What is learning?
Learning is the process by which we acquire knowledge about the world
Our ability to learn things is highly dependent on what we know. Prior knowledge provides massive framework in which we can integrate information.
What is memory?
Memory is the process by which that knowledge of the world is encoded, stored, and later retrieved
What is intelligence?
Intelligence is a very general mental capability that
involves the ability to reason, solve problems, think abstractly, comprehend complex ideas, learn quickly and from experience
What are the measures of human intelligence?
IQ (intelligence quotient)
What is IQ?
General Intelligence” - cognitive and mental ability Measured as IQ (intelligence quotient), score derived from one of several standardised cognitive tests, median score 100 + 15 IQ results are highly reliable
What does psychometric tests measure?
Psychometric tests to measure intelligence cover reasoning, processing speed, executive function,
memory and spatial ability. People who perform well in one domain also tend to perform well in the others.
What is the relationship between cortical volume and intelligence?
Cortical volume has been correlated with intelligence - positive correlations especially in the prefrontal and temporal cortices .
what is short term memory?
Short term memory
memories that last seconds to hours
vulnerable to disruption and readily lost
information initially stored as short-term memory
what is long term memory?
converted from short term memory by consolidation
lasts longer with re-consolidation (e.g. remembering your parents’/siblings’ birthday)
can last for years (e.g. recall of childhood memories)
traumatic event can boost the consolidation of long-term memory e.g. 9/11 event
What is working memory?
temporary form of information storage
limited in capacity and requires rehearsal
retention of a telephone number that has just been given to you by repetition
What is declarative memory?
Declarative (explicit) Memory
episodic – autobiographical info with temporal/spatial context
semantic - memory for facts and events with no associations for example “Kyoto is a city in Japan”
Declarative memories are accessed for conscious recollection, whereas the tasks we learn, as well as the reflexes and emotional associations we have formed, operate smoothly without conscious recollection
Explicit memory because it results from more conscious effort. Easy to form and are easily forgotten.
what is Nondeclarative (implicit) Memory ?
procedural - memory for skills and habits
classical conditioning – emotional responses
non-associative – habituation, sensitization
Implicit memory because it results from direct experience.
Forming nondeclarative memories usually require repetition and practice over a longer period of time, but these memories are less likely to be forgotten.
what is non-associative learning?
Non-associative- learning describes a change in behavioural response that occurs over time in response to a single type of stimulus.
– Habituation: is learning to ignore a stimulus that lacks meaning
–Sensitization: a form of learning that intensifies your response to all stimuli, even ones that previously evoked little or no reaction.
Which part of the brain is associated with declarative memory?
The Temporal Lobes and Declarative Memory The temporal lobe structures hippocampus, subiculum, parahippocampus, rhinal cortical areas,
Effects of Temporal Lobectomy (epileptic subject HM) on declarative memory
removal of temporal lobes had no effect on perception, intelligence, personality
anterograde amnesia so profound cannot perform basic human activities (and partial retrograde amnesia)
did not recognize Brenda Milner, who studied him for nearly 50 years
impaired declarative memory, but spared procedural and working memory
Anterograde amnesia refers to a decreased ability to retain new information Retrograde amnesia (RA) refers to the loss of information that was acquired before the onset of amnesia.
Striatum and Procedural Memory
Type of long-term memory of how to perform different actions and involves the development of motor skills.
Form very early in life as you begin to learn how to walk, talk, eat and play, so ingrained that they are almost automatic.
Striatum (part of the basal ganglia) is important. Patients with Parkinson’s disease have impaired procedural memory.
The prefrontal and parietal cortices and cerebellum are also important for motor learning.
