Tectum

Cross references:  Dictionary    Pretectum       Thalamus Tectal Connections    
Locomotion Sequence
   
Locomotion Sequence Revision       Neuroethology    
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Kolb & Whishaw discuss the tectum on [K&W: 53 & 263]. 

Midbrain tectum (Wiki) 
http://en.wikipedia.org/wiki/Midbrain_tectum   
    "The tectum (Latin: roof) is a region of the brain, specifically the dorsal part of the mesencephalon (midbrain). This is contrasted with the tegmentum, which refers to the region ventral to the ventricular system. The tectum is responsible for auditory and visual reflexes.

    It is derived in embryonic development from the alar plate of the neural tube.   

Contents                

  Colliculi

In adult humans, it only consists of the inferior and the superior colliculi.

  • The superior colliculus is involved in preliminary visual processing and control of eye movements. In non-mammalian vertebrates it serves as the main visual area of the brain, functionally analogous to the visual areas of the cerebral cortex in mammals.

Both colliculi also have descending projections to the paramedian pontine reticular formation and spinal cord, and thus can be involved in responses to stimuli faster than cortical processing would allow. Collectively the colliculi are referred to as the corpora quadrigemina.

Related terms

The term "tectal plate" (or "quadrigeminal plate") is used to describe the junction of the gray and white matter in the embryo. (NeuroNames ancil-453)

Additional images   


http://upload.wikimedia.org/wikipedia/commons/4/4c/Slide4qq.JPG



  • Midbrain tectum

See also

External links

Wikimedia Commons has media related to: Midbrain tectum
Tectum.jpg  
       

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From:   Thalamus Tectal Connections     Th  > Tec   and Tec > MLR   

Searching PubMed for "thalamus tectal connections" located 60 references:   

 
48<60   1981
Efferent tectal pathways in two chondrichthyans, the shark Scyliorhinus canicula and the ray Raja clavata.

    Brief summary:
"
a descending projection to the rhombencephalic reticular formation"      
    See:  Thalamus Tectal Connections  for full Abstract and Related citations .

 
47<60   1981
Organization of extrinsic tectal connections in Goldfish (Caraccius auratus)
.   
    Brief summary
"Ipsilateral tectal afferents include ... the nucleus dorsalis lateralis of the thalamus ... Terminals of the ... nucleus dorsolateralis ... are sparse and widely branching."  
    See:  Thalamus Tectal Connections  for full Abstract and Related citations .   



46<60   1981
Afferent and efferent connections of the optic tectum in the carp (Cyprinus carpio L.).  

    Brief summary:
"
tectal projections to the...  mesencephalic and bulbar reticular formations.
"
Tectal afferents were demonstrated by retrograde HRP transport ... several pretectal nuclei, dorsomedial and dorsolateral thalamic nuclei"   
    See:  Thalamus Tectal Connections  for full Abstract and Related citations .  



45<60  1982

The afferent connections of the tectum mesencephali in two chondrichthyans, the shark Scyliorhinus canicula and the ray Raja clavata
.

    Brief summary
" Diencephalic projections to the tectum originate from the thalamus dorsalis pars medialis, the thalamus ventralis pars lateralis, the nucleus medius infundibuli ..." 
    See:  Thalamus Tectal Connections  for full Abstract and Related citations .  


36<60   
1988
Connections of the tectum opticum in two urodeles, Salamandra salamandra and Bolitoglossa subpalmata, with special reference to the nucleus isthmi
.

    Brief summary:
"...
following horseradish peroxidase injections into the tectum opticum ... retrogradely labelled cells were observed: ipsilaterally in the ...  ventral and dorsal thalamus"  
"
Caudal efferents formed the bilaterally organized tecto-bulbar tracts innervating the rhombencephalon.
    See:  Thalamus Tectal Connections  for full Abstract and Related citations .  


29<60 
199
0
Afferent connections of the optic tectum in channel catfish Ictalurus punctatus.

    Brief summary:
"Both the anterior thalamic nucleus and the ventro-medial thalamic nucleus projected to the ipsilateral optic tectum."  
    See:  Thalamus Tectal Connections  for full Abstract and Related citations .     


14<60    2001
Neural modulation of visuomotor functions underlying prey-catching behaviour in anurans: perception, attention, motor performance, learning. 
    See:  Anurian Prey Catching


2006
Afferents of the lamprey optic tectum with special reference to the GABA input: combined tracing and immunohistochemical study. 
    See:  Lamprey GABA  .   
 
