Chapter 7: Cortical Modules in Memory Flashcards
What was the localization of cerebral function found by Gall?
phrenology
cranial surface lent a tool to describe mapping going on in the cortex
What was the localization of cerebral function found by Brodman?
cortical anatomy/organization
different regions had different structures and cellular makeup, differentiation
What was the localization of cerebral function found by Broca?
specific lesions - speech
specific deficits in specific regions
Wernicke’s can’t produce speech
What was the localization of cerebral function found by Penfield?
human brain mapping - homunculus
somatosensory and motor cortex
Does cerebral localization influence both function and expression of plasticity?
specificity in location of modifications
in the very circuits which control the relevant behavior in the first place
compartmentalization of memory
Who was Karl Lashely?
the original search for the actual memory trace (engram)
How did Karl Lashely first experiment in search for the engram?
series of surgical cuts to interrupt sensory-motor pathways
sensory-motor isolation with knife cuts
learning (group 1) and retention (group 2) unaffected
none of the lesions did anything
What as Karl Lashely’s follow up experiment in search of the engram?
large and specifically placed lesions: only general deficits
only when he almost took out the whole cortex he saw significant deficits
mass action: memories stored diffusely in the brain
equipotentiality: 90% rule, only start to see big deficits once 90% of cells have died
What was the problem with Lashley’s experiments in search of the engram?
such a simple maze, rats could use many strategies to solve it
not specific enough of a task to measure what he was trying to
What was Hebb’s model of distributed cortical memory?
individual neurons don’t encode for anything specific
network of cell activates each other to encode
memory expressed as reverberatory activity in cell assemblies
repeated activity (i.e., rehearsal) stabilizes associations within the assembly; via Hebbian synaptic mechanism - LTP, to explain how these networks worked
one cell activates another in a sequence of activity
What is the mechanism of the experience and development of ocular dominance and orientation columns?
LTD and LTP: LTD for deprived inputs, LTP for non-deprived inputs, both NMDA and non-NMDA dependent
eye patch eye –> LTD, representation shrinks
non-deprived eye –> LTP, representation expands
synaptic sculpting?
map reorganization only during development? –> changes induced in complex environments
What is the cellular histology of cortical changes?
Golgi stain
quantify branching and synaptic specializations (dendritic spines - post synaptic sites)
problem: single measure of a dynamic system
What is the in vivo 2-photon imaging of post-synaptic spines?
direct imaging of dynamic system
50% of all spines are transient in adult brain
problem: very reduced system
How was dramatic changes in digit representation used as an assessment of cortical map changes in adulthood?
stimulate digit on hand and looked at how they changed after severing of digit (3)
areas in cortex that encoded for (3) now encoded for (2) and (4) and areas of the palm around digit (3)
How was learning-induced changes used as an assessment of cortical map changes in adulthood?
vibration detection task on one hand mapped out what kind of space each hand represented
overexpression of cortical space of hand used during the task
