n = 111). Morphological analysis showed that neurons expressing time-dependent inward rectification by I(h) had large somata, extended divergent dendrites dorsally into the superficial layers, and projected axons ventrally and sometimes dorsally, all characteristic features of wide-field vertical cells. Other neurons exhibited heterogeneous morphological properties, such as multipolar, fusiform, horizontal, or pyramidal-shaped cells. In adult rats, a total of 44 neurons showed similar electrophysiological properties except for the last type. These results indicate that the local circuits of the SC include neurons with at least five different firing properties and two different rectification properties; each with distinct electrophysiological and morphological characteristics that may be correlated with the functional output of the SC.
Collapse
Affiliation(s)
- Y Saito
- Department of Integrative Physiology, National Institute for Physiological Sciences, Myodaiji, Okazaki 444-8585, Japan
| | | |
Collapse
|
19
|
Abstract
Intrinsic circuit of the superior colliculus (SC), in particular the pathway from the optic tract (OT) to neurons in the intermediate layer (SGI), was investigated by whole-cell patch-clamp recording in slice preparations obtained from 17- to 24-d-old rats. Stimulation of the OT induced monosynaptic EPSPs in neurons in the superficial gray layer (SGS) and the optic layer (SO), and disynaptic or polysynaptic EPSPs in a majority of SGI neurons. Stimulation of the SGS induced monosynaptic or oligosynaptic EPSPs in the SGI neurons. Both the monosynaptic EPSPs induced in the SGS/SO neurons by stimulation of the OT and those induced in the SGI neurons by stimulation of the SGS were mediated by AMPA- and NMDA-type glutamate receptors. Thus, we have clarified the existence of the glutamatergic excitatory pathway from the OT to the SGI neurons via SGS and SO neurons. The EPSPs in the SGI neurons induced by stimulation of the OT or SGS were remarkably enhanced by bicuculline, suggesting that the signal transmission in this pathway is under strong suppression by the GABAergic system.
Collapse
|
20
|
Abstract
BACKGROUND The medial pulvinar appears to subserve the integration of associative cortical information and projects to visuomotor-related cortex. In contrast to the other pulvinar subdivisions, the medial pulvinar is a polymodal structure. Therefore, we studied the structural organization of the medial pulvinar to determine how it differs from the surrounding unimodal nuclei. METHODS Nissl-stained sections were examined to determine the boundaries of, and the distribution of neuronal sizes within, the medial pulvinar. In addition, Golgi-impregnated neurons were examined and drawn for analysis. Only rhesus monkey specimens were used, and the material had been prepared previously for other studies. RESULTS Projection neurons have round to oval somata and moderate numbers of primary dendrites that extend for short distances before branching into many secondary branches. Two variations of projection neurons (P1 and P2) were distinguished on the basis of the diameters of their dendritic tree. Both varieties have short dendrites that radiate in all directions. They differ in that P2 cells have longer second tier dendrites than P1 cells. Three types of local circuit neurons, tufted, radiating and varicose, were distinguished on the basis of their dendritic morphology. Four types of afferent fibers were identified. Type 1 afferents form cone-shape terminal arbors. Type 2 afferents are similar to those reported for retinal or cortical terminals. Type 3 afferents are of medium thickness and of an unknown origin. Type 4 afferents are thin and have small varicosities consistent with previously described cortical afferents. Afferent fibers are predominantly oriented along the mediolateral axis of the nucleus. We observed putative contacts between some afferents and local circuit neurons and between local circuit neurons and projection neurons. CONCLUSIONS Medial pulvinar neurons are generally smaller and rounder than those found in the adjacent pulvinar nuclei. These results provide additional evidence for structural distinctions between thalamic nuclei having different functions. However, the observed differences are subtle. In addition, the data in this report provide morphological evidence that cortical signals are likely to be integrated by means of the circuitry located within the nucleus.
