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103-417: The receptive field is the area of the body or environment to which a receptor organ and receptor cells respond. For instance, the part of the world an eye can see, is its receptive field; the light that each rod or cone can see, is its receptive field. Receptive fields have been identified for the visual system , auditory system and somatosensory system . While debate exists among neurologists as to

206-465: A ganglion cell in the retina of the eye is composed of input from all of the photoreceptors which synapse with it, and a group of ganglion cells in turn forms the receptive field for a cell in the brain. This process is called convergence. Receptive fields have been used in modern artificial deep neural networks that work with local operations. The auditory system processes the temporal and spectral (i.e. frequency) characteristics of sound waves, so

309-495: A paleosubspecies of the tawny owl, which would make it that species' immediate ancestor. The tawny owl subspecies are often poorly differentiated, and may be at a flexible stage of subspecies formation with features related to the ambient temperature, the colour tone of the local habitat, and the size of available prey. Consequently, various authors have historically described between 10 and 15 subspecies. The seven currently recognised subspecies are listed below. The tawny owl

412-403: A scratch reflex could be elicited in a dog. In 1938, Hartline started to apply the term to single neurons, this time from the frog retina . This concept of receptive fields can be extended further up the nervous system. If many sensory receptors all form synapses with a single cell further up, they collectively form the receptive field of that cell. For example, the receptive field of

515-484: A spectrogram of the acoustic stimulus, which determines how the spectral density of the acoustic stimulus changes over time, often using the Short-time Fourier transform (STFT). Firing rate is modeled over time for the neuron, possibly using a peristimulus time histogram if combining over multiple repetitions of the acoustic stimulus. Then, linear regression is used to predict the firing rate of that neuron as

618-490: A tree hole where it can protect its eggs and young against potential predators. It is non-migratory and highly territorial: as a result, when young birds grow up and leave the parental nest, if they cannot find a vacant territory to claim as their own, they will often starve. The tawny owl is a nocturnal bird of prey . It is able to hunt successfully at night because of its vision, hearing adaptations and its ability to fly silently. It usually hunts by dropping suddenly from

721-426: A 2D grid), so an adequate receptive field is required. Specifically, the receptive field should be sufficient if it is larger than the largest flow magnitude of the dataset. There are a lot of ways that one can increase the receptive field on a CNN. When used in this sense, the term adopts a meaning reminiscent of receptive fields in actual biological nervous systems. CNNs have a distinct architecture, designed to mimic

824-421: A Bird . The parents care for young birds for two or three months after they fledge, but from August to November the juveniles disperse to find a territory of their own to occupy. If they fail to find a vacant territory, they usually starve. The juvenile survival rate is unknown, but the annual survival rate for adults is 76.8%. The typical lifespan is five years, but an age of over 18 years has been recorded for

927-435: A branch close to a tree trunk during the day, and usually roost separately from July to October. Roosting owls may be discovered and "mobbed" by small birds during the day, but they normally ignore the disturbance. Tawny owls are very territorial, and will indicate the location of their chosen territory by their vocalisations, which occur at their greatest frequency during the night, though some owls will continue to call during

1030-473: A correctly oriented bar of light might need to move in a particular direction in order to excite the cell. For hypercomplex receptive fields, the bar might also need to be of a particular length. In extrastriate visual areas, cells can have very large receptive fields requiring very complex images to excite the cell. For example, in the inferotemporal cortex , receptive fields cross the midline of visual space and require images such as radial gratings or hands. It

1133-422: A distance, which could include rustling made by prey moving in vegetation. The tawny owl's hearing is ten times better than a human's, and it can hunt using this sense alone in the dark of a woodland on an overcast night, but the patter of raindrops makes it difficult to detect faint sounds, and prolonged wet weather can lead to starvation if the owl cannot hunt effectively. The commonly heard female contact call

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1236-412: A greater height. The flight of the tawny owl is rather heavy and slow, particularly at takeoff, though the bird can attain a top flight speed of around 50 mph. As with most owls, its flight is silent because of its feathers' soft, furry upper surfaces and a fringe on the leading edge of the outer primaries . Its size, squat shape and broad wings distinguish it from other owls found within its range;

1339-400: A particular region on an animal's body. For example, it could be a hair in the cochlea or a piece of skin, retina, or tongue or other part of an animal's body. Receptive fields have been identified for neurons of the auditory system , the somatosensory system , and the visual system . The term receptive field was first used by Sherrington in 1906 to describe the area of skin from which

1442-420: A particular sound wave traveling in an appropriate transmission medium , by means of sound localization , an auditory space would amount to a reference system that continuously shifts as the animal moves (taking into consideration the space inside the ears as well). Conversely, receptive fields can be largely independent of the animal's location, as in the case of place cells . A sensory space can also map into

