Biological Psychology 5th Edition Breedlove Rosenzweig Boys

From very early times, it has been appreciated that the brain is intrinsically linked to the control of movement, and behaviour. Evidence from ancient Egypt (c3000 BC) and before, suggests that holes were drilled in skulls of living people, presumably for therapeutic purposes. However, at this time it was the heart, not the brain which was believed be the seat of the soul and repository of memories. Hippocrates (c400 BC) was one of the first to challenge this view, and see the importance of the brain in this context: \'Men ought to know that from nothing else but the brain comes joy, delights, laughter and sports, and sorrows, griefs, despondency and lamentations. And by this, in an especial manner, we acquire wisdom and knowledge, and see and hear and know what are foul and what are fair, what are bad and what are good, what are sweet and what are unsavoury …. And by the same organ we become mad and delirious and fears and terrors assail us …. All these things we endure from the brain when it is not healthy …. In these ways I am of the opinion that the brain exercises the greatest power in the man.\' The Greek philosopher, Aristotle, however, retained the view that the heart was the centre of the intellect: he believed that the brain\'s function was to cool the blood.

The Greek physician, Galen (c200 AD), on the basis of visual examination of dissected sheep\'s brains, came to the conclusion that the cerebral cortex was the recipient of sensations, while the cerebellum controlled muscle movement: this actually proved to be remarkably close to the truth, although the reasoning was far from convincing. Given that his observations had shown that the brain contained hollow, fluid filled spaces (ventricles), and in the context of the prevailing view at the time that the body functioned according to a balance between four vital fluids (or humors), he further assumed that movement was controlled by the flow of humors to and from the brain and muscles through the nerves, which he believed to be hollow tubes.

This idea remained largely unchallenged until the advent of modern neuroscience, in the early 1800s. Indeed the view was strengthened by the hydraulic model put forward by the French mathematician and philosopher, René Decartes in 1600s. He believed that the nerves were hollow tubes, carrying a fluid called \'animal spirit\': the pineal gland in the brain (where he believed the soul to be located) pumped animal spirit into the nerves and inflated the muscles to produce movement. Further, he believed that sensation, memory and other mental functions were produced when animal spirits flowed through pores in the brain.

Structure and function

From very early times it was realised that the brain had a major influence on movement and behaviour. In 1823 the French physiologist Marie-Jean-Pierre Flourens showed that destroying small areas of the brains of animals or birds could affect specific functions. From these experiments he concluded, like Galen and the Scottish physician Charles Bell before him, that the cerebral cortex was involved in sensation and perception, and that the cerebellum coordinated movement. At around the same time, Franz Joseph Gall proposed that the bumps on the surface of the skull reflected the bumps on the surface of the brain, and were related to personality traits (phrenology). Although this captured the popular imagination of the time (and indeed still does in some circles!) it did not stand scientific scrutiny. One of the main critics of phrenology was Flourens, who showed, using experimental ablations, that particular traits were not isolated to particular portions of the cerebrum. He actually further proposed that all regions of the cortex participate equally in all cerebral functions, an assertion that was later shown to be wrong.

Paul Broca (c1860), a French neurologist, provided the first strong evidence of localisation of function in the cerebral cortex. Several scientists had described speech difficulties in patients with damage to the frontal cortex, but it was Broca\'s work which provided the clear evidence for such functional specialisation. He worked extensively with a patient, Leborgne, who had severe speech deficits: post mortem examination of his brain showed a localised lesion in the left frontal cortex. Subsequently many other patients with similar speech deficits also proved to have damage to the same brain area. Subsequently, studies with patients with damage to other brain areas have shown regional specificity for many different functions, by correlation of functional deficits to region of damage: much of our understanding of localisation of brain function is based on these sorts of studies on patients with brain damage.

