Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience

1. Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience Edited by Bernard J. Baars and Nicole M. Gage 2007 Academic Press Chapter 1 Mind and Brain “… from the brain, and from the brain alone, arise our pleasures, joys, laughter and jokes, as well as our sorrows, pains, griefs and tears. Through it, in particular, we think, see, hear, and distinguish the ugly from the beautiful, the bad from the good, the pleasant from the unpleasant… all the time the brain is quiet, a man can think properly.” --- Attributed to Hippocrates, 5th century BCE. (Footnote: quoted by Kandel et al., 1991).

2. Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience Edited by Bernard J. Baars and Nicole M. Gage 2007 Academic Press Chapter Outline 1.0 Introduction 2.0 An invitation to mind-brain science 3.0 Some starting points 4.0 Some history, and ongoing debates 5.0 The return of consciousness in the sciences 6.0 Summary

3. Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience Edited by Bernard J. Baars and Nicole M. Gage 2007 Academic Press • 1.0 Introduction • 2.0 An invitation to mind-brain science • Cognitive Neuroscience: the combined study of mind and brain • The advent of neuroimaging techniques has revolutionized the study of human cognition • These new techniques allow us to explore topics like conscious experience, unconscious processes, and mental imagery Neuroimaging techniques allow us to investigate brain structure and dynamic function in healthy individuals. Figure 4.1 shows a 3-dimensional structural head and brain scan (Chapter 4, Figure 1).

4. Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience Edited by Bernard J. Baars and Nicole M. Gage 2007 Academic Press 3.0 Some starting points Distance: seven orders of magnitude from 1 meter to 10-7 meter A brain image of a subject looking at a rotating black and white stimulus A midline view of the cortex, with area V1 marked -- the first place where the visual pathway reaches cortex The head of a fruit fly: the fruit fly brain has about 1,000,000 neurons A single neuron: we have tens of billions in our brain A dopamine molecule: dopamine plays an essential role in working memory, the experience of pleasure, and the control of muscles a b c d e Items a-e represent 7 spatial orders of magnitude

5. Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience Edited by Bernard J. Baars and Nicole M. Gage 2007 Academic Press 3.0 Some starting points Time: ten orders of magnitude -- from years to milliseconds • When you listen to a high musical note, your auditory nerve is firing as fast as the sound waves that vibrate your eardrum, up to 1000 times per second (cycles per second = Hertz =Hz), or one wave per millisecond (ms, 1000th of a second) • Neurons can fire as fast as 1000Hz, although the average neuron n the cortex fires about 10 times per second • The auditory nerve is a bundle of nerve axons, each of which fires slower than 1000 Hz, but together they can respond at millisecond speed

6. Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience Edited by Bernard J. Baars and Nicole M. Gage 2007 Academic Press 3.0 Some starting points Time: ten orders of magnitude -- from years to milliseconds • If the sound track of a movie is delayed by a fraction of second behind the video, you will notice a disconnect between the sounds and the movements of an actor’s mouth. The break-up of audio-visual synchrony occurs after about 100 ms lag, or one-tenth of a second • One hundred ms is also about the fastest we can react to an event that we know will come soon, as in starting a car when a traffic light turns green • By comparison, if you count to yourself from one to ten, your counting takes place on the order of seconds, or tens of seconds. The typical lecture lasts one hour -- more than 3000 seconds

7. Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience Edited by Bernard J. Baars and Nicole M. Gage 2007 Academic Press 3.0 Some starting points The need to make inferences -- going beyond the raw observation Science depends on a constant process of inference, going from raw observations to explanatory concepts. Thousands of years ago, when human beings began to wonder about lights in the sky like the sun, moon, and stars, they noticed that some were predictable and some were not. The ‘wanderers’ in the night sky were called planete by the Greeks, we call them planets in English.

8. Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience Edited by Bernard J. Baars and Nicole M. Gage 2007 Academic Press 3.0 Some starting points The need to make inferences -- going beyond the raw observation It was not until the 17th century that their paths were understood and predicted. Words like ‘planet’, ‘force’, and ‘gravity’ are inferred concepts. They are far removed from the first observations of lights in the sky, yet they explain those raw observations: they are explanatory inferences.

9. Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience Edited by Bernard J. Baars and Nicole M. Gage 2007 Academic Press 3.0 Some starting points The need to make inferences -- going beyond the raw observation Cognitive concepts are based on consistent behavioral observations. Inferred concepts in cognitive neuroscience include areas of study such as language, learning, memory, or vision. Concepts like ‘working memory’ are not given nature, they emerge after many years of testing, when a large body of evidence seems to be explained by an inferred concept.

10. Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience Edited by Bernard J. Baars and Nicole M. Gage 2007 Academic Press 3.0 Some starting points The need to make inferences -- going beyond the raw observation Brain measures of working memory are also inferential. Working memory functions in the brain have been studied using behavioral measures, but also with fMRI, EEG, and single neuron recordings. Each of these measures has its pros and cons, but none of them is the ‘ultimate measure’ of working memory.

11. Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience Edited by Bernard J. Baars and Nicole M. Gage 2007 Academic Press 3.0 Some starting points The importance of convergent measures Overall, brain indices of working memory converge well with behavioral measures. Cognitive neuroscience is based on the study of such combined sources of evidence, but we must be prepared to find that our current concepts may be interpreted in a different way with new findings. New raw observations lead to refined inferred concepts and theories about cognition.

12. Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience Edited by Bernard J. Baars and Nicole M. Gage 2007 Academic Press 3.0 Some starting points Major landmarks of the brain, with a medial (midline) view showing the center portions of the brain between the two cerebral hemispheres, and a lateral (side) view showing the outer aspects of the cerebral cortex.

13. Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience Edited by Bernard J. Baars and Nicole M. Gage 2007 Academic Press 3.0 Some starting points Major planes of sections (slices) of the brain Top panel shows a vertical section of the brain, called sagittal. When brain images are collected in this plane, they go from one side of the brain, across the midline between the two hemispheres, and to far side of the brain. When the slice is exactly through the midline between the two hemispheres it is called mid-sagittal. Center panel shows a horizontal or axial slice through the brain. These slices go from the top of the brain to the bottom. The lower panel shoes a coronal slice (named for its crown shape) that goes from the front of the brain to the back, from the forehead to the nape of the neck. Like horizontal slices, coronal slices include both hemispheres.

14. Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience Edited by Bernard J. Baars and Nicole M. Gage 2007 Academic Press 4.0 Some History, and ongoing debates The mind and the brain -- Rene Descartes Descartes is often considered to be the originator of the mind/body philosophy. The basic question seems simple: is the world basically mental or physical?

15. Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience Edited by Bernard J. Baars and Nicole M. Gage 2007 Academic Press 4.0 Some History, and ongoing debates The mind and the brain -- Rene Descartes Because Descartes was convinced that the the soul or psyche was a unified whole, he rejected the idea that paired structures of the brain could support the (unitary) soul. But almost all of the brain looks doubled to the naked eye: two hemispheres, two eyes, two ears, two subcortical halves. Descartes decided that the tiny pineal gland, which looks like a tiny dot to the naked eye, must be the point of connection between the divine soul and the earthly body.

16. Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience Edited by Bernard J. Baars and Nicole M. Gage 2007 Academic Press 4.0 Some History, and ongoing debates Biology shapes cognition and emotion -- Charles Darwin Human emotion turns out to have deep biological roots in the mammalian brain, regulated by more recent layers of the cortex. As a result, the evolutionary history of the human brain, going back some two hundred million years to early mammals, is relevant to a host of important questions.

17. Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience Edited by Bernard J. Baars and Nicole M. Gage 2007 Academic Press 4.0 Some History, and ongoing debates Biology shapes cognition and emotion -- Charles Darwin More than anyone else, Charles Darwin helped to establish the biological context of the human species. Darwin thought about human emotions as biologically based -- which was not meant to minimize our vast cultural and individual influences of course. Darwin made numerous observations about emotional expressions in animals and humans and subsequently wrote a book called TheExpression of Emotions in Man and Animals.

18. Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience Edited by Bernard J. Baars and Nicole M. Gage 2007 Academic Press 4.0 Some History, and ongoing debates Biology shapes cognition and emotion -- Hermann von Helmholtz Helmholtz was a great sensory physiologist and psychologist in the 19th century whose works on vision and audition are still read. But his biggest claim to fame is the physical law of conservation of energy, which he demonstrated using electrical stimulation of dissected frog’s legs. The idea that the brain and body are pervaded with electricity caught the popular fancy, leading to cult ideas like ‘animal magnetism’.

19. Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience Edited by Bernard J. Baars and Nicole M. Gage 2007 Academic Press 4.0 Some History, and ongoing debates Biology shapes cognition and emotion-- Hermann von Helmholtz The insight that electricity was part of nervous activity led to the discovery of nerve potentials and the electrical activity of the brain in the early 20th century. Today, the electromagnetic activity of the brain gives us a whole set of imaging methods: EEG, evoked potentials, single-neuron recording, and MEG. All brain imaging tools make use of fundamental physics and chemistry.

20. Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience Edited by Bernard J. Baars and Nicole M. Gage 2007 Academic Press 4.0 Some History, and ongoing debates Ramon y Cajal’s neuron doctrine: the working assumption of brain science Santiago Ramon y Cajal was a founder of brain science. An open and important question of his time was regarding the nature of the nervous system -- whether it consisted of billions of separate cells or whether it was essentially one great continuous network.

21. Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience Edited by Bernard J. Baars and Nicole M. Gage 2007 Academic Press 4.0 Some History, and ongoing debates Ramon y Cajal’s neuron doctrine: the working assumption of brain science Cajal used Golgi stains to bring out basic facts about nerve cells under the light microscope.

22. Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience Edited by Bernard J. Baars and Nicole M. Gage 2007 Academic Press 4.0 Some History, and ongoing debates Ramon y Cajal’s neuron doctrine: the working assumption of brain science Cajal is credited with the neuron doctrine, one of the founding assumptions of brain science, stating that “the nervous system consists of numerous nerve cells (neurons), anatomically and genetically independent”. Today’s methods for studying neuronal microstructure are advanced versions of the Golgi-Cajal approach.

23. Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience Edited by Bernard J. Baars and Nicole M. Gage 2007 Academic Press 4.0 Some History, and ongoing debates Pierre-Paul Broca and the localization of speech production Medical observations are also relevant to the mind and brain sciences. It was the French physician, Pierre-Paul Broca, who first discovered a region of the left hemisphere that was tied to language production. Broca had a patient who had lost all ability to speak except to say the single word ‘tan’. After the patient died, Broca was able to perform an autopsy, finding damage to “the posterior part of the third frontal convolution in the left hemisphere”.

24. Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience Edited by Bernard J. Baars and Nicole M. Gage 2007 Academic Press 4.0 Some History, and ongoing debates Pierre-Paul Broca and the localization of speech production He concluded that this part of the frontal lobe was indispensable for speech production. This concept was hotly debated among scientists: were there localized functional areas in the brain or was the brain equipotential, with all regions able to support cognition? This debate continues today. The ‘speaking’ region of the left hemisphere is now called Broca’s area, although it precise function in language production is still being elucidated.

25. Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience Edited by Bernard J. Baars and Nicole M. Gage 2007 Academic Press 4.0 Some History, and ongoing debates Carl Wernicke and the localization of speech comprehension Some years after Broca’s work on speech output, the German scientist Carl Wernicke discovered a part of the brain involved in speech input -- perception and comprehension. Wernicke discovered this by observing a variety of aphasic patients, patients who had brain damage that resulted in language deficits. Wernicke concluded that damage to different areas of the brain resulted in different types of language disorders. Although there was evidence provided by Broca and Wernicke that some aspects of language are processed in specific regions of the brain, this concept remains hotly debated to this day.

26. Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience Edited by Bernard J. Baars and Nicole M. Gage 2007 Academic Press 4.0 Some History, and ongoing debates William James: psychologist, philosopher, physician, and painter James is best known today as a psychologist and philosopher, however he also trained to be a physician and painter. James taught brain anatomy, and his 1890 description of the brain is in good agreement with our understanding today. James’ Principles of Psychology is often considered the best summary of 19th century psychology and brain science in the English language. Among many other points, James discussed the brain studies of Dr. Mosso, who observed that the blood supply to active brain regions increased. That finding is the basis of modern brain imaging methods based on hemodynamics (the flow of blood) including PET and MRI.

27. Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience Edited by Bernard J. Baars and Nicole M. Gage 2007 Academic Press 4.0 Some History, and ongoing debates William James: psychologist, philosopher, physician, and painter James showed Broca’s and Wernicke’s areas based on the medical evidence from brain damage. These 19th century language regions of the left hemisphere are similar to modern neuroimaging findings.

28. Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience Edited by Bernard J. Baars and Nicole M. Gage 2007 Academic Press 4.0 Some History, and ongoing debates The conscious and unconscious mind Nineteenth century scientists were profoundly interested in the question of consciousness. Ramon y Cajal proposed the idea of a ‘psychic neuron’ in the cortex, a type of neuron that would support conscious experiences. The beginning of psychophysics in the early 19th century was very much inspired by an effort to solve the mind-body puzzle. At the end of the 19th century, William James proclaimed that “Psychology is the science of mental life” by which he meant conscious mental life.

29. Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience Edited by Bernard J. Baars and Nicole M. Gage 2007 Academic Press 4.0 Some History, and ongoing debates The conscious and unconscious mind About that time, some began to disagree. Scientists like Helmholtz, Loeb, and Pavlov advocated a more physicalist view of mental life.After 1900, Pavlov became famous for his experiments on classical conditioning in dogs. This helped to convince many psychologists that ultimately all of behavior could be explained in terms of simple behavioral units, based on reflexes. Thus, behaviorism was born and the study of consciousness was criticized as unscientific. For much of the 20th century, human consciousness was avoided by scientists.

30. Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience Edited by Bernard J. Baars and Nicole M. Gage 2007 Academic Press 5.0 The return of consciousness in the sciences How conscious and unconscious brain events are studied today Some examples of conscious and unconscious aspects of cognition

31. Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience Edited by Bernard J. Baars and Nicole M. Gage 2007 Academic Press 5.0 The return of consciousness in the sciences A recent wave of brain studies are investigating conscious and unconscious phenomena in the brain. For example, a fMRI study compared brain activation for conscious and unconscious events: unconscious viewing of words activated visual areas only, while conscious viewing activated expanded regions in the cortex.

32. Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience Edited by Bernard J. Baars and Nicole M. Gage 2007 Academic Press 5.0 The return of consciousness in the sciences Many historical debates are ongoing today: Local vs widespread functions in the brain The neuron doctrine The question of consciousness Capacity limits in the brain Short-term and long-term memory -- are they separate? Nature vs. nurture, gene vs environment And many more!

33. Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience Edited by Bernard J. Baars and Nicole M. Gage 2007 Academic Press 6.0 Chapter Summary What are the central questions being explored in the field of cognitive neuroscience? • The scientific exploration of the relationship between the mind and the brain is a central issue in the study of human cognition. • Ancient questions and new ones are being addressed using modern neuroimaging techniques along with converging evidence from behavioral and medical studies. • Cognitive neuroscience combines psychology, neuroscience, and biology. Questions that could not be addressed earlier are now begin explored.