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An Introduction to Neuropathology

The different diagnoses of diseases and disorders within the nervous system are made using neuropathology in coordination with clinical signs/symptoms and imaging. The imaging techniques discussed in Chapter 9 , coalesced with biopsies, the use of selective antibodies to identify cellular markers, and particular stains to highlight cellular structures, are all used to make a diagnosis. This chapter will present some common neuropathological diseases Stains used…

Functional Systems

The preceding chapters presented the major structures seen at individual levels of the central nervous system (CNS) or in particular views of the brain. This chapter is complementary, using many of the same sections and views to indicate the structures and connections involved in particular neurological functions. We have taken a “bare-bones” approach to this task and indicated only major pathways and connections. Much of the…

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Formation, Modification, and Repair of Neuronal Connections

Previous chapters may have hinted that the parts of the nervous system are interconnected in rigid, immutable ways, but this is far from accurate. The details of the nervous system are much too complex to be completely laid out genetically. Instead, only the general layout of the nervous system is specified genetically; later stages of development are a time of great plasticity, in which neurons and…

Drives and Emotions: The Hypothalamus and Limbic System

We seldom perceive things in a completely neutral fashion. Various sights and sounds make us happy, sad, or angry; some tastes and smells are extremely gratifying, others disgusting. Such feelings engendered by sensory inputs are ultimately the result of brains wired to promote survival and reproduction, and they are variable depending on current physiological needs and the social situation. Food, for example, becomes more attractive when…

Cerebral Cortex

The cerebral cortex is a sheet of neurons and their interconnections. About 1800 cm 2 (2 ft 2 ) in surface area, the cortex covers the corrugated surface of the cerebral hemispheres in a layer just a few millimeters thick. This thin layer of gray matter accounts for nearly half the weight of the brain and is estimated to contain about 25 billion neurons, interconnected by more…

Eye Movements

Photoreceptors are sensitive but slow, and all animals with image-forming eyes have mechanisms to prevent images of interest from moving across the retina too quickly to be analyzed. (Our eyes behave in many respects like cameras with a shutter speed of about of a second.) A widespread strategy is to use some combination of eye movements and head or body movements to keep the direction of…

Cerebellum

Cerebellum means “little brain,” and in a real sense, it is: it accounts for only about 10% of the mass of the brain, but the cerebellum contains as many neurons as all the rest of the central nervous system (CNS) combined. This semidetached mass of neural tissue covers most of the posterior surface of the brainstem, tethered there by three pairs of fiber bundles called cerebellar…

Basal Nuclei

In 1817 James Parkinson, an English country physician, published a brief monograph entitled “An Essay on the Shaking Palsy,” in which he described the symptoms of several individuals who had the disease that now bears his name. Patients with Parkinson's disease, as described in more detail later in this chapter, are characterized by tremor, generally increased muscle tone, and difficulty initiating voluntary movements, which are unusually…

Overview of Motor Systems

Each of us has fewer than a million motor neurons with which to control muscles. Without them, we would be completely unable to interact with the outside world. With them, however, we are capable of an enormous range of complex activities, from automatic and semiautomatic movements such as postural adjustments to the characteristically human movements involved in speaking and writing. The way in which a wide…