Collapse
Affiliation(s)
- T P Ma
- Department of Anatomy, University of Mississippi Medical Center, Jackson 39216-4505, USA.
| | | | | | | | | |
Collapse
|
21
|
Leuba G, Saini K. Colocalization of parvalbumin, calretinin and calbindin D-28k in human cortical and subcortical visual structures. J Chem Neuroanat 1997; 13:41-52. [PMID: 9271194 DOI: 10.1016/s0891-0618(97)00022-7] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Several studies have demonstrated that three calcium-binding proteins parvalbumin (PV), calbindin D-28k (CB) and calretinin (CR) mark distinct subsets of cortical interneurons. This study demonstrates, in cortical and subcortical visual structures, the coexistence of two calcium-binding proteins in some neuronal subpopulations. The human visual cortex (VC), lateral geniculate nucleus (LGN). lateral inferior pulvinar (LIP) and superior colliculus (SC) were examined by a double-labelling immunocytochemical technique. The VC showed mostly separate populations of PV, CB and CR immunoreactive (-ir) interneurons, but also small populations of double-stained PV + CR and CR + CB neurons, while PV + CB neurons were less frequent. An average of 2.5% of the immunoreactive neurons were double-stained for PV + CR and 7.1% for CR + CB in area 17, while this percentage was slightly higher in association area 18 (3.3 and 7.4%, respectively). In the LGN and LIP, double-stained neurons were scarce, but in the fibre capsule of these nuclei, as well as in the optic radiation (OR) and white matter underlying area 17, both double-stained PV + CR or CR + CB and separate populations of PV-ir, CB-ir and CR-ir neurons and fibres were observed. Unlike the thalamic regions, the SC showed some double-stained PV + CR and CR + CB neurons, scattered both in the superficial and deep layers. These findings are discussed in the light of similar observations recently reported from other regions of the human brain.
Collapse
Affiliation(s)
- G Leuba
- University Psychogeriatrics Hospital, Lausanne-Prilly, Switzerland.
| | | |
Collapse
|
22
|
Leuba G, Saini K. Calcium-binding proteins immunoreactivity in the human subcortical and cortical visual structures. Vis Neurosci 1996; 13:997-1009. [PMID: 8961531 DOI: 10.1017/s0952523800007665] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The distribution of neurons and fibers immunoreactive (ir) to the three calcium-binding proteins parvalbumin (PV), calbindin D-28k (CB), and calretinin (CR) was studied in the human lateral geniculate nucleus (LGN), lateral inferior pulvinar, and optic radiation, and related to that in the visual cortex. In the LGN, PV, CR, and CB immunoreactivity was present in all laminae, slightly stronger in the magnocellular than in the parvocellular laminae for CB and CR. PV-ir puncta, representing transversally cut axons, and CR-ir fibers were revealed within the laminae and interlaminar zones, and just beyond the outer border of lamina 6 in the geniculate capsule. In the optic radiation both PV- and CR-immunoreactive neurons, puncta, and fibers were present. CB immunoreactivity was revealed in neurons of all laminae of the lateral geniculate nucleus, including S lamina and interlaminar zones. There were hardly any CB-ir puncta or fibers in the laminae, interlaminar zones, geniculate capsule, or optic radiation. In the lateral inferior pulvinar, immunoreactive neurons for the three calcium-binding proteins were present in smaller number than in the LGN, as well as PV-ir puncta and CR-ir fibers within the nucleus and in the pulvinar capsule. In the white matter underlying area 17, fibers intermingled with a few scattered neurons were stained for both PV and CR, but very rarely for CB. These fibers stopped at the limit between areas 17 and 18. Area 17 showed a dense plexus of PV-ir puncta and neurons in the thalamo-receptive layer IV and CR-ir puncta and neurons both in the superficial layers I-II, IIIC, and in layer VA. Cajal-Retzius CR-ir neurons were present in layer I. CB-ir puncta were almost confined to layer I-III and CB-ir neurons to layer II. Finally the superior colliculus exhibited mostly populations of PV and CR pyramidal-like immunoreactive neurons, mainly in the intermediate tier. These data suggest that in the visual thalamus most calcium-binding protein immunoreactive neurons project to the visual cortex, while in the superior colliculus a smaller immunoreactive population represent projection neurons.
