33- Learning and Memory Flashcards
what is learning?
acquisition of new information/skills
what is memory?
retention of learned information over time - ability to store and recall previous knowledge/ experiences
describe declarative/ explicit memory
the conscious recall of specific facts and events, explicitly stored and recall
includes episodic memory of personal experiences, and semantic experiences of general knowledge
associated with the medial temporal lobe and hippocampus
describe non-declarative/ implicit memory
unconscious recall of motor skills and habits, can perform procedures without conscious awareness
mainly associated with the striatum, also the amygdala (emotional responses) and cerebellum (skeletal muscle memory)
procedural memory = associated with striatum; part of long-term memory, stores information of performing certain procedures like walking and talking
describe the role and location of working memory
role: temporarily holds information available for manipulation and processing for various cognitive tasks
important for cognitive functions - behaviour, decision making, problem-solving
location: prefrontal cortex, with network connections to other areas like the parietal cortex
the delayed response task in monkeys with working memory
pre-frontal cortex is important in working memory - the temporary storage and manipulation of information for cognitive functions
delayed response task = monkey is presented with a cue, then a delay period, then a response phase - monkey must remember the cue during the delay and carry out an appropriate response afterwards
= shows the retention of information during the delay for the required response, working memory
describe short-term memory
temporarily holds information being used or actively processed - information remains in an active, available state for a short period of time
describe long-term memory
lasting, relatively permanent retention of information and skills that could be unlimited - constrained by accessibility
information held for an extended period of time
final stage of the multi-store memory model proposed by the Atkinson-Shiffrin
associated with explicit and implicit memory, procedural, episodic and semantic memory
what is memory consolidation?
memory consolidation = time-dependent process by which recent learned experiences are transformed into long-term memory
describe the two theories and the pathway for memory consolidation
- standard model
- multiple trace model
- standard model
- sensory information from sensory systems sent to neocortical areas
- sent to medial temporal lobe - areas like the hippocampus, parahippocampal cortex and rhinal cortical area
- some information sent to the thalamus and hypothalamus via the fornix
- hippocampus involved in initial stage of memory consolidation = strengthening synaptic connections for synaptic consolidation
- once the memory is consolidated it’s less dependent on the hippocampus as it’s been stored in other brain regions - multiple trace model - suggests the hippocampus plays a further role beyond the initial phase of memory consolidation
- different aspects of a memory can be stored in various brain regions, creating multiple memory traces
- strengthening of synaptic connections and synaptic plasticity with the trisynaptic circuit in the hippocampus
describe the trisynaptic circuit of the hippocampus
trisynaptic circuitry of hippocampus involves synaptic plasticity and strengthening synaptic connections
from entorhinal cortex to dentate gyrus
dentate gyrus - mossy fibres from dentate gyrus synapse with CA3 hippocampal area neurons
CA3 to CA1 hippocampal area via Schaffer collaterals/ axons
define synaptic plasticity
biological process by which specific patterns of synaptic activity result in changes in synaptic strength
what is amnesia?
serious loss of memory and/or ability to learn
causes: concussion, chronic alcoholism, encephalitis, brain tumour, stroke
describe the role of the prefrontal cortex, the neocortex, the striatum and the hippocampus in different types of memory
prefrontal cortex - executive functions and working memory
- working memory = temporarily holding information and manipulating it for cognitive functions
- episodic memory = encoding and retrieving personal experiences
neocortex - higher cognitive functions
- semantic, episodic and procedural memory
striatum - key role in non-declarative memory, procedural memory and habit formation; the unconscious recall of skills and habits
- part of the basal ganglia
hippocampus - consolidation of new memories, especially declarative
- episodic and semantic memory consolidation
- trisynaptic circuitry to reinforce synaptic plasticity and strengthen synaptic connections
- sends information back to cortical associated areas to reinforce memory and the interconnected neural network that represents a memory
describe the process of long term potentiation
long-term potentiation = persistent strengthening of synapses based on recent patterns of activity; produce long-lasting increase in signal transmission between two neurons
glutamate binds to post-synaptic AMPA receptors = Na+ influx depolarising post-syn membrane
glutamate also binds to NMDA receptors which are both ligand and voltage gated - Mg2+ ion block removed with sufficient depolarisation and glutamate binding causes NMDA receptor to open = Na+ and Ca2+ influx
Ca2+ influx = increase in intracellular Ca2+ conc = activates calmodulin protein kinase II and other kinases
calmodulin protein kinase II phosphorylates AMPA receptors = increases Na+ conductance and depolarisation = increases post-synaptic neurone response
also increases the number of AMPA receptors on the post-synaptic membrane = increased sensitivity to glutamate
enhancement of synaptic transmission, structural change of synapse = long term potentiation
