Spatial view cells

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Spatial view cells are neurons in primates' hippocampus; they respond when a certain part of the environment is in the animal's field of view. [1]

Contents

They are related to place cells and head direction cells. Spatial view cells differ from place cells, since they are not localized in space. They also differ from head direction cells since they don't represent a global orientation (like a compass), but the direction towards a specific object. Spatial view cells are the cells that respond in the hippocampus when a particular location is being recalled. These cells are identified in the hippocampus of test subjects by monitoring individual neurons while the test subject is moved around in a cue controlled spatial environment. The spatial view cells are the cells that fire consistently when the monkey is looking at a certain direction in the environment; this is independent of the head direction or the location of the monkey. Also, these cells are confirmed to be spatial view cells by observing that there is minimal randomized firing of the cells without the appropriate stimulus present. [2]

Characteristics

Spatial view cells can be characterized by the following features: [3]

The spatial view cells that respond in the absence of visual cues are generally found in the Cornu Ammonis area 1, the parahippocampal gyrus, and the presubiculum, while the ones that do not respond are found in the Cornu Ammonis region 3. The cells found in the CA1, parahippocampal gyrus, and presubiculum regions often provide a longer response even after the stimulus is removed for up to several minutes in complete darkness. Spatial view cells update their representations by the use of idiothetic inputs in the dark and these cells are commonly found in the CA1, parahippocampal gyrus, and presubiculum regions. [5] [6]

Uses

Spatial view cells are used by primates for storing an episodic memory that helps with remembering where a particular object was in the environment. Imaging studies have shown that the hippocampus plays an important role in spatial navigation and episodic memories. [7] Also, spatial view cells enable them to recall locations of objects even if they are not physically present in the environment. The neurons associated with remembering the location and object are often found in the primate hippocampus. These spatial view cells do not only recall specific locations, but they also remember distances between other landmarks around the place in order to gain a better understanding of where the places are spatially.

In real world applications, monkeys remember where they saw ripe fruit with the aid of spatial view cells. Humans use spatial view cells when they try to recall where they may have seen a person or where they left their keys. Primates' highly developed visual and eye movement control systems enables them to explore and remember information about what's present at places in the environment without having to physically visit those places. These sorts of memories would be useful for spatial navigation in which the primates visualize everything in an allocentric, or worldly manner that allows them to convey directions to others without physically going through the entire route. These cells are used by primates in regular day-to-day lives. [8]

Removal of spatial view cell

Diseases and illnesses that harm the brain and the hippocampus can also damage spatial view cells, which are located in the hippocampus. Strokes, meningitis, and encephalitis are only a few of the various illnesses that can cause harm to the spatial view cells. Some clinical symptoms present in patients with damage to the central nervous system include: fever, altered mental status, and neck stiffness. Lesion studies have shown that damage to the hippocampus or to some of its connections, such as the fornix, in monkeys produces deficits in learning about the places of objects and about the places where responses should be made. This sort of damage to the brain often results in impaired object-place memory. Object-place memory tasks require the monkey to not only remember the object seen, but they must also remember where the object was seen in the environment. It has been shown that posterior para-hippocampal lesions in macaques impair even a simple type of object-place learning in which only one pair of unique stimuli are needed for memory. [9]

Relationship to other diseases

Patients with damage to spatial view cells will often show similar symptoms from other diseases such as: vascular dementia, Alzheimer's disease, amnesia fugue, macular degeneration, and optic nerve damage. [10] Another illness that reflects signs of spatial view damage is fornix lesions that impair conditional left–right discrimination learning. Patients with damage to the temporal lobe which also includes the hippocampus can sometimes have amnesia. Patients with amnesia often have memory impairments in which they have difficulty remembering both what they saw and where they saw the object or event take place. These signs point to the possible damage to spatial view cells found in the hippocampus. [11]

