Cranial nerves > Cerbral cortex layers > Flashcards

Cerbral cortex layers Flashcards

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1
Q

What is the cerebral cortex?

A

• Outer covering of grey matter • Covers the cerebral hemispheres • Grey matter contains neuronal cell bodies

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2
Q

What types of cortex make up the cerebral cortex?

A

• Neocortex • Allocortex

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3
Q

Which type of cortex makes up most of the cerebral cortex?

A

• Neocortex • Covers >90% of the cerebral cortex

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4
Q

What is the neocortex?

A

• Most recently evolved cortex • Outermost layer of cerebral hemispheres • Organised into six layers (I–VI)

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5
Q

What is the allocortex?

A

• Older form of cortex • Closely associated with the limbic system

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6
Q

What are the two parts of the allocortex?

A

• Paleocortex • Archicortex

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7
Q

What structures make up the paleocortex?

A

• Entorhinal cortex (medial temporal lobe) • Piriform cortex • Specialised for olfaction (smell)

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8
Q

What structures make up the archicortex?

A

• Hippocampus • Involved in memory and spatial processing

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9
Q

How much of the cerebral cortex is neocortex?

A

• More than 90%

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10
Q

How many layers does the neocortex have?

A

• Six layers • Numbered I to VI

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11
Q

On what basis are neocortical layers distinguished?

A

• Predominant cell type • Arrangement of nerve fibres • Cell size and shape

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12
Q

What are the two main cell types in the neocortex?

A

• Pyramidal cells • Stellate (granular) cells

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13
Q

What are pyramidal cells?

A

• Neurons with pyramid-shaped cell bodies • Have long axons • Possess apical and basal dendrites

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14
Q

What proportion of cortical neurons are pyramidal cells?

A

• Approximately 75% of cortical neurons

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15
Q

What is the main function of pyramidal cells?

A

• Principal output neurons of the cortex • Send signals out of the cortex

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16
Q

In which neocortical layers are pyramidal cells found?

A

• Layers II to V

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17
Q

What are Betz cells?

A

• Largest pyramidal cells • Located in layer V • Found in motor cortex • Important for voluntary movement

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18
Q

What are stellate cells also called?

A

• Granular cells

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19
Q

What is the shape of stellate cells?

A

• Small multipolar neurons • Star-shaped due to radiating dendrites

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20
Q

What are the two types of stellate cells?

A

• Spiny stellate cells → excitatory • Smooth stellate cells → inhibitory

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21
Q

Which neocortical layer contains the most stellate cells?

A

• Layer IV • Major input layer of the cortex

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22
Q

What is the main role of stellate cells?

A

• Local interneurons • Transmit signals within the same cortical region

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23
Q

Do stellate cell axons leave the cortex?

A

• ❌ No • Axons are short and remain within the cortex

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24
Q

Are pyramidal cells interneurons?