The German neuroanatomist, Korbinian Brodman (c1900) did a very detailed anatomical analysis of the human cerebral cortex, on the basis of which he constructed a cytoarchitectural map of the cortex, in which cortical areas were separated, and given a number, on the basis of their specific cytoarchitecture. Subsequent functional studies have confirmed what Brodman guessed, namely that these anatomically defined regions mapped on to functional correllates, thus providing a link between structure and function.

Recent technological advances in brain imaging have opened up a new route of investigation of regional brain function. Functional magnetic resonance imaging (fMRI) allows us to visualise changes in activity in localised areas of the brain, during performance of motor, perceptual and cognitive tasks. Importantly, many of these studies have confirmed and extended the findings from studies on brain damaged patients.

Lecture 1 will look at regional specialisation of the brain in both structure and function, and will discuss some of the studies on which our understanding is based. In later lectures we will look in more detail at some of these studies in the context of specific brain functions.

Neurotransmission

Around 1800, the Italian physiologist, Luigi Galvani challenged Descartes\' animal spirit model, when he showed that a frog\'s leg muscle could be made to twitch when a small electrical current was applied to the nerve supplying it, so giving rise to the idea that nerves acted through electrical mechanisms rather that by hydraulics. However, the conduction speed in nerves was found to be several orders of magnitude slower than electricity in wires, indicating a biological basis for the electrical transmission of information along nerves.

We now know that electrical transmission in nerve cells (neurones) is mediated through rapid changes in distribution in charged particles (ions) into and out of the cells. The second lecture of the series will examine the ionic basis of membrane potentials and will look at the mechanisms of electrical transmission in neurones.

The junctions between neurones are called synapses, and it was originally thought that trans-synaptic transmission was also electrical. However, work by Otto Loewi in the 1920s (for which he was awarded a Nobel Prize), showed that transmission at some synapses, is controlled by chemicals, called neurotransmitters. It was not until the 1950s that it was established that trans-synaptic transmission is predominantly chemical. The second lecture will also look at the mechanisms of chemical transmission across the synapse, and consider some of the biochemical processes occurring at the synapse.

From very early times, it has been appreciated that the brain is intrinsically linked to the control of movement, and behaviour. Evidence from ancient Egypt (c3000 BC) and before, suggests that holes were drilled in skulls of living people, presumably for therapeutic purposes. However, at this time it was the heart, not the brain which was believed be the seat of the soul and repository of memories. Hippocrates (c400 BC) was one of the first to challenge this view, and see the importance of the brain in this context: \'Men ought to know that from nothing else but the brain comes joy, delights, laughter and sports, and sorrows, griefs, despondency and lamentations. And by this, in an especial manner, we acquire wisdom and knowledge, and see and hear and know what are foul and what are fair, what are bad and what are good, what are sweet and what are unsavoury …. And by the same organ we become mad and delirious and fears and terrors assail us …. All these things we endure from the brain when it is not healthy …. In these ways I am of the opinion that the brain exercises the greatest power in the man.\' The Greek philosopher, Aristotle, however, retained the view that the heart was the centre of the intellect: he believed that the brain\'s function was to cool the blood.

The Greek physician, Galen (c200 AD), on the basis of visual examination of dissected sheep\'s brains, came to the conclusion that the cerebral cortex was the recipient of sensations, while the cerebellum controlled muscle movement: this actually proved to be remarkably close to the truth, although the reasoning was far from convincing. Given that his observations had shown that the brain contained hollow, fluid filled spaces (ventricles), and in the context of the prevailing view at the time that the body functioned according to a balance between four vital fluids (or humors), he further assumed that movement was controlled by the flow of humors to and from the brain and muscles through the nerves, which he believed to be hollow tubes.

This idea remained largely unchallenged until the advent of modern neuroscience, in the early 1800s. Indeed the view was strengthened by the hydraulic model put forward by the French mathematician and philosopher, René Decartes in 1600s. He believed that the nerves were hollow tubes, carrying a fluid called \'animal spirit\': the pineal gland in the brain (where he believed the soul to be located) pumped animal spirit into the nerves and inflated the muscles to produce movement. Further, he believed that sensation, memory and other mental functions were produced when animal spirits flowed through pores in the brain.