Collapse
Affiliation(s)
- G Leuba
- University Psychogeriatrics Hospital, Lausanne-Prilly, Switzerland
| | | |
Collapse
|
23
|
Manning KA, Wilson JR, Uhlrich DJ. Histamine-immunoreactive neurons and their innervation of visual regions in the cortex, tectum, and thalamus in the primate Macaca mulatta. J Comp Neurol 1996; 373:271-82. [PMID: 8889927 DOI: 10.1002/(sici)1096-9861(19960916)373:2<271::aid-cne9>3.0.co;2-0] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The histaminergic system is involved in the control of arousal in the brain and may impact significantly on visual processing. However, little is known about the histaminergic innervation of visual areas, or the histamine system in the primate brain, in general. We examined in Macaca mulatta the location of histamine-immunoreactive neurons and the innervation of important cortical and subcortical visual areas by histamine-immunoreactive axons. Brain sections were treated with an antibody to histamine and processed with standard immunohistological procedures. Histamine-immunoreactive neurons (20-45 microns in diameter) were localized bilaterally in the hypothalamus, particularly in ventral, lateral, posterior, and perimammillary hypothalamic areas. These hypothalamic cells appear to provide the sole neural source of histamine in the macaque brain. A plexus of varicose histamine-immunoreactive axons was present throughout the superior colliculus, the dorsal and ventral lateral geniculate nuclei of the thalamus, the reticular nucleus of the thalamus, the lateral posterior/pulvinar complex, and the visual cortex, including areas 17, 18, and the nearby extrastriate cortex. The axons nearly homogeneously innervated every region and layer in these structures, except for an increase in density in layer 1 of the visual cortex and in the superficial-most layers of the superior colliculus. Histaminergic axons broadly innervated every visual region examined. In comparison with the other aminergic and the cholinergic projection systems, which show considerable projection specificity, the histaminergic projection exhibited great homogeneity. The breadth of the distribution of histaminergic axons ensures that virtually all levels of visual processing in the primate can be influenced, either directly or indirectly, by the neuromodulatory effects of histamine.
Collapse
Affiliation(s)
- K A Manning
- Department of Anatomy, University of Wisconsin Medical School, Madison 53706, USA.
| | | | | |
Collapse
|
24
|
Ma TP, Hazlett JC. Cytoarchitecture of the substantia nigra pars lateralis in the opossum (Didelphis virginiana): a correlated light and electron microscopic study. Anat Rec (Hoboken) 1995; 241:563-78. [PMID: 7604970 DOI: 10.1002/ar.1092410414] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
BACKGROUND The substantia nigra has been divided into three subdivisions. However, the cytoarchitecture of one of these subdivisions, the pars lateralis (SNl), has not been previously examined in detail at the light and electron microscopic levels in any species. In the adult opossum, the three nigral subdivisions can be easily distinguished as distinct, rostrocaudally oriented cell groups separated by neuron-free zones. Thus it was possible to determine the boundaries of the SNl unambiguously. This report covers the results of an examination of the morphology and organization of the SNl in the opossum. METHODS Material from 13 opossums was used for this study. Eight of the animals had been previously stained for Nissl substance (n = 4) or impregnated by the Golgi technique (n = 4). The remaining five animals were prepared for electron microscopic studies using standard procedures. RESULTS Two cell types were identified on the basis of morphological differences, small and medium-large neurons. Small neurons (10-18 microns long axis) have large nuclei with moderate amounts of heterochromatin and a thin rim of cytoplasm. They have long (up to 500 microns), spine-free dendrites. Medium-large neurons (18-54 microns long axis) have rounded nuclei with electron-lucent nucleoplasm. Few indentations of the nuclear envelope were observed. The surrounding cytoplasm has dense arrays of organelles. Nissl bodies are particularly prominent in the form of pyramids with their bases at juxtanuclear positions and their apices directed toward emerging dendrites. Dendrites of medium-large neurons are long (some > 1 mm in length), are primarily oriented in the frontal plane, and extend along the dorsal surface of or into the cerebral peduncle. Some cells have dendrites that are moderately spinous, whereas other neurons possess sparsely spinous dendrites. Relatively few synaptic profiles are observed to contact somata and proximal dendrites. CONCLUSION This report provides added morphological support for the idea that the SNl is a distinct subdivision of the substantia nigra, a distinction previously made on the basis of the physiologically characterized relationship between the lateral substantia nigra and orienting behaviors and seizure-related function.