A

• ❌ No • They are output neurons

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25
**Are stellate cells projection neurons?**
• ❌ **No** • They are **local interneurons**
26
**Which cortex is evolutionarily newer: neocortex or allocortex?**
• **Neocortex**
27
**Give a one-line summary of cortical organisation.**
• **Neocortex**: >90%, 6 layers, pyramidal + stellate cells • **Allocortex**: paleocortex (smell) + archicortex (hippocampus)
28
Question
Answer
29
**What is archicortex?**
• An **evolutionarily older cortex** • Part of the **allocortex** • Has **fewer layers** than neocortex • Strongly linked to **memory**
30
**What is meant by the hippocampus proper?**
• Refers to the **Cornu Ammonis (CA) regions** • Includes **CA1, CA2, CA3** • ❌ Does **not** include the dentate gyrus
31
**What type of cortex is the hippocampus proper?**
• **Archicortex**
32
**How many cellular layers does the hippocampus proper have?**
• **Three layers** • Not six like the neocortex
33
**What are the three layers of the hippocampus proper (CA regions)?**
• **Molecular layer** • **Pyramidal cell layer** • **Polymorphic layer (stratum oriens)**
34
**What is the molecular layer of the hippocampus proper?**
• The **outermost layer** of the CA cortex
35
**What does the molecular layer mainly contain?**
• **Dendrites of pyramidal neurons** • **Incoming axons** • **Numerous synapses** • Very **few cell bodies**
36
**Why is the molecular layer called molecular?**
• Contains a dense mesh of **dendrites, axons, and synapses** • Has **few neuron cell bodies** • Appears as a fine network
37
**How does the molecular layer receive signals?**
• Pyramidal neuron cell bodies lie below • Their **dendrites extend into the molecular layer** • **Axons from other neurons enter this layer** • Neurotransmitter release onto dendrites forms **synapses**
38
**What is a synapse?**
• A **junction** where one neuron communicates with another • Usually via **neurotransmitter release** across a small gap
39
**Why do synapses mainly occur in the molecular layer?**
• Designed for **connectivity** • Large space for dendritic branching • Many incoming axons • Few cell bodies → less crowding
40
**What is the main function of the molecular layer?**
• **Synaptic integration** • Incoming inputs connect onto dendrites • Signals are combined before pyramidal neurons fire
41
**What is the pyramidal cell layer?**
• The **middle layer** of the hippocampus proper • Contains **cell bodies of pyramidal neurons**
42
**What are pyramidal neurons in the hippocampus proper?**
• The **main excitatory output neurons** of CA regions
43
**In which CA regions are pyramidal cells found?**
• **CA1** • **CA2** • **CA3**
44
**What is the main role of the pyramidal cell layer?**
• Generates the **principal output** of hippocampus proper • Fires action potentials • Sends signals in memory circuits
45
**Why is the pyramidal layer considered the main layer?**
• Contains the **principal neuron cell bodies** • Responsible for most hippocampal output
46
**What is the polymorphic layer also called?**
• **Stratum oriens**
47
**Why is the polymorphic layer called polymorphic?**
• Contains **many different cell shapes and types** • Not a uniform cell population
48
**What does the polymorphic layer contain?**
• **Interneurons** (often inhibitory) • Local connections • Passing axons
49
**What is the main function of the polymorphic layer?**
• **Modulation and control** • Fine-tunes pyramidal neuron firing • Provides inhibitory braking
50
**Why is inhibition important in hippocampal circuits?**
• Prevents excessive excitation • Reduces **seizure risk** • Improves signal precision for memory
51
**Describe the information flow across hippocampal layers.**
• Inputs arrive at **molecular layer** • Integration and firing in **pyramidal layer** • Output modulation in **polymorphic layer**
52
**Does the hippocampus proper contain granule cells?**
• ❌ **No** • Granule cells belong to the **dentate gyrus**
53
**Does the hippocampus proper have six layers like neocortex?**
• ❌ **No** • It has **three layers**
54
**What is a simple mnemonic for hippocampus proper layers?**
• **M–P–P** • Molecular = meet & mix signals • Pyramidal = principal output • Polymorphic = policing/control
