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Chapter Five Cognitive Neuroscience
In the 1930s Wilder Penfield developed groundbreaking surgical techniques for the treatment of epilepsy. He created a preoperative procedure that involved direct electrical stimulation of brain tissue that is still in use today. Adapted from earlier animal studies, Penfield discovered that application of direct electrical stimulation of the convoluted surface of the brain, referred to as the cerebral cortex, allowed mapping the areas of the cortex responsible for important functions such as perception, motor control, and language, thus allowing the surgeon to remove the abnormal tissue associated with epileptic seizures while sparing as much critical functioning brain tissue as possible. Penfields work also documented the fact that electrical stimulation of the cortical surface of the human brain was associated with changes in mental experience.
Wilder Penfields Brain Stimulation
Because the brain itself does not possess pain receptors, patients were operated on under local anesthesia and were therefore awake and able to report their mental experience when told their brain was being electrically stimulated. Patients would respond with reports of changes in visual perception, such as falling stars when visual areas were stimulated, and they would report perception of auditory events (e.g., hearing music and insisting that a radio was playing in the room when it was not) when auditory areas were stimulated. Penfield mapped the cortical areas responsible for voluntary motor control of the body and demonstrated that the neurons in this region were organized like a map of the human body. He also discovered supplementary motor areas that seemed to be involved in motor planning as well as motor control. He reported on a patient whose hand moved when the portion of the motor control area representing the hand was stimulated, and the patient reported the mental experience that the doctor had moved the hand. However, when the nearby supplementary motor area, associated with planning of volitional movements of the same hand, was stimulated the patients hand moved and now the patient claimed to have moved it voluntarily. These examples raise questions regarding the association of physical changes in the brain and mental experience, as well as questions regarding how
different regions of cortex may implement different cognitive processes, questions that are at the heart of a new and rapidly changing area of research called cognitive neuroscience. Pinky and the Brain. Before getting too serious about the brain you can visit YouTube to view Pinky and the Brain singing the brain song. It is entertaining as well as educational.
Parts of the Brain Song
Defines the relatively new scientific discipline of cognitive neuroscience. Explains the 2 major influences leading to the rapid emergence of cognitive
neuroscience. Discusses 2 questions of debate during the development of neuroscience. Provides a brief introduction to the basic principles of neural communication in
the brain. Provides a brief introduction to the basic functions of the major neuroanatomical
structures of interest to cognitive scientists. Provides a focused review of selected cognitive neuroscience methodologies
from 3 broad classes of methods.
Outline of Topics I. Definition and Development of Cognitive Neuroscience II. Major Historical Questions about the Brain
A. The Mind/Brain Question B. Localization of Cortical Function
III. Neural signaling A. Structures of the Prototypical Neuron B. Electrical Signaling within Neurons C. Chemical Signaling between Neurons D. Signaling versus Computation
IV. Functional Neuroanatomy for Cognitive Scientists A. Introduction to the Cerebral Cortex B. 4 Cortical Lobes Plus 1 Important Additional Area C. 2 General Principles of Cortical Function D. Cortical Processing E. Subcortical Structures of Importance to Cognitive Scientists F. Cerebellum & Brainstem
V. Methods of Cognitive Neuroscience A. Studying Electrophysiological Processes
1. Direct Electrical Recording 2. Electroencephalography (EEG) 3. Event-related Potentials (ERP)
B. Imaging the structure and function of the brain 1. MRI 2. PET 3. Functional MRI (fMRI)
C. Lesion analysis 1. Single & Double Dissociations 2. Transcranial magnetic stimulation (TMS)
I. Definition and Development of Cognitive Neuroscience Cognitive neuroscience is a relatively new scientific discipline that combines the study of cognitive and biological processes in the brain, primarily in humans. Cognitive neuroscience is a scientific discipline that is the result of a fairly recent coming together of researchers in cognitive psychology and neuroscience to better understand how cognitive processes such as thoughts, emotions, perceptions, memory, and goals are implemented in the brain. Cognitive neuroscience has emerged as a distinct discipline only recently in response to 2 major influences. First, for many years cognitive psychologists studied cognitive processing in humans with only minimal attention to how such processes might be physically implemented due to a strong belief that that processing steps used to complete a cognitive task were not directly dependent on the underlying physical substrate, in this case the brain, performing the computations. Similarly, neuroscientists focused primarily on the physical functioning of the neurons and brains. One major impetus for the emergence of cognitive neuroscience was that cognitive psychologists and neuroscientists started serious discussions of how their respective areas of inquiry could complement each other and lead to a fuller understanding of how the human brain implements human cognition. On this view, neuroscientists could develop a better understanding of physical brain processes by considering the cognitive theories developed by psychologists, and cognitive psychologists could benefit from the knowledge of neuroscientists regarding how the brain worked to implement cognitive processes. A second force leading to the emergence of cognitive neuroscience was the development of techniques for observing the operation of the brain in a living human being (i.e., in vivo) from outside of the scalp and skull (i.e., noninvasive). Moreover, a critical technical development in 1990 (Ogawa et al., 1990) led to the realization that a widely available medical scanning technology that had been used for making images of the structure of the tissues of the body, magnetic resonance imaging (MRI), could be easily modified to produce functional images of the pattern of neural activity in the brain during performance of a cognitive task. Due to the fact that a large number of MRI
scanners were already in widespread use in medical centers and medical schools, this new functional MRI (fMRI) technique for imaging the function of the human brain became accessible to a large number of researchers in a short amount of time, leading to an explosion in the number of functional brain imaging studies and a rapid increase in the number of scientists wanting to focus on the new and exciting discipline of cognitive neuroscience.
How the MRI Works
II. Major Historical Questions about the Brain
Homo sapiens, modern humans, emerged in Africa about 200,000 years ago, and migrated out of Africa about 70,000 years ago. When they reached Western Europe during the last ice age, they encountered another tool using primate, the Neanderthals, who had been successfully living there for over 100,000 years, having come as part of an earlier wave of migration out of Africa. However, Neanderthals became extinct about 25,000 years ago, leaving just one tool-making primate, us, standing. What is it that made us so successful
where other similar primate species were not? Scientists point to our tool use, spoken language, and social cooperation as potential sources for our competitive advantage. If this is the case, then it simply begs the question of what changed in our specific version of the primate brain that sparked these skills to be used in new and innovative ways? For many thousands of years Neanderthals used the same basic tools to live in much the same way that they had when they left Africa, but when modern humans came they upped the ante. Modern humans produced cave art that amazes us to this day. They buried their dead, and they began to use more complicated hunting technologies such as throwing sticks and bows and arrows. Scientists have recently begun to analyze Neanderthal DNA in hopes of finding genetic differences in genes that controlled brain development between Neanderthals and modern humans. The emergence of human cognitive abilities with the appearance of homo sapiens is an exciting area of science that promises new discoveries as to how modern humans leapt to the front of the line in terms of cognitive processing abilities. Human Spark. To learn more about this exciting work consult the website for The Human Spark, a 3-hour Public Broadcasting System (PBS) series hosted by Alan Alda, first airing January of 2010.
In her poem, The Brain is wider than the Sky, Emily Dickenson (1860s) wonders at the amazing ability of the human brain to contain (or represent?) the immense universe that we find ourselves a part of. This poem points to the complex relationship between mind and brain. How can it be that an organ that fits in the human skull can contain such immenseness as the sky itself? Dickinson suggests that it is because the brain can think about the sky, and not only that but the brain can also, with disarming effortlessness, think about the person who