Shepherd GM. Spinal cord. In: Synaptic Organization of the Brain. 5th ed. Oxford, UK: Oxford University Press; 2003: Chapter 3.
29.
Saccades act to move a specific part of the visual scene to the fovea, the retinal area of highest acuity, for detailed inspection.
30.
There are specialized circuits and areas in the brainstem for control of vertical and horizontal eye movements. These areas are used both by the cortex (when voluntary eye movements are made) and by the sensory input that initiates reflexive eye movement.
Shepherd GM. Cerebellum. In: Synaptic Organization of the Brain. 5th ed. Oxford, UK: Oxford University Press; 2003: Chapter 7.
Shepherd GM. Basal ganglia. In: Synaptic Organization of the Brain. 5th ed. Oxford, UK: Oxford University Press; 2003: Chapter 9.
Xiao J, Cerminara NL, Kotsurovskyy Y, et al. Systematic regional variations in Purkinje cell spiking patterns. PLoS ONE. 2014;9: e105633.
Upon completion of this chapter, the student should be able to answer the following questions: 1.
What is the basic layering pattern of the neocortex, and how do cortical inputs and outputs align with this layering pattern? What is the functional significance of the variation in the layering pattern between cortical areas?
2.
What are the major functions of each of the lobes of the cerebrum?
3.
How does the electroencephalogram (EEG) reflect cortical activity? What are evoked potentials?
4.
How does cerebral dominance correlate with language and hand preference?
5.
What is aphasia, and what is compromised in the different types of aphasia?
6.
How do synaptic and cellular processes support learning and memory? How is memory distributed in the brain?
7.
What role does plasticity play in neural development and in response to damage of the nervous system?
n earlier chapters, the interaction of the nervous system with the body and the outside world was discussed in terms of the transduction and analysis of sensory events, the organization of motor function, and relatively simple central processes that link them, such as reflexes (e.g., the stretch reflex and the vestibuloocular reflex). The nervous system has other capabilities, so-called integrative or higher functions, that are less directly tied to specific sensory modalities or motor behavior. These functions, in particular, require interactions between different parts of the cerebral cortex, and, as is being increasingly recognized, between the cerebral cortex and other parts of the brain. The neural basis for some of these higher functions is discussed in this chapter. Because these functions (as well as sensory perception and voluntary motor function) are so highly dependent on the cerebral cortex, its basic organization is described first.
The Cerebral Cortex
The human cerebral cortex occupies a volume of about 600 cm3 and has a surface area of 2500 cm2. The surface of the cortex is highly convoluted and folded into ridges known as gyri. Gyri are separated by grooves called sulci (if shallow) or fissures (if deep; see
Fig. 4.7 ). This folding greatly increases the surface area of cortex that can be fit into the limited and fixed volume within the skull. Indeed, most of the cortex cannot be seen from the brain surface because of this folding.
The cerebral cortex can be divided into the left and right hemispheres and subdivided into a number of lobes (Fig.
10.1
Fig. 4.7 ), including the frontal, parietal, temporal, and occipital lobes. The frontal and parietal lobes are separated by the central sulcus; both are separated from the temporal lobe by the lateral fissure. The occipital and parietal lobes are separated (on the medial surface of the hemisphere) by the parieto-occipital fissure (see
Fig.