Current research involving spatial view cells

Optimal firing rate

Current research shows that the maximum firing rate of spatial view cells is obtained when the test agent is allowed to explore the environment freely. Tests in which the monkey was not allowed to have active locomotion provided very few results of spatial view cells being detected in the hippocampus. Majority of the experiments conducted for spatial view cells involved the use of macaque monkeys as test subjects. These types of cells are identified by monitoring the hippocampus of the monkeys while the brains are stimulated by presenting various images and objects in the monkey's vision. Various researchers use different methodologies in sync with the experiment being conducted in order to identify these spatial view cells. For example, in a delayed spatial response task, the monkey is shown a stimulus on one side of a screen and then the stimulus is taken away. After a short while, the stimulus is again presented to the monkey in the same location and the firing of the cell in the hippocampus that is specifically associated with the location at which the monkey is looking and is independent of the location of the monkey helps identify the spatial view cell. The monkeys in this of experiment are encouraged by rewarding them with fruit juice when they correctly identify the same object in the same location twice in a row and if they get it incorrect, the monkeys receive a saline taste. [9]

Association with episodic memories

The experiments often use object-place memory tasks because they are representative of episodic memories and often employ similar parts of the brain. [6] [9] It is also believed that whenever an episodic memory is stored, part of the context from that event is also stored along with it. As a result, recalling a certain place can link up the emotions at that time. These recollections do not only happen if a place is recalled, but they are prone to occur if the person is in the same mood as they were at the time of the event. Rewards are also remembered along with the place at which it was received. Spatial view cells have been proven to be independent of head direction and place cells. Spatial view cells have been shown to respond even in the dark without any visual cues as long as the test subject was facing in the proper direction. It is believed that in the absence of visual cues, spatial view cells respond from the inputs being received from head direction cells and place cells along with eye position of the primate. The use of the vestibular system and proprioceptive cues also provide a sense of direction the animal is facing in the dark. [12]

Ability to update with new information

Research has led to the finding the spatial view cells are consistently updated with other inputs from the body. For example, when a monkey is oriented in a different position spatially such as being upside down, the spatial view cells still respond when the test subject faces the appropriate direction. This implies that there is stream of new information being received by the spatial view cells constantly. [13] This integration from various inputs develops continuous attractor networks. Continuous attractor neural networks, also known as CANN, are routinely used when studying spatial view cells from an idiothetic stand point. CANNs allow researchers to closely monitor the associated head direction cells and place cells along with the spatial view cells as one close "packet of neural activity". [12]

Related Research Articles

<span class="mw-page-title-main">Entorhinal cortex</span> Area of the temporal lobe of the brain

The entorhinal cortex (EC) is an area of the brain's allocortex, located in the medial temporal lobe, whose functions include being a widespread network hub for memory, navigation, and the perception of time. The EC is the main interface between the hippocampus and neocortex. The EC-hippocampus system plays an important role in declarative (autobiographical/episodic/semantic) memories and in particular spatial memories including memory formation, memory consolidation, and memory optimization in sleep. The EC is also responsible for the pre-processing (familiarity) of the input signals in the reflex nictitating membrane response of classical trace conditioning; the association of impulses from the eye and the ear occurs in the entorhinal cortex.

<span class="mw-page-title-main">Hippocampus</span> Vertebrate brain region involved in memory consolidation

The hippocampus is a major component of the brain of humans and other vertebrates. Humans and other mammals have two hippocampi, one in each side of the brain. The hippocampus is part of the limbic system, and plays important roles in the consolidation of information from short-term memory to long-term memory, and in spatial memory that enables navigation. The hippocampus is located in the allocortex, with neural projections into the neocortex, in humans as well as other primates. The hippocampus, as the medial pallium, is a structure found in all vertebrates. In humans, it contains two main interlocking parts: the hippocampus proper, and the dentate gyrus.

<span class="mw-page-title-main">Limbic system</span> Set of brain structures involved in emotion and motivation

The limbic system, also known as the paleomammalian cortex, is a set of brain structures located on both sides of the thalamus, immediately beneath the medial temporal lobe of the cerebrum primarily in the forebrain.