1545-529: A perch and seizing its prey, which it swallows whole. It mainly hunts rodents , although in urbanized areas its diet includes a higher proportion of birds. It also sometimes catches smaller owls, and is itself sometimes hunted by the eagle owl and the Eurasian goshawk . Its retina is no more sensitive than a human's. Its directional hearing skill is more important to its hunting success: its ears are asymmetrically placed, which enables it to more precisely pinpoint

1648-439: A small heat detecting thermometer in the membrane which begins the polarization of the neural fiber when exposed to changes in temperature. Ultimately, this allows us to detect ambient temperature in the warm/hot range. Similarly, the molecular cousin to TRPV1, TRPM8, is a cold-activated ion channel that responds to cold. Both cold and hot receptors are segregated by distinct subpopulations of sensory nerve fibers, which shows us that

1751-410: A specific area of the brain. While the term sensory cortex is often used informally to refer to the somatosensory cortex , the term more accurately refers to the multiple areas of the brain at which senses are received to be processed. For the five traditional senses in humans, this includes the primary and secondary cortices of the different senses : the somatosensory cortex, the visual cortex ,

1854-404: A system which connects its output to its own input, thus ever-moving without any external input. The prime example is the brain, with its default mode network . Receptive field The receptive field , or sensory space , is a delimited medium where some physiological stimuli can evoke a sensory neuronal response in specific organisms . Complexity of the receptive field ranges from

1957-402: A way of detecting contrast, and is used for detecting objects' edges . Each receptive field is arranged into a central disk, the "center", and a concentric ring, the "surround", each region responding oppositely to light. For example, light in the centre might increase the firing of a particular ganglion cell, whereas light in the surround would decrease the firing of that cell. Stimulation of

2060-455: A weighted sum of the spectrogram. The weights learned by the linear model are the STRF, and represent the specific acoustic pattern that causes modulation in the firing rate of the neuron. STRFs can also be understood as the transfer function that maps an acoustic stimulus input to a firing rate response output. A theoretical explanation of the computational function of early auditory receptive fields

2163-588: A wide range of prey , mainly woodland rodents , but also other mammals up to the size of a young rabbit , and birds , earthworms and beetles . In urban areas, birds make up a larger proportion of the diet, and species as unlikely as mallard and kittiwake have been killed and eaten. Prey is typically swallowed whole, with indigestible parts regurgitated as pellets . These are medium-sized and grey, consisting mainly of rodent fur and often with bones protruding, and are found in groups under trees used for roosting or nesting. Less powerful woodland owls such as

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2266-435: A wild tawny owl, and of over 27 years for a captive bird. Predators of the tawny owl include large birds such as Ural owls , eagle owls , Eurasian goshawks , golden eagles , and common buzzards . Pine martens may raid nests, especially where artificial nest boxes make the owls easy to find, and several instances have been recorded of Eurasian jackdaws building nests on top of a brooding female tawny owl leading to

2369-669: Is genetically controlled, and studies in Finland and Italy indicate that grey-morph tawny owls have more reproductive success, better immune resistance, and fewer parasites than brown birds. Although this might suggest that eventually the brown morph could disappear, the owls show no colour preference when choosing a mate, so the selection pressure in favour of the grey morph is reduced. There are also environmental factors involved. The Italian study showed that brown-morph birds were found in denser woodland, and in Finland, Gloger's rule would suggest that paler birds would in any case predominate in

2472-669: Is non-migratory and has a distribution stretching discontinuously across temperate Europe, from Great Britain and the Iberian Peninsula eastwards to western Siberia . It is absent from Ireland - probably because of competition from the long-eared owl ( Asio otus ) - and only a rare vagrant to the Balearic and Canary Islands . In the Himalayas and East Asia it is replaced by the Himalayan owl ( Strix nivicolum ) and in northwest Africa it

2575-481: Is a shrill, kew-wick but the male has a quavering advertising song hoo...ho, ho, hoo-hoo-hoo-hoo . William Shakespeare used this owl's song in Love's Labour's Lost (Act 5, Scene 2) as "Then nightly sings the staring owl, Tu-whit; Tu-who, a merry note, While greasy Joan doth keel the pot", but this stereotypical call is actually a duet, with the female making the kew-wick sound, and the male responding hooo . The call

2678-499: Is also believed that in the fusiform face area , images of faces excite the cortex more than other images. This property was one of the earliest major results obtained through fMRI ( Kanwisher , McDermott and Chun, 1997); the finding was confirmed later at the neuronal level ( Tsao , Freiwald, Tootell and Livingstone , 2006). In a similar vein, people have looked for other category-specific areas and found evidence for regions representing views of places ( parahippocampal place area ) and