Hippocampus and Spatial Memory
Spatial Memory is the part of memory responsible for recording information about one’s environment and its spatial orientation
Spatial memory is required to navigate around a familiar city
Hippocampus is important for spatial memory
Place cells in the hippocampus - neurons that only fire when person is at a particular location
A place cell is a kind of pyramidal neuron within the hippocampus that becomes active when an animal enters a particular place in its environment,
Grid cells in the entorhinal cortex – the neurons activate in a unique spatial pattern in a hexagonal grid
The entorhinal cortex (EC) is an area of the brain located in the medial temporal lobe and functions as a hub in a widespread network for memory, navigation and the perception of time. The EC is the main interface between the hippocampus and neocortex.
Prefrontal Cortex and Working Memory
considered a limited capacity system that allows one to temporarily hold on to and process information over a brief time period.
a system for temporary storage of information to enable one to work on complex tasks while being able to keep information in mind.
e.g. the ability to work on a complicated mathematical problem utilizes one’s working memory
highly developed in humans
important in problem solving, complex planning and self-awareness
interconnected with medial temporal lobe
Does Photographic Memory Exist?
Photographic memory is the ability to remember and recall large volumes of numbers or text in great detail. There is no scientific evidence that this type of memory exists.
Eidetic memory is the ability to faithfully recall or reproduce a visual or mental image that is captured. This form of memory is subject to distortions.
Most individuals identified as having eidetic memory are children and prevalence range from 2 – 10 % with no gender difference.
What are different stages of memory formation?
- sensory information is perceived and acquired
* influenced by attention, motivation, ability to learn
• crucial first step to creating a new memory
• the perceived item of interest to be converted into a construct that can be stored within the brain
require consolidation to commit to longer term memory
stabilisation of memory trace after acquisition
two specific processes (1) synaptic consolidation (which occurs within
the first few hours after learning or encoding) and (2) system
consolidation (where hippocampus-dependent memories become
independent of the hippocampus over a period of weeks to years)
utilizes a phenomenon called long-term potentiation, which allows a
synapse to increase in strength .
subsequent re-accessing of events or information from the past, which
have been previously encoded and stored in the brain.
Hebbian Theory - memory results from synaptic modification
Fire together wire together
Out of sync lose their link
Neural basis of memory
- Learning and memory occur at synapses and result from modifications of synaptic transmission
- Synaptic plasticity (ability of the synapse to change in strength in response to either use or disuse) is an important neurochemical foundation of learning and memory
- Long term potentiation (LTP) of synaptic transmission in the hippocampus - primary experimental model for investigating the synaptic basis of learning and memory in vertebrates
LTP in the Hippocampus
Mechanisms of LTP in CA1
Activation of AMPA/Kainate receptors by glutamate causes post-synaptic membrane depolarisation
Mg2+ is dissociated from NMDA channels, facilitation of Ca++ entry
Activation of protein kinases Ca2+ /calmodulin-dependent kinase (CaMKII), Ca2+ /phospholipid dependent kinase (PKC)
Resulting in postsynaptic protein phosphorylation of AMPA receptors
Recruitment of AMPA receptors to post-synaptic membrane and upregulation of AMPA receptor
Mechanisms of LTD in CA1
Facilitation of postsynaptic Ca++ entry through NMDA receptors
Key difference between LTP and LTD – level of NMDA receptor activation
LTD – weak depolarization of postsynaptic neurons, partial blocking of NMDA channels by Mg++, trickle of Ca++ entry
Activation of protein phosphatases instead of kinases, resulting in protein dephosphorylation
Dendritic spines are sources of synaptic contact that can be altered by experience
Structural plasticity of dendritic spines underlies
learning, memory and cognition in the cerebral cortex
Induction of LTP causes enlargement of spine heads,
while LTD causes spine head shrinkage
Major risk factor for neurodegenerative diseases
Age is a major risk factor for many neurodegenerative diseases
most neurodegenerative diseases have unknown etiology
delayed onset; age is a major risk factor
selective neuronal vulnerability, despite widespread expression of diseaserelated proteins during the whole lifetime;
abnormal protein processing and aggregation
many display symptoms of memory loss
one of the most common form of neurodegenerative disease is Alzheimer’s