The occipital lobe is located at the lower central back of the brain. It is considered as the primary center for processing visual stimuli. This lobe is also involved in color and movement discrimination, and visuospatial processing. Any significant trauma at the back of the head can cause subtle changes in the visual-perception area. It covered by cortical tissue, this is also called the visual cortex. This part is divided into many subdivisions, each plays role in processing visual data from the outside environment.
As light reaches the sight enters, it passes through a complex pathway in the occipital lobe. After the light hits the retina, the information received is transmitted to the thalamus. The brain interprets the light that the eyes received. From there, the axons show the image in the visual cortex that tells what the eyes are seeing.
The temporal lobe is situated on either side of the brain, just above the ears, that curve forward from the occipital lobes to below the frontal lobes. Its main function is to process auditory stimuli. It has several divisions that deal with smell, taste, visual associations, bearing, some aspects of memory, and sense of self. A head injury that affects the temporal lobe part of the brain may cause direct and diffuse effects.
The temporal lobe has many subdivisions like the occipital lobe. When the auditory region of the temporal lobe is stimulated, sensations of sound are formed. And also, the auditory association area has connections to the primary regions and other parts of the brain. It aids in the perception of auditory inputs, allowing for the interpretation of what we are hearing. The neurons in this region have specific jobs, such as registering a sound’s loudness, pitch and timbre.
Lying mostly in the temporal lobe, is the Wernicke’s area. This area is very vital for speech. This allows for us to comprehend or interpret speech when speaking.
The parietal lobes are flat, plate-like areas, located at the upper middle part of the brain above the temporal lobe. It consists of two major divisions, the anterior and posterior parts, that plays complementary roles. It includes the sensory cortex and association areas. These are involved in processing information about body sensation, touch and spatial organization. The parietal lobe is also involved in secondary language and visual processing.
At the anterior part of the lobe, behind the motor cortex, lies a strip of cells called the somatosensory cortex. It receives information, such as touch and temperature, sensations of pain and pressure from the skin and proprioception. This is the primary region responsible for incoming stimuli.
While the posterior part of the lobe, is the one that analyzes and integrates all the information to give a sense of spatial awareness. The brain is able to know where each part of the body is located in relation to its surroundings. Damage to this part, would result to apraxia or clumsiness in manipulating objects.
Lastly, the parietal lobes help in maintaining focus or spatial attention. This helps a person shift attention from location to location.
The frontal lobe is considered to be the largest part of the cortex, and performs the most complex function. It is situated in the front of the brain and extending back to the top of the head. One of the roles of this lobe is concerned with intellectual functioning, such as thought processes, planning, behaviour and memory. It is also the center of voluntary and planned behaviours. We have the ability to control parts of our body at will.
The motor cortex, which is strip of cells that stretches across the top of the brain, is where nearly all neural activities of muscular movements are directed. The strips have areas that governs specific movements of the muscle.
The Broca’s area/motor speech area is also located in the left hemisphere of the frontal lobe, contained by the supplemental motor area. This is connected with the Wernicke’s area by the bundle of nerve fibers called the arcuate fasciculus. This facilitates the words assembled from the Wernicke’s area and then relayed to Broca’s area to translate into proper sounds.
The large part of the lobe, the “silent” area or the prefrontal cortex, is free from processing sensory data and movement. This is the part of the brain that defines what humanity is. It is also referred to as the association cortex, where information from both the inner and outer worlds are interpreted.
The limbic system is a network of ring-shaped structures, located in the center of the brain, on the top of the brain stem. It is associated with emotions and behaviours, such as motivation, gratification, thought and memory. It is also responsible for controlling body temperature, blood pressure, and blood sugar.
It regulates the complexity of emotions, together with the sensory and motor systems, which leads to complex human behaviour.
The structures of the limbic system are the one that receives input from all the sense, where the sense of smell plays an important role. The limbic system is closely connected with the Cerebral cortex and the reticular formation.
The effects of the limbic system when it comes to emotions are widespread. Most communications sent by the limbic system, ends up in the hypothalamus, connected directly below the pituitary gland. This gland controls the body’s hormones that regulate the behaviour and autonomic system.
How does the aging process impact the neurological system?
