At this point, you are probably wondering what strange disorder this woman has. As you think about this story, a number of possibilities may come to mind. Could she be blind? This seems unlikely. She recognized the pizza (by its distinctive round shape and red color) and incorrectly grabbed an item that looked similar to the apple pie, a package of tortillas, rather than something quite different in shape and size, like a milk carton. Another possibility is that she has a memory problem, such that she can’t remember the features or locations of objects. But this possibility seems unlikely, too. She remembered the locations of the stove and the sink. Furthermore, her memory for objects must be intact because she recognized the apple pie as soon as she smelled it and the kettle as soon as she felt it.

The case history in the opening vignette describes the maternal grandmother of one of the authors (M.T.B.). Although the disease was never formally diagnosed, she surely had Alzheimer’s or some similar dementia. In many ways, her case was typical, characterized by loss of memory, difficulties in spatial processing, disorientation, and changes in personality, especially paranoia. The course was unremittingly downward, although she died from heat stroke before becoming totally bedridden.

In this chapter, we discuss disorders, such as Alzheimer’s disease, that are distinct from the neuropsychological syndromes covered elsewhere in this book. In our discussions so far, we have emphasized the breakdown of specific cognitive functions, such as visual recognition, and precisely described the circumscribed nature of the deficits.

Language is the mental faculty that many people consider most distinctly separates us from other species. Language has also long been studied by scientists. Symptoms like those experienced by Bill Rieger and Jim Hurdle first led Paul Broca in the late 1800s to realize that the hemispheres have different functions, an event that heralded the advent of modern-day neuropsychology and cognitive neuroscience. Broca noticed that a lesion to a specific region of the left hemisphere causes a loss of fluent speech even though the person’s speech comprehension is relatively spared. This syndrome, known as Broca’s aphasia, has provided a window to understanding the neurological organization for language.

Aphasia is the loss of a language processing ability after brain damage. In this chapter, we discuss a variety of aphasias, gleaning lessons about the neurological organization for language.

In this book, we explore how the neurological organization of the brain influences the way people think, feel, and act. Critical to our understanding of the link between brain and mind is cognitive neuroscience, which comprises investigations of mental functions linked to neural processes, ranging from investigations in animals to humans and from experiments performed in the laboratory to computer simulations. Much earlier work in this area comes from human neuropsychology, which examines changes in behavior as a result of brain trauma.

The case of Dr. P illustrates how brain damage can cause deficits in executive functions – which include the ability to plan actions to reach a goal, to use information flexibly, to think abstractly, and to make inferences. As illustrated by this case study, difficulties in executive function can arise despite normal functioning in other domains of intellectual processing, such as those measured by IQ tests (retention of knowledge, vocabulary, spatial processing abilities, and so forth).

The term executive function serves as an umbrella to describe a set of abilities. To better understand the types of abilities that we discuss in this chapter, let’s consider, by analogy, the skills and attributes required of a company executive. First, an executive must have a master plan. For example, the executive’s goal may be to increase customer satisfaction, diversify markets, or raise production.

The patient in the opening vignette of this chapter is known in the scientific literature by his initials, H.M. After realizing the unintended effects of the operation, his surgeon, Dr. Henry Scoville, contacted Brenda Milner and her colleagues at McGill University in Montreal to unravel the mystery of his memory loss. Professor Milner discovered the divide in H.M.’s memory that we just discussed: the paradox that while certain aspects of memory were lost after removal of his medial temporal lobe, others were retained (Scoville and Milner, 1957). This work was critical in demonstrating the existence of at least two separable systems that support our ability to remember. As noted by Eric Kandel, who won the Nobel Prize in Physiology and Medicine in 2000 for his work on the molecular mechanisms of memory formation, “[t]he study of H.M. by Brenda Milner stands as one of the great milestones in the history of modern neuroscience.

Because the majority of the world’s population speaks more than one language, in this chapter we consider that a “bilingual mental lexicon” can be viewed as the default, which may be a more accurate way of exploring lexical and conceptual memory. We transition to examine how concepts and words are represented in the mind, with a particular emphasis on the dynamic, developmental nature of word-to-concept mapping and the distributed, overlapping characteristics of semantic representations. Against this background, we review several theoretical models of word processing – including word recognition, production, and translation. The first set of models includes the Word Association Model and the Concept Mediation Model. We then discuss another set of models that offer a more detailed account of the conceptual system by emphasizing the degree of overlap that exists between conceptual representations in the two languages. In the last section of the chapter, we review two localist-connectionist models: the BIA/BIA+/BIA-d and the Multilink Models.

The case study in the opening vignette illustrates some of the important ways that neuropsychological disorders observed developmentally can differ from those observed later in life. In adults, the inability to read is often associated with damage to particular regions of the left hemisphere (see Chapter 8). However, in Dan’s case, no evidence of localized brain damage was apparent. Whereas adults with alexia acquired the ability to read and then lost it, Dan never could read with a reasonable degree of proficiency. Thus, cognitive deficits can have different origins and different neural correlates, depending on whether they were acquired in adulthood or during the process of development.

The case of Dan and children with other developmental disabilities helps us to realize that the brain is dynamically changing.

As in other areas of cognitive neuroscience, much of what we know about the brain and mental illness has been based on observations of people with damage to the brain. The depression that led Joe Gray to suicide was most likely due to more than his inability to accept his impairments, although no doubt the loss of independence and reduced intellectual capacity contributed to his despair. Damage to parts of the left hemisphere, especially frontal regions and their interconnections, can often lead to clinical depression (Padmanabhan et al., 2019). Findings such as these underscore the importance of particular brain circuits in contributing to psychiatric disorders.

Fully understanding mental illness, or psychopathology, involves much more than understanding the brain. Psychopathology can be fruitfully approached from many different psychological perspectives, including not only the biological but also cognitive, social, and cross-cultural levels.

The brain seems to capture the public imagination like no other topic in science. Aided by striking color images intended to show “the brain in action,” media stories stoke the public’s interest in research that promises to reveal the secrets of human thought and behavior. Everyday people may look to neuroscience for a deeper understanding of their own behaviors or the behaviors of those around them. Scholars are actively exploring the potential relevance of cognitive neuroscience research to critical domains of society, including education, business, and the law, as seen in this chapter’s opening vignette. Meanwhile, profiteers may seek to capitalize on the public’s eagerness for “all things neuro” in order to make a dime. Yet, public enthusiasm notwithstanding, the science of the brain is very much in flux, as material from all the prior chapters can attest.

A central challenge, then, is to navigate the public dissemination of knowledge about neuroscience research such that legitimate findings with important societal implications can be separated from hype, even as knowledge in the field shifts from year to year.

The story about C.J. helps to illustrate that spatial processing is not a single cognitive function, but rather consists of many different abilities. Some of C.J.’s spatial abilities, such as understanding the relationship between the map and the surrounding terrain, and knowing geographical points of reference (north, south, east, and west), were compromised by her stroke, yet other abilities – such as determining left and right – were unaffected. In this chapter, we examine the many ways in which spatial relations among items can be computed and the brain systems that enable these computations.

We learned in Chapter 5 that the visual cortex provides a precise retinotopic map of space. However, a retinotopic map is inadequate for fully understanding the space around us. First, as we have already discussed in relation to object recognition, the retina only provides two-dimensional information about the three-dimensional world.