Collapse
Affiliation(s)
- T P Ma
- Department of Anatomy and Neurology, University of Mississippi Medical Center, Jackson 39216-4505, USA
| | | |
Collapse
|
25
|
Zhu JJ, Lo FS. Physiological properties of the output neurons in the deep layers of the superior colliculus of the rabbit. Brain Res Bull 1995; 38:495-505. [PMID: 8665274 DOI: 10.1016/0361-9230(95)02021-i] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Using antidromic and orthodromic stimulation techniques, we studied physiological properties of the output neurons in the deep layers of the superior colliculus (SC) of 34 Now Zealand rabbits. SC cells antidromically activated from the contralateral predorsal bundle (PDB) could also be activated by stimulation of the contralateral SC and ipsilateral central lateral nucleus of the thalamus (CL). The majority of these output neurons responded predominantly to the stimulation of the optic nerve, and only a small proportion of the output neurons were responsive to the stimulation of somatosensory and auditory (and/or vestibular) nerves. These results suggest that the orienting reflex might be elicited mainly by visual afferents in the rabbit. The output SC neurons were subject to a 70 ms inhibition after antidromic stimulation of the PDB and a 40 ms inhibition after transsynaptic (orthodromic) stimulation of the optic chiasm (OX), indicating that the output neurons in the deep layers of the SC might be subject to at least two inhibitory circuits. These results are discussed in the context of a putative saccadic suppression circuitry model.
Collapse
Affiliation(s)
- J J Zhu
- Brain Research Institute, Chinese Academy of Sciences, Shanghai, People's Republic of China
| | | |
Collapse
|
26
|
Crossland WJ, Hu XJ, Rafols JA. Morphological study of the rostral interstitial nucleus of the medial longitudinal fasciculus in the monkey, Macaca mulatta, by Nissl, Golgi, and computer reconstruction and rotation methods. J Comp Neurol 1994; 347:47-63. [PMID: 7528228 DOI: 10.1002/cne.903470105] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
We have studied the morphology of silver-impregnated neurons (rapid Golgi technique) in the rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF), a center involved in the control of vertical and torsional saccadic eye movements. This morphological study of riMLF neurons in the rhesus monkey was undertaken to further our understanding of the functional circuitry of the oculomotor system. Our study employed Nissl, Golgi, and computer-assisted methods. The cytoarchitectonic boundaries of the riMLF and its relationships to neighboring structures were determined in both Nissl and Golgi preparations. Five (I-V) distinct morphological types of riMLF neurons were distinguished in the Golgi impregnations on the basis of soma size, dendritic size, numbers of primary dendrites, number of dendritic branch points, as well as form, number, and distribution of dendritic appendages. Type I neurons impregnated most frequently and had the most extensive and highly branched dendritic tree. Type II neurons displayed thick dendrites with complex dendritic appendages, but the dendritic tree was much more compact than that of type I cells. Type III and type V cells had fusiform somas and relatively unbranched dendritic trees but differed greatly in size as well as dendritic morphology. The type IV cell was the smallest neuron and had many characteristics of the local interneurons found in other thalamic, subthalamic, hypothalamic and midbrain centers. The type V was the largest neuron, least frequently impregnated, and found only at rostral riMLF levels. Digitized reconstructions of each type of neuron were rotated by the computer, which revealed that the dendritic trees of types I, III, and V occupy a disk-like compartment in the riMLF neuropil. In contrast, the tree of types II and IV occupy a roughly spherical compartment. We suggest that three of the cell types are well suited for specific purposes: type II cells for receiving topographically organized inputs that contain spatial information, type I cells for short-lead burst neuron output to the motor neurons or other premotor centers, and type IV cells for inhibitory inputs to type I cells.