55
Question
Answer
56
**What is archicortex?**
• An **evolutionarily older cortex** • Part of the **allocortex** • Has **fewer layers** than neocortex • Strongly linked to **memory**
57
**What is meant by the hippocampus proper?**
• Refers to the **Cornu Ammonis (CA) regions** • Includes **CA1, CA2, CA3** • ❌ Does **not** include the dentate gyrus
58
**What type of cortex is the hippocampus proper?**
• **Archicortex**
59
**How many cellular layers does the hippocampus proper have?**
• **Three layers** • Not six like the neocortex
60
**What are the three layers of the hippocampus proper (CA regions)?**
• **Molecular layer** • **Pyramidal cell layer** • **Polymorphic layer (stratum oriens)**
61
**What is the molecular layer of the hippocampus proper?**
• The **outermost layer** of the CA cortex
62
**What does the molecular layer mainly contain?**
• **Dendrites of pyramidal neurons** • **Incoming axons** • **Numerous synapses** • Very **few neuron cell bodies**
63
**Why is the molecular layer called molecular?**
• Dense mesh of **dendrites, axons, and synapses** • **Few cell bodies** • Appears as a fine network
64
**How does the molecular layer receive signals?**
• Pyramidal neuron cell bodies lie below • Their **dendrites extend upward** into the molecular layer • **Axons from other neurons enter** this layer • Neurotransmitter release onto dendrites forms **synapses**
65
**What is a synapse?**
• A **junction** where one neuron communicates with another • Usually via **neurotransmitter release** across a small gap
66
**Why do synapses mainly occur in the molecular layer?**
• Built for **connectivity** • Space for dendritic branching • Many incoming axons • Few cell bodies → less crowding
67
**What is the main function of the molecular layer?**
• **Synaptic integration** • Incoming inputs connect onto dendrites • Signals are combined before pyramidal neurons fire
68
**What is the pyramidal cell layer?**
• The **middle layer** of the hippocampus proper • Contains **cell bodies of pyramidal neurons**
69
**What are pyramidal neurons in the hippocampus proper?**
• The **main excitatory output neurons** of the CA regions
70
**In which CA regions are pyramidal cells found?**
• **CA1** • **CA2** • **CA3**
71
**What is the main role of the pyramidal cell layer?**
• Generates the **principal output** of hippocampus proper • Fires action potentials • Sends signals onward in memory circuits
72
**Why is the pyramidal layer considered the main layer?**
• Contains the **principal neuron cell bodies** • Responsible for most hippocampal output
73
**What is the polymorphic layer also called?**
• **Stratum oriens**
74
**Why is the polymorphic layer called polymorphic?**
• Contains **many different cell shapes and types** • Not a uniform cell population
75
**What does the polymorphic layer contain?**
• **Interneurons** (often inhibitory) • Local connections • Axons passing through
76
**What is the main function of the polymorphic layer?**
• **Modulation and control** • Fine-tunes pyramidal neuron firing • Provides inhibitory braking
77
**Why is inhibition important in hippocampal circuits?**
• Prevents excessive excitation • Reduces **seizure risk** • Improves signal precision for memory
78
**Describe the information flow across hippocampal layers.**
• Inputs arrive at **molecular layer** • Integration and firing in **pyramidal layer** • Output modulation in **polymorphic layer**
79
**Does the hippocampus proper contain granule cells?**
• ❌ **No** • Granule cells belong to the **dentate gyrus**
80
**Does the hippocampus proper have six layers like neocortex?**
• ❌ **No** • It has **three layers**
81
**What is a simple mnemonic for hippocampus proper layers?**
• **M–P–P** • Molecular = meet & mix signals • Pyramidal = principal output • Polymorphic = policing/control
82
Question
Answer
83
**What is the entorhinal cortex?**
• Cortex in the **medial temporal lobe** • Acts as the **main gateway between neocortex and hippocampus**
84
**Why is the entorhinal cortex important in memory?**
• Funnels **cortical information into the hippocampus** • Carries **processed hippocampal output back to cortex**
85
