Lecture 12 - The Ancient Forebrain - Basal Ganglia, Hippocampus and Amygdala

Question 1

How many nuclei does the basal ganglia encompass?

Answer 1

putamen, 
caudate nuclei, 
globus palidus, 
substatia nigra
subthalamic nuclei

Question 2

Where is the basal ganglia located?

Answer 2

Located laterally to thalamus and deep within the cortex. Subthalamic nuclei below thalamus.
Substantia nigra in midbrain but contributes to circuitry of basal nuclei

Question 3

What is the Putamen and Caudate nucleus collectively known as?

Answer 3

The striatum

Question 4

Is the basal ganglia another control centre in the brain?

Answer 4

yes,

Circuitry passess through here controlling motor action, executive function and emotional/procedural memory

Question 5

How does the basal ganglia manage to be closed?

Answer 5

This works through a series of inhibitory and disinhibitary connections;

All circuits take a route through the thalamus, which projects into the appropriate cortex site.

These circuits may mediate our actions depending on experience

Question 6

What is the Motor, Associative and Limbic loop?

Answer 6

Motor - motor control
Associative - Executive function
Limbic - Procedural Memory

Question 7

Describe the process of movement, and how motor loop is some ‘go’ signal?

Answer 7

1. Neurons in the Globus Pallidus fire at rest and inhibit VL in the thalamus
2. Commands for movement come from primary motor cortex and excite putamen neurons, which inhibit Globus pallidus neurons
3. These release Thalamic VL neurons from inhibition
4. These activate SMA in motor cortex

Question 8

In monkeys what neurones fire before any activity takes place?

Answer 8

PMA neurons

Question 9

What doe executive movements consist of?

Answer 9

involve learning new tasks, making decisions based on prior experience, optimise movements

Question 10

What does procedural memory consist of?

Answer 10

habits e.g. bike riding also known as non-declaritive memory

Question 11

What is the formation of factual memory created by?

Answer 11

the hippocampus

Question 12

What happens when structures are removed from the temporal lobe?

Answer 12

profound amnesia, suggests that memories are formed in the temporal lobe but not stored there

Question 13

what is the hippocampus important for?

Answer 13

formation and storage of declaritive memory, spatial memory and relational memory

Question 14

where is the hippocampus located?

Answer 14

part of the temporal lobe of the cerebrum, hidden from outside view and extends anteriorly into the brain

Question 15

Describe the appearance of the hippocampus?

Answer 15

It has a cylindrical/tubular structure that tapers as it extends back into the brain.

Like the verntricles and …this is a curved “C” structure which bends back on itself over the thalamus.

It looks like a seahorse

Question 16

What is the C shape of the hypothalamus continuous?

Answer 16

is continuous wih a white matter tract know as the fornix – this traverses the thalamus and ends at the hypothalamus

Question 17

what part of the brain is associated with emotive processing?

Answer 17

Limbic system

Question 18

What happens to hippocampus during Alzheimers?

Answer 18

Hippocampus degenerates during Alzheimer’s leading to memory loss and unchecked emotive expression.

Question 19

The hippocampus is linked to the hypothalamus (via fornix), which links to…?

Answer 19

Limbic lobe, more accurately known as the cingulate cortex – which has projections to hippocamus but also to neocrotex involved in sensory processing

Question 20

What is the hippocampus mainly associated with?

Answer 20

declarative memory - – facts, figures, events

may also be associated with working memory as well

Question 21

What may be the result of removing temporal lobe?

Answer 21

shows dimished ability to form working memories demonstrating a role for the hippocampus in this.

However, more evidence seems to show that the hippocampus provides context for long-term declarative memory

Question 22

What is relational memory?

Answer 22

the theory that the brain remembers things and spaces in an interconnected fashion

Question 23

What happens to people who have lost their temporal lobe to disease?

Answer 23

People who have lost temporal lobe funciton through disease or lobotomy, often have severe antergorade amnesia

Question 24

Do neurones fire when in a specific place it recognises?

Answer 24

yes, this is known as autobiographical memory

Question 25

What is the amygdala?

Answer 25

egg shaped portion of grey matters in the medial temporal lobe connected to the fronterior hippocampus

Question 26

What nuclei is the amygdala split into?

Answer 26

the corticomedial nuclei (middle of the cortex), basolateral nuclei (at the bottom) and the central nucleus

Question 27

What affect does lesions of the amygdala have in humans?

Answer 27

Have shown an emotional flattening.

Further, people have demonstrated difficultires in identifying the expression of fear in people.

Question 28

How does amygdala process information?

Answer 28

sensory informaiton is projected into the basolateral
nuclei

Basolateral also ouput to the cerebral cortex where conscience processign of the emotional experience occurs.

The central nucleur receive inputs from…and ouput to the hypothalamus (auonmic response) and brain-stem which can eleicit motor responses

Question 29

Give a summary of the forebrain?

Answer 29

Thalamus integrates sensory information

Hypothalamus controls bodies homeostasis and drive

Basal ganglia involved in initiating and mediating movement (including habit forming)

Hippocampus associated with declarative (factual) memory

Amygdala appears to process information on fear