Brain Pathways Flashcards

1
Q

What is the PNS divided into?

A

Somatic and autonomic
Somatic; LMN, sensory fibres
Autonomic; sympathetic and parasympathetic; smooth muscle and glands

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the diencephalon?

A

Thalamus and hypothalamus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What does the lateral (sylvian) fissure separate?

A

The frontal/parietal lobes from the temporal lobe

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the function of the superior termporal gyrus?

A

Primary auditory cortex

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the function of the cingulate gyrus?

A

Involved in emotion and memory

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the function of the corpus callosum?

A

White matter that connects left and right hemisphere

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What makes up the basal ganglia?

A
Caudate nucleus
Putamen 
Globus pallidus
Substantia nigra
Subthalamic nucleus
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the telencephalon?

A

Cortex
Basal ganglia
Limbic system

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the metencephalon?

A

Cerebellum

Pons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the myelencephalon?

A

Medulla

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the mesencephalon?

A

Midbrain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the basic function of the thalamus?

A

Relay station that sends information from the body to the cortex; specifically the post-central gyrus of the parietal lobe; somatosensory cortex
It also relays vision, auditory information and balance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is special about olfactory information?

A

Does not pass through the thalamus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What do cortical projections to the thalamus play a role in?

A

Selective attention

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the main functions of the frontal lobe?

A
Reasoning
Movement 
Speech (brocas area) 
Personality 
Emotional behaviour
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the main functions of the parietal lobe?

A

Somatosensory processing

Integrating visual and motor signals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are the main functions of the temporal lobe?

A

Higher level visual perception
Auditory perception
Language
Memory

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How many cortical layers make up the laminar structure of the neocortex?

A

6

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

At what layer does sensory information from the thalamus reach the cortex?

A

Layer 4

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Aside from sensory information, what layer does information from other regions of the cortex reside in?

A

2,4 and 5

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

From what layer of the neocortex do outputs to the brainstem and spinal cord originate from?

A

5

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

From what layer do outputs back to the thalamus originate from?

A

6

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

From what layer do cortical-cortical projections arise from?

A

Superficial layers 2 and 3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is special about the primary visual cortex in terms of the laminar structure?

A

Has a large layer 4 (input layer)

Small layer 5 (output to spinal cord and brainstem)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What is special about the laminar structure of the primary motor cortex?

A

Very small layer 4; sensory input

Large layer 5; motor information to spinal cord

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What are some key brodmann areas?

A
Area 6; supplementary and premotor area. Planning of movement 
Area 4; primary motor cortex
Somatosensory cortex; 3, 1 and 2
Posterior parietal cortex; areas 5 and 7
Visual cortex; areas 17, 18, 19
Primary visual cortex; area 17
Auditory cortex; areas 41,42
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What is the function of the polymodal association cortex?

A

For example, posterior parietal cortex

Involved in high level sensory representations for example representing the space around us

28
Q

What if the function of the prefrontal cortex?

A

Higher level planning and decision making

29
Q

What are the dorsal and ventral visual streams?

A

2 major hierarchal pathways that visual information can follow:
Dorsally; Posterior parietal cortex
Ventrally; inferotemporal cortex

30
Q

What is the role of the dorsal stream/ posterior parietal cortex?

A

Spatial perception

Damage in this region causes spatial neglect

31
Q

What is the role of the ventral stream/ inferotemporal (IT) cortex?

A
Object recognition 
Semantic memory (what objects are, people, words and facts)
32
Q

What is the role of the lateral prefrontal cortex?

A

Executive function
Planning
Working memory

33
Q

What is the role of the ventromedial/ orbitofrontal cortex?

A

Social cognition
Decision making
Substantially damaged in phineus gage

34
Q

What is the role of the anterior cingulate cortex?

A

Reward based learning

Social cognition

35
Q

What is working memory?

A

Holds things in mind whilst you are thinking about something

36
Q

What role does the lateral PFC play in working memory?

A

Densely interconnected with different cortex regions

Thought to provide a transient buffer linking memory representations stored in separate cortical regions

37
Q

Where is the hippocampus located?

A

Deep within the medial temporal lobe next to the lateral ventricle

38
Q

What cortical regions of the medial temporal lobe surrounds the hippocampus?

A

Entorhinal cortex
Rhinal sulcus
Perirhinal cortex
Parahippocampal cortex

39
Q

What layers of tissue forms the hippocampus along the rostral/caudal section of the brain?

A

CA3 and CA1

Dentate gyrus

40
Q

What is the flow of information between processing in the MTL for memory?

