W6L1 - HM and Temporal Lobes

Question 1

What does HM have initially

Answer 1

Severe epilepsy

Question 2

What are epilepsy seizures caused by

Answer 2

Sudden excitation in groups of neurons, with a loss of inhibitory potential

Question 3

What is the biochemistry behind seizures

Answer 3

Inhibitory: GABA - Increases nervous system stability
Excitation: Glutamate - Increases spread of excitation

Seizures decreases GABA.

Question 4

Definition of Temporal Lobe Epilepsy (TLE)

Answer 4

Recurrent unprovoked seizures originating from medial or lateral temporal lobe

Question 5

What are the types of TLE

Answer 5

1. ) Simple partial seizures (without loss of awareness)

2. ) Complex partial seizures (with loss of awareness)

Question 6

What is the most common pathphysiology (disordered physiological processes associated with injury) of TLE

Answer 6

Hippocampal sclerosis (HS)

Question 7

What is hippocampal sclerosis (HS) caused by

Answer 7

• Neuronal loss

- Gliosis (excess growth of glial cells after neuronal cell loss occurs in a region)

Question 8

Which age does HS occur often

Answer 8

Early in life (About 20)

Question 9

What happens to seizures when a leisoned hippocampus is surgically removed

Answer 9

Can reduce the number of seizures

Question 10

How many gyri and sulci of the Temporal Lobe

Answer 10

Gyrus: Superior, Middle, Inferior
Sulcus: Superior, Inferior

Question 11

Where is the hippocampus located

Answer 11

Within the parahippoocampal gyrus (MTL)

Question 12

What is the parahippocampal gyrus posterior to

Answer 12

Anterior: Perihinal
Middle: Entorhinal
Posterior: Parahippocampal Gyrus

Question 13

What did HM undergo. Which parts of his brain was removed

Answer 13

Bilateral resection of extensive amount of medial temporal tissue (Amygdala, Hippocampi, part of parahippocampal gyrus)

Question 14

What did HM retain after surgery

Answer 14

Normal attention span
Normal Intelligence
Retrograde memory recovered over time

Question 15

What is the difference between retrograde amnesia and anterograde amnesia

Answer 15

Retrograde: Impairment for memory PRIOR to injury

Anterograde: Impairment for memory AFTER injury

Question 16

What condition did HM have after surgery

Answer 16

Severe antereograde amnesia (particular declarative memory)

Question 17

What is the difference between declarative and procedural memory

Answer 17

Declarative: Conscious access to information learnt previously

Procedural: “Muscle Memory”/”How To” (playing piano)

Question 18

DId HM lose declarative/procedural memory. How do we know?

Answer 18

Declarative: Severely impaired
Procedural: Retained

Able to learn new skills and normal performance on procedural memory task (star)

Question 19

What did HM tell us about memory and MTL

Answer 19

1) Essential for memory function
2) More essential for anterograde than retrograde memory
3) Distinction between Declarative and Procedural
memory

Question 20

Anatomy of Memory: What have we learnt since HM

Answer 20

Intact memory function relies on a neuroanatomical network (many regions)

Temporal Lobes (TL) are the ‘engine’ of memory.

Question 21

Memory function in TLE patients

Answer 21

‘Material-specific’ memory deficits related to involved medial temporal lobe (MTL)
Left leision: Verbal Impairment
Right leision: Non-Verbal/Visual Impairment

Question 22

What is the hippocampus also known as

Answer 22

Cornu Ammonis: CA1 to CA3

Question 23

Hippocampal formation

Answer 23

Dentate Gyrus + CA3 - CA1 + Subiculum

Question 24

What is the schematic representation and processes of the MTL

Answer 24

Unimodal/Polymodal Association 
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Perihinal Cortex + Parahippocampal Cortex
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Entorhinal Cortex
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Hippocampal Formation

Information flows from sensory and sent to hippocampal for long-term storage. Memory assessed by hippocampal formation to temporal neocortex

Question 25

What is the role of Hippocampal Formation

Answer 25

Hippocampal formation and surrounding structures are essential for learning and consolidating novel information

Question 26

What are the 2 theories on hippocampal formation

Answer 26

1. ) Consolidation Theory: After a period of consolidation, information can be retrieved INDEPENDENT of hippocampal formation involvement
2. ) Multiple Trace Theory (MTT): Retrieval of autobiographical/episodic experiences ALWAYS INVOLVE hippocampal formation

Question 27

What are paired association learning task

Answer 27

Required to remember an association between arbitrary (unrelated) pieces of information e.g. word and object

Hippocampal formation particular necessary for relational memory tasks