Collapse
Affiliation(s)
- W J Crossland
- Department of Anatomy and Cell Biology, Wayne State University, School of Medicine, Detroit, Michigan 48201
| | | | | |
Collapse
|
27
|
Lynch JC, Hoover JE, Strick PL. Input to the primate frontal eye field from the substantia nigra, superior colliculus, and dentate nucleus demonstrated by transneuronal transport. Exp Brain Res 1994; 100:181-6. [PMID: 7813649 DOI: 10.1007/bf00227293] [Citation(s) in RCA: 181] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The purpose of these experiments was to study the subcortical input to the frontal eye field (FEF) and to determine which subcortical structures might project to the FEF via pathways that contain only a single intervening synapse. We used retrograde transneuronal transport of herpes simplex virus type 1 (HSV-1) to label second-order neurons that send information to the FEF of cebus monkeys. The saccade region of the FEF was identified physiologically using intracortical stimulation and then injected with a strain of HSV-1 known to be transported transneuronally in the retrograde direction. Retrograde transport of virus labeled neurons was observed in all the thalamic sites known to innervate the FEF. In addition, we found neurons labeled by transneuronal transport in three subcortical sites: the pars reticulata of the substantia nigra, the optic and intermediate gray layers of the superior colliculus, and a posterior portion of the dentate nucleus of the cerebellum. Each of these sites has been shown in prior studies to project to thalamic regions that innervate the FEF. Moreover, the neurons labeled through transneuronal transport were located in a subregion of each subcortical site that is known to be involved in oculomotor control. These observations demonstrate that signals from the substantia nigra, superior colliculus and dentate nucleus can have a significant influence on the output of the FEF.
Collapse
Affiliation(s)
- J C Lynch
- Department of Anatomy, University of Mississippi Medical Center, Jackson 39216
| | | | | |
Collapse
|
28
|
Mooney RD, Nikoletseas MM, King TD, Savage SV, Huang X. Correlations between the receptive field properties and morphology of neurons in the deep layers of the hamster's superior colliculus. J Comp Neurol 1993; 335:214-27. [PMID: 8227515 DOI: 10.1002/cne.903350206] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Extracellular and intracellular recording, receptive field mapping, and intracellular HRP injection techniques were used to define the morphological classes of cells in the deep laminae of the hamster's superior colliculus and to determine whether there are any correlations between the structural and functional characteristics of these neurons. A total of 110 neurons were characterized and reconstructed. Of these, 23.6% (N = 26) were visual, 60% (N = 66) were somatosensory, 0.9% (N = 1) were bimodal (visual-somatosensory), and 15.4% (N = 17) were unresponsive. Of the somatosensory neurons, 72.7% (N = 48) were low threshold, 4.5% (N = 3) had a wide dynamic range, 9.1% (N = 6) responded only to noxious stimulation, and 13.6% (N = 9) had complex somatosensory receptive fields. Deep layer cells were divided into eight morphological classes. These classes were multipolar cells (26.4%, N = 29), bipolar cells (9.1%, N = 10), widefield vertical cells (7.3%, N = 8), horizontal cells (13.6%, N = 15), stellate cells (10.9%, N = 12), ventrally directed cells (5.5%, N = 6), sparse radial cells (17.3%, N = 19), and small sparse radial cells (6.4%, N = 7). Four cells (3.6%) did not fit into this classification scheme. Univariate and multivariate analyses of variance of properties such as soma area, number of branch points, total dendritic length, and volume and orientation of dendritic arbor indicated that these classes were significantly different. However, chi 2 analysis and multivariate analysis of variance indicated no significant relationships between morphological class and either laminar location or receptive field type. There was a significant positive relationship between the possession of dendrites that extended into the superficial laminae and visual responsivity.
