Frontal lobes and hippocampus Flashcards
Lesions at DLPFC
Perseveration, environmental dependency (can’t focus attention –> require environmental cues to accomplish tasks)
Lesions at VMPFC
Characteristic Iowa Gambling Task performance (continue to draw from “bad” decks). Fail to show stress responses from bad decks.
disinhibition of aggression, sexual behavior, anxiety, appetitive functions
Lesions at the anterior cingulate cortex
abulia (lack of will) = patients able to follow conversations, but feel no will to respond to questions.
deficits of focused mental effort
executive function of DLPFC
intention and attention
executive function of VMPFC
positive and negative valence of stimuli, computing potential gains and losses of potential actions (with amygdala, ventral striatum and nucleus accumbens input)
executive function of anterior cingulate cortex
detection of conflicts between current attention or behavior and desired results –> motivation
hippocampus function
formation of long-term memory, memory “search engine”
nearly all hippocampal functions are performed in collaboration with several of its partners and strongly influenced by subcortical neuromodulators
Bilateral hippocampal dysfunction
Patient HM. deficits in declarative memory, spatial memory, episodic memory
Place cells
cells in hippocampus that fire when you are in a certain “place” in space
grid cells
cells in entorhinal cortex that encode a cognitive representation of Euclidian space –> dynamic computation of self-position
3 regions of hippocampal formation
dentate gyrus, hippocampus (aka Ammon’s horn), subiculum (zone between hippocampus and entorhinal cortex)
hippocampus location
body extends caudally along the inferior horn of the lateral ventricle
major cell types of dentate gyrus
granule cells, inhibitory interneurons
major cell types of the hippocampus
pyramidal cells, inhibitory interneurons
CA 3
adjacent to dentate, extending through the opening of the dentate
CA 1
merges with the subiculum
Two major inputs to the hippocampal formation
entorhinal cortex and septal nuclei
“trisynaptic circuit” through the hippocampal formation
entorhinal cortex –> dentate gyrus –> granule cells –> CA 3 of hippocampus –> pyramidal cells –> CA 1 and fornix.
CA1 –> subiculum –> entorhinal cortex –> cortical association areas
Perforant path
major projection from entorhinal cortex to dentate gyrus and hippocampus
Mossy fibers
axons of granule cells –> CA 3
Schaeffer collaterals
axons from CA 3 to CA 1
Autoassociative memory
neural network that enables you to retrieve entire memories from only a tiny sample of itself
“A day that will live in ____”
Memory consolidation
interaction between hippocampus and neocortex during sleep
representations of recent experiences are transferred from hippocampus to neocortex –> long-term memories
Standard model of memory consolidation
novel info is originally recorded and registered –> memory retention in both hippocampal and cortical regions –> hippocampus’ representations become active in recall during wake or sleep
Assumptions of Standard model of memory consolidation
hippocampus rapidly and automatically acquires information, is a limited capacity storage system (rapid forgetting), transfers info to be permanently stored in cortex, plays a critical role in the genesis of cortical memories
How long is memory retained in the hippocampus?
one week after initial learning
How does a memory become hippocampus independent
information is recalled –> strengthening of cortico-cotical connection –> slow transferring of info to neocortex –> permanent storage
