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Tingarri Men and Initiates at Marabindinya. In this painting by the Aboriginal Australian artist, Anatjari Tjampitjinpa, Tingarri instructors are depicted as concentric circles and their young initiates are shown as horseshoe shapes along the boundaries. The background of the painting depicts the sandhill country of the central Australian desert. Such symbolic representations recall the neural representations of episodic memories, consisting of events taking place in space and time, encoded in the firing of grid cells and place cells in the entorhinal cortex and hippocampus, respectively. (© Estate of the artist licensed by Aboriginal Artists Agency Ltd.)
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MOTOR AND SENSORY FUNCTIONS take up less than one-half of the cerebral cortex in humans. The rest of the cortex is occupied by the association areas, which coordinate events arising in the motor and sensory centers. Three association areas—the prefrontal, parietal-temporal-occipital, and limbic—are involved in cognitive behavior: speaking, thinking, feeling, perceiving, planning skilled movements, learning, memory, decision-making, and consciousness.
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Most of the early evidence relating cognitive functions to the association areas came from clinical studies of brain-damaged patients. Thus, the study of language in patients with aphasia yielded important information about how human mental processes are distributed in the two hemispheres of the brain and how they develop. More refined analyses have come from human imaging studies using functional magnetic resonance imaging (fMRI) and other methods.
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Deeper insights into the neural circuitry and cellular mechanisms giving rise to cognitive processes have come from electrophysiological recordings and genetic-based manipulations, including cell type–specific gene deletions and cell type–specific optogenetic excitation or inhibition in experimental animals, particularly in rodents. Such studies can evaluate the relative contribution of specific genes, neurons, and synaptic connections to specific types of behavior.
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So far in this book, we have considered neural mechanisms associated with basic functions of the brain, including primary sensory perception, movement, and homeostatic control. In this part and the next, we begin to consider the more complex, higher-order brain functions mentioned earlier, the realm of cognitive neural science. The aim of this merger of neurophysiology, anatomy, developmental biology, cell and molecular biology, theory, and cognitive psychology is to ultimately provide an understanding of the neural mechanisms of the mind.
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Until the latter part of the 20th century, the study of higher mental function was approached through behavioral observations gleaned from brain-damaged patients and animals with experimental lesions. In the first part of the 20th century, to avoid untestable concepts and hypotheses, psychology became rigidly concerned with behaviors defined strictly in terms of observable stimuli and responses. Orthodox behaviorists thought it unproductive to deal with consciousness, feeling, attention, or even motivation. By concentrating only on observable actions, behaviorists asked: What can an organism do, and how does it do it? Indeed, careful quantitative analysis of stimuli and responses has contributed greatly to our understanding of the acquisition ...