BRAIN ORGANIZATION

Question 1

Anterior or Rostral

Answer 1

Front

Question 2

Posterior or Caudal

Answer 2

Back

Question 3

Dorsal

Answer 3

Top

Question 4

Ventral

Answer 4

Bottom

Question 5

Lateral

Answer 5

Side

Question 6

Medial

Answer 6

Middle

Question 7

Frontal lobe

Answer 7

Decision-making, planning, motor control

Question 8

Parietal lobe

Answer 8

Touch, spatial transformations

Question 9

Occipital lobe

Answer 9

Vision

Question 10

Temporal lobe

Answer 10

Hearing, higher-level vision

Question 11

FIrst-order thalamic areas

Answer 11

Thalamic areas that recieve major input directly from the sensory periphery (eye, ear, skin)

Question 12

Prefrontal association area

Answer 12

Personality

Question 13

Limbic association area

Answer 13

Emotional behavior

Question 14

Wernicke’s area

Answer 14

Language comprehension

Question 15

Cerebral cortex can be thought of as being hierarchically organized

Answer 15

– Cerebral cortex contains primary sensory areas, secondary sensory areas, higher-order areas
– Low-level (i.e., simple) sensory information represented in primary sensory areas
e.g., line orientation in primary visual cortex
– Higher-level (i.e., more complex/abstract) information represented in higher-order areas
e.g., objects in inferior temporal cortex; or goals in prefrontal cortex

Question 16

Feedforward pathways are directed from posterior to anterior cortical areas

Answer 16

– Feedforward pathways generally carry information about the sensory environment
– Higher-level information is processed more anteriorly along the pathway

Question 17

Feedback pathways are directed from anterior to posterior cortical areas

Answer 17

– Feedback pathways carry information about, e.g., goals, attention priorities, or predictions
– Feedback tends to modulate (increase or decrease) neural activity in more posterior areas
e.g., to amplify or filter out information based on behavioral context

Question 18

What is the role of the indirect pathways between the cortical areas via the higher-order thalamus?

Answer 18

Hypothesis: Indirect pathways facilitate processing of only the behaviorally relevant info in the cortex

Direct pathways between cortical areas carry detailed info about sensory stimuli

Question 19

Neocortex has 6 layers

Answer 19

But different brain areas show different layering

Question 20

Cytoarchitectonics

Answer 20

Arrangement of neurons in the brain

Cytoarchitectonic maps:
– For example, Brodmann (1909)

Question 21

Vertical (radial) organization of neurons in the cortex:

Answer 21

– If you move an electrode into the brain, perpendicular to the
cortical surface, cells tend to share similar response properties
– E.g., cells may signal the same location and/or stimulus feature
– These cells are interconnected and/or share extrinsic connections

Question 22

Scale of vertical organization

Cortical column

macrocolumn

Answer 22

– Extends down through cortical layers
– About 0.4-0.5 mm in diameter

Columns and minicolumns repeat across the cortex

Question 23

Scale of vertical organization

Cortical minicolumn

microcolumn

Answer 23

– Column comprised of minicolumns
– Minicolumn about 30-50 microns in diameter

Columns and minicolumns repeat across the cortex

Question 24

Cell types in the cerebral cortex

Answer 24

Inhibitory cells hyperpolarize post-synaptic cells
Excitatory cells depolarize post-synaptic cells

Question 25

Prefrontal cortex predominantly granular frontal cortex

Answer 25

Rodents do not have a granular (sizeable - layer 4 present) frontal cortex

Question 26

Cell level

Answer 26

Think about whether cell is excitatory or inhibitory and about size and orientation of the dendritic field

Large dendritic field integrates input from more cells over larger area

Question 27

Circuit level

Answer 27

Think about lamination pattern (layering) or other arrangement of cells, whether connections are feedforward or feedback, and circuit connections and which are absent

Question 28

Systems level

Answer 28

Think about which brain areas are connected and which are not. Are there reciprocal connections? Unidirectional?

Unidirectional connection imposes constraints on processing

Question 29

Canonical microcircuit of the cerebral cortex

Answer 29

– Layer 4 receives feedforward input from thalamus or another cortical area
– Layer 2/3 sends feedforward output to another cortical area
– Layer 5 sends feedforward output to subcortical areas
– Layer 6 sends feedback output to the thalamus or another cortical area
– Layer 1 receives feedback input from another cortical area (and thalamus)