Download Memory notes Explaining memory Learning required memorisation

Memory notes
Explaining memory
Learning required memorisation
Memory defined as storage and retrieval of info acquired through learning.
Encoding is the process of converting info into useful form or ‘code ‘so that it can enter and be stored
in memory.
Storage is the retention of info over time
Retrieval is the process of locating and recovering the stored info from memory so that we are
consciously aware of it.
How info is encoded determines exactly what info is stored and how that info is stored, which can
limit what can be subsequently be retrieved.
Students sometimes rely on automatic encoding when effortful encoding would be far more effective.
Neural basis of memory
Role of the neuron in memory formation
Kandel has identified changes in the structure and functioning of neurons in the brain when forming
the memory of a newly learned experience. He was recognised with a Nobel Prize in Physiology or
Medicine in 2000.
He studied Aplysia californica, a very large seaweed munching sea slug found along the coast of
California in America. They have a far less complex nervous system than that of humans and other
mammals.
Many of Kandel’s studies with Aplysia involved using a very thin electrode to mildly stimulate a part
of the body called the siphon. The siphon is like a tail and the stimulation caused it to reflexively
contract. An Aplysia would also immediately withdraw its delicate gill in case whatever shocked the
siphon also shocked the gill. If done a moment late an Aplysia would withdraw its gill even more
quickly. If shocked an hour late it retracted at the same speed as the first time it was shocked as it if
can’t remember being shocked previously. However, with repeated stimulation of the siphon, an
Aplysia withdrew it gill less and less. This indicates a simple form of learning called habituation: it
learns that stimulation of the siphon is not dangerous to it. Kandel he continued this and observed
that if an Aplysia is tested the same way over weeks, each day its habituates faster than the day
before, suggesting it developed an enduring memory that lasts for a few days or weeks.
According to Kandel when Aplysia acquire new memory through repeated stimulation, significant
changes occur in neurons involved in the process.
One change – the way the neuron functions as there is an increase in the amt of the
neurotransmitter being produced and released by the neurons; that is the specific chemical substance
used by neurons to communicate.
Second change – to the structure of the slug’ neuron where the number of branches increases as they
become bushier through the growth of smaller ‘offshoots’ called dendritic spines and thereby
strengthen the connection.
Third change – involves the synapse; when a memory is formed, new synaptic connections form and
this strengthens the connection between neurons and makes it easier to transmit to each other the
next time.
The more the neurons in a circuit are activated through use, the ‘easier’ it becomes for info to travel
through the circuit.
(Get your poster of neuron and note how the information is sent through a neuron to another neuron
using Kandel’s sea slug on page 336.
Kandel’s research findings indicate that any experience that results in memory produces physical
changes in the brain at the neuronal level, strengthening connections between neurons involved in
the process, thus making communication easier next time.
These changes create and strengthen a memory circuit for info that has been learned.
-With STM memory storage there is only an increase in the release of neurotransmitter.
-with LTM memory storage all structural and functional changes occur.
It is difficult to generalise from sea slug to human because of the complexity of our brain and its
neural circuits. However, research studies have found that long-term potentiation assoc with
memory formation occurs in fish, chicks and mammals such as rats, mice and cats.
Role of the hippocampus & the temporal lobe
It is located just above the ear and 4 cm straight into the brain
It looks like a sea horse (after which it is named) and it is 3.5cm long and we have two of them: one
in the lower region of the temporal lobe of each hemisphere
The medial temporal lobe (medial =middle) is the inner surface area towards the middle of the TL
that includes the hippocampus, the amygdala and other cortical tissue.
Henry Molaison (HM) had severe epilepsy since the age of 10 and the epilepsy was unresponsive to
anti-convulsant medications and other treatments. Surgeons removed the medial temporal lobe
from each hemisphere – 5cm from each lobe.
Medically the surgery was successful. HM seizures declined and could be controlled by medication.
His personality was unchanged and many cognitive functions remained unaffected.
The surgery left him with a memory problem. He could not remember things he experienced after
his surgery.
He was incapable of forming long-term episodic (personal events) memories or semantic (general
knowledge) memories. He could not remember his doctor’s names and each time had to be
introduced, what he had for lunch or breakfast that day.
Each time he was told his uncle had died he reacted as being told the first time.
HM short term working memory was fine, as long as he paid attention to the task at hand. As soon
as he was distracted he immediately forgot about it.
HM case provides evidence that the hippocampus and medial temporal lobes are involved in the
formation of new long-term memories.
The hippocampal area of the TL has an important role in formation and encoding of new declarative
explicit memories (semantic and episodic) but not in the formation or retrieval of implicit (implied)
procedural memories.
Damage to this area results in formation and retrieval of declarative (facts) memories are affected,
but not procedural memories.
The hippocampal area is not involved in short-term storage. It is suggested that HM could retrieve
old memories as they had been stored elsewhere and had well-established circuits linking the
components of the events.
Consolidation theory
Consolidation theory
Extraneous and confounding variables- individual participant differences, non-standardised
instructions and procedures,