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Who came up with the astonishing hypothesis?
Francis Crick in his 1994 book of the same name
What are the fundaments of the astonishing hypothesis?
- Consciousness arises when sets of neurons fire in a co-ordinated way, at frequencies around 40 Hertz
- We have no free will, the unconscious mind makes plans and these appear in the conscious as if by random
How does Crick employ the scientific method?
- We must find the cells in the brain responsible for consciousness
- We can then determine how the decisions on what objects (or thoughts) we are aware of at any point and which are relegated to the subconscious
Describe the evolution of the notion that nerves conducted electricity
- First investigated on frogs and hearts by shocking them with electricity stored in Leyden jars (Caldani, 1756)
- Galvani found, through shocking frog muscle, that contraction would occur without fluid and in the absence of oxygen, concluding that it must be something else
- Strapped a frog to a conductor outside during thunderstorms and found that atmospheric and generated electricity acted in the same way
- Used insulated material to conclude it was electricity
Describe the evolution of the neurone doctrine
- Began when Schwann (1839) proposed that all tissue was made up of cells
- Microscopes were rudimentary at the time so neutrons were investigated by lightly mashing tissue with water and putting it between slides to view in a light microscope
- Golgi (1873) created a silver staining technique allowing them to be seen more easily but wrongly concluded that neurones were a closed system as they all appeared as a single mesh
- Cajal (1891) pioneered the theory of nerve cells stating they were
- Finally the evolution of the electron microscope helped to settle the debate and we now know that nerve transmission occurs down axons separated by synapses (Renato & Sabbatini, 2003)
How did Cajal (1891) describe neurones?
- Independent of each other
- Made up of dendrites, axon and cell body
- Polarised due to their excitation at one end
What is single unit recording?
- Arguably the first recording was by Adrian (1928) in 'The basis of sensation' using a Lippmann electrometer
- Involves insertion of a micro electrode to measure electrical energy generated by neurones
- Measures action potentials in nerves and allows us to locate where nerves are firing during certain actions
- This helped us to localise brain function
What are place cells?
- Neurones in the prefrontal cortex that become active when an individual enters a particular place in the environment
- The larger the environment, the more fields in a place cell- Fenton et al (2008)
- Discovered by O’Keefe and Dostrovsky (1971), especially in the hippocampus that is responsible for spatial awareness
- O'Keefe, John (1978). The Hippocampus as a Cognitive Map (place cells fired more rapidly when new items were added to the environment
- Help to create cognitive maps
What are cognitive maps?
- Tolman (1948)
- A type of mental representation which serves an individual to acquire, code, store, recall, and decode information about the relative locations and attributes of phenomena in their everyday or metaphorical spatial environment
- Pyramidal cells are involved in the creation of these maps- Manns & Eichenbaum (2009)
Who was Tan and who investigated him?
- Patient Leborgne
- Studied by Broca (1861)
- Only able to say the word 'tan'
- Upon posthumous examination of the brain damage was found in the left hemisphere of the frontal lobe and it was hypothesised that this region was responsible for language production (later named the Broca's area)
- Kept detailed notes of patient behaviour and linked with autopsy
- Modern technology found that both patients’ lesions extended significantly into medial regions of the brain, in addition to the surface lesions observed by Broca and inconsistencies were found between the area that Broca thought was responsible and the Broca's area (Dronkers et al, 2007)
How is Lucy a fallacy?
- We use more than 10% of our brains
- FMRI showed constant activation of multiple regions during the showing of a quiz show (
What are the fundaments of behaviourism?
- All behaviour is just response to stimuli
- There is no point measuring things that aren't observable such as thoughts and feelings
- Thorndike's (1898) law of effect
- Operant conditioning: Skinner (1950) pigeon ping pong
- Classical conditioning: Pavlov (1927) dog salivating
What started the cognitive revolution?
- A rat conditioned to run a maze bit the researcher's finger, ran across the top of the maze (behaviour never reinforced or enacted) and got the food
- If its behaviour was entirely down to response to stimulus then this could never happen
- Tolman (1948) devised an experiment in which a rat was conditioned to run a maze down one passage to get a reward. This passage was then blocked and a number of passages were made available to the rat, one leading directly to the reward.
- The rat chose this passage, suggesting that the conditioning was irrelevant and the rat had an internal representation of its surroundings