2781-753: Is easily imitated by blowing into cupped hands through slightly parted thumbs, and a study in Cambridgeshire found that this mimicry produced a response from the owl within 30 minutes in 94% of trials. A male's response to a broadcast song appears to be indicative of his health and vigour; owls with higher blood parasite loads use fewer high frequencies and a more limited range of frequencies in their responses to an apparent intruder. The vocal activity of tawny owls depends on sex, annual cycle stage and weather, with males being more vocal than females year-round, with peak vocal activity during incubation and post-breeding. Although both colour morphs occur in much of

2884-845: Is evidence of an overall increase. This owl is not believed to meet the IUCN Red List criterion of declining more than 30% in ten years or three generations and is therefore evaluated as being of least concern . In the UK it is on the RSPB Amber List of Concern. This species has expanded its range in Belgium, the Netherlands, Norway and Ukraine , and populations are stable or increasing in most European countries. Declines have occurred in Finland, Estonia, Italy and Albania. Tawny owls are listed in Appendix II of

2987-518: Is given in. In the somatosensory system, receptive fields are regions of the skin or of internal organs . Some types of mechanoreceptors have large receptive fields, while others have smaller ones. Large receptive fields allow the cell to detect changes over a wider area, but lead to a less precise perception. Thus, the fingers, which require the ability to detect fine detail, have many, densely packed (up to 500 per cubic cm) mechanoreceptors with small receptive fields (around 10 square mm), while

3090-447: Is higher on the head than the larger right ear and tilts downward, improving sensitivity to sounds from below. Both ear openings are hidden under the facial disk feathers, which are structurally specialized to be transparent to sound, and are supported by a movable fold of skin (the pre-aural flap). The internal structure of the ear, which has large numbers of auditory neurons , gives an improved ability to detect low-frequency sounds at

3193-597: Is increasingly affected by avian malaria , the incidence of which has tripled in the last 70 years, in parallel with increasing global temperatures. An increase of one degree Celsius produces a two- to three-fold increase in the rate of malaria. In 2010, the incidence in British tawny owls was 60%, compared to 2–3% in 1996. The tawny owl hunts almost entirely at night, watching from a perch before dropping or gliding silently down to its victim, but very occasionally it will hunt in daylight when it has young to feed. This species takes

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3296-749: Is mainly a lowland bird in the colder parts of its range, but breeds to 550 metres (1,800 ft) in Scotland, 1,600 m (5,200 ft) in the Alps , 2,350 m (7,710 ft) in Turkey , and up to 2,800 m (9,200 ft) in Myanmar . The tawny owl has a geographical range of at least 10 million km (3.8 million mi ) and a large population including an estimated 970,000–2,000,000 individuals in Europe alone. Population trends have not been quantified, but there

3399-445: Is poorly developed except in daytime hunters such as the short-eared owl . Hearing is important for a nocturnal bird of prey , and as with other owls, the tawny owl's two ear openings differ in structure and are asymmetrically placed to improve directional hearing. A passage through the skull links the eardrums, and small differences in the time of arrival of a sound at each ear enables its source to be pinpointed. The left ear opening

3502-462: Is processed and interpreted. Chemoreceptors, or chemosensors, detect certain chemical stimuli and transduce that signal into an electrical action potential. The two primary types of chemoreceptors are: Photoreceptors are neuron cells and are specialized units that play the main role in initiating vision function. Photoreceptors are light-sensitive cells that capture different wavelengths of light. Different types of photoreceptors are able to respond to

3605-521: Is replaced by the closely related Maghreb owl ( Strix mauritanica ). This species is found in deciduous and mixed forests, and sometimes mature conifer plantations, preferring locations with access to water. Cemeteries, gardens and parks have allowed it to spread into urban areas, including central London . Although tawny owls occur in urban environments, especially those with natural forests and wooded habitat patches, they are less likely to occur at sites with high noise levels at night. The tawny owl

3708-475: Is shell. The typical clutch of two or three eggs is incubated for 30 days to hatching, and the altricial , downy chicks fledge in a further 35–39 days. Incubation is usually undertaken by the female alone, although the male has rarely been observed to assist. The young usually leave the nest up to ten days before fledging, and hide on nearby branches. This species is fearless in defence of its nest and young, and, like other Strix owls, strikes for

3811-424: Is still a quiescent state for the cochlea, since there is a well-defined mode of power input that it receives (vibratory energy on the eardrum), which provides an unambiguous definition of "zero input power". Some sensory systems can have multiple quiescent states depending on its history, like flip-flops , and magnetic material with hysteresis . It can also adapt to different quiescent states. In complete darkness,

3914-444: Is the outer segment (OS), where it is responsible for capturing light and transducing it. The second compartment is the inner segment (IS), which includes the necessary organelles that function in cellular metabolism and biosynthesis. Mainly, these organelles include mitochondria, Golgi apparatus and endoplasmic reticulum as well as among others. The third compartment is the connecting cilium (CC). As its name suggests, CC works to connect

