Localisation of function in the brain

Question 1

Name the structure of the human nervous system

Answer 1

Central peripheral
/ \ / \
spinal cord Brain autonomic somatic
/ \
sympathetic parasympathetic

Question 2

What is the function of the frontal lobe

Answer 2

• Functions include: planning, judgement, problem solving, aspects of personality and emotions
  Primary motor cortex; responsible for skeletal muscle movement (each region controls different parts of the body, contra-lateral function: left primary cortex controls right, vice versa)

Question 3

What is the function of the temporal lobe

Answer 3

Processes auditory information as well as higher order visual information

Question 4

What is the function of Wernicke’s area

Answer 4

Function: Comprehension of speech

Question 5

What is the function of Geschwind’s territory

Answer 5

Provides parallel pathway connecting Broca’s area and processing the multiple properties of words, how they sounds look and represent

Question 6

process of neurotransmission

Answer 6

1. Presynaptic neuron receives input from a stimulus e.g. pain, heat neurotransmitter
2. Stimulus generates an action potential
3. The action potential propagates through the neuron and along the axon until it reaches the terminal button as the synapse
4. An action potential causes voltage-gated calcium channels to open and an influx of Ca 2+ ions
5. Increase in calcium causes vesicles containing neurotransmitter to fuse with the presynaptic cell membrane and release their contents into the synaptic cleft
6. The released neurotransmitter molecules diffuse across the synaptic cleft and bind to specific receptors on the postsynaptic membrane (lock and key process)
7. Depending on type of neurotransmitter released, receptor binding causes graded potential

Question 7

when does an action potential occur

Answer 7

action potential occurs if the combination of graded potentials exceeds the threshold (-55mV)

Question 8

What is glutamate and its function

Answer 8

• Major excitatory neurotransmitter in the CNS
• Plays critical role in cognitive, motor and sensory functions
• Primary mediator of nervous systems plasticity (memory)

Question 9

What is GABA and its function

Answer 9

• Major inhibitory neurotransmitter in the brain
• Plays a critical role in regulating neural activity and normal functioning (e.g. maintaining respiratory rate, inhibition of unwanted motor signals)

Question 10

what is acetylcholine and its function

Answer 10

• First neurotransmitter to be discovered and plays a major role in both nervous systems and is mainly excitatory but can also be inhibitory (depending on the receptor sub type activated)
• Is synthesised in and is released from cholinergic neurons
• Central cholinergic neurons are found in the basal forebrain, limbic system, basal ganglia and brain stem. They have vast projections to the cerebral cortex, hippocampus and cerebellum
• The central cholinergic system is important for:
  -> Memory formation (consolidation of short term memory)
  -> Attention and motivation and executive functioning
  -> modulation of arousal and sleep wake cycle
  -> control of tone, posture and initiation of movement or selection of wanted patterns of activity
• In the peripheral cholinergic system is important for:
  -> control of the parasympathetic response - decreases heart rate and blood pressure (vasodilation), bronchoconstriction, constriction of the pupils, stimulation of salivation, stimulation of digestion and urination (smooth muscle contraction)
  -> control of skeletal muscle contraction

Question 11

what is dopamine and its function, and where is it located?

Answer 11

Can be excitatory or inhibitory neurotrasmitter, depending on subtype activated. located in the midbrain and thalamus. Responsible for reward and motivation

Question 12

Dopamine location and function

Answer 12

• Is an excitatory or inhibitory neurotransmitter (depending on the receptor sub type activated). It is synthesised in and released from dopaminergic neurons and adrenal medulla (adrenal gland)
• CNS: Dopaminergic neurons are found in the mid-brain (substantia nigra) and hypothalamus. They have projections to the basal ganglia, limbic system and frontal cortex
• The dopaminergic system is involved in:
  -> selection of relevant motor programs and inhibition of irrelevant ones
  -> promotes smooth coordinated muscle movements
  -> motivation reward, biological drives, and addictive behaviours
  -> reward related learning and emotion
  -> attention, planning decision making, impulse control, sleep, memory and cognition
  -> regulation of renal function
• Dysfunction of dopaminergic system has been linked to
  -> Parkinson’s disease

Question 13

Seretonin location and function

Answer 13

• Serotonin plays a major role in the central and peripheral nervous system and can be inhibitory (main action) or excitatory (depending on the receptor sub type activated). Synthesised and released from serotonergic neurons
• Serotonergic neurons are found in the brainstem (midbrain) and they have widespread projections that innervate every major subdivision in the CNS. Serotonin is also provided in the GI tract
• Serotonergic system is involved in
  -> Regulation of mood, aggression, anger, perception, reward, neuroendocrine secretion, appetite, pain sensitivity, sexual behaviour, attention, memory and sleep wake cycles. Also involved in regulation of GI tract (contractions)
  -> major modulatory action (excitability of other neural systems e.g. increase excitability of motor neurons)