AGING PROCESS IMPACT TO NEUROLOGICAL SYSTEM
Some of the age-related neurologic manifestations may include the ff: cognition, pain, sensation and motor responses. Changes in both the function and the structure of the cells and tissues that are responsible for physiologic responses, produces these manifestations. Neurologic functions are altered as a result of these changes in the cells and tissues. Typical changes that occur are the ff:
Decrease in brain mass
Enlargement of cerebral ventricles
Decrease number of neurons, processes of dendrites and synapses
Altered production of neurotransmitters
Most of the functional alterations of the neurologic system results from the involvement of peripheral nerves and degenerative alterations of the spine and muscles. It is also typical of aging. Factors that are vital to the promotion of neurologic responses, like neurotransmitters, enzymes, and receptors, are altered by the aging process.
Often the structural changes that occur in the body are the ff: sensory deficits, motor dysfunction, sleep disturbances, impaired memory and cognition. The time it takes for a task to be accomplished is prolonged when the central processing becomes slow. Other changes that are associated with aging are mild forgetfulness, decrease in vocabulary and learning difficulties.
When cognitive functions decline, elderly often experiences depression and anxiety. Psychological disorders may complicate physical health, such as reducing motivation or ability to maintain health by doing everyday task.
Compare and contrast the sympathetic and parasympathetic nervous systems in terms of function.
SYMPATHETIC NERVOUS SYSTEM
PARASYMPATHETIC NERVOUS SYSTEM
It is a partition of the Autonomic Nervous System that controls such activities as hormone secretion and heartbeat. During the fight or flight response, the SNS releases norepinephrine, pupil dilation, increases the heartbeat, it dilates the airways and the blood vessels in the muscles, increase blood pressure, oliguria, constipation, and decrease activity of the digestive system.
The PNS is the one responsible for the slowing and steadying of the body’s internal activity, such as the following: Decreased heart rate and respiratory rate, pupil constriction, release of acetylcholine, increase blood flow to the organs involved in the digestion, increased salivation, release of digestive juices, polyuria, diarrhea
WEB OUTPUTS (http://www.internationalbrain.org/?q=node/149)
Chemosensory impairment is common after a head trauma that often results chemosensory disturbances. These disturbances are often a hindrance to a person’s everyday activities.
Following traumatic brain injury, the patient commonly experience olfactory dysfunction, and less common, gustatory disturbances, depending on the severity of the injury. These disturbances that the patient experiences may be the following: complete or partial, sensory loss, distortion, or the present of phantom sensations.
Olfactory disturbances may result from mechanical blockage or disruption from fractured bones. These fractures cause a number of injuries and alterations in the olfactory system.
Neurosensory deficits may result from the mechanical injuries of the olfactory pathways, sticking or damaging important olfactory neurons that are protected by bones. Direct injury or sear force can cause damage to it.
Olfactory critical center deficits may occur from bruises or bleeding of the tissues in the brain caused by trauma.
Projectiles and fractures may post risk to cortical centers. However, a direct injury to the cortical center would not cause a complete loss of sense of smell (anosmia), but rather, it only causes impairment in odor recognition, and not detection.
Gustatory sensory losses are not mostly affected by head trauma, but rather, are results from medications used to manage head trauma patients. The use of antidepressants, anticonvulsants, antipsychotics and narcotic analgesics, may render salivary production.
Although neurosensory deficits are possible in head trauma patients, it is also unlikely to happen as the arrangements of neurons are deeper and protected.
Olfactory disturbances have higher prevalence than the gustatory system, but taste deficits are more likely to happen than olfactory deficits. As the foods pass through the cavity, it releases odorants that ate detected by the olfactory epithelium.
The assessment of the chemosensory impairment often happens during the rehabilitation phase of the client. Most often, identification of the deficits are delayed, because of the management done to the patient.
A thorough history taking should be done to head trauma patients. It should explain the nature of the deficit, potential causes, and impact of the disturbance. Secondary sources may also provide information, if the patient can’t.
Examinations of the patient require neurologic evaluation. Lacerations, edema, and tenderness can further explain the causative mechanism of the trauma.
Nasal endoscopy is also performed on patients with chemosensory complaints. This will help visualize or give information that may contribute to the disturbance.
The oral cavity is inspected and evaluated for gustatory complaints. Nerve injuries are suggested by laceration, bony fragments, bloody or CSF discharge from the ear and etc. Assessment of the reflexes would also help verify the integrity of cranial nerves.
Radiologic testing is also helpful in determining the pathological mechanism of the different disturbances that occurs in a head trauma patient. This can help identify and locate the trauma or fractures.
Clinical test is also performed to help find more answers to the sensory deficits.
There is no specific treatment for these deficits. Surgical repair can be done for mechanical disruptions, while medical therapies are done to compensate for other disturbances. Patients should also do counselling for further learning about safety issues and compensatory strategies.