Memory 7.1 Flashcards
The Central Executive:
is the control centre for working memory; it coordinates attention and the exchange of information among the three storage components
o It does so by examining what information is relevant to the persons goals, interests, and prior knowledge and then focusing attention on the working memory component whose information will be most useful in that situation
o Regions within the frontal lobes of the brain are responsible for carrying out these tasks for the central executive
Long-Term Memory Systems
Declarative and Non-declarative
LTM has a number of different components
o Declarative memories (or explicit memories): are memories that we are consciously aware of and that can be verbalized, including facts about the world, and one’s own personal experiences
o Non-declarative memories (or implicit memories): include actions or behaviours that you can remember and perform without awareness
Declarative memory comes in two varieties
o Episodic memories: are declarative memories for personal experiences that seem to be organized around “episodes” and are recalled from a first person (“I” or “my”) perspective
o Semantic memories: are declarative memories that include facts about the world
Non-declarative memory
o Can take many different forms:
Procedural memories: patterns of muscle movements (motor memory) such as how to walk, play piano or drive a car
Classical conditioning: when a previously neutral stimulus produces a new response because it has a history of being paired with another stimulus that produces that response
o Priming: a laboratory technique of testing non-declarative memory
Based on the idea that previous exposure to a stimulus will affect an individual’s later responses – either to that same stimulus or to something related to it
This effect occurs regardless of whether the primed stimulus was consciously perceived or attended to
Declarative and non-declarative memories do not work in isolation
many day-to-day tasks involve both declarative and non-declarative memory
The Cognitive Neuroscience of Memory
Memory at the Natural Level
o Memory at the cellular level are summed up by: cells that fire together, wire together (Donald Hebb)
When neurons fire at the same time, it leads to chemicals and physical changes in the neurons, making them more likely to fire together again in the future
o Long-term potentiation (LTP)
a process that demonstrated that there is an enduring increase in connectivity and transmission of neural signals between nerve cells that fire together
No evidence that LTP is memory, but the strengthening of the synapses of the hippocampus when stimulated, shown in LTP studies, may be one of the mechanisms that allow memories to form
o Microscopic detail relating to memory:
Relates to the process of classical conditioning (tone and eye blinking): a simultaneous activation of neurons firing due to the tone and due to eye blinking provides the opportunity for synapses to become strengthened, representing the first stages of memory
This relationship is not permanent
o Consolidation
the process required for lasting memories where short-term memories are converted into long term memories in the brain
May happen at the level of small neuronal groups across the cortex
Cellular consolidation: when neurons fire together a number of times, allowing them to adapt and make the changes more permanent
• Involves physical changes to the synapse between the cells so that the presynaptic cell is more likely to stimulate a specific postsynaptic cell (or group of cells)
• Without the consolidation process, the initial changes to the synapse eventually fade away, and presumably so does the memory: Use it or lose it
The initial strengthening of synapses and longer term consolidation of these connections allow us to form new memories, thus providing us with an ability to learn and to adapt our behaviour based on previous experiences
These processes are not performed in all areas of the brain—specific structures and regions serve essential roles in allowing us to form and maintain our memories
Memory, the Brain and Amnesia
o Amnesia: a profound loss of at least one form of memory
o Anterograde amnesia: subtype of amnesia that has the inability to form new memories for events occurring after a brain injury
Not due to problems with sensory memory or STM
LTM is also intact as patients usually remember memories of their past
Patients are still able to form new implicit memories and learn new skills
Due to problems with one of the control processes associated with those stores – could not transfer declarative memories from STM to LTM
Medial temporal lobes (includes the hippocampus and surrounding cortex as well as the amygdala) of both hemispheres is responsible for this disability
• This structure is critical for the process of consolidation
o Hippocampus
maintains LTP networks until the acquired behaviour can form more connections throughout the brain
Not where most declarative memories are stored
Without the hippocampus, the new cortical networks formed to make memories will never be formed because the original LTP and consolidation processes would not have been completed
Is essential for spatial memories and is linked to consolidation—remembering spatial information involves updating a memory with new information
The size of a person’s hippocampus can vary with the amount of spatial information that people are asked to consolidate
o Demanding memory
alters the structure of brain areas related to memory consolidation and spatial memory
o Reconsolidation
a process in which the hippocampus functions to update, strengthen, or modify existing long-term memories
These memories then form networks in different regions of the cortex, where they can sometimes be retrieved when necessary
o Cross-cortical storage
when long-term declarative memories are distributed throughout the cortex of the brain, rather than being localized in one region
Some of the memory networks will no longer need input from the hippocampus
The cortical networks will become self-sustaining – the more the memory is retrieved, the larger and more distributed that network will become