Collapse
Affiliation(s)
- R D Mooney
- Department of Anatomy, Medical College of Ohio, Toledo 43699
| | | | | | | | | |
Collapse
|
29
|
Mize RR, Luo Q. Visual deprivation fails to reduce calbindin 28kD or GABA immunoreactivity in the rhesus monkey superior colliculus. Vis Neurosci 1992; 9:157-68. [PMID: 1504025 DOI: 10.1017/s0952523800009627] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Antibody labeling of the calcium-binding protein calbindin 28kD (CaBP) and gamma-aminobutyric acid (GABA) is altered by short-term monocular deprivation in the lateral geniculate nucleus and visual cortex of adult primates. It is not known whether these alterations occur in other subcortical visual structures. We therefore have examined antibody labeling to CaBP and GABA in the superior colliculus (SC) of visually deprived Rhesus monkeys. One group was monocularly enucleated as adults. The other monkeys experienced different types of monocular and binocular deprivation from birth, including occlusion of one eye, and/or surgically induced aphakia, optically corrected with extended-wear contact lenses, or an intraocular lens implant. Some of these monkeys also had one eye enucleated prior to perfusion. In the SC of normal monkeys, CaBP-immunoreactive neurons formed three laminar tiers within SC, one within the zonal layer (ZL) and upper superficial gray layer (SGL), another bridging the optic and intermediate gray layers, and a third within the deep gray layer. CaBP neurons within the upper tier had small pyriform or stellate morphologies while those in the deeper tiers were slightly larger neurons, most with a stellate morphology. GABA-immunoreactive neurons were densely distributed within the SGL and more sparsely distributed within the deeper layers. These cells were mostly small neurons with horizontal, pyriform, or stellate morphologies. Neither monocular enucleation nor occlusion nor aphakia combined with continuous occlusion of the fellow eye produced any visible reduction in antibody labeling in cells or neuropil within the SC. Full-field measures of labeling intensity (optical density) within the ZL and upper SGL revealed no consistent differences between the SC contralateral or ipsilateral to the affected eye in either CaBP- or GABA-labeled sections. Measures of the optical density, number, and size of labeled neurons also showed no consistent effects of enucleation and/or occlusion. We therefore conclude that the retino-geniculostriate and retino-collicular systems differ in their response to deprivation which is likely due to the significant overlap of retinal axons from the two eyes that occurs in the SC of the Rhesus monkey.
Collapse
Affiliation(s)
- R R Mize
- Department of Anatomy and Neurobiology, College of Medicine, University of Tennessee, Memphis
| | | |
Collapse
|
30
|
Ma TP, Hu XJ, Anavi Y, Rafols JA. Organization of the zona incerta in the macaque: a Nissl and Golgi study. J Comp Neurol 1992; 320:273-90. [PMID: 1319431 DOI: 10.1002/cne.903200302] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The zona incerta has been implicated in the control of the initiation of saccadic eye movements in the primate. Complex interactions within the zona incerta must take place to integrate its varied inputs and to produce a coherent efferent signal in order for this function to occur. However, whether the anatomical substrates exist within the zona incerta to allow this integration to take place has not been established. The zona incerta in monkeys (Macaca mulatta) was examined in frontally, horizontally, and sagittally sectioned preparations stained for Nissl, myelinated fibers, or cytochrome oxidase, or impregnated by the Golgi technique. This nucleus can be separated into dorsal and ventral laminae on the basis of staining and morphological differences between these two subdivisions. Neurons are more densely packed, more darkly stained, and larger in the ventral lamina. In addition, the neuropil of the ventral lamina is much more intensely stained after cytochrome oxidase histochemistry. Two neuronal types, principal cells and interneurons, were identified on the basis of neuronal cell body, dendritic, and axonal features in Golgi-impregnated preparations. Principal cells have fusiform or polygonal somata (long axis from 18 to 40 microns) and dendrites that extend for up to 750 microns within the lamina in which the cell bodies are located. Putative local interneurons have small (12-16 microns), round or oval cell bodies with wavy dendrites (up to 400 microns). Numerous multilobed appendages and axon-like processes originate from these dendrites and make apparent contacts with other interneurons or with dendrites of principal cells. Dendrites of most neurons in both laminae are oriented preferentially along the principal axis, dorsolateral-to-ventromedial, of the nucleus. Therefore, within the limits of light microscopy, the zona incerta appears to possess the morphological heterogeneity to form complex intrinsic interactions. These interactions are hypothesized to form the integrative substrate for the large array of incertal inputs that are utilized to produce an efferent signal involved in the initiation of saccadic eye movements.
