Ian Q. Whishaw and Megan Okuma
A brain lesion is an area of damage, injury, or abnormal change to a part of the brain. Brain lesions may be caused by head injury, disease, surgery, or congenital disorders, and they are classified by the cause, extent, and locus of injury. Lesions cause many behavioral symptoms. Symptom severity generally corresponds to the region and extent of damaged brain. Thus, behavior is often a reliable indicator of the type and extent of a lesion. Observations of patients suffering brain lesions were first recorded in detail in the 18th century, and lesion studies continue to shape modern neuroscience and to give insight into the functions of brain regions. Recovery, defined as any return of lost behavioral or cognitive function, depends on the age, sex, genetics, and lifestyle of patients, and recovery may be predicted by the cause of injury. Most recovery occurs within the first 6 to 9 months after injury and likely involves a combination of compensatory behaviors and physiological changes in the brain. Children often recover some function after brain lesions better than adults, though both children and adults experience residual deficits. Brain lesion survival rates are improved by better diagnostic tools and treatments. Therapeutic interventions and treatments for brain lesions include surgery, pharmaceuticals, transplants, and temperature regulation, each with varying degrees of success. Research in treating brain lesions is progressing, but in principle a cure will only be complete when brain lesions are replaced with healthy tissue.
G. Campbell Teskey
The kindling phenomenon is a form of sensitization where, with repetition, epileptiform discharges become progressively longer and behavioral seizures eventually appear and then become more severe. The classic or exogenous kindling technique involves the repeated application of a convulsant stimulus. This technique also lowers seizure thresholds, the minimum intensity of a stimulus required to evoke an electrographic seizure, a process known as epileptogenesis. Endogenous kindling typically occurs following a brain-damaging event which lowers seizure thresholds to the point where self-generated epileptiform discharges recur, lengthen, propagate, and drive progressively more severe behavioral seizures. While exogenous kindling results in alterations in neuronal molecular, cellular/synaptic, and network function that give rise to altered behavior, there is a paucity of evidence for loss of neurons. In contrast, brain-damaging events, with neuronal loss, typically give rise to endogenous kindling. Kindling is a pan-species phenomenon and all mammals that have been examined, including humans, manifest exogenous kindling when seizure-genic (forebrain) structures have been targeted. Since humans display both exogenous and endogenous kindling phenomena this serves as a sober warning to clinicians to prevent seizures. Kindling serves as a robust and reliable model for epileptogenesis, focal as well as secondarily generalized seizures, and certain epileptic disorders.
The sensation of vision arises from the detection of photons of light at the eye, but in order to produce the percept of the world, extensive regions of the brain are required to process the visual information. The majority of information entering the brain via the optic nerve from the eye projects via the lateral geniculate nucleus (LGN) of the thalamus to the primary visual cortex, the largest visual area, having been reorganized such that one side of the brain represents one side of the world.
Damage to the primary visual cortex in one hemisphere therefore leads to a loss of conscious vision on the opposite side of the world, known as hemianopia. Despite this cortical blindness, many patients are still able to detect visual stimuli that are presented in the blind region if forced to guess whether a stimulus is present or absent. This is known as “blindsight.” For patients to gain any information (conscious or unconscious) about the visual world, the input from the eye must be processed by the brain. Indeed, there is considerable evidence from functional brain imaging that several visual areas continue to respond to visual stimuli presented within the blind region, even when the patient is unaware of the stimulus. Furthermore, the use of diffusion imaging allows the microstructure of white matter pathways within the visual system to be examined to see whether they are damaged or intact. By comparing patients who have hemianopia with and without blindsight it is possible to determine the pathways that are linked to blindsight function. Through understanding the brain areas and pathways that underlie blindsight in humans and non-human primates, the aim is to use modern neuroscience to guide rehabilitation programs for use after stroke.