A

Unimodal/ polymodal association areas (frontal, temporal and parietal)
These relay to the parahippocampal and perirhinal cortex
These relay to the entorhinal cortex
The entorhinal cortex relays to the hippocampus
The hippocampus will then finally relay to the subcortical areas via the fornix
All of these connections are bidirectional; information flows both in and out

41
Q

Describe the trisynaptic circuit of the hippocampus

A

The entorhinal cortex initially sends projections to the dentate gyrus (perforant pathway)
These projections make synaptic connections with the dentate granule cells
These granules send projections to CA3 via mossy fibre
The CA3 neurons then project to CA1 via Schaffer collateral pathway
CA1 then sends projections back to the EC either directly or via subiculum

42
Q

What are some of the first cells to show pathological changes in AD?

A

Layer 2 entorhinal stellate neurones that provide the main input to the dentate gyrus and CA3

43
Q

How do the CA3 neurons form an autoassociative network?

A

The neurons from CA3 not only project to CA1 via schaffer collateral pathway but also loop back to project onto their own dendrites (recurrent collaterals)

44
Q

Why is the autoassociative network of CA3 important?

A

The neurons can change in strength, there is a simple form of learning
It also allows for pattern completion (this is to do with synaptic plasticity and learning)

45
Q

What is the role of the fornix?

A

Connects the hippocampus to the anterior nucleus of thalamus, mamillary bodies, cingulate gyrus and hypothalamus (diencephalon)

46
Q

What is the papez circuit?

A
Subcortical projections of the hippocampus via the fornix 
Fornix to: 
- Mamillary bodies
- Hypothalamus (emotional expression) 
- Anterior nucleus of thalamus
- Cingulate cortex (emotional experience) 
- Neocortex (emotional colouring) 
- Back to hippocampus 
Damage can cause memory impairment
47
Q

What is the limbic system?

A

Group of structures involved in emotion and memory

48
Q

What is involved in the limbic system?

A

Fornix (carries info from hippocampus to mamillary bodies)
Mamillary body (memory, connections with amygdala and hippocampus
Septal nucleus (pleasure, reward and reinforcement)
Hypothalamus (hormonal influence via anterior pituitary)
Amygdala (fearful and anxious emotions)
Hippocampus (memory)
Parahippocampal gyrus (memory)
Cingulate cortex - above corpus callosum (emotion and memory)

49
Q

What motor loops are present between the basal ganglia and the cortex?

A

Motor area to basal ganglia and back

Motor area to cerebellum then into the basal ganglia

50
Q

Describe the direct pathway in the basal ganglia

A
Facilitates movement (inhibition of inhibition) 
Neurons from striatum sends inhibitory neurons to the internal segment of globus pallidus allowing movement via thalamus
51
Q

Describe the indirect pathway of the basal ganglia

A
Inhibits movement (via STN)
Inhibitory signals sent from striatum to external globus pallidus
This prevents GPe from inhibiting the STN which allows the STN to increase output to GPi - and therefore inhibits the thalamus and consequentially movement
52
Q

Describe the hyperdirect pathway of the basal ganglia

A
Inhibits movement (supresses unwanted movement) 
Cortical outputs contact STN directly. This then projects to GPi; inhibits thalamus
53
Q

What type of neurons make up the striatum and globus pallidus?

A

Inhibitory

54
Q

At a cellular level, what is the striatum made up from?

A

Medium spiny neuron (MSN)

55
Q

Describe the inputs to medium spiny neurons (MSN)

A

Excitatory via glutamate from cortex and thalamus
Inhibitory via GABAergic interneurons
Excitatory or inhibitory via dopaminergic neurons from pars compacta of substantia nigra

56
Q

What is the overarching output of medium spiny neurons?

A

Inhibitory

57
Q

What makes up the pars reticulata of the substantia nigra?

A

GABA inhibitory neurons

58
Q

Describe the excitatory pathway of the direct pathway in respect to dopamine

A

Direct pathway expresses D1 receptors
These are Gs linked and triggers an intracellular cascade that ultimately leads to an increased excitability of the neuron

59
Q

Describe the inhibitory pathway of the the indirect pathway in respect to dopamine

A

Expression of D2 receptors

These inhibit the cAMP pathway which ultimately leads to a decreased excitability of the cell

60
Q

Why does dopamine have an overall effect of facilitating movement in the basal ganglia?

A

It activates the direct pathway; increases excitability of neuron
Inhibits the inhibitory pathway; causes overall decrease in excitability of the cell

61
Q

What are betz cells?

A

Neurons present in layer 5 of the primary motor cortex

Cell bodies whose axons run down to the corticospinal tract

62
Q

What is the difference between the anterior and lateral corticospinal tract?

A

Anterior; proximal musculature; decussation at level of LMN

Lateral; distal musculature; decussation at pyramids

63
Q

Describe an UMN lesion

A

Weakness or paralysis
Hyperactive reflexes
Decreased motor control
Spastic muscle tone

64
Q

Where do LMNs leave the spinal cord?

A

Alpha motor neurons leave the ventral (anterior) root of the spinal cord to innervate muscle

65
Q

What is a motor unit?

A

An alpha motor neuron and all of the muscle fibres that it innervates