4017-409: Is the state the system converges to when there is no input power. It is not always well-defined for nonlinear, nonpassive sensory organs, since they can't function without input energy. For example, a cochlea is not a passive organ, but actively vibrates its own sensory hairs to improve its sensitivity. This manifests as otoacoustic emissions in healthy ears, and tinnitus in pathological ears. There

4120-530: Is the tawny owl’s prototypical call, is actually a call and response between a male and a female. The tawny owl is a robust bird, 37–46 cm (15–18 in) in length, with an 81–105 cm (32–41 in) wingspan. Weight can range from 385 to 800 g (0.849 to 1.764 lb). Its large rounded head lacks ear tufts, and the facial disc surrounding the dark brown eyes is usually rather plain. The nominate race has two morphs which differ in their plumage colour, one form having rufous brown upperparts and

4223-417: Is then transmitted to the thalamus , which in turn projects the signal to several regions of the neocortex , including the gustatory cortex. The neural processing of taste is affected at nearly every stage of processing by concurrent somatosensory information from the tongue, that is, mouthfeel . Scent, in contrast, is not combined with taste to create flavor until higher cortical processing regions, such as

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4326-528: The Convention on International Trade in Endangered Species (CITES) meaning international trade (including in parts and derivatives) is regulated. Tawny owls pair off from the age of one year, and stay together in a usually monogamous relationship for life. An established pair's territory is defended year-round and maintained with little, if any, boundary change from year to year. The pair sit in cover on

4429-421: The auditory cortex , the primary olfactory cortex , and the gustatory cortex . Other modalities have corresponding sensory cortex areas as well, including the vestibular cortex for the sense of balance. The human sensory system consists of the following subsystems: Located in the parietal lobe , the primary somatosensory cortex is the primary receptive area for the sense of touch and proprioception in

4532-515: The barn owls . Within its genus, the tawny owl's closest relatives are Hume's owl , Strix butleri , (formerly considered to be conspecific ), the Himalayan owl , Strix nivicolum , (sometimes considered conspecific), its larger northern neighbour, the Ural owl , S. uralensis , and the North American barred owl , S. varia . The Early – Middle Pleistocene Strix intermedia is sometimes considered

4635-405: The brown owl , is a stocky, medium-sized owl in the family Strigidae . It is commonly found in woodlands across Europe, as well as western Siberia , and has seven recognized subspecies . The tawny owl's underparts are pale with dark streaks, whilst its upper body may be either brown or grey (in several subspecies, individuals may be of both colours). The tawny owl typically makes its nest in

4738-404: The cerebellum ), and motor control (via Brodmann area 4 ). See also: S2 Secondary somatosensory cortex . The visual cortex refers to the primary visual cortex, labeled V1 or Brodmann area 17 , as well as the extrastriate visual cortical areas V2-V5. Located in the occipital lobe , V1 acts as the primary relay station for visual input, transmitting information to two primary pathways labeled

4841-430: The dorsal and ventral streams . The dorsal stream includes areas V2 and V5, and is used in interpreting visual 'where' and 'how.' The ventral stream includes areas V2 and V4, and is used in interpreting 'what.' Increases in task-negative activity are observed in the ventral attention network, after abrupt changes in sensory stimuli, at the onset and offset of task blocks, and at the end of a completed trial. Located in

4944-531: The fovea where they can be a few minutes of arc like a dot on this page, to the whole page. For example, the receptive field of a single photoreceptor is a cone-shaped volume comprising all the visual directions in which light will alter the firing of that cell. Its apex is located in the center of the lens and its base essentially at infinity in visual space. Traditionally, visual receptive fields were portrayed in two dimensions (e.g., as circles, squares, or rectangles), but these are simply slices, cut along

5047-492: The great grey owl ( Strix nebulosa ), Eurasian eagle-owl ( Bubo bubo ) and Ural owl ( Strix uralensis ) are similar in shape, but much larger. An owl's eyes are placed at the front of the head and have a field overlap of 50–70%, giving it better binocular vision than diurnal birds of prey (overlap 30–50%). The tawny owl's retina has about 56,000 light-sensitive rod cells per square millimetre (36 million per square inch); although earlier claims that it could see in

5150-470: The infrared part of the spectrum have been dismissed, it is still often said to have eyesight 10 to 100 times better than humans in low-light conditions. However, the experimental basis for this claim is probably inaccurate by at least a factor of 10. The owl's actual visual acuity is only slightly greater than that of humans, and any increased sensitivity is due to optical factors rather than to greater retinal sensitivity; both humans and owl have reached