Collapse
Affiliation(s)
- T P Ma
- Department of Anatomy, University of Mississippi Medical Center, Jackson 39216
| | | | | | | |
Collapse
|
31
|
|
32
|
Mize RR, Jeon CJ, Butler GD, Luo Q, Emson PC. The calcium binding protein calbindin-D 28K reveals subpopulations of projection and interneurons in the cat superior colliculus. J Comp Neurol 1991; 307:417-36. [PMID: 1713236 DOI: 10.1002/cne.903070307] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The calcium binding protein calbindin-D 28K (CaBP) has been localized in the cat superior colliculus (SC). Four important features of SC organization have been revealed by using CaBP immunocytochemistry. 1) CaBP neurons formed three laminar tiers in SC, one within the upper one half of the superficial gray layer (SGL), the second bridging the deep optic (OL) and intermediate gray layers (IGL), and the third within the deep gray layer (DGL). 2) CaBP labeled several classes of interneuron in SC. In the upper CaBP tier, the labeled neurons were all small, but they varied in morphology and included horizontal, pyriform, and stellate neurons. A unique class of interneuron was labeled by anti-CaBP in the OL-IGL tier. This cell was stellate-like with highly varicose dendrites and broad dendritic trees. Other labeled neurons in the intermediate and deep tiers included nonvaricose stellate neurons and rare large neurons in the DGL. 3) A few anti-CaBP neurons were projection neurons. Virtually no CaBP neurons were retrogradely labeled after injections of HRP into the predorsal bundle and dorsolateral midbrain tegmentum or into the lateral posterior nucleus. However, 2.4% of anti-CaBP neurons were retrogradely labeled after HRP injections into the dorsal and ventral lateral geniculate nuclei. These represented 14.7% of all neurons projecting to the LGN complex. 4) A small percentage of CaBP neurons co-localized GABA. A two-chromagen double-labeling technique showed that about 4.0% of labeled neurons were labeled by both antibodies. In summary, antibodies to CaBP densely labeled subpopulations of neurons in the cat SC, most of which were interneurons, some of which projected to the LGN, and a few of which co-localized GABA.
