Lecture 8 Flashcards

Question

Thinking Machines – Three ways that the computer analogy changed psychology (3) Psychologists as software engineers

Answer 1

3 – Psychologists as software engineers Allowed psychology to define itself among the sciences They are the software engineers in this metaphor. They do not need really to understand the brain (how it is stored etc). They just need to understand the software, the operations performed. Algorithms: lists of instructions that converts a given input, via a fully defined series of steps, into the desired output

Answer 2

The mind brain problem – how do the mind (an aggregate of faculties that humans have to feel think remember and want) and the brain interact. Descartes thought they were different substances interacting from the pineal – dualism, the mind and the body are distinct and separable. The opposite is materialism – all things, including mental aspects and consciousness are results of material interactions. This was prevalent from the time of psychology in psychology

Answer 3

We now have a new way: Functionalism in the mind body problem (Kind of like cognitive dualism) Different from the James functionalism. If your brain is a Turing machine and I can map the whole profile of zeroes and ones in a brain, I can copy all of those in an electrical circuit. And sop your activation can be duplicated on another machine. The dualism here is that the certain profile of zeros and ones is important in its on right and it can be implemented on a variety of supports. What matters is the information. It is still materialism as the information still exists in a physical form (like electrical activity) but Boolean mathematics means that any machine that can represent zeros and ones could support this pattern.

Answer 4

Music. Certain pieces of music can be “encoded” on a variety of supports e.g., vinyl, mp3 etc. The music is the same, encoded on a variety of supports.

Answer 5

Cognitive psychologists already defined psychologists as the software engineers. But there has been a long tradition in brain research that is interested in how these algorithms are implemented in the brain.

Answer 6

Localisation of Brain Function 1 There is a debate between localisation and equipotentiality. Frans Gall was a brilliant brain anatomist He proposed that psychological faculties were located within specific brain areas Proposes that bumps on skull reflect the size of the brain beneath (obviously dumb) Phrenology One woman with strong erotic inclinations had a big cerebellum bump and so decided this was a sign of eroticism – localized in the cerebellum (amativeness) People were interested, he decided he was onto something and mapped the rest of the cranium with his student Spurzhirm

Answer 7

Called it Cranioscopy (later phrenology by his disciple Spurzheim) Was popular with the public but never academics Both got kicked out of Vienna and moved to Paris. There was a dispute, Spurzheim splits, calls it phrenology and exports it to the UK and USA Was very popular, Galton was into it

Answer 8

But became a scam, the Fowler brothers promoted it in the USA. Started mapping craniums in Manhattan. They made a journal to make it look more scientific They have casts of famous peoples skulls and do an exhibition. Basically, a circus thing. Total BS

Answer 9

Pierre Flourens is a serious scientist. Took out systematically parts of the brain in animals. He realised that the big structures like the spine, brainstem, cerebellum and hemispheres have special functions but that WITHIN them, there is no specialisation (equipotentiality) The level of impairment is proportional to the lesion Cerebellum is involved in motor coordination not sexual drive

Answer 10

There is often a phase after surgeries where the animals have a phase of deficits but that they recover. Shows plasticity as the lesion has not grown back. Hence there is no specificity as tall parts of the cortex can accomplish any task via plasticity.

Answer 11

Jean-Baptise Bouillaud showed that language deficits were associated with lesions in the frontal lobe Was one of Gall’s students. Wants to prove that this mentor was right at least partly. He had limited data. Based on autopsies (8/14 patients with language deficits also had frontal lesions while the remaining 6/14). So, he hypothesised that language is localised ion the frontal lobes. He wasn’t taken seriously because he was the student of Gall. So he shook it up with an offer to pay 500 francs to anyone who could show a case of frontal lobe damage without a speech deficit. There were a few patients fitting this. Waited for them to die. Paul Broca performed the autopsy of a man who could only say Tan. He had Broca’s aphasia – can understand but cannot speak. When he autopsied him, he found a lesion in what is now Broca’s aphasia

Answer 12

Physiologists continued to try and map the brain. Fritsch and Hitzig used electrical stimulation of the brain study function and find movement area.

Answer 13

David Ferrier followed up on this and identified the sensory strip, visual cortex and auditory cortex.

Answer 14

Karl Wernicke described sensory aphasia in a group of 10 patients unable to understand speech and with fluent, but meaningless language (sensory aphasia) He identified Wernicke’s area in the temporal lobe

Answer 15

The later, he predicted a new type of aphasia, conduction aphasia. Broca’s and Wernicke’s must be able to communicate. They communicate through a bundle of white matter. If this is sectioned they should be able to understand and be able to talk but when they talk, they will have paraphasia’s, small errors and when he found the patient that proved it, he found they could not repeat either (he did not predict this). So he came up with a theory, made predictions and tested them. Very solid model and science.

Answer 16

Freud studied with his mentor and originally proposed to tackle aphasia like Wernicke but instead, fell into working with hysteria.

