Organs Cerebral Cortex Functional
Primary Motor Cortex
The primary motor cortex, or M1, is one of the principal brain areas involved in motor function. M1 is located in the frontal lobe of the brain, along a bump called the precentral gyrus The role of the primary motor cortex is to generate neural impulses that control the execution of movement. Signals from M1 cross the bodies midline to activate skeletal muscles on the opposite side of the body, meaning that the left hemisphere of the brain controls the right side of the body, and the right hemisphere controls the left side of the body. Every part of the body is represented in the primary motor cortex, and these representations are arranged somatotopically — the foot is next to the leg which is next to the trunk which is next to the arm and the hand. The amount of brain matter devoted to any particular body part represents the amount of control that the primary motor cortex has over that body part. For example, a lot of cortical space is required to control the complex movements of the hand and fingers, and these body parts have larger representations in M1 than the trunk or legs, whose muscle patterns are relatively simple. This disproportionate map of the body in the motor cortex is called the motor homunculus. Source
The premotor cortex is an area of motor cortex lying within the frontal lobe of the brain just anterior to the primary motor cortex. It occupies part of Brodmann’s area 6. The functions of the premotor cortex are diverse and not fully understood. It projects directly to the spinal cord and therefore may play a role in the direct control of behavior, with a relative emphasis on the trunk muscles of the body. It may also play a role in planning movement, in the spatial guidance of movement, in the sensory guidance of movement, in understanding the actions of others, and in using abstract rules to perform specific tasks.
Frontal Eye Field
The frontal eye fields (FEF) are a region located in the frontal cortex, more specifically in Brodmann area 8 or BA8, of the primate brain. In humans, it can be more accurately said to lie in a region around the intersection of the middle frontal gyrus with the precentral gyrus, consisting of a frontal and parietal portion. The FEF is responsible for saccadic eye movements for the purpose of visual field perception and awareness, as well as for voluntary eye movement. The FEF communicates with extraocular muscles indirectly via the paramedian pontine reticular formation. Destruction of the FEF causes deviation of the eyes to the ipsilateral side. The cortical area called frontal eye field (FEF) plays an important role in the control of visual attention and eye movements. Electrical stimulation in the FEF elicits saccadic eye movements. The FEF have a topographic structure and represents saccade targets in retinotopic coordinates. The frontal eye field is reported to be activated during the initiation of eye movements, such as voluntary saccades and pursuit eye movements. There is also evidence that it plays a role in purely sensory processing and that it belongs to a “fast brain” system through a superior colliculus – medial dorsal nucleus – FEF ascending pathway.
Broca area, also called convolution of Broca, region of the brain that contains neurons involved in speech function. This area, located in the frontal part of the left hemisphere of the brain, was discovered in 1861 by French surgeon Paul Broca, who found that it serves a vital role in the generation of articulate speech. Damage to the frontal lobe can result in a speech disorder known as Broca aphasia, which is characterized by deliberate, telegraphic speech with very simple grammatical structure, though the speaker may be quite clear as to what he or she wishes to say and may communicate successfully. Source
The prefrontal cortex is the section of the frontal cortex that lies at the very front of the brain. Executive function describes the activity of a system that manages other cognitive systems, in much the way an executive of a company would. In this sense, the prefrontal cortex is involved in managing complex processes like reason, logic, problem solving, planning, and memory. It is thought that, through the integration of these multiple processes, the prefrontal cortex plays a significant part in directing attention, developing and pursuing goals, and inhibiting counterproductive impulses. The prefrontal cortex plays an important role in determining our personality. if you took away our prefrontal cortex we would be ruled by our desires and impulses, lacking an ability to plan for the future or think about the consequences of our actions. Source
Primary Auditory Cortex
It is that region of the brain which dispenses sound and is responsible for the ability to hear. It is an essential section of the cerebral cortex which accepts auditory data from the medial geniculate body. It is the primary cortical area of the auditory passageway. It is situated in the temporal lobe (on the superior temporal gyrus), which is located right above the ears. It receives each and every data from the ventral dissection of the medial geniculate complex. The Auditory Area is a significant part of the hearing process. Its primary function is to process sound along with its volume and pitch. The location of the sound is also processed via primary auditory cortex. This auditory cortex is essential to comprehend the spoken language and is concerned with tasks such as finding out and separating the auditory objects. Any kind of severe damage to the primary auditory cortex of the nervous system may lead to complete loss of hearing. Such an individual may not be aware of the different kinds of sounds in the surroundings. However, the ability to automatically respond to sound would still persist. This is due to the reason that both the ears are connected to the left and right auditory cortex. Thus, a person who has experienced a wound on one part of the auditory cortex can classify the different sound frequencies conveniently. Source
The central sulcus is a sulcus, or fold, in the cerebral cortex in the brains of vertebrates. Also called the central fissure, it was originally called the fissure of Rolando or the Rolandic fissure, after Luigi Rolando. It is sometimes confused with the medial longitudinal fissure. The central sulcus is a prominent landmark of the brain, separating the parietal lobe from the frontal lobe and the primary motor cortex from the primary somatosensory cortex. Its primary function is to separate the parietal lobe of the cerebral cortex from the frontal lobe. The parietal lobe also referred to as the Parietal cortex, is the section of the cerebral cortex in either brain hemisphere that is situated under the crown of the head. The frontal lobe, on the other hand, is positioned exactly behind the forehead. It also separates the primary somatosensory cortex from the primary motor cortex. Source
Primary Somatosensory Cortex
