Brain And Behavior Lecture 1 PDF

[24/09/24] [Prof. Tim Andrews ] [Brain and behaviour -- lecture 1 (a history of the brain)] *[This session:]* The link between mind and brain\ Immaterial soul\ Dualism\ Materialism\ The relationship between structure and function in the brain\ Localized\ Distributed\ Techniques in cognitive...

[24/09/24] [Prof. Tim Andrews ] [Brain and behaviour -- lecture 1 (a history of the brain)] *[This session:]* The link between mind and brain\ Immaterial soul\ Dualism\ Materialism\ The relationship between structure and function in the brain\ Localized\ Distributed\ Techniques in cognitive neuroscience\ Single neuron recording\ EEG, MEG\ PET, fMRI\ TMS [The ancient Egyptians and the brain ] During mumification, the brain was removed and throw away because they believed that the heart was the essence of life as well as the source of good and evil. The brain was considered a minor, unimportant organ. The Egyptians believed that the heart was associated with behaviour. [Plato, Aristotle and the soul\ ]First attempt to separate the mind and the soul into different components. Aristotle was the first to question where the mind/soul was -- believed that it was separate to the body and resided in the heart. If there is damage to the heart you die straight away. Aristotle believed that there were 3 main divisions of the mind -- imagination, reasoning and memory. Aristotle believed the brains function was to cool the blood. Plato believed the mind/soul could be divided into 3 parts -- reason (logos), emotion (thymos) and desire (eros). Psyche -- goddess of the mind, where the term psychology comes from. [Hippocrates, Galen and materialism] Hippocrates believed that the brain controlled emotions "joy, laughter, sorrow, pain, grief and tears arrive from the brain and the brain alone". Hippocrates described how injuries to one side of the head lead to convulsions in the opposite side of the body. Galen believed that the brain controlled the body and was central to the way we think and act -- he looked at nerves that connected the brain to different parts of the body in animals. He found that behavioural changes often accompanied injuries to the head. Galen believed that water filled ventricles in the brain sent fluids known humors along the nerves. He believed that balances of humors in the body (different fluids) gave us our personality -- the fluids were black bile (wisdom), yellow bile (bad temper), blood (enthusiasm) and phlegm (relaxed or peaceful). Materialism believed that the brain was solely responsible for behaviour. [Leonardo, Michelangelo and the renaissance ] Leonardo's drawings of the brain were very influenced by Galen's theories -- focused on the fluid filled regions of the brain (the ventricles). He associated lateral ventricle with common sense (convergence of senses), the III ventricle with cognition or thinking and the IV ventricle with memory. [Descartes and dualism ] Dualism describes the mind and the brain as being separate. Descartes believed the brain was like a machine -- thought that the brain controlled the body in a similar way to a clock etc. He suggested that higher mental facilities found in man such as intellect and emotion require a mind -- the combination of brain and mind gives a rise to dualism. Descartes believed that the pineal gland was where information passed from the brain to the mind, but it was the mind not the brain that contains a person's thoughts and desires. Problems with dualism: damage to the pineal gland does not have a big effect on behaviour, sheep have a large pineal gland but are not overly intelligent, fluid is not communicated in nerves. People who had mental disorders were believed to have lost the connection between their brain and their mind "lost their mind"- believed they were no longer people anymore and likened to animals because it was believed that animals don't have minds either. [West riding pauper lunatic asylum ] Here patients with epilepsy were studied and found that seizures that affected the left side of the brain affected the right side of the body. The movement of the seizure across the brain resulted in a similar graded change in the body. These findings helped our understanding of how behaviour is represented in the brain and that Materialism being the current explanation for the link between mind and brain. [Thomas Willis -- father of neuroscience ] He introduced terms such as the cerebral cortex, corpus callosum etc. And he assigned functions to each region of the brain. He was the first to attribute function to the brain rather than the fluid filed ventricles. [Gall, phrenology and the localisation of function] Franz Gall proposed the concept of localisation of function -- proposed that different aspects of the brain were involved in different aspects of behaviour. He believed that differences in behaviour would be reflected by a growth of particular parts of the brain that could be detected by measuring the size of bumps on the skull. [Equipotentiality -- a direct challenge to functional localization] Pierre flourens rejected the entire concept of localization and believed that the mind functions as a whole. Karl Lashley did experiments