frontal lobes and hippocampus Flashcards
compare the primary, secondary, tertiary and quaternary cortex
Primary Cortex-Unimodal, serves a single behavioral function. Secondary Cortex- Unimodal, Association for primary corticies. Tertiary Cortex- Heteromodal, Integrates info from secondary corticies. Quaternary Cortex- Heteromodal, Integrates information from tertiary corticies
Prefrontal cortex functions
executive function- directly enhance or inhibit certain networks (ie. motor or sensory function)
Defecits observed with injury to dorsolateral prefrontal cortex
Inability to employ intention (goals) to modulate attention (task at hand). Patients’ failure to switch attention appropriately gives rise to perseveration, while the lack of internally generated goal direction results in an undue requirement for environmental cues to accomplish task, a problem known as environmental dependency.
Defecits observed with injury to ventromedial prefrontal cortex
Characteristic perfromance on Iowa gambling task. Also demonstrate inadequate inhibition of aggression, sexual behavior, anxiety, and appetitive functions. This is all due to inability to estimate risk/reward associated with behaviors
Defecits observed with injury to anterior cingulate cortex
acutely- patient has abulia, or lack of will. Can be completely akinetic and mute in some cases. Long term- almost full recovery
Understand the result of bilateral hippocampal dysfunction
Loss of the ability to form declarative or episodic memory (memory of facts and events), particularly spatial memory.
Architecture of hippocampal formation
Includes dentate gyrus, hippocampus and subiculum (transition zone btw three layered hippocampus and 6 layered entorhinal cortex)
How many cell layers does the hippocampus have and what are the principal cell type
3 layers- pyramidal cells are predominate cell type.
inputs to hippocampus
entorhinal cortex,and the septal nuclei. The most important pathway originates from the entorhinal cortex
and is often described as a “trisynaptic circuit” through the hippocampal formation
Describe the trisynaptic circuit through hippocampus
entorhinal cortex > projects to dentate gyrus via the perforant path> granule cells send axons (mossy fibers) to CA3 field of hippocampus > Pyramidal cells send Schaffer collaterals to CA1 field > subiculum > entorhinal cortex > cortical association areas
What is autoassociative memory
Form of neural network that enables one to retrieve entire memories from only a tiny sample of itself
How are autoassociative memories formed
By CA3 which allows arbitrary associations btw imputs from different parts of cortex to be formed
Understand the apparent importance of sleep in hippocampal-dependent memory consolidation
During sleep representations of recent experiences are transferred from hippocampus to neocortex, by
a process called consolidation, to form long-term memories. Memory is retained in hippocampus for one week while newly learned info from hippocampus is relayed to neocortex, integrating it with previously learned material