5253-451: The lateral geniculate nucleus . Receptive fields are similar to those of ganglion cells, with an antagonistic center-surround system and cells that are either on- or off center. Receptive fields of cells in the visual cortex are larger and have more-complex stimulus requirements than retinal ganglion cells or lateral geniculate nucleus cells. Hubel and Wiesel (e.g., Hubel, 1963; Hubel-Wiesel 1959 ) classified receptive fields of cells in

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5356-686: The little owl and the long-eared owl cannot usually co-exist with the stronger tawny owls, which may take them as food items, and are found in different habitats; in Ireland the absence of the tawny owl allowed the long-eared owl to become the dominant owl. Similarly, where the tawny owl has moved into built-up areas, it tends to displace barn owls from their traditional nesting sites in buildings. The tawny owl, like its relatives, has often been seen as an omen of bad luck; William Shakespeare used it as such in Julius Caesar (Act 1 Scene 3): "And yesterday

5459-417: The olfactory bulb . The chemoreceptors in the receptor neurons that start the signal cascade are G protein-coupled receptors . The central mechanisms include the convergence of olfactory nerve axons into glomeruli in the olfactory bulb, where the signal is then transmitted to the anterior olfactory nucleus , the piriform cortex , the medial amygdala , and the entorhinal cortex , all of which make up

5562-474: The somatosensory system . This cortex is further divided into Brodmann areas 1, 2, and 3. Brodmann area 3 is considered the primary processing center of the somatosensory cortex as it receives significantly more input from the thalamus , has neurons highly responsive to somatosensory stimuli, and can evoke somatic sensations through electrical stimulation . Areas 1 and 2 receive most of their input from area 3. There are also pathways for proprioception (via

5665-588: The tawny owl , the ratio is closer to 1000:1. Ganglion cells reside in the adrenal medulla and retina where they are involved in the sympathetic response . Of the ~1.3 million ganglion cells present in the retina, 1-2% are believed to be photosensitive ganglia . These photosensitive ganglia play a role in conscious vision for some animals, and are believed to do the same in humans. Mechanoreceptors are sensory receptors which respond to mechanical forces, such as pressure or distortion . While mechanoreceptors are present in hair cells and play an integral role in

5768-408: The temporal lobe , the auditory cortex is the primary receptive area for sound information. The auditory cortex is composed of Brodmann areas 41 and 42, also known as the anterior transverse temporal area 41 and the posterior transverse temporal area 42 , respectively. Both areas act similarly and are integral in receiving and processing the signals transmitted from auditory receptors . Located in

5871-426: The vestibular and auditory systems , the majority of mechanoreceptors are cutaneous and are grouped into four categories: Thermoreceptors are sensory receptors which respond to varying temperatures . While the mechanisms through which these receptors operate is unclear, recent discoveries have shown that mammals have at least two distinct types of thermoreceptors: TRPV1 is a heat-activated channel that acts as

5974-544: The European range, brown birds predominate in the more humid climate of western Europe, with the grey morph becoming more common further east; in the northernmost regions, all the owls are a cold-grey colour. The Siberian and Scandinavian subspecies are 12% larger and 40% heavier, and have 13% longer wings than western European birds, in accordance with Bergmann's rule which predicts that northern forms will typically be bigger than their southern counterparts. The plumage colour

6077-650: The OS and the IS regions together for the purpose of essential protein trafficking. The fourth compartment contains the nucleus and is a continuation of the IS region, known as the nuclear region. Finally, the fifth compartment is the synaptic region, where it acts as a final terminal for the signal, consisting of synaptic vesicles. In this region, glutamate neurotransmitter is transmitted from the cell to secondary neuron cells. The three primary types of photoreceptors are: cones are photoreceptors which respond significantly to color . In humans,

6180-454: The back and legs, for example, have fewer receptors with large receptive fields. Receptors with large receptive fields usually have a "hot spot", an area within the receptive field (usually in the center, directly over the receptor) where stimulation produces the most intense response. Tactile-sense-related cortical neurons have receptive fields on the skin that can be modified by experience or by injury to sensory nerves resulting in changes in

6283-489: The bird of night did sit/ Even at noon-day upon the market-place/ Hooting and shrieking." John Ruskin is quoted as saying "Whatever wise people may say of them, I at least have found the owl's cry always prophetic of mischief to me". Wordsworth described the technique for calling an owl in his poem "There Was a Boy". And there, with fingers interwoven, both hands Pressed closely palm to palm and to his mouth Uplifted, he, as through an instrument, Blew mimic hootings to

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6386-415: The body ( Extrastriate body area ). However, more recent research has suggested that the fusiform face area is specialised not just for faces, but also for any discrete, within-category discrimination. A theoretical explanation of the computational function of visual receptive fields is given in. It is described how idealised models of receptive fields similar to the biological receptive fields found in