**Is the entorhinal cortex neocortex or allocortex?**
• **Transitional cortex (peri-/mesocortex)** • Lamination like neocortex • Connectivity like allocortex
86
**How many layers does the entorhinal cortex have?**
• **Six layers (I–VI)** • Only **II, III, and V** are exam-critical
87
**What is special about Layer II of the entorhinal cortex?**
• **Main input layer to the hippocampus** • Key entry point for memory processing
88
**Where does Layer II project to?**
• **Dentate gyrus** (and CA3) • Via the **perforant path**
89
**What type of neurons are found in Layer II?**
• Mainly **stellate cells** • Excitatory projection neurons
90
**Why is Layer II important for memory?**
• First cortical station sending information into **hippocampal memory circuits**
91
**What is the main role of Layer III of the entorhinal cortex?**
• Sends information **directly to CA1** of the hippocampus
92
**How does Layer III differ from Layer II?**
• **Layer II → dentate gyrus / CA3** • **Layer III → CA1 directly** • Different hippocampal targets
93
**What is special about Layer V of the entorhinal cortex?**
• **Main output layer** from hippocampus to cortex
94
**What information reaches Layer V?**
• **Processed hippocampal output** • Memory-encoded information
95
**Where does Layer V send information?**
• Back to **widespread neocortical areas**
96
**Why is Layer V crucial for memory consolidation?**
• Allows **hippocampal memories to be redistributed to cortex** • Supports long-term storage
97
**What is Layer I of the entorhinal cortex?**
• **Molecular layer** • Contains dendrites and synapses • Very few cell bodies
98
**What should you know about Layers IV and VI of the entorhinal cortex?**
• **Less prominent or variable** • Not commonly tested in detail for MRCPsych Part A
99
**Describe the information flow through the entorhinal cortex.**
• Neocortex → entorhinal cortex • **Layer II → dentate gyrus / CA3** • **Layer III → CA1** • Hippocampus processes memory • **Layer V → neocortex**
100
**Does the entorhinal cortex send input only to the dentate gyrus?**
• ❌ **No** • **Layer III sends input directly to CA1**
101
**Is the entorhinal cortex part of the hippocampus proper?**
• ❌ **No** • It is **separate**, but tightly connected
102
**Is Layer V an input layer?**
• ❌ **No** • **Layer V is an output layer** to neocortex
103
**What is an easy way to remember entorhinal cortex layers?**
• **2 IN, 5 OUT** • Layer II → in to dentate gyrus • Layer III → in to CA1 • Layer V → out to neocortex
104
**Give a one-line summary of entorhinal cortex function.**
• **Entrance and exit hub** between neocortex and hippocampus for memory
105
Question
Answer
106
**What is the big-picture concept of the paleocortex?**
• A type of **allocortex** (older cortex) • Primarily involved in **olfaction (smell)** • Has **fewer layers than neocortex** • Safely learned as having **three functional layers** for exams
107
**What is the paleocortex?**
• An **evolutionarily older cerebral cortex** • Part of the **allocortex** • Specialised for **olfactory processing**
108
**Where is the paleocortex found?**
• **Piriform cortex** (core olfactory cortex) • Areas around the **olfactory tract** • Strong connections to **limbic structures** (emotion and memory)
109
**How many functional layers does the paleocortex have?**
• **Three functional layers** • Molecular layer • Cell body (principal neuron) layer • Deep/polymorphic layer
110
**What is the molecular layer of the paleocortex?**
• **Outermost layer** of the paleocortex • Contains **very few neuron cell bodies**
111
**What structures are found in the molecular layer?**
• **Dendrites** of deeper neurons • **Incoming axons** (especially from olfactory bulb) • **Large numbers of synapses**
112
**How does the molecular layer receive smell signals?**
• Odour activates receptors → signals reach **olfactory bulb** • Axons project **directly** to paleocortex • Axons enter at **molecular layer** • Dendrites extend upward • **Synapses form here**
113
**Why do synapses mainly occur in the molecular layer?**
• Designed for **connectivity** • Large open space • Dense dendritic branching • Few cell bodies • Enables rapid signal spread
114
