Behavioral Neuro Test 3 Flashcards
Pavlovian Learning
CS=Sound, US=blow of air, CR=blink
Hebbian Learning
if presynapse becomes active at same time as postsynaptic neuron(repeatedly), relationship will be strengthened between the two.
“neurons that fire together wire together”
Engram
biological substrate of memory
anything that has been biologically changed (strengthened synapse)
Karl Lashley
most of his work is wrong, but we can learn from it.
- believed size of deficit in rat brain corresponded to size of cortical lesion (used maze running to test this) – bigger lesion= worse off
- concluded that engram was diffuse (stored across the brain) and intact brain regions can compensate for damage (equipotential)
How was Karl Lashley’s work wrong
- equipotentially- believed that all parts of cortex contribute equally to complex behaviors and all any part of cortex can substitute (this is not true lol)
- needed to look at more than 1 task- doesn’t represent all learning types
- mass action- cortex works as a whole, more cortex= better. This was wrong.
- his task was too complex
- cerebral cortex isn’t the only place to look for engram
Modern day search for engram
Task used: eyeblinking
Location: engram found in cerebellum (lateral interpostitus nucleus)
Method: pavlovian conditioning. used muscimol to shut down areas of the brain.
CR: blinking with tone and no air.
Groups that had red nucleus inhibited, didn’t blink. When it was activated after a few days, they did blink right away, indicating that they had learned the association but couldn’t actually blink due to motor skills involved in red nucleus. On the last day, they inhibited the red nucleus again and found that they didn’t blink, supporting the finding that red nucleus was involed in the action of blinking
Groups that had cerebellum inactivated didn’t blink. When they activated the cerebellum, individuals slowly started blinking over trials, meaning they were just beginning to learn and the cerebellum was involved in learning. On the final day, they inhibited the cerebellum again and individuals did not blink, indicating that the cerebellum was not only where the learning took place, but it was also where it was stored, thus where the engram was located.
a->b->c->d->e->f
you need ALL parts of the process for learning to occur
eyeblink conditioning in humans- neural findings
PET Scans- developing eyeblink conditioning response is associated with increased activity in cerebellum and red nucleus
Cerellar damage= weaker conditioned eyeblings, and blinks are less accurately timed relative to onset of air puff
HM- who was he, why do we care
had epilespy. doctors found out medial temporal lobe was where the issue was, so they removed it. seizures went away but now had memory issues.
intact areas HM
reterograde memory
immediate memory
IQ
vision
logic/reasoning
language
motor control
impaired things HM
anterograde amnesia
retrieving recent memories pre operation ( a little retrograde amnesia)
retrograde amnesia
cannot remember events prior to damage. Temporally graded, function of consolidation, only episodic memories only are impaired
temporally graded meaning + another name for
recent memories impacted, older aren’t as much. called ribots law
episodic memories
memories unique to your experience
semantic memory
vocab or facts
Patient EP
also had MTL damage(but it was due to injury).
Patient EP vs patient HM (what was wrong with the brain)
HM: Bilateral MTL lobectomy to treat epilepsy
EP: viral encephalitis damaged the brain
Why do we care about HM and EP?
demonstrates that certain brain areas can be tied to particular memory functions. Memory isn’t diffusely or equivalently spread throughout the whole brain as Lashley thought.
Also demonstrates that there are different modes of storage for short term vs long term memory vs remote memory. this led to the concept of memory consolidation (ST to LT memory conversion)
Demonstrates there are multiple memory systems in the brain
HM had damage to declarative/explicit memory system, but he also had damage to the area around it. (the entire medial temporal lobe and amygdala)
medial temporal lobe consists of
hippocampus and parahippocampal gyrus (entorhinal perirhinal, parahippocampal(aka postrhinal in rats))
medial temporal cortex consists of what
parahippocampal gyrus (entorhinal, perirhinal, parahippocampal)
name for parahippocampal in rats
postrhinal
declarative/explicit memory
recall and recognition
Monkey Experiment for memory
Method: give monkey object and underneath it is food. Then cover animal’s view of the object(I.e. lowering a screen. When the screen is opened, give them the same object (no longer food under it) and a different object (w new food)
Results: does monkey know they ate the old food? Monkeys with MTL lesions had major decrease in object recognition.
The longer the delay period was, the worse memory was.
location of hippocampus (rodents vs monkey)
rodents: more dorsal
monkey: more ventral