Structure and function

From very early times it was realised that the brain had a major influence on movement and behaviour. In 1823 the French physiologist Marie-Jean-Pierre Flourens showed that destroying small areas of the brains of animals or birds could affect specific functions. From these experiments he concluded, like Galen and the Scottish physician Charles Bell before him, that the cerebral cortex was involved in sensation and perception, and that the cerebellum coordinated movement. At around the same time, Franz Joseph Gall proposed that the bumps on the surface of the skull reflected the bumps on the surface of the brain, and were related to personality traits (phrenology). Although this captured the popular imagination of the time (and indeed still does in some circles!) it did not stand scientific scrutiny. One of the main critics of phrenology was Flourens, who showed, using experimental ablations, that particular traits were not isolated to particular portions of the cerebrum. He actually further proposed that all regions of the cortex participate equally in all cerebral functions, an assertion that was later shown to be wrong.

Paul Broca (c1860), a French neurologist, provided the first strong evidence of localisation of function in the cerebral cortex. Several scientists had described speech difficulties in patients with damage to the frontal cortex, but it was Broca\'s work which provided the clear evidence for such functional specialisation. He worked extensively with a patient, Leborgne, who had severe speech deficits: post mortem examination of his brain showed a localised lesion in the left frontal cortex. Subsequently many other patients with similar speech deficits also proved to have damage to the same brain area. Subsequently, studies with patients with damage to other brain areas have shown regional specificity for many different functions, by correlation of functional deficits to region of damage: much of our understanding of localisation of brain function is based on these sorts of studies on patients with brain damage.

The German neuroanatomist, Korbinian Brodman (c1900) did a very detailed anatomical analysis of the human cerebral cortex, on the basis of which he constructed a cytoarchitectural map of the cortex, in which cortical areas were separated, and given a number, on the basis of their specific cytoarchitecture. Subsequent functional studies have confirmed what Brodman guessed, namely that these anatomically defined regions mapped on to functional correllates, thus providing a link between structure and function.

Recent technological advances in brain imaging have opened up a new route of investigation of regional brain function. Functional magnetic resonance imaging (fMRI) allows us to visualise changes in activity in localised areas of the brain, during performance of motor, perceptual and cognitive tasks. Importantly, many of these studies have confirmed and extended the findings from studies on brain damaged patients.

Lecture 1 will look at regional specialisation of the brain in both structure and function, and will discuss some of the studies on which our understanding is based. In later lectures we will look in more detail at some of these studies in the context of specific brain functions.

Neurotransmission

Around 1800, the Italian physiologist, Luigi Galvani challenged Descartes\' animal spirit model, when he showed that a frog\'s leg muscle could be made to twitch when a small electrical current was applied to the nerve supplying it, so giving rise to the idea that nerves acted through electrical mechanisms rather that by hydraulics. However, the conduction speed in nerves was found to be several orders of magnitude slower than electricity in wires, indicating a biological basis for the electrical transmission of information along nerves.

We now know that electrical transmission in nerve cells (neurones) is mediated through rapid changes in distribution in charged particles (ions) into and out of the cells. The second lecture of the series will examine the ionic basis of membrane potentials and will look at the mechanisms of electrical transmission in neurones.

The junctions between neurones are called synapses, and it was originally thought that trans-synaptic transmission was also electrical. However, work by Otto Loewi in the 1920s (for which he was awarded a Nobel Prize), showed that transmission at some synapses, is controlled by chemicals, called neurotransmitters. It was not until the 1950s that it was established that trans-synaptic transmission is predominantly chemical. The second lecture will also look at the mechanisms of chemical transmission across the synapse, and consider some of the biochemical processes occurring at the synapse.