<span class="mw-page-title-main">Fornix (neuroanatomy)</span> Bundle of nerve fibers in the brain

The fornix is a C-shaped bundle of nerve fibers in the brain that acts as the major output tract of the hippocampus. The fornix also carries some afferent fibers to the hippocampus from structures in the diencephalon and basal forebrain. The fornix is part of the limbic system. While its exact function and importance in the physiology of the brain are still not entirely clear, it has been demonstrated in humans that surgical transection—the cutting of the fornix along its body—can cause memory loss. There is some debate over what type of memory is affected by this damage, but it has been found to most closely correlate with recall memory rather than recognition memory. This means that damage to the fornix can cause difficulty in recalling long-term information such as details of past events, but it has little effect on the ability to recognize objects or familiar situations.

<span class="mw-page-title-main">Spatial memory</span> Memory about ones environment and spatial orientation

In cognitive psychology and neuroscience, spatial memory is a form of memory responsible for the recording and recovery of information needed to plan a course to a location and to recall the location of an object or the occurrence of an event. Spatial memory is necessary for orientation in space. Spatial memory can also be divided into egocentric and allocentric spatial memory. A person's spatial memory is required to navigate around a familiar city. A rat's spatial memory is needed to learn the location of food at the end of a maze. In both humans and animals, spatial memories are summarized as a cognitive map.

<span class="mw-page-title-main">Place cell</span> Place-activated hippocampus cells found in some mammals

A place cell is a kind of pyramidal neuron in the hippocampus that becomes active when an animal enters a particular place in its environment, which is known as the place field. Place cells are thought to act collectively as a cognitive representation of a specific location in space, known as a cognitive map. Place cells work with other types of neurons in the hippocampus and surrounding regions to perform this kind of spatial processing. They have been found in a variety of animals, including rodents, bats, monkeys and humans.

<span class="mw-page-title-main">Cognitive map</span> Mental representation of information

A cognitive map is a type of mental representation which serves an individual to acquire, code, store, recall, and decode information about the relative locations and attributes of phenomena in their everyday or metaphorical spatial environment. The concept was introduced by Edward Tolman in 1948. He tried to explain the behavior of rats that appeared to learn the spatial layout of a maze, and subsequently the concept was applied to other animals, including humans. The term was later generalized by some researchers, especially in the field of operations research, to refer to a kind of semantic network representing an individual's personal knowledge or schemas.

Explicit memory is one of the two main types of long-term human memory, the other of which is implicit memory. Explicit memory is the conscious, intentional recollection of factual information, previous experiences, and concepts. This type of memory is dependent upon three processes: acquisition, consolidation, and retrieval.

In relation to psychology, pair by association is the action of associating a stimulus with an arbitrary idea or object, eliciting a response, usually emotional. This is done by repeatedly pairing the stimulus with the arbitrary object.

<span class="mw-page-title-main">Subiculum</span> Most inferior part of the hippocampal formation

The subiculum is the most inferior component of the hippocampal formation. It lies between the entorhinal cortex and the CA1 subfield of the hippocampus proper.

<span class="mw-page-title-main">Parahippocampal gyrus</span> Grey matter region surrounding the hippocampus

The parahippocampal gyrus is a grey matter cortical region of the brain that surrounds the hippocampus and is part of the limbic system. The region plays an important role in memory encoding and retrieval. It has been involved in some cases of hippocampal sclerosis. Asymmetry has been observed in schizophrenia.

Head direction (HD) cells are neurons found in a number of brain regions that increase their firing rates above baseline levels only when the animal's head points in a specific direction. They have been reported in rats, monkeys, mice, chinchillas and bats, but are thought to be common to all mammals, perhaps all vertebrates and perhaps even some invertebrates, and to underlie the "sense of direction". When the animal's head is facing in the cell's "preferred firing direction" these neurons fire at a steady rate, but firing decreases back to baseline rates as the animal's head turns away from the preferred direction.