Collapse
Affiliation(s)
- R R Mize
- Department of Anatomy and Neurobiology, College of Medicine, University of Tennessee, Memphis 38163
| | | | | | | | | |
Collapse
|
33
|
Ma TP, Graybiel AM, Wurtz RH. Location of saccade-related neurons in the macaque superior colliculus. Exp Brain Res 1991; 85:21-35. [PMID: 1715825 DOI: 10.1007/bf00229983] [Citation(s) in RCA: 58] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The locations of saccade-related neurons were studied in the superior colliculi of two adult rhesus monkeys (Macaca mulatta) by placing marking lesions at the sites of physiologically characterized cells and comparing these histologically identified sites with the collicular laminae and acetylcholinesterase (AChE)-rich patches. Three major conclusions were drawn on the basis of 39 histologically identified sites at which saccade-related neurons were recorded. First, saccade-related neurons were distributed from the ventral half of the optic layer through the deep gray layer, and were most concentrated in the intermediate gray and white layers. Second, there was a clear relationship between the discharge characteristics of these saccade-related neurons and the depths at which they were found. Neurons having presaccadic bursts, defined as clipped and partially-clipped, tended to be encountered more dorsally, and neurons that did not have bursts (unclipped) were encountered more ventrally. Although cells having different discharge characteristics seemed to be organized along a dorsoventral axis, there was no compelling evidence that these properties were specified by their laminar locations. Third, there was no clear correlation between the locations of saccade-related neurons and the distribution of individual AChE-rich patches. Saccade-related cells were found both in the caudal superior colliculus where patches were located and in the rostral superior colliculus where patches were not found; both within and between the two tiers of AChE-rich patches in the caudal superior colliculus; and both within and between individual AChE-rich patches. However, the depth-level at which saccade-related neurons occurred generally matched the region bounded by the two tiers of AChE-rich patches in the intermediate and deep layers, and the dorsal and ventral extent of saccade-related neurons was the same as that of the AChE-rich patches.
Collapse
Affiliation(s)
- T P Ma
- Laboratory of Sensorimotor Research, National Eye Institute, National Institutes of Health, Bethesda, MD 20892
| | | | | |
Collapse
|
34
|
Mize RR, Jeon CJ, Hamada OL, Spencer RF. Organization of neurons labeled by antibodies to gamma-aminobutyric acid (GABA) in the superior colliculus of the Rhesus monkey. Vis Neurosci 1991; 6:75-92. [PMID: 2025611 DOI: 10.1017/s0952523800000924] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The inhibitory neurotransmitter gamma-aminobutyric acid (GABA) is found in the superior colliculus (SC) of many mammalian species. In cat, several distinct classes of putative GABAergic neuron have been identified using antibodies directed against the neurotransmitter. It is not known whether these classes are found in other species. To study this, we examined the distribution, morphology, ultrastructure, and synaptic organization of GABA immunoreactive neurons in the SC of the Rhesus monkey (Macaca mulatta). Antibody-labeled neurons were distributed throughout the monkey SC, but were most densely concentrated within the zonal and superficial gray layers (32.5% of the total). These neurons were all small cells ranging from 6.6-16.3 microns in average diameter, and had granule, pyriform, and horizontal morphologies. Four types of labeled profile were identified in single ultrathin sections with the electron microscope. Presynaptic dendrites (PSDs) contained pleomorphic vesicles, received synaptic input from unlabeled axon terminals, and sometimes formed symmetric synaptic contacts with postsynaptic profiles. Two subtypes were found. One type contained loose accumulations of synaptic vesicles throughout the profile and had a distinctive varicose shape. The other type contained small discrete clusters of synaptic vesicles near the site of synaptic apposition. The former were much more common. Profiles with typical axon terminal morphology were also found. These profiles usually contained numerous flattened vesicles and formed symmetric synapses with postsynaptic profiles, both dendrites and cell bodies. Some conventional dendrites and myelinated axons were also labeled. Serial ultrathin section reconstructions revealed that PSDs formed complex synaptic relationships with other elements. Retinal terminals, identified by their characteristic pale mitochondria, established synaptic contacts with both types of PSD. These PSDs also established contact with each other, providing a possible anatomical substrate for disinhibition. We conclude that the monkey SC has multiple GABAergic cell types, similar to those found in cat, and may represent an organization common to both mammals and some other vertebrate species. The circuitry established by these cell types may provide a mechanism for disinhibition as well as inhibition in the mammalian SC.
Collapse
Affiliation(s)
- R R Mize
- Department of Anatomy and Neurobiology, College of Medicine, University of Tennessee Health Science Center, Memphis
| | | | | | | |
Collapse
|