**What is the cell body (principal neuron) layer?**
• **Middle layer** of the paleocortex • Contains **principal excitatory neurons** and **interneurons**
115
**What is special about neurons in the cell body layer?**
• **Less orderly arrangement** than neocortex • Reflects **primitive cortical organisation**
116
**What is the function of the cell body layer?**
• Receives integrated input from molecular layer • **Processes smell information** • Links smell with **emotion and memory**
117
**Why is the paleocortex simpler than neocortex?**
• Smell is an **ancient sense** • Requires speed and emotional salience • Prioritises **fast limbic connections**
118
**What is the deep (polymorphic) layer of the paleocortex?**
• **Deepest layer** • Called polymorphic due to **varied cell shapes**
119
**What structures are found in the deep layer?**
• **Interneurons** (mainly inhibitory) • Axons projecting to **limbic structures** and other cortex
120
**What is the function of the deep/polymorphic layer?**
• **Modulates cortical activity** • Prevents over-excitation • Directs output to **amygdala** and **hippocampus**
121
**How does smell information flow through the paleocortex?**
• Olfactory bulb → **molecular layer** • Processing in **cell body layer** • Output via **deep layer** to limbic system
122
**What is the key exam twist about olfaction?**
• Smell reaches the cortex **without an initial thalamic relay**
123
**How does paleocortex differ from neocortex?**
• Paleocortex: older, ~3 layers, smell, strong limbic links • Neocortex: newer, 6 layers, cognition and perception
124
**Which statements about the paleocortex are false?**
• ❌ Has 6 layers • ❌ Molecular layer full of cell bodies • ❌ Smell first relays in thalamus • ❌ Paleocortex equals neocortex
125
**What mnemonic helps remember paleocortex layers?**
• **M–C–D** • Molecular = meet smell signals • Cell body = compute meaning • Deep = direct and dampen output
126
**What phrase summarises paleocortex function?**
• **Paleo = Primitive Perfume Pathway** • Old cortex • Smell • Fast limbic links
127
**What are the five key exam facts about the paleocortex?**
• Allocortex for **olfaction** • **Three functional layers** • Molecular = synaptic input • Cell body = processing • Deep = modulation and limbic output
128
```csv
129
Question
Answer
130
What is the overall job of the entorhinal–hippocampal system?
To encode, organise, and export memories.
131
What is the role of the entorhinal cortex in the memory system?
It acts as the gateway between the neocortex and hippocampus.
132
What is the role of the hippocampus proper (CA1–CA3)?
It processes and integrates memory information.
133
What is the role of the neocortex in memory?
Long-term memory storage.
134
What is meant by the hippocampus proper?
The Cornu Ammonis (CA) regions of the hippocampus.
135
Which regions are included in the hippocampus proper?
CA1, CA2, and CA3.
136
Which structure is NOT part of the hippocampus proper?
The dentate gyrus.
137
What layers does each CA region have?
Three layers: molecular layer, pyramidal cell layer, and polymorphic layer (stratum oriens).
138
What is the function of the molecular layer in CA regions?
Receives synaptic inputs onto dendrites.
139
What is the function of the pyramidal cell layer?
Contains principal pyramidal neurons that generate output.
140
What is the function of the polymorphic layer (stratum oriens)?
Inhibition and modulation of hippocampal activity.
141
What is the main role of CA3?
Associative memory and pattern completion.
142
What is meant by pattern completion in CA3?
Reconstructing a full memory from partial input.
143
How does information reach CA3?
From entorhinal cortex Layer II via the dentate gyrus.
144
Which fibres carry information from the dentate gyrus to CA3?
Mossy fibres.
145
What are mossy fibres?
Axons of dentate gyrus granule cells.
146
From where to where do mossy fibres project?
From the dentate gyrus to CA3 pyramidal neurons.
147
Where do mossy fibres synapse?
On proximal dendrites of CA3 pyramidal neurons in the molecular layer.
148
Why are mossy fibres important?
They provide strong, sparse input that supports pattern separation.
149
What is the key exam fact about mossy fibres?