The problem of time in psychology, which first became the object of attention and investigation by scientific psychology concerning the aspect of temporal measurement of mental processes, has been addressed since the early 20th century with regard to the perception of time, also called the subjective experience of time. The reaction time paradigm, defined as the minimum time between the presentation of a stimulus and the participant’s response to it, is closely related to the birth of experimental psychology. The determination of an objective parameter of the speed of the nerve impulse, therefore, represented the initial purpose of the psychochronometric studies. Defining the object of study for experimental psychology as immediate conscious experience or subjective experience of consciousness has led psychologists to reflect on the distinction between physical time and psychological time—a distinction already present in the philosophical field—and to analyze the latter in all its manifestations through sophisticated and complex experimental investigations. Psychologists, although aware of the reflections on time developed by philosophical doctrines and prepared to take these into account, generally tried to steer clear of the questions relating to the typical problems of philosophy—the nature of the idea of time and its corresponding reality—preferring to concentrate their analysis on the subjective experience of time. In relation to the different varieties of the temporal experience, experiments have been conceived and set up to analyze, measure, and precisely define them using the psychophysical and psychophysiological research paradigm. Between the end of the 19th century and the first decade of the 20th century researches concerning perception of the present, simultaneity, succession, instant, and time interval were developed.
Neil E. Rowland
Thirst is a specific and compelling sensation, often arising from internal signals of dehydration but modulated by many environmental variables. There are several historical landmarks in the study of thirst and drinking behavior. The basic physiology of body fluid balance is important, in particular the mechanisms that conserve fluid loss. The transduction of fluid deficits can be discussed in relation to osmotic pressure (osmoreceptors) and volume (baroreceptors). Other relevant issues include the neurobiological mechanisms by which these signals are transformed to intracellular and extracellular dehydration thirsts, respectively, including the prominent role of structures along the lamina terminalis. Other considerations are the integration of signals from natural dehydration conditions, including water deprivation, thermoregulatory fluid loss, and thirst associated with eating dry food. These mechanisms should also be considered within a broader theoretical framework of organization of motivated behavior based on incentive salience.
Mutsumi Imai, Junko Kanero, and Takahiko Masuda
The relations among language, culture, and thought are complex. The empirical evidence from diverse domains suggests that culture affects language, language affects thought, and universally shared perception and cognition constrain the structure of language. Although neither language nor culture determines thought, both seem to highlight certain aspects of the world, with stronger influence when there are no clear perceptible categories. Research must delve into how language, culture, perception, and cognition interact with one another across different domains.
Barbara A. Wilson
Neuropsychological rehabilitation (NR) is concerned with the amelioration of deficits caused by insult to the brain. It adopts a goal-planning approach and addresses real-life difficulties. Neuropsychology studies how the brain affects behavior, emotion, and cognition. Rehabilitation is a process whereby people who are disabled work together with professional staff, relatives, and others to achieve optimum physical, psychological, and vocational well-being. Rehabilitation is not synonymous with recovery, nor is it treatment. It is a two-way interactive process with professional staff and others who aim to remediate or alleviate difficulties, adopting a holistic approach in which cognition, emotion, and psychosocial problems are treated together, aided by an increasing use of technological aids.
NR enables people with disabilities to achieve their optimum level of well-being, reduce problems in everyday life, and help them return to the most appropriate environments. There may also be some partial or limited recovery of function and certainly some substitution of function. Accepting that return of normal functioning is highly unlikely, rehabilitation finds ways to help people learn more efficiently, compensate for their difficulties, and, when necessary, modify the environment.
While theoretical models have proved helpful, indeed essential, in identifying cognitive strengths and weaknesses, in explaining phenomena, and in making predictions about behavior, they are insufficient, on their own, to seriously influence rehabilitation aimed at making lives more adaptable to problems encountered in everyday living. NR should focus on goals relevant to a person’s individual everyday life, it should be implemented in the environment where the person lives, and have personally meaningful themes, activities, settings, and interactions.
We know from numerous studies that NR can be clinically effective. Although rehabilitation can be expensive in the short term, there is evidence that it is cost-effective in the long term.