on pigeons and rats -- results suggested that it was the size of the lesion rather than the location of the legion that was critical in affecting complex behavior. [Brain lesions reveal distinct behavioral deficits] Support for localization - damage to particular regions of the brain gave rise to specific deficits in behaviour. Broca discovered a patient with damage to the left frontal region of the brain -- was only able to say the word tan but could understand language just not produce it. Wernicke found a different patient who had damage to a different region in the left brain. This person was unable to understand language. The case of Phineas Gage who had damage to the frontal part of the brain in a construction accident shows that complex behaviour such as a person's personality is also a function of the brain -- after his accident his behaviour completely changed. [Golgi, Cajal, Brodmann and the neuron doctrine] The discovery of the microscope (Hooke), the microtome (Guddens) and the development of stains to show neurons lead to the next development in understanding the brain. For the first time, we were able to see the structure of the brain. The brain appears to be densely packed with nerve cells or neurons. Golgi developed a stain that allowed only a proportion (1:20) of neurons to be visible. He interpreted these images as showing that neurons were all interconnected tubes supporting the distributed theory. Cajal noticed bumps at the end of axons (synapses). He suggested that the cells (or neurons) were distinct entities -- the neuron doctrine. Also suggested that axons send information and dendrites receive information. Brodmann took a look at the organization of neurons in different parts of the brain and found that they varied in their arrangement. He concluded that because the organization was different then the function was also different. So, Cajal and Brodmann argued for localization of function. modern neuroscience appears to confirm the principle of functional localization: complex behaviours involve many brain areas. Also, a single brain area can be involved in many complex behaviours. [Techniques in cognitive neuroscience ] *[Face recognition:]* Damage to regions in the temporal lobe can lead to a condition known as prosopagnosia (face blindness) but leave the ability to recognise objects unaffected. A range of evidence suggests that faces are processed by specialized processes in the brain. EEG reveals face responses in the human brain and fMRI has been used to locate regions of the brain involved in face perception *[Single neurone recordings:] (electrophysiological recording in animals)* Single electrodes record action potentials from individual neurons. These are electrical signals that neurons use to communicate with each other. The number of action potentials from individual neurons is averaged over many trials. This gives the indication of the response to one stimulus Can also be done in humans before they undergo surgery, for example, for epilepsy -- however it is very invasive so can only be done on humans undergoing surgery or animals. *[Electroencephalography (EEG) and Magnetoencephalography (MEG):]* EEG and MEG are non-invasive and record electrical activity from the brain. Electrodes or sensors are placed on the scalp and, unlike single neuron recordings, record the activity of many active neurons. The response to a task is measured many times and averaged. This generates a series of peaks and troughs that can be related to different cognitive functions. Contour maps can be used to infer which regions of the brain are active at what time. MEG is a variant of EEG and measures the magnetic signal associated with electrical signals. The advantage of MEG is that magnetic fields are not affected by the skull/scalp. *[Functional magnetic resonance imaging (fMRI):]* The most widely used and popular method for assessing brain activity. Measures changes in blood flow that accompany changes in neural activity. Neural activity uses energy. This energy is replenished by nutrients (glucose and oxygen) in the blood. fMRI detects changes in magnetic signal that occurs with the increase in blood flow. It measures the change in magnetic signal caused by the ratio of oxy/deoxyhaemoglobin. *[Transcranial magnetic stimulation -- TMS:]* Transcranial magnetic stimulation provides a non-invasive approach to disrupt brain processing. A strong magnetic pulse causes electrical activity in a specific region of the brain which disturbs neural signalling. Demonstrates how different regions of the brain are associated with different functions. *[Spatial and temporal resolution of techniques in cognitive neuroscience:]* Modern approaches to understanding the link between brain and behaviour typically involve using many techniques. The reason for using many techniques is that they all have advantages and disadvantages. For example, some have better spatial resolution (fMRI), whereas others have better temporal resolution (EEG/MEG). Temporal resolution refers to the accuracy with which one can measure *when* an event occurred. Spatial resolution refers to the accuracy with which you can measure *where* an event occurred.