<span class="mw-page-title-main">Hippocampal formation</span> Region of the temporal lobe in mammalian brains

The hippocampal formation is a compound structure in the medial temporal lobe of the brain. It forms a c-shaped bulge on the floor of the temporal horn of the lateral ventricle. There is no consensus concerning which brain regions are encompassed by the term, with some authors defining it as the dentate gyrus, the hippocampus proper and the subiculum; and others including also the presubiculum, parasubiculum, and entorhinal cortex. The hippocampal formation is thought to play a role in memory, spatial navigation and control of attention. The neural layout and pathways within the hippocampal formation are very similar in all mammals.

<span class="mw-page-title-main">Grid cell</span>

A grid cell is a type of neuron within the entorhinal cortex that fires at regular intervals as an animal navigates an open area, allowing it to understand its position in space by storing and integrating information about location, distance, and direction. Grid cells have been found in many animals, including rats, mice, bats, monkeys, and humans.

The perirhinal cortex is a cortical region in the medial temporal lobe that is made up of Brodmann areas 35 and 36. It receives highly processed sensory information from all sensory regions, and is generally accepted to be an important region for memory. It is bordered caudally by postrhinal cortex or parahippocampal cortex and ventrally and medially by entorhinal cortex.

<span class="mw-page-title-main">Retrosplenial cortex</span> Part of the brains cerebral cortex

The retrosplenial cortex (RSC) is a cortical area in the brain comprising Brodmann areas 29 and 30. It is secondary association cortex, making connections with numerous other brain regions. The region's name refers to its anatomical location immediately behind the splenium of the corpus callosum in primates, although in rodents it is located more towards the brain surface and is relatively larger. Its function is currently not well understood, but its location close to visual areas and also to the hippocampal spatial/memory system suggest it may have a role in mediating between perceptual and memory functions, particularly in the spatial domain. However, its exact contribution to either space or memory processing has been hard to pin down.

<span class="mw-page-title-main">Boundary cell</span>

Boundary cells are neurons found in the hippocampal formation that respond to the presence of an environmental boundary at a particular distance and direction from an animal. The existence of cells with these firing characteristics were first predicted on the basis of properties of place cells. Boundary cells were subsequently discovered in several regions of the hippocampal formation: the subiculum, presubiculum and entorhinal cortex.

The neuroanatomy of memory encompasses a wide variety of anatomical structures in the brain.

Episodic-like memory is the memory system in animals that is comparable to human episodic memory. The term was first described by Clayton & Dickinson referring to an animal's ability to encode and retrieve information about 'what' occurred during an episode, 'where' the episode took place, and 'when' the episode happened. This ability in animals is considered 'episodic-like' because there is currently no way of knowing whether or not this form of remembering is accompanied by conscious recollection—a key component of Endel Tulving's original definition of episodic memory.

The hippocampus participates in the encoding, consolidation, and retrieval of memories. The hippocampus is located in the medial temporal lobe (subcortical), and is an infolding of the medial temporal cortex. The hippocampus plays an important role in the transfer of information from short-term memory to long-term memory during encoding and retrieval stages. These stages do not need to occur successively, but are, as studies seem to indicate, and they are broadly divided in the neuronal mechanisms that they require or even in the hippocampal areas that they seem to activate. According to Gazzaniga, "encoding is the processing of incoming information that creates memory traces to be stored." There are two steps to the encoding process: "acquisition" and "consolidation". During the acquisition process, stimuli are committed to short term memory. Then, consolidation is where the hippocampus along with other cortical structures stabilize an object within long term memory, which strengthens over time, and is a process for which a number of theories have arisen to explain the underlying mechanism. After encoding, the hippocampus is capable of going through the retrieval process. The retrieval process consists of accessing stored information; this allows learned behaviors to experience conscious depiction and execution. Encoding and retrieval are both affected by neurodegenerative and anxiety disorders and epilepsy.

