Brain: Superior colliculus
Section through superior colliculus (unlabeled) showing path of oculomotor nerve
Scheme showing central connections of the optic nerves and optic tracts. The optic nerve, also called cranial nerve II, is the Nerve that transmits visual information from the Retina to the Brain. (Superior colliculus visible near center. )
Gray's	subject #188 806
Part of	Tectum
NeuroNames	hier-456
MeSH	Superior+Colliculus

The superior colliculus (Latin, higher hill) is a paired structure that is part of the brain's tectal area. This is a list of the subjects in Gray's Anatomy: IX Neurology The tectum (Latin roof) is a region of the Brain, specifically the dorsal part of the Mesencephalon (midbrain NeuroNames is a system of nomenclature for the human and/or macaque Brain. Medical Subject Headings ( MeSH) is a huge Controlled vocabulary (or metadata system for the purpose of indexing journal articles and books Latin ( lingua Latīna, laˈtiːna is an Italic language, historically spoken in Latium and Ancient Rome. The brain is the center of the Nervous system in animals All Vertebrates and the majority of Invertebrates have a brain The tectum (Latin roof) is a region of the Brain, specifically the dorsal part of the Mesencephalon (midbrain Superior Colliculus neurons respond to visual, auditory and somatosensory stimuli. Neurons (ˈnjuːɹɒn also known as neurones and nerve cells) are responsive cells in the Nervous system that process and transmit information ^[1][2]

Structure and relations

The two superior colliculi sit below the thalamus and surround the pineal gland in the mesencephalon of vertebrate brains. The thalamus (from Greek θάλαμος = room chamber, IPA= /ˈθæləməs/ is a pair and symmetric part of the brain The pineal gland (also called the pineal body, epiphysis cerebri, or epiphysis) is a small endocrine gland in the vertebrate Brain In biological anatomy the mesencephalon (or midbrain) comprises the Tectum (or corpora quadrigemini Tegmentum, the ventricular mesocoelia (or "iter" Vertebrates are members of the Subphylum Vertebrata, Chordates with backbones or spinal columns The grouping sometimes includes It comprises the caudal aspect of the midbrain, posterior to the periaqueductal gray and immediately superior to the inferior colliculus. In fields of Anatomy, anatomical terms of location are descriptive terms to help identify relative positions or directions within a species In biological anatomy the mesencephalon (or midbrain) comprises the Tectum (or corpora quadrigemini Tegmentum, the ventricular mesocoelia (or "iter" Periaqueductal gray (PAG also called the "central gray" is the Midbrain Grey matter that is located around the Cerebral aqueduct within the The inferior colliculi ( Latin, lower hills) together with the superior colliculi form the eminences of the Corpora quadrigemina, and also part The inferior and superior colliculi are known collectively as the corpora quadrigemina (Latin, quadruplet bodies). In the Brain, the corpora quadrigemina ( Latin for "quadruplet bodies" are the four colliculi—two inferior, two superior —located

Function

In humans, the superior colliculus (SC) is involved in the generation of saccadic(fast) eye movements and eye-head coordination. Human beings, humans or man (Origin 1590–1600 L homō man OL hemō the earthly one (see Humus A saccade is a fast movement of an eye, head or other part of an animal's body or device Afferents to the SC originate in the cerebral cortex, inferior colliculus, retina, basal ganglia, and spinal cord. In the Nervous system, afferent neurons --otherwise known as sensory or receptor Neurons -carry nerve impulses from receptors or sense The cerebral cortex is a structure within the Brain that plays a key role in Memory, Attention, perceptual Awareness, Thought, The inferior colliculi ( Latin, lower hills) together with the superior colliculi form the eminences of the Corpora quadrigemina, and also part The vertebrate retina is a light sensitive part inside the inner layer of the Eye. The basal ganglia (or basal nuclei) are a group of nuclei in the Brain interconnected with the Cerebral cortex, Thalamus and The spinal cord is a long thin tubular bundle of Nerves that is an extension of the Central nervous system from the brain and is enclosed in and protected Efferents project to the paramedian pontine reticular formation, spinal cord, and elsewhere. The paramedian pontine reticular formation, or PPRF, is part of the pontine Reticular formation, a Brain region without clearly defined borders in the center The spinal cord is a long thin tubular bundle of Nerves that is an extension of the Central nervous system from the brain and is enclosed in and protected In humans, as in most larger vertebrates, sensory information that goes to the mesencephalon will be relayed via the thalamus to the cerebral cortex for interpretation. Vertebrates are members of the Subphylum Vertebrata, Chordates with backbones or spinal columns The grouping sometimes includes The thalamus (from Greek θάλαμος = room chamber, IPA= /ˈθæləməs/ is a pair and symmetric part of the brain However, the SC can also mediate some oculomotor movements without cortical involvement. The oculomotor nerve is the third of twelve paired Cranial nerves.