6489-414: The center of an on-center cell's receptive field produces depolarization and an increase in the firing of the ganglion cell, stimulation of the surround produces a hyperpolarization and a decrease in the firing of the cell, and stimulation of both the center and surround produces only a mild response (due to mutual inhibition of center and surround). An off-center cell is stimulated by activation of

6592-564: The colder climate. The species was given its current scientific name Strix aluco by Carl Linnaeus in the tenth edition of his Systema Naturae in 1758. The binomial derives from the Greek strix "owl" and Italian allocco "tawny owl" (which in turn comes from the Latin ulucus "screech-owl"). The tawny owl is a member of the wood-owl genus Strix , part of the typical owl family Strigidae, which contains all species of owl other than

6695-612: The corresponding area in both retinas (one in each eye). Although these can be mapped separately in each retina by shutting one or the other eye, the full influence on the neuron's firing is revealed only when both eyes are open. Hubel and Wiesel advanced the theory that receptive fields of cells at one level of the visual system are formed from input by cells at a lower level of the visual system. In this way, small, simple receptive fields could be combined to form large, complex receptive fields. Later theorists elaborated this simple, hierarchical arrangement by allowing cells at one level of

6798-445: The data that the neurons represent is typically an image; each input neuron represents one pixel from the original image. The first layer of neurons is composed of all the input neurons; neurons in the next layer will receive connections from some of the input neurons (pixels), but not all, as would be the case in a MLP and in other traditional neural networks. Hence, instead of having each neuron receive connections from all neurons in

6901-644: The day. The owl's home range is determined in early autumn, and the territory is defended throughout the winter and into spring when the breeding season begins. The tawny owl typically nests in a hole in a tree , but will also use old European magpie nests, squirrel drey or holes in buildings, and readily takes to nest boxes . It nests from February onwards in the south of its range, but rarely before mid-March in Scandinavia . The glossy white eggs are 48 mm × 39 mm (1.9 in × 1.5 in) in size and weigh 39.0 g (1.38 oz), of which 7%

7004-535: The death of the adult and chicks. A Danish study showed that predation by mammals, especially red foxes , was an important cause of mortality in newly fledged young, with 36% dying between fledging and independence. The mortality risk increased with fledging date from 14% in April to more than 58% in June, and increasing predation of late broods may be an important selective agent for early breeding in this species. This species

7107-453: The differences in firing rates of cells in the center and surround. This allows them to transmit information about contrast. The size of the receptive field governs the spatial frequency of the information: small receptive fields are stimulated by high spatial frequencies, fine detail; large receptive fields are stimulated by low spatial frequencies, coarse detail. Retinal ganglion cell receptive fields convey information about discontinuities in

7210-417: The distribution of light falling on the retina; these often specify the edges of objects. In dark adaptation, the peripheral opposite activity zone becomes inactive, but, since it is a diminishing of inhibition between center and periphery, the active field can actually increase, allowing more area for summation. Further along in the visual system, groups of ganglion cells form the receptive fields of cells in

7313-403: The field's size and position. In general these neurons have relatively large receptive fields (much larger than those of dorsal root ganglion cells). However, the neurons are able to discriminate fine detail due to patterns of excitation and inhibition relative to the field which leads to spatial resolution. In the visual system, receptive fields are volumes in visual space . They are smallest in

7416-441: The information coming into the spinal cord is originally separate. Each sensory receptor has its own "labeled line" to convey a simple sensation experienced by the recipient. Ultimately, TRP channels act as thermosensors, channels that help us to detect changes in ambient temperatures. Nociceptors respond to potentially damaging stimuli by sending signals to the spinal cord and brain. This process, called nociception , usually causes

7519-410: The input that produces the feature. Basically, it is a measure of association of an output feature (of any layer) to the input region (patch). It is important to note that the idea of receptive fields applies to local operations (i.e. convolution, pooling). As an example, in motion-based tasks, like video prediction and optical flow estimation, large motions need to be captured (displacements of pixels in

7622-440: The insula and orbitofrontal cortex. Most sensory systems have a quiescent state, that is, the state that a sensory system converges to when there is no input. This is well-defined for a linear time-invariant system , whose input space is a vector space, and thus by definition has a point of zero. It is also well-defined for any passive sensory system, that is, a system that operates without needing input power. The quiescent state

7725-468: The intruder's head with its sharp talons. Because its flight is silent, it may not be detected until it is too late to avoid the danger. Dogs, cats and humans may be assaulted, sometimes without provocation. Perhaps the best-known victim of the tawny owl's fierce attack was the renowned bird photographer Eric Hosking , who lost his left eye when struck by a bird he was attempting to photograph near its nest in 1937. He later called his autobiography An Eye for

