The left cerebral hemisphere is responsible for language dominance in most individuals. Wernicke's area, located in the posterior temporal lobe, is responsible for language comprehension. On the other hand, Broca's area, found in the inferior frontal lobe, is responsible for language expression. The neocortex consists of pyramidal cells and various types of interneurons. Thalamocortical afferent fibers primarily terminate in layer IV of the neocortex, while diffuse thalamocortical afferent fibers synapse in layers I and VI. Layer V pyramidal cells' axons serve as the primary output source to subcortical targets such as the spinal cord, brainstem, striatum, and thalamus. The cortical structure varies across different regions, with Brodmann's designations reflecting these structural variations, which correspond to functionally distinct areas. The electroencephalogram (EEG) reflects the electrical fields generated by pyramidal cell activity and can vary based on the sleep-wake cycle, disease, and other factors. Cortical evoked potentials, which are stimulus-triggered changes in the EEG, provide valuable clinical information about sensory transmission. During sleep, EEG patterns can be categorized into slow-wave and REM forms. Slow-wave sleep progresses through stages 1 to 4, each characterized by a specific EEG pattern. REM sleep is when most dreams occur. Sleep is actively produced by a brainstem mechanism, and its circadian rhythmicity is regulated by the suprachiasmatic nucleus. Information is primarily transferred between the two hemispheres through the corpus callosum. The right hemisphere excels in spatial tasks, facial expression, body language, and speech intonation. On the other hand, the left hemisphere specializes in language comprehension and generation, logic, and mathematical computation. Learning and memory can be studied on a cellular level in invertebrates and higher animals. Memory encompasses short-term, recent, and long-term storage processes, along with a retrieval mechanism. The hippocampal formation plays a crucial role in storing declarative and spatial memory. Plasticity in the brain can be observed through lesion studies and behavioral studies, indicating that it occurs throughout life. However, plasticity is more pronounced in early life, and synaptic competition during "critical periods" is vital for establishing neural circuitry. After completing 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 specific actions of parasympathetic and sympathetic innervation of the eye, and what symptoms arise from the loss of parasympathetic or sympathetic innervation? 3. How does the balance of parasympathetic and sympathetic activity to the bladder change 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?
•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?