•Fig. 10.11 Representationofthedigitregionoftheleftfirstsomatosensory(SI)cortex(A) andreorganizationofthisrepresentation (B) afteramputationofthesecondandthirddigits.(FromHainesDE[ed].Fundamental Neuroscience for Basic and Clinical Applications. 3rded.Philadelphia:ChurchillLivingstone;2006.) 1. The cerebral cortex can be divided into lobes on the basis of the pattern of gyri and sulci. Each lobe has distinctive functions, as shown by the effects of lesions. The left cerebral hemisphere is dominant for language in most individuals. Wernicke’s area (in the posterior temporal lobe) is responsible for the understanding of language, and Broca’s area (in the inferior frontal lobe) is responsible for its expression.
2. The neocortex contains pyramidal cells and several kinds of interneurons. Specific thalamocortical afferent fibers terminate mainly in layer IV of the neocortex; diffuse thalamocortical afferent fibers synapse in layers I and VI. Axons from pyramidal cells in layer V are the major source of output to subcortical targets, including the spinal cord, brainstem, striatum, and thalamus.
3.
The cortical structure varies in different regions. Brodmann’s designations reflect these variations in cortical structure and correspond to functionally discrete areas.
4.
The EEG reflects electrical fields generated by the activity of pyramidal and varies with the state of the sleep-wake cycle, disease, and other factors. Cortical evoked potentials are stimulus-triggered changes in the EEG and are useful clinical data about sensory transmission.
5.
EEG patterns during sleep are divided into slow-wave and REM forms. Slow-wave sleep progresses through stages 1 through 4, each with a characteristic EEG pattern. Most dreams occur in REM sleep. Sleep is produced actively by a brainstem mechanism,
Squire L, Berg D. Fundamental Neuroscience. 4th ed. New York: Academic Press; 2012.
and its circadian rhythmicity is controlled by the suprachiasmatic nucleus.
6.
Information is transferred between the two hemispheres primarily through the corpus callosum. The right hemisphere is more capable than the left in spatial tasks, facial expression, body language, and speech intonation. The left hemisphere is specialized for the understanding and generation of language, for logic, and for mathematical computation.
7.
Learning and memory can be studied on the cellular level, in invertebrates, and in higher animals. Memory includes short-term (lasting minutes), recent, and long-term storage processes and a retrieval mechanism. The hippocampal formation is important for storing declarative and spatial memory.
8.
Lesion studies and behavioral studies indicate that plasticity occurs in the brain throughout life. However, there appears to be more plasticity early in life, and synaptic competition in “critical periods” is important for the establishment of neural circuitry.
Upon completion of this chapter, the student should be able to answer the following questions: 1.
What are the similarities and differences in the general organizations of the parasympathetic and sympathetic systems?
2.
What are the respective actions of the parasympathetic and sympathetic innervation of the eye, and what symptoms arise when the parasympathetic or sympathetic innervation is lost?
3.
What are the changes in the balance of parasympathetic and sympathetic activity to the bladder that occur during micturation?
4.
What is meant by a “servomechanism”?
5.
What are the specific feedback loops that regulate body temperature, feeding and body weight, and water intake?
6.
What is the role of the hypothalamus in each of these feedback loops?