7828-473: The layer before (i. e. a neuron in a higher layer "looks" at a larger portion of the image than does a neuron in a lower layer). In this way, each successive layer is capable of learning increasingly abstract features of the original image. The use of receptive fields in this fashion is thought to give CNNs an advantage in recognizing visual patterns when compared to other types of neural networks. Tawny owl The tawny owl ( Strix aluco ), also called

7931-434: The limit of resolution for the retinas of terrestrial vertebrates . Adaptations to night vision include the large size of the eye, its tubular shape, large numbers of closely packed retinal rods, and an absence of cone cells , since rod cells have superior light sensitivity. There are few coloured oil drops, which would reduce the light intensity. Unlike diurnal birds of prey, owls normally have only one fovea , and that

8034-439: The location from which a sound originates. The tawny owl holds a place in human folklore: because it is active at night and has what many humans experience as a haunting call, people have traditionally associated it with bad omens and death. Many people think that all owl species make a hooting sound, but that is an overgeneralization based on the call of this particular species. In addition, the double hoot, which many people think

8137-407: The olfactory cortex, the gustatory pathway operates through both peripheral and central mechanisms. Peripheral taste receptors , located on the tongue , soft palate , pharynx , and esophagus , transmit the received signal to primary sensory axons, where the signal is projected to the nucleus of the solitary tract in the medulla , or the gustatory nucleus of the solitary tract complex. The signal

8240-444: The other greyish brown, although intermediates also occur. The underparts of both morphs are whitish and streaked with brown. Feathers are moulted gradually between June and December. This species is sexually dimorphic ; the female is much larger than the male, 5% longer and more than 25% heavier. The tawny owl flies with long glides on rounded wings, less undulating and with fewer wingbeats than other Eurasian owls, and typically at

8343-432: The perception of pain . They are found in internal organs, as well as on the surface of the body. Nociceptors detect different kinds of damaging stimuli or actual damage. Those that only respond when tissues are damaged are known as "sleeping" or "silent" nociceptors. All stimuli received by the receptors listed above are transduced to an action potential , which is carried along one or more afferent neurons towards

8446-413: The previous layer, CNNs use a receptive field-like layout in which each neuron receives connections only from a subset of neurons in the previous (lower) layer. The receptive field of a neuron in one of the lower layers encompasses only a small area of the image, while the receptive field of a neuron in subsequent (higher) layers involves a combination of receptive fields from several (but not all) neurons in

8549-442: The primary olfactory cortex. In contrast to vision and hearing, the olfactory bulbs are not cross-hemispheric; the right bulb connects to the right hemisphere and the left bulb connects to the left hemisphere. The gustatory cortex is the primary receptive area for taste . The word taste is used in a technical sense to refer specifically to sensations coming from taste buds on the tongue. The five qualities of taste detected by

8652-452: The receptive field consists of the center and surround region. Each ganglion cell or optic nerve fiber bears a receptive field, increasing with intensifying light. In the largest field, the light has to be more intense at the periphery of the field than at the center, showing that some synaptic pathways are more preferred than others. The organization of ganglion cells' receptive fields, composed of inputs from many rods and cones, provides

8755-423: The receptive fields of neurons in the auditory system are modeled as spectro-temporal patterns that cause the firing rate of the neuron to modulate with the auditory stimulus. Auditory receptive fields are often modeled as spectro-temporal receptive fields (STRFs), which are the specific pattern in the auditory domain that causes modulation of the firing rate of a neuron. Linear STRFs are created by first calculating

8858-419: The region of the retina where the action of light alters the firing of the neuron. In retinal ganglion cells (see below), this area of the retina would encompass all the photoreceptors, all the rods and cones from one eye that are connected to this particular ganglion cell via bipolar cells , horizontal cells , and amacrine cells . In binocular neurons in the visual cortex, it is necessary to specify

8961-481: The response of a specific receptor to a physical stimulus. The receptors which react to the stimulus and initiate the process of sensation are commonly characterized in four distinct categories: chemoreceptors , photoreceptors , mechanoreceptors , and thermoreceptors . All receptors receive distinct physical stimuli and transduce the signal into an electrical action potential . This action potential then travels along afferent neurons to specific brain regions where it

9064-467: The retina, the LGN and the primary visual cortex can be derived from structural properties of the environment in combination with internal consistency to guarantee consistent representation of image structures over multiple spatial and temporal scales. It is also described how the receptive fields in the primary visual cortex, which are tuned to different sizes, orientations and directions in the image domain, enable

9167-404: The retinal cells become extremely sensitive, and there is noticeable " visual snow " caused by the retinal cells firing randomly without any light input. In brighter light, the retinal cells become much less sensitive, consequently decreasing visual noise. Quiescent state is less well-defined when the sensory organ can be controlled by other systems, like a dog's ears that turn towards the front or