The SC receives visual, as well as auditory, inputs in its superficial layers, and the deeper layers of the colliculus are connected to many sensorimotor areas of the brain. In Psychology, visual perception is the ability to interpret information from Visible light reaching the Eyes The resulting Perception is also The colliculus as a whole is thought to help orient the head and eyes toward something seen and heard. ^[3][4][5][6]

Hind- and mid-brains; postero-lateral view. Superior colliculus labeled in blue.

Diversity

Primates

It is usually accepted that the primate superior colliculus is unique among mammals, in that it does not contain a complete map of the visual field seen by the contralateral eye. A primate is a member of the biological order Primates ( Latin: "prime first rank" the group that contains Lemurs the Aye-aye Mammals ( class Mammalia) are a class of Vertebrate Animals characterized by the presence of Sweat glands, including sweat glands Instead, like the visual cortex and lateral geniculate nucleus, each colliculus only represents the contralateral half of the visual field, up to the midline, and excludes a representation of the ipsilateral half. The term visual cortex refers to the primary visual cortex (also known as striate cortex or The lateral geniculate nucleus ( LGN) of the Thalamus is a part of the Brain, which is the primary processor of visual information received from the The term visual field is sometimes used as a Synonym to Field of view, though they do not designate the same thing ^[7] This functional characteristic is explained by the absence, in primates, of anatomical connections between the retinal ganglion cells in the temporal half of the retina and the contralateral superior colliculus. A ganglion cell (more correctly a retinal ganglion cell or RGC) is a type of Neuron typically located near the inner surface of the Retina The vertebrate retina is a light sensitive part inside the inner layer of the Eye. In other mammals, the retinal ganglion cells throughout the contralateral retina project to the contralateral colliculus. This distinction between primates and non-primates has been one of the key lines of evidence in support of the flying primates theory proposed by Australian neuroscientist Jack Pettigrew in 1986, after he discovered that flying foxes (megabats) resemble primates in terms of the pattern of anatomical connections between the retina and superior colliculus. The flying primates theory conjectures that Megabats a sub-group of Chiroptera (also known as flying foxes) form an evolutionary Sister group John Douglas ("Jack" Pettigrew (born 1943 is Emeritus Professor of Physiology and Director of the Vision Touch and Hearing Research Centre at the For other uses of the term "Flying fox" see Flying fox (disambiguation Megabats is the term used informally to refer to bats ^[8]

Other vertebrates

In echolocating bats, the SC has been shown to influence vocalization parameters and ear movements, both orienting components of the bat's biosonar system, thereby assisting in orienting movements. The microbats constitute the suborder Microchiroptera within the order Chiroptera ( Bats. Echolocation, also called biosonar, is the biological Sonar used by several Animals such as Dolphins Shrews most Bats ^[9]

The comparable area of the mesencephalon of non-mammalian vertebrates is called the optic tectum. In amphibians, reptiles, and fish, the optic tectum is the largest visual processing area, though its function remains largely unknown. Prehistoric amphibian Amphibians (class Amphibia such as Frogs Toads Salamanders Newts Gymnophiona, Sirens and Reptiles, or members of the class Reptilia are air-breathing Cold-blooded Vertebrates that have skin covered in scales as opposed to hair or feathers Fish are aquatic Vertebrate animals that are typically ectothermic (previously Cold-blooded) covered with scales, and equipped with two It seems to be required for predator/prey discrimination leading to escape or hunting behavior respectively. In contrast, the role of the SC for visual discrimination is less prominent in more complex vertebrates.

In snakes with infrared vision like pythons and pit vipers though the initial neural input is through trigeminal nerve instead of optic nerve, the rest of the processing circuits for this form of sense is quite similar to visual sense and thus involves the superior colliculi. A snake is an elongate Reptile of the suborder Serpentes Like all reptiles snakes are covered in scales. Infrared vision can be defined as the capability of biological or artificial systems to detect Infrared radiation. Common names pythons The Pythonidae are a family of non- Venomous Snakes found in Africa, Asia Common names: pit vipers pitvipers The Crotalinae, or crotalines are a subfamily of venomous vipers found The trigeminal nerve (the fifth Cranial nerve, also called the fifth nerve or simply V) is responsible for sensation in the face The optic nerve, also called cranial nerve II, is the Nerve that transmits visual information from the Retina to the Brain.

See also

• List of regions in the human brain

Additional images

Superficial dissection of brain-stem. Anatomical regions of the brain are listed vertically following hierarchies that are standard in Neuroanatomy. Lateral view.	Dissection of brain-stem. Lateral view.	Deep dissection of brain-stem. Lateral view.	Deep dissection of brain-stem. Lateral view.
Transverse section of mid-brain at level of superior colliculi.

External links

• Brainstem at UWisc 23Colliculus
• BrainMaps at UCDavis superior colliculus

References