Lecture 19 Flashcards
Perceptual learning
Learning to recognize stimuli as distinct entities
Unconscious, implicit
Requires modification of strength of connections between neurons in primary and association cortices.
Both the ventral and dorsal streams involved
See an object which implies movement, activates both what (for recognition) and where (for processing movement). You need activation in cortical movement areas to accurately perceive this.
Motor learning
Learning to make skilled, choreographed movements. Procedural learning.
Feedback from movements from joints, vestibular system, eyes, ears etc. Use this to improve movements.
Rapid, instant component then a slower, between session component to learning. Some of this is done asleep but not all.
Cerebellum, thalamus, basal ganglia and motor cortex are all involved
Relational learning
Learning relationships among individual stimuli. Stimulus-stimulus learning.
Stimulus-response learning
Learning to perform a particular behavior when a particular stimulus is present
Unconscious (implicit)
non-declarative
Memories that influence behavior in an automatic way
To probe these say @show me@
Procedural - ride a bike
perceptual - tell identical twins apart unconsciously
stimulus-response memories - saliva to tone
Conscious memories (explicit)
declarative
Say “tell me”
Episodic
Semantic
Stimulus response memory
implicit and explicit
Classical and operant conditioning
Stability of memory
Sensory memory - lasts for a couple of seconds only
Allows an individual to retain the experience of sensation slightly longer than the original stimulus
Eg if you are not listening, you might start paying attention and realize you do remember the last 2 seconds of a sentence
STM
Seconds to minutes
Few items capacity
Can last longer through rehearsal
LTM
Consolidated from STM
Can be recalled throughout life and strengthened with increased retrieval
Visual agnosias
Damage to brain regions involved in visual perception also impair memory of familiar stimuli that require them
Such people can copy a picture of something they cannot recognize, but cannot replicate it seconds later.
Stimulus-response learning details (instrumental conditioning)
Is operant conditioning
The process of reinforcement strengthens the connection between neural circuits involved in perception and those involved in movement
2 pathways
DIRECT transcortical connections
one are of cortex to another
Acquire complex motor sequences that involve deliberation or instruction
INDIRECT via the basal ganglia
The basal ganglia integrates sensory and motor input from all over the brain
1) At first ganglia is a passive observer
2) eventually, takes over most of the process - at this point, thought is no longer required consciously
3) Strength to cortical inputs is moderated by dopamine’s signaling
4) major input nucleus of the basal ganglia is the striatum, it consists of the caudate, putamen and nucleus accumbens
Dopamine input into the striatum (for instrumental conditioning)
Dopamine neurons ion the midbrain (esp the substantia nigra and ventral tegmental area) strongly innervate the striatum.
In general, this level off dopamine signaling correlates with motivational level and the value of moving and engaging within the environment.
ALSO transient dopamine signaling that is brief and can be intense signals unexpected good or bad an event was
Different areas of the striatum process different types of information. The nucleus accumbens in the ventral striatum receives input from the limbic areas like the hippocampus and PFC. It regulates priorities.
Role of the basal ganglia in habitual thought
As action sequences are repeated, they become more habitual
Across the transition, different circuits within the basal ganglia become involved. Beginners use the medial ganglia, experts use the lateral.
Lesions of the basal ganglia disrupt reinforcement learning and habit learning. They do not impact perceptual learning nor stimulus-stimulus learning.
Relational learning (Stimulus-stimulus) and the role of the hippocampus
Includes declarative, episodic and semantic knowledge.
Hippocampus is very important for this. HM, retrograde for last 2 years, total anterograde.
Brief working memory and high IQ
Hippocampus is not the location of STM or LTM
Pts with hippocampal damage can remember events that happened before their brain was damaged and their STM is normal
It is involved with converting STM to explicit LTM via consolidation
Korsakoff’s syndrome
vit B1 deficiency Alcoholism Brain damage Perm anterograde amnesia Confabulation: reporting of memories that did not happen without the intention to deceive
Memory consolidation and encoding
Sensory info enters STM, rehearsal keeps it there, eventually the information goes to LTM, where it is stored permanently.
Generally it is thought that the information is not stored in the hippocampus but that it forms a node (or index) that is capable of representing and reactivating the sensory systems that initially encoded an experience.
Over years, memory becomes less dependent on the hippocampus.
One theory for this is that the hippocampus trains the cortex, causing a reorganization of synaptic weights in the cortex so that intra-cortical connections can support memory recall alone.
Some say the cortex only has semantic info (facts). In this model, all info is episodic so starts of with the hippocampus nodes interacting with the cortex. Over time, facts emerge from repeated episodic experiences and these are permanently stored cortically.
This might involve the same pattern of activity created for multiple memories due to its intrinsic, factual basis and hence this common area becomes fact and can be activated without the hippocampus but the attached events still need the hip.
And so over years a node forms in the cortex for the semantic content but not the episodic content.