Mossy fibres = dentate gyrus → CA3.
150
Why does CA3 require mossy fibre input?
To receive separated inputs and prevent memory overlap.
151
How does CA3 send information to CA1?
Via Schaffer collaterals.
152
What are Schaffer collaterals?
Axon branches of CA3 pyramidal neurons.
153
From where to where do Schaffer collaterals project?
From CA3 to CA1.
154
Are Schaffer collaterals neurons or axons?
They are axons.
155
Where do Schaffer collaterals synapse?
On dendrites of CA1 pyramidal neurons in the molecular layer.
156
What is the function of Schaffer collaterals?
They transfer processed associative memory from CA3 to CA1.
157
Why are Schaffer collaterals high-yield for exams?
They are a classic site of long-term potentiation (LTP).
158
What is the main role of CA1?
Final integration and output of hippocampal processing.
159
What inputs does CA1 receive?
Input from CA3 via Schaffer collaterals and direct input from entorhinal cortex Layer III.
160
Why does CA1 receive two inputs?
To compare stored memory patterns with current cortical context.
161
Why is CA1 considered the main output region?
Most hippocampal output originates from CA1 pyramidal neurons.
162
Where does CA1 send its output?
To entorhinal cortex Layer V, then to the neocortex.
163
What clinical vulnerability is associated with CA1?
High sensitivity to hypoxia, especially after cardiac arrest.
164
What is the primary role of CA2?
Social and contextual memory.
165
How is CA2 different from CA1 and CA3?
It is smaller, has fewer recurrent connections, and a modulatory role.
166
Which neurons generate hippocampal output?
CA1 pyramidal neurons.
167
In which layer are CA1 pyramidal neurons located?
The pyramidal cell layer.
168
How does hippocampal output leave the system?
CA1 → entorhinal cortex Layer V → neocortex.
169
Why is entorhinal cortex Layer V important?
It is the exit layer for hippocampal output.
170
Describe the full entorhinal–hippocampal memory circuit.
Neocortex → EC → EC Layer II → dentate gyrus → CA3 via mossy fibres → CA1 via Schaffer collaterals → EC Layer V → neocortex.
171
Which statement is false: Mossy fibres project CA3 to CA1?
False.
172
Which statement is false: Schaffer collaterals are neurons?
False.
173
Which statement is false: Hippocampal output leaves from the molecular layer?
False.
174
Which statement is false: CA3 is the main output region?
False.
175
What is the simplest mnemonic for hippocampal fibres?
Mo → 3, Sch → 1.
176
What does the mnemonic Mo → 3 mean?
Mossy fibres project to CA3.
177
What does the mnemonic Sch → 1 mean?
Schaffer collaterals project to CA1.
178
What is a one-line role summary of CA3?
Builds associations.
179
What is a one-line role summary of CA1?
Checks, integrates, and exports memory.
180
What is a one-line role summary of CA2?
Social memory modulation.
181
What are the key MRCPsych Part A take-home points?
Mossy fibres = dentate → CA3; Schaffer collaterals = CA3 → CA1; inputs synapse in molecular layer; output from pyramidal layer; CA1 is main output; exit via entorhinal Layer V.
182
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183
```csv
184
Question
Answer
185
What is the entorhinal cortex?
A cortical area in the medial temporal lobe that acts as the main gateway between the neocortex and the hippocampus and is essential for memory formation and consolidation.
186
Is the entorhinal cortex part of the hippocampus?
No. It is a separate cortical structure that is tightly connected to the hippocampus.
187
Is the entorhinal cortex paleocortex?
No. Paleocortex is primarily involved in olfaction; the entorhinal cortex functions as a memory gateway.
188
What type of cortex is the entorhinal cortex?
A transitional cortex, also called peri-allocortex or mesocortex, lying between neocortex and allocortex.
189
How is the entorhinal cortex described in exam phrasing?
It has lamination like neocortex but connectivity like allocortex.
190
How many layers does the entorhinal cortex have?
Six layers (Layers I–VI).
191
Which entorhinal cortex layers are exam-critical?
Layers II, III, and V.
192
Why are Layers II, III, and V high-yield?
They carry all major information flow: Layer II and III provide hippocampal input, and Layer V carries hippocampal output.
