Obtaining Structural Images of the Living Human Brain - Essay Example

Describe and compare the various techniques commonly used for obtaining structural images of the living human brain. One technique used to obtain structural images of the living human brain is called a Computerized Tomography (CT) scan. This type of brain scan uses a series of x-rays from different angles to create images of the brain. CT scans can show a 3D view of both the bone and soft tissue of a brain at the same time. Magnetic Resonance Imaging (MRI) can also be used to obtain structural images of the living human brain.

MRI uses magnetic fields to provide high definition images of the brain. Unlike CT scans, MRI provides greater image detail and can show both the coronal and sagittal areas of the brain. Also, a Diffusion-tensor MRI can detect the direction of fibers in the brain which can be used to create connectivity graphs of the brain. The modern model of sensory system organization features three important principles. Name them and explain them. Draw a representation of the modern model. One important principle of the modern model of organization is that the sensory system is parallel.

This means that information moves between different structures along multiple pathways simultaneously. Another important principle of the modern model is that the system is functionally segregated. This means that structures in the system are comprised of different parts that specialize in different kinds of analysis. A third important principle of the modern model is that the system is organized hierarchically, which means that information flows through brain structures in a specific order based on how functionally and nueroanatomically complex they are.

The chemical senses are unique in several ways. Describe and discuss two ways in which either the gustatory or olfactory systems is different from other sensory systems. One way the olfactory system is different from other systems is that there is no thalamic relay when sensory activity is transferred to the olfactory bulb. This means that the olfactory system bypasses the thalamus; which controls the flow of information to the cortex. Another way the olfactory system is different is that the receptor neurons of the system are continuously replaced through mitotic division.

This continual replacement occurs because olfactory neurons are exposed directly to the environment; therefore the neurons have a very high vulnerability and need to be replaced continuously. Discuss the two effects of damage to the posterior parietal cortex. One effect of damage to the posterior parietal cortex is known as Apraxia, which usually occurs as a result of damage to the left side of the cortex. Apraxia inhibits voluntary action. One example would be not being able to lift your arm on command.

Another effect of this type of damage is called Contralateral Neglect. This damage usually occurs on the right side of the cortex and makes the person unable to respond to stimuli on the opposite side where the damage occurs. People with this type of damage often ignore putting make-up on or shaving one side of their face; usually the left side. Discuss the concept of central sensorimotor programs. Describe and discuss three of their important features. Central sensorimotor programs are programs of activity that are programmed into the sensorimotor system.

One feature of central sensorimotor programs is that all but the highest levels of the sensorimotor system have programs built into them and basal ganglia and cerebellum coordinate these programs. Another feature is called motor equivalence. This means that programs are stored at a higher level than the muscle level so that a particular movement can be achieved using different muscles and in different ways. A third feature is that the system achieves greater speed by shifting the program controls to lower levels.

This frees up higher levels of the system to achieve more complex tasks.