9270-418: The screen on which the researcher presented the stimulus, of the volume of space to which a particular cell will respond. In the case of binocular neurons in the visual cortex , receptive fields do not extend to optical infinity . Instead, they are restricted to a certain interval of distance from the animal, or from where the eyes are fixating (see Panum's area ). The receptive field is often identified as

9373-434: The sides as the brain commands. Some spiders can use their nets as a large touch-organ, like weaving a skin for themselves. Even in the absence of anything falling on the net, hungry spiders may increase web thread tension, so as to respond promptly even to usually less noticeable, and less profitable prey, such as small fruit flies, creating two different "quiescent states" for the net. Things become completely ill-defined for

9476-576: The specific number of senses due to differing definitions of what constitutes a sense , Gautama Buddha and Aristotle classified five 'traditional' human senses which have become universally accepted: touch , taste , smell , vision , and hearing . Other senses that have been well-accepted in most mammals, including humans, include pain , balance , kinaesthesia , and temperature . Furthermore, some nonhuman animals have been shown to possess alternate senses, including magnetoreception and electroreception . The initialization of sensation stems from

9579-604: The surround and inhibited by stimulation of the center (see figure). Photoreceptors that are part of the receptive fields of more than one ganglion cell are able to excite or inhibit postsynaptic neurons because they release the neurotransmitter glutamate at their synapses , which can act to depolarize or to hyperpolarize a cell, depending on whether there is a metabotropic or ionotropic receptor on that cell. The center-surround receptive field organization allows ganglion cells to transmit information not merely about whether photoreceptor cells are exposed to light, but also about

9682-405: The temporal lobe, the primary olfactory cortex is the primary receptive area for olfaction , or smell. Unique to the olfactory and gustatory systems, at least in mammals , is the implementation of both peripheral and central mechanisms of action. The peripheral mechanisms involve olfactory receptor neurons which transduce a chemical signal along the olfactory nerve , which terminates in

9785-486: The three different types of cones correspond with a primary response to short wavelength (blue), medium wavelength (green), and long wavelength (yellow/red). Rods are photoreceptors which are very sensitive to the intensity of light, allowing for vision in dim lighting. The concentrations and ratio of rods to cones is strongly correlated with whether an animal is diurnal or nocturnal . In humans, rods outnumber cones by approximately 20:1, while in nocturnal animals, such as

9888-424: The tongue include sourness, bitterness, sweetness, saltiness, and the protein taste quality, called umami . In contrast, the term flavor refers to the experience generated through integration of taste with smell and tactile information. The gustatory cortex consists of two primary structures: the anterior insula , located on the insular lobe , and the frontal operculum , located on the frontal lobe . Similarly to

9991-405: The unidimensional chemical structure of odorants to the multidimensional spacetime of human visual field , through the bidimensional skin surface, being a receptive field for touch perception. Receptive fields can positively or negatively alter the membrane potential with or without affecting the rate of action potentials . A sensory space can be dependent of an animal's location. For

10094-422: The varying light wavelengths in relation to color, and transduce them into electrical signals. Photoreceptors are capable of phototransduction , a process which converts light ( electromagnetic radiation ) into, among other types of energy , a membrane potential . There are five compartments that are present in these cells. Each compartment corresponds to differences in function and structure. The first compartment

10197-442: The visual cortex into simple cells , complex cells , and hypercomplex cells . Simple cell receptive fields are elongated, for example with an excitatory central oval, and an inhibitory surrounding region, or approximately rectangular, with one long side being excitatory and the other being inhibitory. Images for these receptive fields need to have a particular orientation in order to excite the cell. For complex-cell receptive fields,

10300-445: The visual system to be influenced by feedback from higher levels. Receptive fields have been mapped for all levels of the visual system from photoreceptors, to retinal ganglion cells, to lateral geniculate nucleus cells, to visual cortex cells, to extrastriate cortical cells. However, because the activities of neurons at any one location are contingent on the activities of neurons across the whole system, i.e. are contingent on changes in

10403-410: The visual system to handle the influence of natural image transformations and to compute invariant image representations at higher levels in the visual hierarchy. The term receptive field is also used in the context of artificial neural networks , most often in relation to convolutional neural networks (CNNs). So, in a neural network context, the receptive field is defined as the size of the region in

10506-422: The way in which real animal brains are understood to function; instead of having every neuron in each layer connect to all neurons in the next layer ( Multilayer perceptron ), the neurons are arranged in a 3-dimensional structure in such a way as to take into account the spatial relationships between different neurons with respect to the original data. Since CNNs are used primarily in the field of computer vision ,

10609-415: The whole field, it is unclear whether a local description of a particular "receptive field" can be considered a general description, robust to changes in the field as a whole. Studies based on perception do not give the full picture of the understanding of visual phenomena, so the electrophysiological tools must be used, as the retina, after all, is an outgrowth of the brain. In retinal ganglion and V1 cells,

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