Martin J. Packer and Michael Cole
There is growing appreciation of the role of culture in children’s psychological development (also called human ontogenesis). However, there are several distinct approaches to research on this matter. Cross-cultural psychology explores the causal influence of culture on differences in children’s development, treated as dependent variables. Researchers interested in the role of cultural learning in human evolution view culture as beliefs and values that are transferred from the mind of one individual to that of another.
By contrast, “cultural psychology” views culture not as a cause, but a constituent of human psychological functioning. It invites us to pay attention to the fact that humans live in societies filled with material artifacts, tools, and signs that mediate human activity; that is to say, they provide the means with which people interact with the world around them and with one another. From this perspective, culture provides constituents that are essential to human development: it has a constitutive role in development.
Although there continues to be much debate over how to define culture, it is generally agreed that different human social groups have distinct cultures, and it is common to assume that cultural differences lead to differences in the trajectories of children’s development. This is true, but it is also the case that culture is a universal requirement for development. Every child is born into a family and community with a language, customs, and conventions, and in which people occupy institutional roles with rights and responsibilities. These facts define universal requisites of human psychological development and include the acquisition of language, the development of a social identity, the understanding of community obligations, and the ability to contribute to the reproduction of the community. The interdependence of human communities—which probably had its origins in collaborative foraging and cooperative childrearing—seems to have placed species-specific demands on children’s development, selecting for the capacity to acquire a sensitivity not only to people’s goals and intentions but also to rights and responsibilities.
Neil E. Rowland
Hunger is a specific and compelling sensation, sometimes arising from internal signals of nutrient depletion but more often modulated by numerous environmental variables including taste or palatability and ease or cost of procurement. Hunger motivates appetitive or foraging behaviors to find food followed by appropriate proximate or consummatory behaviors to eat it. A critical concept underlying food intake is the flux of chemical energy through an organism. This starts with inputs of food with particular energy content, storage of excess energy as adipose tissue or glycogen, and finally energy expenditure as resting metabolic rate (RMR) or as metabolic rate is modified by physical activity. These concepts are relevant within the context of adequate theoretical accounts based in energy homeostasis; historically, these are mainly static models, although it is now clear that these do not address practical issues such as weight gain through life. Eating is essentially an episodic behavior, often clustered as meals, and this has led to the idea that the meal is a central theoretical concept, but demonstrations that meal patterns are greatly influenced by the environment present a challenge to this tenet. Patterns of eating acquired during infancy and early life may also play a role in establishing adult norms. Direct controls of feeding are those that emphasize food itself as generating internal signals to modify or terminate an ongoing bout of eating, and include a variety of enteroendocrine hormones and brainstem mechanisms. Additionally, many studies point to the essential rewarding or hedonic aspects of food intake, including palatability, and this may involve integrative mechanisms in the forebrain and cerebral cortex.
Trevor A. Harley
Research in the psychology of language has been dogged by some enduring controversies, many of which continue to divide researchers. Furthermore, language research has been riven by too many dichotomies and too many people taking too extreme a position, and progress is only likely to be made when researchers recognize that language is a complex system where simple dichotomies may not be relevant. The enduring controversies cover the width of psycholinguistics, including the work of Chomsky and the nature of language, to what extent language is innately determined and the origin of language and how it evolved. Chomsky’s work has also influenced our conceptions of the modularity of the structure of the mind and the nature of psychological processing. Advances in the sophistication of brain imaging techniques have led to debate about exactly what these techniques can tell us about the psychological processing of language. There has also been much debate about whether psychological processing occurs through explicit rules or statistical mapping, a debate driven by connectionist modeling, deep learning, and techniques for the analysis of “big data.” Another debate concerns the role of prediction in language and cognition and the related issues of the relationship between language comprehension and language production. To what extent is language processing embodied, and how does it relate to controversies about “embedded cognition”? Finally, there has been debate about the purpose and use of language.