Answer 17

Karl; Lashley conducts studies between 1915 and 1929 (the height of behaviourism). He is looking for the site of learning. Finds that the deficits are simply proportional to the size of the lesion and the difficulty of the maze. All the cortex can do anything. No specialised area for learning. Equipotentiality – neural plasticity. Healthy areas can take over the function of damaged areas.

Answer 18

Wilder Penfield American, studied at Princeton and Oxford before working in New York. Arrived at McGill in 1928 and was one of the founders of the Montreal Neurological Institute. In the 1930s does a lot of work mapping the brain in patients with epilepsy. Epileptics often have auras before their seizures. These can be sensory or emotional. Penfield thinks if we can find the spot of the brain that produced the aura and remove it, we can cure epilepsy. He does it, very invasive surgery. Tried to stimulate the brain to give the symptoms of epilepsy. When he finds it, he will remove it. By doing this, over time he builds up a cartography of the brain. Very detailed. Was the first and was ground-breaking. You are stimulating the brain; the patient is awake and describes it. Must have been amazing.

Answer 19

Other neurologists had tried this, but it was really dangerous. Penfield had the clinical justification; he did cure most patients epilepsy and it allowed us to understand the brain.

Answer 20

Lashley had shown that there was no specific place in the brain that stored memories. Penfield found that he could get experiential responses – they would recall experiencing past experiences of their lives. Could be trivial or meaningful (like a wedding). Patients would have these experiential responses, super vivid. He wondered of he had found the region for memory. He was skeptical because these may seem like memories but the way the patients describe them are too vivid and it is not the way we usually remember.

Answer 21

He also thought that when he stimulated the brain, it was not that he was stimulating it but that he was releasing inhibition. Under this inhibition, the place where the memories were stored would be elsewhere. Just that he removed inhibition. So he was reluctant to interpret those findings this way.

Answer 22

One thing he could never recreate was the sensation of free will. They would experience many things but that they were happening to them. Not that they were in control. Hence, towards his career he had more dualistic ideas. But other neurologists had more materialistic interpretations of his work.

Answer 23

Donald Hebb McGill’s most famous psychologies. Top 20 most cited psychologists. First degree was in literature. Works with troubled kids. Was the time when psychology was close to education. He began a masters at McGill with another Prof. In 1934 his wife died in a car crash. Moved to Chicago to work with Carl Lashley to do a PHD. He was 30 when he did it. Follows Lashley to Harvard and graduated in 1936. In 1937 goes back to MTL to work with Penfield. Spent time working in Florida and Queens in Ontario. In 1947 obtains a professorship at McGill.

Answer 24

In 1949 he published the “organisation of behaviour” in which he related behaviour to cell assemblies. How is it possible that our brain can perceive an infinity of shapes in any environment with a finite set of neurons. He realises that it is not caused by one neuron but by combinations of them. This way there are near infinite synapses. This is the idea of the cell assembly. What is important is how neurons organise themselves into cell assemblies. The idea that cells that fire together, wire together – the Hebbian Synapse. The coactivation strengthens the links between the neurons. So, if a circle causes many neurons to fire a lot, they wire together. Even when the circle is not there, they all stay wired. The system has learned about the circle and that knowledge is kept in these synapses. The engram ad he called it can now be activated by partial circles or anything else. A partial circle might cause activation in some, these links will cause them all to fire and the whole shape will be recovered. This is pretty damned correct. He predicted this theoretically and they were confirmed later. Had a huge impact on multiple fields. Neural networks and machine learning all comeback to Hebb.

Answer 25

An amazing psychologist researcher. 1940 studied psychology at Cambridge but stopped during the war. She was directed towards war efforts. In 1944, moved to Montreal. Fluent in French. She taught at UdeM and was one of the first professors there. She completed her PHD with Penfield and Hebb on the topic of lobe damage. She was offered a tenure track position at McGill, but the MNI took her.

Answer 26

In 1955 she met H.M. (Henry Molaison). He had a severe case of epilepsy. The surgeon decided that it was bilateral in the temporal lobe. He removed these structures including the hippocampus and amygdala. It cured the epilepsy, but it gave him complete anterograde amnesia. He never recognised Brenda Milner even though he saw her regularly for 30 years. But certain aspects of his memory were preserved. He could learn complex visuo-motor tasks. He could improve with practice like everyone else. It was a mirror copying task and he succeeded in learning. He still had procedural memory, Led Brenda Milner to conclude that we have different memory systems. H.M. had no declarative memory. A lot of neuropsychology (especially of that era) is waiting for the right person with the right lesion to turn up. Brenda Milner seized the opportunity. She replicated this in large cohorts and also did many other things, but this was what made her famous more or less.

Answer 27

More generally, this kind of work in the 50s was the start of neuropsychology. This is the area that is interested in the deficits of brain lesions. In the 2nd half of the 20th century, neurologists study less and less the behavioural consequences of lesions. Psychologists take over and are better at deriving tests to measure the effects. This allows the neurologist to focus more on the brain itself.