193
What is the main role of entorhinal cortex Layer II?
It is the main input layer to the hippocampus.
194
What type of neurons are found in Layer II of the entorhinal cortex?
Mainly stellate cells, which are excitatory (glutamatergic).
195
Where does entorhinal cortex Layer II project?
To the dentate gyrus and indirectly to CA3 via the perforant path.
196
What is the perforant path?
The major fibre pathway carrying input from entorhinal cortex Layer II into the hippocampus.
197
What is the key exam fact about Layer II projections?
Layer II projects to the dentate gyrus and CA3 via the perforant path.
198
How does Layer II input reach hippocampal neurons step by step?
Layer II axons travel via the perforant path, enter the hippocampus at the molecular layer, and synapse on dendrites of pyramidal neurons whose cell bodies lie in the pyramidal layer.
199
Why do Layer II inputs synapse in the molecular layer?
Because the molecular layer contains dendrites, which are the sites of synaptic input.
200
What is the role of entorhinal cortex Layer III?
It provides direct cortical input to CA1.
201
Which hippocampal region does Layer III project to?
CA1 of the hippocampus proper.
202
How does Layer III differ from Layer II?
Layer II projects to the dentate gyrus and CA3, whereas Layer III projects directly to CA1.
203
Where do Layer III axons synapse in CA1?
In the molecular layer of CA1 on dendrites of pyramidal neurons.
204
How does the hippocampus proper handle entorhinal inputs?
Inputs arrive in the molecular layer, pyramidal neurons in the pyramidal layer integrate and fire, and the polymorphic layer provides modulation and inhibition.
205
Do CA1, CA2, and CA3 follow the same basic laminar organisation?
Yes. All have molecular, pyramidal, and polymorphic layers.
206
What is special about entorhinal cortex Layer V?
It is the main output layer carrying information out of the hippocampus.
207
Which hippocampal neurons generate the main output signal?
CA1 pyramidal neurons.
208
In which layer are CA1 pyramidal neurons located?
The pyramidal cell layer.
209
How does hippocampal output reach entorhinal cortex Layer V step by step?
CA1 pyramidal neurons fire, their axons project to the entorhinal cortex, and they synapse onto Layer V pyramidal neurons.
210
What type of neurons are found in entorhinal cortex Layer V?
Pyramidal neurons that act as long-range projection neurons.
211
Where does entorhinal cortex Layer V send information?
To widespread areas of the neocortex, including association, prefrontal, and temporal cortices.
212
Why is Layer V essential for memory consolidation?
It redistributes hippocampal-processed memories to the neocortex for long-term storage.
213
Describe the full information flow involving the entorhinal cortex.
Neocortex → entorhinal cortex → Layer II to dentate gyrus/CA3 → Layer III to CA1 → hippocampal processing → CA1 to entorhinal Layer V → neocortex.
214
Which statement is false: The entorhinal cortex is paleocortex?
False.
215
Which statement is false: The entorhinal cortex is part of the hippocampus proper?
False.
216
Which statement is false: Layer V is an input layer?
False.
217
Which statement is false: All entorhinal input goes via the dentate gyrus?
False.
218
Which statement is false: Inputs synapse on pyramidal cell bodies?
False.
219
What is the best mnemonic for entorhinal cortex layers?
2 IN, 3 IN, 5 OUT.
220
What does the mnemonic '2 IN' refer to?
Layer II input to dentate gyrus and CA3.
221
What does the mnemonic '3 IN' refer to?
Layer III input directly to CA1.
222
What does the mnemonic '5 OUT' refer to?
Layer V output to neocortex.
223
What phrase summarises entorhinal cortex function?
Entorhinal cortex is the entrance and exit of memory.
224
What are the seven key MRCPsych Part A facts about the entorhinal cortex?
It is the gateway between neocortex and hippocampus, it is not paleocortex, it is transitional cortex, it has six layers, Layer II projects to dentate gyrus/CA3, Layer III projects to CA1, and Layer V sends output to neocortex.
225
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Cranial nerves
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