Week 1 - introduction Flashcards
Learning definition
acquisition of an altered behavioural response due to an environmental stimulus
What type of learning applies to most learning?
associative learning
Memory definition
The processes through which learned information is stored. Memory can be short lasting or long lasting
Retrieval definition
A conscious or unconscious process that accesses stored information
What are three types of the experimental analysis of memory with examples?
Observations - e.g brain imaging
Loss of function - establishes whether a process is necessary for memory - e.g lesion studies
Gain of function - establishes whether a process is sufficient for memory - e.g Pharmacological activation of a molecule
Describe Karl Lashleys 1950 lesion study
Method:
Trained rats on a navigation task
Lesioned every part of the cortex bit by bit, in different orders
Results:
Huge variability in memory ability following rats cortical lesion
There is not one single brain region where all memories are located
Conclusion:
Memory is distributed throughout
What is one criticism of Lashleys conclusion
He was considering general memory. However we now know that specific memories are located in specific areas of the brain
Strengths and weaknesses of lesion studies
Strengths: Requirement of brain regions for memory can be determined. This will identify the location of stored memory
Weaknesses: : Lesion may affect performance in the behavioural task, preventing
assessment of memory. Lesion may also cause effects in other brain regions.
What are strengths and weaknesses of imaging studies
Strengths: Identification of brain regions relevant for memory without inference.
Weaknesses: Studies just observe activity in various brain regions. But, are these
regions really important?
Describe the Morris water maze
An animal is submerged in murky water and needs to locate the hidden platforms by using clues inside the room.
What is Semons 1921 proposal
Memories are stored as engrams
Engrams are lasting physical changes in brain state and structure that occur in response to an experience
What is the hebb postulate?
neurons that fire together wire together
Describe the Autophosphorylation proposal of CaMK11q
Lisman (2017) proposed that kinase that can phosphorylate itself could store memory. CaMK11 was discovered a year later that has Autophosphorylation properties and can possibly act as a memory storing molecule.
Describe details of hebbian plasticity
Neurons wire together when one is repeatedly and persistently exciting the other
Its not the whole neuron that becomes more excitable when it is wired together with another neuron - it is the specific single connection between that neuron and another neuron
This often involves the LTD of other inputs. So you are essentially biasing the recipients neuron to one input over another
What is the cell assembly?
Groups of neurons that are connected through hebbian plasticity to mediate perceptual binding
Our memory system has the ability to complete a pattern based on limited information. Cell assemblies can explain this.
Assemblies (groups of neurons) are activated by a stimulus.
After the stimulus, activity reverberates across the groups.
Hebbian plasticity selectively strengthens recipricol connections between active neurons.
The strengthened connection among the neurons contain the engram.
Partial stimulus activates part of the assembly, which in turn activates the whole assembly (pattern completion)
What is the phase sequence?
Sequencing assemblies over time and space into complex percepts
Outline Clayton, Bussey and Dickinson’s scrub Jay studies
Scrub jays have sophisticated episodic memory
They hide their worms and nuts and remember exactly where they buried them
They always recover the worms before the nuts because nuts are preserved for longer
If another bird is watching them bury the food, they will come back later when they are no longer watching, and move all their food
Outline Kandel’s study on habituation in aplasia sea slugs
aplasia have giant neurons that are easy to clamp and get intraneuron recordings
He discovered habituation
If you squirt water onto the slugs gill it will initially withdraw the gill. If you keep doing it it will stop the gill from withdrawing.
Kandel found that as this happens, the sensory neuron is as electrically active as before, however the motor neuron is no longer active. This suggests that the synapse has weakened.
Why is most memory work on mice?
It is mammal - more related to humans
It produces large litters
Short gestation time
Matures quickly
Amenable to genetic engineering: molecular mechanisms can be suppressed or enhanced; cell type markers and activity-dependent markers can be expressed; opto-genetic and chemo-genetic actuators can be expressed; diseases with known genetic causes can be modelled
What is Korsakoff syndrome
Patients that were losing episodic memory
Found to be caused by drinking bad alcohol with methanol that caused a lesion in a small part of the brain called the mammillary bodies
This shows that there are some memory centres specific to very specific types of memory
What are two subtypes of declarative/explicit memory
semantic
episodic
What are two subtypes of non declarative memory
Associative
Non-associative
