The Corticohippocampal Circuit: Anatomy

Question 1

what controls executive control in the circuit?

Answer 1

dlPFC

Question 2

what connection controls dopaminergic modulation?

Answer 2

connection between midbrain and dlPFC

Question 3

what controls integration and storage of multiple sources and modalities of information

Answer 3

sensory association areas

Question 4

what controls encoding and recall of declarative memories?

Answer 4

hippocampal formation

Question 5

how does information move in this circuit?

Answer 5

bidirectional, generalized and flexible circuit

Question 6

cortical regions

Answer 6

nearly 360 distinct cortical regions

Question 7

Brodmann areas

Answer 7

identified nearly 50 on each hemisphere

Question 8

how did brodmann identify areas?

Answer 8

• looking at post-mortem brain
• looking at the structure of cells in the cortex

Question 9

columns and layers in cortical region

Answer 9

columns and layers within columns
(ex. single rat whisker has one to one connection with column in brain) similar to humans

Question 10

1 to 1 ratio in humans

Answer 10

can do this with visual, audio, sense of touch, motor functioning in humans

Question 11

homunculus through the years

Answer 11

got it wrong, between single one to one mapping is action/ body, which creates better control of body and mind

Question 12

columns layer 3

Answer 12

intra cortical communication
primarily supports PFC connections with other regions
(critical executive control) how different layers of cortex communicate with each other

Question 13

column layers 4

Answer 13

input

Question 14

column layers 5-6

Answer 14

output
to all subcortical targets (hippocampus, amygdala, VS, thalamus, brainstem)

Question 15

layers

Answer 15

gabaergic inhibitory neurons (shaping input and output of pyramidal neurons)

Question 16

communication between dlPFC and sensory association areas

Answer 16

dorsal (“Where”) stream
primary visual cortex (goes to dorsal and ventral)
ventral (“What”) stream

Question 17

unimodal –> heteromodel (info processing)

Answer 17

(goes from one to many modes of info processing)
PFC - heteromodal hotspots

Question 18

where does dlPFC get info from?

Answer 18

auditory cortex, posterior parietal cortex, motor structures, medial temporal structures, inferior temporal cortex

Question 19

STUDY: brain size and connectivity

Answer 19

early brain development experiences a massive expansion of size
- no new neurons but greater connections of existing neurons (synaptic density)

Question 20

what is synaptic density?

Answer 20

greater connection of existening neurons
differentianes human brain from other brains

Question 21

pruning

Answer 21

around 6 years old, thinning of connections
activity dependent pruning, to make us a highly efficient system

Question 22

why PFC last to mature?

Answer 22

takes not of time to separate the signal from the noise

Question 23

Hippocampal formation

Answer 23

supports declarative memories
little change with development bc critical to survival

Question 24

HF anatomy

Answer 24

tail, body, head
“seahorse”

Question 25

gray matter of HF

Answer 25

cornu ammonis (CA)

Question 26

anatomy of tail

Answer 26

dentate gyrus –> cornu ammonis –> entorhinal cortex –> parahippocampal cortex
subiculum around

Question 27

midbrain

Answer 27

DA signaling from VTA critical for input-dependent activity of dlPFC