The Contribution Of David Hunter Hubel

DISCUSSION: Rat #4 demonstrated similar responses during light on and light off periods. However, it learned to press more during light on periods, as it pressed 109 times when the light was on, and only 92 times when the light was

After being shown a picture of an elephant they eye will take the light that is reflected from the object and it will enter the eye through the pupil. Then the light will be focused by the cornea and the lens to form a sharp image of the elephant in the retina. The retina is the network of neurons that cover the back of the eye and contains the visual receptors for a person vision. The visual receptors are made up of cones and rods that contain light sensitive chemicals called visual pigments. Visual pigments reacht to light and cause a triggered electrical signals to occur. These electrical signals will then flow through a network of neurons and this network of neurons is what makes up a persons retina. After the flow through the network of neurons occurs the electrical signals will emerge from the back of the eye in the area

For an extensive period of time, Marcus Hiles has built rich and moderate gatherings over the state of Texas. From Dallas and San Antonio down to Corpus Christi and past, his association has spent the latest decade endeavoring to make life remarkable for persisting Texans all around. Recently, the city of Houston has gotten a kick out of an augmentation in life quality, on account of the steady work and responsibility of Marcus Hiles.

Introduction: We perceive stimuli through nerve cells in our eyes, ears, nose, tongue, and skin. When a nerve cell is stimulated, it sends an electrical signal to the brain. After the signal is processed by the brain, other signals are sent to our muscles as we react to the stimulus.

() who stated that stimulation of dMT axonal fibers with brief light pulses did not evoke fast synaptic inputs in CeL neurons. Only small, slow inward currents were reported following high frequency light stimulation. The diverging results may be the consequence of differing viral transduction efficiency or stimulation conditions. Interestingly, the apparent connectivity of dMT and BA was substantially greater as compared to dMT and CeL. Furthermore, synaptic responses evoked in BA PNs were larger as compared to those in CeL neurons regarding absolute amplitudes of AMPAR- and NMDAR-mediated currents under similar stimulation conditions. The effect may be due to stronger innervation of the BA by dMT efferents, to increased presynaptic transmitter release or to increased postsynaptic receptor expression. The AMPAR/NMDAR ratio, which may give an indication of input-independent basal synaptic strength based on postsynaptic AMPAR occupancy, did not reveal any differences dMT-BA and dMT-CeL synapses. Interestingly, AMPAR silent synapses were discovered in the CeL. These synapses may be recruited during periods of increased synaptic input and facilitate

Triangle, a novel written by David Von Drehle, is about the working conditions that caused “the deadliest workplace disaster in New York history [for ninety years to come]” (Drehle 3). It occurred in the early 1930’s, and about the events that led to protests for better conditions so that the incident that happened on March 25, 1911, in the Triangle Waist building, would not be replicated. Due to the inadequate working conditions, some buildings experienced disasters because “[The] workplace safety was scarcely regulated, and workers’ compensation was considered newfangled or even socialist” (Drehle 3). Most who lost their lives that unfaithful day at the Triangle building, were taken to the pier, “the makeshift morgue at the end of the pier

The pioneering experiments performed by Hubel and Wiesel in the mammalian visual cortex provided crucial insights into the experience-dependency of normal cortical development. Hubel and Wiesel capitalized on the finding of physiologically distinct neurons in the visual cortex that responded to varying degrees to monocular and binocular visual stimulation (ref), and by tangentially traversing through layer 4 of the V1 cortex while recording from individual neurons, they found that neurons responsive to the left or right eyes were separated into ocular dominance columns (ODCs) (Hubel and Wiesel 1962). The anatomical representation of these columns could be visualized by injecting a transneuronal radiolabel, H3-proline, into the eye of an animal to see projections of eye-specific LGN afferents to the cortex (Hubel Wiesel 1974). Using these techniques, they demonstrated that monocular deprivation corresponded to a substantial loss of cortical neurons stimulated by the deprived eye (ref), and resulted in an anatomical shrinkage of deprived eye columns with a concomitant enlargement of normal eye columns (ref). Further experiments suggested that experience-dependent maturation of ODCs relies on a competition-based mechanism whereby normal eye afferents become stabilized relative to deprived eye afferents (refs), and that there was a developmental critical period in which MD could influence ODCs that was maintained throughout adulthood (ref). Based on these observations as well as