This part of the brain processes sensations, or external stimuli, from our environment. The somatosensory cortex receives all sensory input from the body. Cells that are part of the brain or nerves that extend into the body are called neurons. Neurons that sense feelings in our skin, pain, visual, or auditory stimuli, all send their information to the somatosensory cortex for processing. Each neuron takes its information to a specific place in the somatosensory cortex. Next, that part of the somatosensory cortex gets to work on figuring out what the information means. Some neurons are very important and a big chunk of the somatosensory cortex is devoted to understanding their information. The senior neuron sends the most important information to our somatosensory cortex, and it spends a lot of time understanding it. However, our junior neurons gather less important information, so somatosensory cortex spends less time on that data. Source
Somatosensory Association Cortex
The somatosensory association cortex (areas 5 and 7) is directly posterior to the sensory cortex in the superior parietal lobes. This receives synthesized connections from the primary and secondary sensory cortices. These neurons respond to several types of inputs and are involved in complex associations. Damage can affect the ability to recognize objects even though the objects can be felt (tactile agnosia). Cortical damage, particularly in the area of cortex where the posterior parietal lobe meets the anterior occipital and the posterior, superior temporal lobe, can cause neglect of the contralateral side of the world. This typically happens with nondominant hemisphere lesions since this hemisphere appears necessary to distribute attention to both sides of the body. The dominant hemisphere appears to only “pay attention” to the associated (usually right) side of the world. Therefore, neglect usually involves the left side and can be so severe that the individual even denies that their left side belongs to them. Source
Gustatory Cortex Wernicke’s Area
The primary gustatory cortex is a brain structure responsible for the perception of taste. It consists of two substructures: the anterior insula on the insular lobe and the frontal operculum on the inferior frontal gyrus of the frontal lobe. Wernicke’s area is one of the two parts of the cerebral cortex that are linked to speech (the other is Broca’s area). It is involved in the comprehension or understanding of written and spoken language (in contrast to Broca’s area that is involved in the production of language). Damage caused to Wernicke’s area results in receptive, fluent aphasia. This means that the person with aphasia will be able to fluently connect words, but the phrases will lack meaning. This is unlike non-fluent aphasia, in which the person will use meaningful words, but in a non-fluent, telegraphic manner.
Visual Association Area
The visual cortex of the brain is a part of the cerebral cortex that processes visual information. It is located in the occipital lobe in the back of the head. Visual information coming from the eye goes through the lateral geniculate nucleus in the thalamus and then reaches the visual cortex. The part of the visual cortex that receives the sensory inputs from the thalamus is the primary visual cortex, also known as visual area 1 (V1), and the striate cortex. The extrastriate areas consist of visual areas 2 (V2), 3 (V3), 4 (V4), and 5 (V5). Both hemispheres of the brain contain a visual cortex, the visual cortex in the left hemisphere receives signals from the right visual field, and the visual cortex in the right hemisphere receives signals from the left visual field.
Auditory Association Area
The cortical area that receives auditory information from the medial geniculate body. Its an area in the temporal lobe of the brain within Wernicke’s area (area 22) near the lateral cerebral sulcus, which is critical for processing acoustic signals so they can be interpreted as speech, music or other sounds. Part of the temporal lobe that processes auditory information in humans and other vertebrates. It is a part of the auditory system, performing basic and higher functions in hearing. Neurons in the auditory cortex are organized according to the frequency of sound to which they respond best. Neurons at one end of the auditory cortex respond best to low frequencies, and neurons at the other end respond best to high frequencies. There are multiple auditory areas (much like the multiple areas in the visual cortex), which can be distinguished anatomically and on the basis that they contain a complete “frequency map.” The purpose of this frequency map (known as a tonotopic map) is unknown and is likely to reflect the fact that the cochlea is arranged according to sound frequency. The auditory cortex is involved in tasks such as identifying and segregating auditory “objects” and identifying the location of a sound in space. Source
Primary Visual Cortex
The primary visual cortex is the most studied visual area in the brain. In mammals, it is located in the posterior pole of the occipital lobe and is the simplest, earliest cortical visual area. It is highly specialized for processing information about static and moving objects and is excellent in pattern recognition.
The primary visual cortex is found in the occipital lobe in both cerebral hemispheres. It surrounds and extends into a deep sulcus called the calcarine sulcus. The primary visual cortex makes up a small portion of the visible surface of the cortex in the occipital lobe, but because it stretches into the calcarine sulcus, it makes up a significant portion of cortical surface overall. The primary visual cortex is sometimes also called the striate cortex due to the presence of a large band of myelinated axons that runs along the eges of the calcarine sulcus. These axons, referred to as the line of Gennari. The primary visual cortex, often called V1. When visual information leaves the retina, it is sent via the optic nerve (which soon becomes the optic tract) to a nucleus of the thalamus called the lateral geniculate nucleus. From there, it is carried in a tract often called the optic radiation, which curves around the wall of the lateral ventricle in each cerebral hemisphere and reaches back to the occipital lobe. The axons included in the optic radiation terminate in the primary visual cortex in what is called a retinotopic manner, meaning that axons carrying information from a specific part of the visual field terminate in a location in V1 that corresponds to that location in the visual field. For example, axons carrying information about the inferior portion of the visual field terminate in areas of V1 that lie above the calcarine sulcus, while those that carry information about the superior portion of the visual field project to areas below the calcarine sulcus. These projections to the primary visual cortex from the thalamus travel along at least three distinct pathways. One pathway arises from large neurons in the retina called magnocellular, or M, cells, another pathway projects from smaller neurons called parvocellular, or P, cells, and a third pathway travels to V1 from small neurons called koniocellular, or K, cells. Source