Problem 3

Question 1

Gating system

Answer 1

Involves the basal ganglia being a gate that regulates the passage of information from one neural circuit to the other

–> this way it solves action selection problems

e.g. Can be applied to motor system as well as WM (motor vs PFC)

Question 2

Name the traditional role of the medium spiny neurons in motor gating.
(Go vs No-go cells)

Answer 2

1. Go cells facilitate recurrent thalamo-cortical information flow
   - -> opens gate
2. No-go cells block this info flow
   - -> close gate

THUS: planned motor action triggers activity in go cells via corticospinal projection
- at the same time alternative action plans trigger no-go cells

e.g. thalamus –> motor neurons –> movement

Question 3

Updated view of the role of medium spiny neurons in motor gating.

Answer 3

Both types of cells are co-active when initiating motor movement and do not work independently

Question 4

Input gating of WM

Answer 4

1. Go cells facilitate recurrent thalami-prefrontal info flow for WM updating
   - -> when useful info becomes available in the environment
2. No-go cells are triggered by distracting sensory representations
   - -> updating thus prevented

Question 5

Output gating of WM

Answer 5

Biased competition model of prefrontal function

–> info residing in WM actively biases behavior

THUS: not all info in WM might be relevant and might interfere with action at hand

Question 6

Solution to the biased competition model of PF function

Answer 6

Humans are capable of selecting info from within WM

–> BG-mediated gating mechanisms select the outputs of WM

Question 7

How is WM reallocated when the already-stored info later turns out to be irrelevant ?

Name the 3 possibilities.

Answer 7

1. Active removal process is necessary
2. Passive decay
3. Irrelevant representations linger until they are overwritten with new info

Question 8

Input, output & reallocation of WM items.

Answer 8

1. Input
   - -> what items go into WM
2. Output
   - -> what items can be used
3. Re-allocation
   - -> what items can be eliminated because they become obsolete

Question 9

Cognitive deficits in people suffering from Parkinsons disease

Answer 9

Set shifting abilities

–> ability to alter behavior according to changes in the dimensional relevance of stimuli

Question 10

Task-set switching procedure

Answer 10

Requires the subjects to switch between letter- and digit-naming tasks on every second trial

–> each stimulus consisted of 2 closely adjacent characters presented side by side

Question 11

Cross-talk condition

Task-set switching procedure

Answer 11

Stimulus contains

1. both a letter and a digit
   - -> character relevant to competing task + actual relevant one
2. or the relevant character adjacent to neutral character/symbol
   - -> e.g. “#”

THUS: Filtering of irrelevant information is needed to perform well on this task

Question 12

No cross-talk condition

Task-set switching procedure

Answer 12

Stimulus consists of attributes only associated to the relevant task

–> filtering of irrelevant info is NOT required

Question 13

The striatum can be divided into several subdivisions. Name them.

Answer 13

Dorsal, ventral + central striatum

Question 14

Dorsal striatum

Answer 14

Consists of

1. Caudate nucleus
2. Putamen

–> which are separated by internal capsule

AND: receives input from sensory motor areas

3. Nucleus accumbens

Question 15

Ventral striatum

Answer 15

Consist of

1. Nucleus accumbens
2. Medial + ventral Caudate and putamen

AND: receives input from limbic areas

Question 16

Where does the striatum receive its input from ?

Answer 16

1. Cerebral cortex
   - -> topographic input
2. Thalamus
3. Brain stem
   - -> dopaminergic cells

BUT: input from cortex + thalamus terminate in general topographic manner

Question 17

Where does the striatum send its output to ?

Answer 17

1. Pallidal complex
   - -> Globus pallidus external, internal segment (GPi, GPe) + ventral pallidum
2. Substantia nigra
   - -> pars reticulata vs compacta (SNr, SNc)

Question 18

Name the main striatal cells.

Answer 18

1. Projection neurons
   - -> Medium spiny neurons (95%)
2. Interneurons

Question 19

Direct cortico-basal ganglia pathway

Answer 19

1. Output from the GPi and SNr
2. to Thalamus
3. Cortex

Question 20

Indirect cortico-basal ganglia pathway

Answer 20

1. Output from GPe and VP
2. to subthalamic neucleus
3. GPi

Question 21

Hyperdirect pathway

Answer 21

STN receives direct projection rom all parts of the frontal cortex