References

  1. ↑ Franzius M, Sprekeler H, Wiskott L (2007). "Slowness and sparseness lead to place, head-direction, and spatial-view cells". PLOS Computational Biology. 3 (8): 1605–22. Bibcode:2007PLSCB...3..166F. doi: 10.1371/journal.pcbi.0030166 . PMC   1963505 . PMID   17784780.
  2. ↑ Georges-François P, Rolls ET, Robertson RG (1999). "Spatial view cells in the primate hippocampus: allocentric view not head direction or eye position or place". Cereb. Cortex. 9 (3): 197–212. doi: 10.1093/cercor/9.3.197 . PMID   10355900.
  3. ↑ de Araujo IE, Rolls ET, Stringer SM (2001). "A view model which accounts for the spatial fields of hippocampal primate spatial view cells and rat place cells". Hippocampus. 11 (6): 699–706. CiteSeerX   10.1.1.15.6551 . doi:10.1002/hipo.1085. PMID   11811664. S2CID   15203881.
  4. ↑ Rolls ET (1999). "Spatial view cells and the representation of place in the primate hippocampus". Hippocampus. 9 (4): 467–80. CiteSeerX   10.1.1.7.5431 . doi:10.1002/(SICI)1098-1063(1999)9:4<467::AID-HIPO13>3.0.CO;2-F. PMID   10495028. S2CID   7685147.
  5. ↑ Robertson RG, Rolls ET, Georges-Fran ois P (March 1998). "Spatial view cells in the primate hippocampus: effects of removal of view details". J. Neurophysiol. 79 (3): 1145–56. doi:10.1152/jn.1998.79.3.1145. PMID   9497397.
  6. 1 2 Rolls ET (December 2010). "A computational theory of episodic memory formation in the hippocampus". Behav. Brain Res. 215 (2): 180–96. doi:10.1016/j.bbr.2010.03.027. PMID   20307583. S2CID   13605251.
  7. ↑ Jacobs J, Kahana MJ, Ekstrom AD, Mollison MV, Fried I (April 2010). "A sense of direction in human entorhinal cortex". Proc. Natl. Acad. Sci. U.S.A. 107 (14): 6487–92. Bibcode:2010PNAS..107.6487J. doi: 10.1073/pnas.0911213107 . PMC   2851993 . PMID   20308554.
  8. ↑ Rolls ET, Robertson RG, Georges-François P (August 1997). "Spatial view cells in the primate hippocampus". Eur. J. Neurosci. 9 (8): 1789–94. doi:10.1111/j.1460-9568.1997.tb01538.x. PMID   9283835. S2CID   17993926.
  9. 1 2 3 Rolls ET, Xiang JZ (2006). "Spatial view cells in the primate hippocampus and memory recall". Rev Neurosci. 17 (1–2): 175–200. doi:10.1515/REVNEURO.2006.17.1-2.175. PMID   16703951. S2CID   147636287.
  10. ↑ Dr. Manish N. Patel, Resident Physician at St. Vincent's Medical Center Department of Family Medicine. Interview date October 19th, 2010.
  11. ↑ Rolls ET, Treves A, Robertson RG, Georges-François P, Panzeri S (April 1998). "Information about spatial view in an ensemble of primate hippocampal cells". J. Neurophysiol. 79 (4): 1797–813. doi:10.1152/jn.1998.79.4.1797. PMID   9535949.
  12. 1 2 Stringer SM, Rolls ET, Trappenberg TP (January 2005). "Self-organizing continuous attractor network models of hippocampal spatial view cells". Neurobiol Learn Mem. 83 (1): 79–92. CiteSeerX   10.1.1.67.2605 . doi:10.1016/j.nlm.2004.08.003. PMID   15607692. S2CID   2513451.
  13. ↑ Rolls ET, Stringer SM (November 2005). "Spatial view cells in the hippocampus, and their idiothetic update based on place and head direction". Neural Netw. 18 (9): 1229–41. doi:10.1016/j.neunet.2005.08.006. PMID   16257507.
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