 
2007
Afferent connections of the optic tectum in lampreys: an experimental study. 
http://www.ncbi.nlm.nih.gov/pubmed/16926536  
Abstract
    "Tectal afferents were studied in adult lampreys of three species (Ichthyomyzon unicuspis, Lampetra fluviatilis, and Petromyzon marinus) following unilateral BDA injections into the optic tectum (OT). In the secondary prosencephalon, neurons projecting to the OT were observed in the pallium, the subhipoccampal lobe, the striatum, the preoptic area and the hypothalamus. Following tectal injections, backfilled diencephalic cells were found bilaterally in: prethalamic eminence, ventral geniculate nucleus, periventricular prethalamic nucleus, periventricular pretectal nucleus, precommissural nucleus, magnocellular and parvocellular nuclei of the posterior commissure and pretectal nucleus; and ipsilaterally in: nucleus of Bellonci, periventricular thalamic nucleus, nucleus of the tuberculum posterior, and the subpretectal tegmentum, as well as in the pineal organ. At midbrain levels, retrogradely labeled cells were seen in the ipsilateral torus semicircularis, the contralateral OT, and bilaterally in the mesencephalic reticular formation and inside the limits of the retinopetal nuclei. In the hindbrain, tectal projecting cells were also bilaterally labeled in the dorsal and lateral isthmic nuclei, the octavolateral area, the sensory nucleus of the descending trigeminal tract, the dorsal column nucleus and the reticular formation. The rostral spinal cord also exhibited a few labeled cells. These results demonstrate a complex pattern of connections in the lamprey OT, most of which have been reported in other vertebrates. Hence, the lamprey OT receives a large number of nonvisual afferents from all major brain areas, and so is involved in information processing from different somatic sensory modalities.
"    
    102 Related citations:   
http://www.ncbi.nlm.nih.gov/pubmed?linkname=pubmed_pubmed&from_uid=16926536     


Superior colliculus (Wiki)
https://en.wikipedia.org/wiki/Superior_colliculus  
    "
The superior colliculus, (Latin, upper hill) is a paired structure of the mammalian midbrain. In other vertebrates this is known as the optic tectum or simply tectum, and the adjective tectal may also be used. The superior colliculus forms a major component of the midbrain. The tectum is a layered structure, with a number of layers that varies by species. The superficial layers are sensory-related, and receive input from the eyes as well as other sensory systems.[1] The deep layers are motor-related, capable of activating eye movements as well as other responses. There are also intermediate layers, with multi-sensory cells and motor properties.

The general function of the tectal system is to direct behavioral responses toward specific points in egocentric ("body-centered") space. Each layer of the tectum contains a topographic map of the surrounding world in retinotopic coordinates, and activation of neurons at a particular point in the map evokes a response directed toward the corresponding point in space. In primates, the superior colliculus has been studied mainly with respect to its role in directing eye movements. Visual input from the retina, or "command" input from the cerebral cortex, create a "bump" of activity in the tectal map, which, if strong enough, induces a saccadic eye movement. Even in primates, however, the tectum is also involved in generating spatially directed head turns, arm-reaching movements,[2] and shifts in attention that do not involve any overt movements.[3] In other species, the tectum is involved in a wide range of responses, including whole-body turns in walking rats, swimming fishes, or flying birds; tongue-strikes toward prey in frogs; fang-strikes in snakes; etc.

In some vertebrates, including fish and birds, the tectum is one of the largest components of the brain. In mammals, and especially primates, the massive expansion of the cerebral cortex reduces the tectum ("superior colliculus") to a much smaller fraction of the whole brain. It remains nonetheless important in terms of function as the primary integrating center for eye movements.

Note on terminology: This article follows terminology established in the literature for the analogous structure in mammals/non-mammals (see above), using the term "superior colliculus" when discussing mammals and "optic tectum" when discussing either specific non-mammalian species or vertebrates in general.

Contents

  • 1 Structure
  • 2 Function
  • 3 Other animals
  • "

    Lamprey

    The lamprey has been extensively studied because it has a relatively simple brain that is thought in many respects to reflect the brain structure of early vertebrate ancestors. Beginning in the 1970s, Sten Grillner and his colleagues at the Karolinska Institute in Stockholm have used the lamprey as a model system to work out the fundamental principles of motor control in vertebrates, starting in the spinal cord and working upward into the brain.[24] In a series of studies, they found that neural circuits within the spinal cord are capable of generating the rhythmic motor patterns that underlie swimming, that these circuits are controlled by specific locomotor areas in the brainstem and midbrain, and that these areas in turn are controlled by higher brain structures including the basal ganglia and tectum. In a study of the lamprey tectum published in 2007,[25] they found that electrical stimulation could elicit eye movements, lateral bending movements, or swimming activity, and that the type, amplitude, and direction of movement varied as a function of the location within the tectum that was stimulated. These findings were interpreted as consistent with the idea that the tectum generates goal-directed locomotion in the lamprey as it does in other species.

    "

  • 4 See also
  • 5 Additional images
  • 6 External links
  • 7 Notes
  • 8 References
"        






 
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