Universität zu Köln, Wintersemester 06/07
Sprachwissenschaften B-Seminar: Psycholinguistics
Abgabedatum: 24.01.07

Brain Structure and Language

von: Steffen Blatt

Contents

1. Introduction 1

2. Brain Structure

2.1 General Structure 2
2.2 Hemispheric Structure and Function 4
2.3 Main Language Areas in the Brain 5
2.4 The Auditory System 7
2.5 The Visual System 9

3. Methods of Investigation 11

3.1 Early Attempts 11
3.2 The Wada Test 11
3.3 The Tachistoscopic Presentation 12
3.4 The Dichotic Listening Technique 12
3.5 The CAT-Scan 12
3.6 The PET-Scan 13
3.7 MRI and fMRI 13
3.8 ERP 13

4. Conclusion 14

References 15

1. Introduction

The brain is probably the most important part of the body. Its function is to control almost all body movements which also include the vegetative system like the digesting organs or the heart. Of course, it is also responsible for producing and receiving language. This paper will introduce the main structure of the brain with special attention to those areas of the brain which are involved in language. It starts with the general structure and then explains the different hemispheric functions and the main language areas in the brain. These not only include those which are necessary for speaking because language means more. That is the reason for explaining the auditory and visual pathways from their origin, the ear respectively the eye, all the way to their associated processing areas in the brain, as well (chapters 2.4 and 2.5).

The second main part of this paper will give a short overview of the investigation methods which were and are used to map the brain and to gain knowledge about how the brain works in correlation with language. This overview reaches from the early attempts of post-mortem examination to the high-tech methods of today neurolinguistics.

2. Brain structure

2.1 General Structure

The weight of an average human adult brain is around 1 to 1.75kg but it almost needs onefifth of the body’s blood supply (Gleason & Bernstein Ratner, 1998, p.60). But neither the size of the brain nor the relation between body size and brain size is important for the intelligence. For example, this relation in a 13 year old child and in a three year old chimpanzee is about the same and there is no doubt that the child should be more intelligent than the chimpanzee (Steinberg et al. 2001, p.311). A special part of the brain can be seen as a hint for higher intelligence because it has developed later in evolution than other parts. It is the cerebral cortex. This part is barely visible in lower vertebrates like fish or birds but much more developed in higher vertebrates like humans, apes or dolphins. The cerebral cortex is concerned with higher intellectual functions as well as language (Steinberg et al. 2001, p.312). The brain itself is organised in different structures which are relatively easy to locate.

The biggest parts of the brain are the cerebral hemispheres. They are divided horizontally into a left and a right hemisphere and are only connected by the corpus callosum and some fibre bundles, so there is still an exchange of information between the two hemispheres (Obler & Gjerlow 1999, p.18). Together, they are also called the cerebrum. Furthermore, there are several other subcortical structures which are located below the cerebrum and the further down one goes the more basic are the functions of the brain parts. At first, there are the basal ganglia which work together with the cerebrum and are responsible for the fine-tune body movements. Surrounded by the basal ganglia is the interbrain or diencephalon which mainly consists of the thalamus and hypothalamus. The main function of these parts is the control of the central vegetative systems, for example body core temperature regulation. Below that as the upper part of the brainstem is the midbrain or mesencephalon (3 see next picture). The brainstem also consists of the pons or metencephalon and the medulla oblongata or myelencephalon. All of these parts have something to do with vital functions for the body. Even further down, already at the level of the neck, is the spinal cord (7) and behind the brainstem is the cerebellum (4). The cerebellum controls the coordination of the muscles and the bodily equilibrium and it has its own two hemispheres (Garman 2000, pp.50-51; Merriam- Webster Online Dictionary; healthline.com).

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