lecture 29 Flashcards
(17 cards)
What are the 6 layers of the cortex?
- molecular layer: few neuronal bodies, mostly axon terminals and synapses on dendrites
- external granular layer: mostly stellate cells (or granule cells; interneurons)
- external pyramidal layer: mostly small pyramidal cells (excitatory)
- internal granular layer: mostly stellate cells
- internal pyramidal layer: mostly large pyramidal cells that are the main source of cortical efferent to subcortical regions
- multiform layer: pyramidal, fusiform and other cell types; important origin of cortical efferents that target thalamic nuclei
Broadman areas divide the cortex based on…
- thickness and cell composition
- often the structure maps closely to function (area 17 - V1, area 4 - M1
Where is the hippocampus?
it is in located in your medial temporal lobe, but can only be seen through dissection
What are the areas of the hippocampus region?
- hippocampus (CA1, CA2, CA3)
- dentate gyrus
- subiculum
What are the three layers of the hippocampus?
- molecular
- pyramidal
- polymorphic
the hippocampus has strong connectivity with ____
the entorhinal cortex
The hippocampus formation is crucial for _____
forming new memories
What and why does bilateral removal medial temporal lobe cause?
- anterograde amnesia (inability to form new memories)
- this is because the hippocampus is found in the MTL, so when this is removed the hippocampus is removed, which functions in memory formation
What happened with patient H.M? and what did they discover?
- he had bilateral removal of temporal medial lobes which result in anterograde amnesia (the inability to form new memories)
- his personality was unchanged, but IQ increased
- he was living proof that ability to form new facts and memories relies on MTL, cognitive function and motor function do not
What are and explain the different types of memory?
- episodic: autobiographical events that can be recalled (ex. 10th birthday)
- semantic: fact-based memory that can be communicated (ex. knowing who the royal family is)
- declarative: memories that can be verbalized
- non-declarative: less broadly accessible, not easy to verbalize (ex. riding a bike)
What is the difference between explicit and implicit memory
- explicit the person is aware of what they’ve learned and teach it
- implicit is unaware of everything they’re actually doing
for example: learning how to teach a skill vs. actually doing the skill
how is the entorhinal cortex involved in memory?
- the entorhinal cortex sends signals to the dentate gurus of the hippocampus
- when stimulated this leads to increased EPSPs in dentate gyrus overtime, a process known as LTP, which strengthens synaptic connections and supports long-term memory formation
- patient H.M lost brain structures necessary for LTP
How can scientists use immediate early gene (IEG) expression to map memory networks over time?
- by measuring IEG like Fos after memory recall, scientist identify active brain regions.
- correlating this activity across brain regions, reveals memory networks which can be compared at different time points (e.g. 1 day vs 36 days) to show memory traces over time
What areas are involved in short-term and long-term memory?
- short term storage and learning is associated with hippocampus
- long term storage and consolidation is associated with cerebral cortex and thalamus
what are epileptic seizures and what do they do?
- epileptic seizures are pathological excitation which spread through the brain network
- such excessive synchronization/co-activation can impact functional networks such as LTP and exicitotoxicty)
- this impairs healthy networks and causes deficits in memory
The hippocampus is strongly connected to…
- the default mode network seen in fMRI (a region activated during no task, such as daydreaming)
HC and DMN experiment results
- the more connected the diseased HC is with DMN the worse memory is post-surgery
- the more connected the healthy HC with the DMN the better memory is post surgery
