Search Results

Jean-Baptiste Bouillaud was the most ardent supporter of cortical localization in the cerebral cortex during the second quarter of the 19th century. He found support from his son-in-law Simon Alexandre Ernest Aubertin and Paul Broca. In March 1861, Broca delivered a paper on the relationship between brain size and intelligence. The more he thought about it, the less willing he was to accept the idea that all parts of the cerebral hemispheres function in the same way. Broca raised the possibility that the frontal lobes may serve other executive functions, including judgment, reflection, and abstraction. In his 1865 paper on cerebral dominance, Broca was forced to deal with some recently surfaced exceptions to the idea that the center for articulate language resides in the third frontal convolution of the left hemisphere. Broca contributed significantly to human physical anthropology and wrote important papers on the anatomy of the brain.

This chapter characterizes the nature of the hemispheric biases in social cognition. This includes both description and discussion of the literature examining the extent of hemispheric specialization in firstly how we identify and interpret the mental states of other people, and secondly how we perceive emotion. Overall, research continues to demonstrate the importance of the right cerebral hemisphere for social cognitive processes. The role of the right hemisphere is most apparent in studies involving patients with brain damage(i.e., the brain lesion approach)and in studies of healthy participants using behavioral paradigms, such as chimeric faces or tachistoscopic procedures.

This chapter can be regarded as a sequel to George Ettlinger's 1984 paper, ‘Humans, apes and monkeys: the changing neuropsychological viewpoint’. He noted that in 1963 ‘there was no evidence for cerebral functional asymmetry in any nonhuman animal’. He then reviewed a number of findings of functional asymmetries in other primates, reported in the following twenty years and concluded that while ‘it might be prudent not to assert that cerebral hemispheric specialization is homologous in man and in monkey…the likelihood of such an eventual outcome has increased enormously’. This chapter contends that there is not only homology across vertebrate taxa for a number of individual specializations, but there is probably some evolutionary continuity in relationships between specializations.

This chapter provides an overview of the organization of the different cortical layers, the general principles of organization of the fiber tracts, and a conceptual approach to the major functional divisions of the cerebral hemispheres.

This chapter examines some of the most well-developed models of human neurological disorders that involve the cerebral hemispheres. It discusses cortical organization in rats and models of neurological disorders.

The size and prominent position of the corpus callosum in the brain led to it being one of the earliest structures to be investigated. While much progress has been made since that time in researchers' understanding of the role that the corpus callosum plays in the transfer of information between the two cerebral hemispheres, there are still gaps in their knowledge. This chapter attempts to review what has been learnt about interhemispheric communication in the monkey, where the corpus callosum and anterior commissure between them contain about 53 million fibres, and compares this with what is known about the role of the corpus callosum and anterior commissure in humans.

Thomas Willis was born in England twenty-five years after the birth of René Descartes. Willis can be considered the first of the new breed of medical physiologists who were more influenced by clinical and laboratory insights than by Graeco-Roman theories held sacred by their forefathers. Willis claimed that the brain can best be understood by envisioning different levels of function. He thought that those structures located higher in the brain must do those things that are unique to advanced organisms, whereas lower structures, such as the cerebellum, must be responsible for more elementary functions, those that vary little across vertebrates. Willis was accurate in rejecting the ventricles in favor of the cerebrum as the center for memory, cognition, volition, and imagination. He was also right to distinguish between the functions of the gray and white matter of the cerebral hemispheres. This chapter also looks at Willis's theory on the corpus striatum, the link between cerebellum and involuntary actions, and his work on psychiatry.

Current theoretical models of face perception postulate separate routes for processing information needed in the recognition of a familiar face, for matching photographs of unfamiliar faces, and for the analysis of facial expressions. This study investigated this claim in a group of ex-servicemen who had sustained unilateral brain injuries affecting posterior areas of the left or right cerebral hemisphere. Care was taken to confirm the nature of impairment by using two different tasks to assess each of the three theoretically defined abilities (leading to a total of six tasks). The results showed selective impairments of all three abilities on accuracy scores. Response latency data confirmed the finding of a selective deficit in the processing of facial expressions, but produced evidence suggesting that impairments affecting familiar face recognition and unfamiliar face matching were not completely independent from each other in this group of ex-servicemen.

This chapter examines the tonotopic organization of the human auditory cortex using intracerebrally recorded evoked potentials studied as a function of the anatomical recording site. The sensitivity of a neuronal population to a given frequency is determined from fluctuations in auditory evoked potential (AEP) amplitude between different recording sites in the primary auditory cortex and surrounding secondary areas like the planum temporale. The chapter particularly explores the tonotopic organization of the human auditory cortex in both cerebral hemispheres. In the right hemisphere, clear spectrally organized tonotopic maps wre observed with distinct separations between different frequency-processing regions. AEPs for high frequencies were recorded medially, whereas AEPs for low frequencies were recorded laterally. However, in the left hemisphere, this tonotopic organization was less evident, with different regions involved in the processing of a range of frequencies. The hemisphere-related difference in the processing of tonal frequency is discussed in relation to pitch perception.

This chapter provides a discussion on the evidence on musical sound processing. Data acquired in the mismatch negativity (MMN) paradigm have shown that temporally and spectrally complex sounds as well as their relations are automatically represented in the human auditory cortex. Furthermore, the MMN data indicate that these neural sound representations are spatially distinct between phonetic and musical sounds within and between the cerebral hemispheres. The majority of the MMN studies were conducted in pitch dimension but also temporal aspects of sound processing are under increasing experimentation. Up to some extent, also musical expertise is reflected in sound representation accuracy as indexed by the MMN. In addition, an overview on studies using musical sounds and sound successions to investigate the automatic neural sound processing is given. The chapter then outlines the recent studies comparing musicians and nonmusicians. In general, the results offer fundamental insight to the brains' ability to encode and differentiate acoustically complex sounds despite the focus of the listener's attention.

Chapter 1 reviews the history of thought concerning specialization of function in the brain, particularly regarding speech and music. This history begins in the nineteenth century with the work of the phrenologists Gall and Spurzheim, and later with studies of brain-damaged patients, particularly by Broca and Wernicke. It continues into the mid-twentieth century with the work of Luria and others, also focusing on patients who have suffered brain damage, then considers recent work. The roles of the left and right hemispheres are discussed, particularly their roles in speech. The abilities of left-handers, right-handers, and mixed-handers are compared, especially relating to music and speech. This chapter is a prelude to Chapter 2, which explores a number of musical illusions that, statistically, are heard differently by left- and right-handers.

This chapter discusses developmental vitamin D (DVD) deficiency as a potential risk factor for schizophrenia. Over the last decade, evidence has accumulated demonstrating that vitamin D plays an important role in brain development; hence, vitamin D deficiency may result in a higher risk for schizophrenia. Scientist conducted an experiment on rats to demonstrate how DVD deficiency can alter neurobiological features, which are consistent with that of schizophrenia. The finding shows that DVD deficient rats had cerebral hemispheres that were longer but not wider than common rats, and increased mitosis across the embryonic brain. These results suggest that vitamin D exerts a pro-differentiation and pro-apoptotic function in the developing brain. The altered brain size and shape in DVD-deficient rats may be the result of the disrupted normal progression of brain cells.