In this study, experimenters selectively lesioned layers 1-2 (M pathway) and 3-6 (P pathway), then mapped out the corresponding visual field area that suffered the lesions. They found that lesions of the P geniculate layers generated severe impairments in contrast sensitivity and stereoscopic vision at high spatial frequencies, as well as color, texture, pattern, and one of the shape discrimination tasks (Fig x). Lesion to M layers, on the other hand, produced impairment in flicker detection and the two motion detection tasks they studied. Interestingly, they noticed that neither M or P lesions alone led to significant impairment in brightness discrimination, or in coarse shape discrimination. These findings imply that M pathway seems sufficient to preserve some shape discrimination, and challenges the view that P pathway is the sole input for extrastriatal form

The Magnocellular pathway carries information from the M ganglion cells at rapid speed along the dorsal stream to the parietal lobe to help us understand motion, spatial relationships and contrast. The Parvocellular pathway carries information from the P ganglion cells at slower speed along the ventral stream to the temporal lobe to help us process fine details of such as color and form of an object. It is thought that the Parvocellular pathway is our primary source for recognition and identification, but there are speculations that its allocentric frame of reference can also be used in a more egocentric approach (i.e., the Parvocellular pathway is able to elicit an autonomic response like the Magnocellular pathway). This research expands on these theories by studying the role of color vision in autonomic attention responses. The experiment attempts to study the relationship between the Magnocellular pathway and Parvocellular pathway through color cues and its effects in capturing attention and control visual behavior (e.g., moving the eyes to locate the

After investigating spatial cognition and the construction of cognitive maps in my previous paper, "Where Am I Going? Where Have I Been: Spatial Cognition and Navigation", and growing in my comprehension of the more complex elements of the nervous system, the development of an informed discussion of human perception has become possible. The formation of cognitive maps, which serve as internal representations of the world, are dependent upon the human capacities for vision and visual perception (1). The objects introduced into the field of vision are translated into electrical messages, which activate the neurons of the retina. The resultant retinal message is organized into several forms of sensation and is

According to current research there are about 800,000 ganglion cells in the human optic nerve (J.R. Anderson, 2009,pg. 35). The ganglion cells are where the first encoding of the visual information happens. Encoding is the process of recognizing the information and changing it into something one’s brains can understand and store. Each ganglion cell is dedicated to encoding information from a specific part of the retina. The optic nerve goes then to the visual cortex and the information enters the brain cells. There are two types of cells that are subcortical, or below the cortex; the lateral geniculate nucleus and the superior colliculus. The lateral geniculate nucleus is responsible for understanding details and recognizing objects. The superior colliculus is responsible for understanding where objects are located spatially. This collection of cells working together is called the “what-where” distinction. The division of labor continues, as the information is further processes. The “what” information travels to the temporal cortex, the “where” information travels to the parietal regions of the brain.

While head trauma or tumors often induce the "psychic" blindness of these patients, a model has been developed in monkeys by removing all or part of the primary visual cortex. These monkeys are able to respond to visual inputs. They can be trained to touch illuminated bulbs rather than unlit ones and identify certain colors and patterns in order to obtain food. This phenomenon is believed to parallel human blindsight because when trained to respond differently according to whether there is a visual cue or not, these monkeys respond as if there were no cue when a visual input is presented to the blind field (1). It is therefore believed that these animals are able to respond to and identify features of a visual cue even though they do not report seeing it.

Microvillar photoreceptors, similarly to tapetum, are located in the retina of spiders’ eyes and are sensitive to polarized light. The microvilli, “minute projections from the surface of [retinal] cells”, are set in the direction parallel to the polarized light, which is why spider’s eyes are sensitive to polarized light. As polarized light only vibrates in one plane in order for it to be detected, the surface with which it makes contact, in the spider’s case, the microvillar photoreceptors, must lie on the same plane. Different sets of eyes contain microvilli, and these microvilli are set at different angles. This maximizes the amount of polarized light that is received and detected by spiders, thus heightening their navigational abilities at night

Normal vision occurs by a coordinated synthesis of the retinal images into a single brain image. If, however, one of the eyes does not transmit a coordinated or useful image the brain may choose to ignore this image when conducting its synthesis. The region of the

In somatosensory, lateral inhibition happens at the thalamus and cortex. During physical contact, neurons within the close proximity of the area of the contact are excited. The closer the neuron is to the contact, the bigger the magnitude of excitation. However, lateral inhibition occurs between adjacent neurons. The lateral inhibition given off by a neuron is equal to the excitatory input of the neuron. Additionally, the total lateral inhibition felt by a neuron is the sum of lateral inhibition dealt