Week 5 - external environment & one's own representations Flashcards
The memory process - what is encoding, retrieval and storage?
Encoding - processing info into the memory system
Storage - retention of the coded information over time
Retrieval - retrieving information from storage
Plasticity and memory - what is plasticity and how is it related to memory?
Plasticity refers to the ability of neural circuits to remodel due to experience –> property at the level of the brain
Plasticity is a continuous process
Different regions of the brain contribute to different types of learning and memory (faces, words, episodic)
What can we conclude re DBL DISS in memory?
Can postulate from double dissociations surrounding memory that 2 memory systems utilise 2 different cognitive systems
These systems may be able to mapped onto 2 neural circuits
How are memories formed? Why does our ability to remember diminish with age?
When we have a sensory experience, this is converted into electrical energy. This energy is transferred to the LTM in the hippocampus and other storage regions. Repeated communication between neurons results in more efficient transmission = formation of memories. Memories are more strongly encoded when more ATTENTION is paid –> in this situation, we are more deeply engaged and we assign more meaning to the sensory experience, hence are more likely to remember it.
Ability to remember diminishes with age because of decreased NT production, Brain shrinkage and loss of hippocampal neurons
Causes of amnesia
Malnutrition Trauma Stroke Ischaemia Stress Ageing Vitamin deficiency Encaphalitis Ischaemia ECT Dementia Alzheimer's
LTM vs STM?
STM –> limited capacity, info which is currently ‘in mind’
LTM –> unlimited capacity, when something is ‘brought to mind’, it enters the STM. Comprises information which doesn’t need to be currently assessed.
Recognition vs recall?
Recognition -> identification of targets from possible targets
Recall -> retrieval of information from memory (eg in an exam)
Dissociations in memory
Recall///recognition STM///LTM anterograde///retrograde amnesia episodic///semantic explicit///implicit
CASE JL (Mayes et al., 2003)
Details: JL has closed head injury. Hippocampal structures mostly intact. Some temporal neocortical damage.
Observations of case study: slowly developing anterograde amnesia, impaired visual recognition tasks (defecits in recognition of recently studied visual information). Impaired consolidation of emotional memories (inability to recognise fear). Cognitive functioning mostly preserved.
CASE JL (Mayes et al., 2003) –> conclusions
- Impaired flow of visual processing of objects into the left perihineal cortex
- Patient COULD STILL RECALL SOME RECENTLY PRESENTED VISUAL OBJECTS —> other intact routes are available despite cortical damage (via hippocampus?).
CASE HM - background
Patient suffering with quite severe epilepsy
Has medial temporal structures removed (including most of the hippocampus)
CASE HM - observations
Retrograde amnesia - couldn’t remember his age pr where he lived
Anterograde amnesia for most ongoing events BUT could speak and learn new motor skills but couldn’t remember having done previously
CASE HM - implications
Double dissocation between declarative and non declarative memory (explicit/implicit) –> these aspects of memory are controlled by different areas of the brain
Declarative mems stored in the neocortex?
Case VC (Cipolotti et al., 2001)- outline
MRI of patient VC showed shrunken hippocampus and bilateral abnormalities (amygdala)
Case VC (Cipolotti et al., 2001)- observations and conclusions
Extensive ungraded retrograde amnesia (up to 40 years prior)
Severe anterograde amnesia (acquisition of new semantic knowledge)
SO:
Ret amnesia extensive and ungraded when limited to the hippocampus. Abnormal signal return from the left amygdala may present as conflicting evidence that suggests that the Hippocampus is the only structure vital to memory –> amygdala important in re-representation and learning