Question 14

Norepinephrine location and function

Answer 14

• Norepinephrine acts as a neurotransmitter and hormone. Major role in the central and peripheral nervous system and can be excitatory or inhibitory
• Norepinephrine is mainly synthesised in and released from adrenergic neurons that are found in the sympathetic nervous system and brainstem. They have projections to the hippocampus, cerebellum, amygdala, hypothalamus, spinal cord and cerebral cortex
• Norepinephrine is also secreted from adrenal medulla
• Serotonergic and noradrenergic systems help regulate many of the same functions CNS
• The adrenergic system is involved in:
  -> modulation of other neural systems
  -> Attention, alertness and the sleep wake cycle, appropriate responses to stressors, temperature, eating drinking, reproductive behaviour, emotional behaviour
  -> influences cognition behaviour
• The adrenergic system is critical for sympathetic response
  -> increase in blood pressure via vasoconstriction -> used to treat people with critical hypotension
  -> increase in heart rate and cardiac contractility
  -> dilation of pupils, inhibit salivation, inhibits urination

Question 15

Epinephrine location and function

Answer 15

• Acts as a hormone and an excitatory neurotransmitter. It plays a major role in the peripheral nervous system
• Epinephrine is mainly synthesised In and released from the adrenal medulla
• Epinephrine-containing neurons in the CNS are found in the brainstem and they project to the hypothalamus and thalamus. The functions of these neurons is not well understood
• Epinephrine is involved in the sympathetic response (hormone action)
  -> increased heart rate and blood flow
  -> increased inspiration (breathing) and lung capacity via vasodilation of the smooth muscles in the blood vessels and the bronchioles
  -> higher doses can increase pressure via vasoconstriction

Question 16

2 types of spinal reflexes

Answer 16

1. Monosynaptic
   
   2. Polysynaptic

Question 17

What is the cerebellum responsible for

Answer 17

• Responsible for smooth, coordinated voluntary movements, planning and execution of movement, maintenance of posture
• Determines the force, direction and momentum necessary to ensure each contraction is smooth and coordinated
• Continually compares the brains motor intention with the actual motor performance and sends out the messages to initiate the appropriate corrective action

Question 18

basal ganglia

Answer 18

• Provides feedback mechanisms to motor cortices for initiation and control of voluntary movements. Regulate posture and assist in learning new motor skills
• It is a collection of nuclei that include the caudate nucleus, the putamen, the globus pallidus. Highly complex connections with other parts of central nervous systems, like the cerebral cortex, the thalamus and brainstem. Two most important structures closely related to basal ganglia are the substantia are the nigra pf the midbrain and the subthalamic
• Info can flow in different pathways
  
  1. The direct pathways result in excitation of the motor cortex assisting with the initiation and execution of the desired voluntary movement
  2. The indirect pathway results in the inhibition of the motor cortex, which actually helps the motor cortex by suppressing the unwanted muscle contraction while producing voluntary movement

Question 19

primary motor cortex

Answer 19

• Houses neurons responsible for execution of voluntary movements of different parts of the body (mainly contralateral)
• Primary motor cortex has a somatotopic arrangement - the nuclei of neurons that will control a certain region of the body that are organised together so that the nuclei will control the muscles of the face are organised in one specific region of cortex, while all of the nuclei associated with controlling the foot are organised in another
• The proportion of the primary motor cortex, or the number of neurons dedicated to a particular movement depends upon how much that muscle, or group of muscles, is actually used. So, the more nuclei will be dedicated to it within the cortex. This is independent upon the size or mass of the muscle

Question 20

thalamus

Answer 20

The gateway for sensory input and relays information to areas pf the brain involved in sensory processing

Question 21

hypothalamus

Answer 21

Regulation of hormones
Part of the HPA-axis that controls the autonomic nervous system and therefore the stress response

Question 22

hippocampus

Answer 22

The key structure involved in memory formation (encoding) and spatial navigation

Question 23

amygdala

Answer 23

Activation and processing of emotions (especially fear)
Classical conditioning (fear and punishment)
Encoding, storage and retrieval of memories (emotion creates a stronger memory trace)

Question 24

pre frontal cortex

Answer 24

Coordinating and controlling emotion processing
Regulating and modifying emotional responses
Emotional decision making

Question 25

What are the steps of monosynaptic reflex? give example

Answer 25

1. receive input from stimulus
2. detection
3. propagation of action potential via afferent pathways
4. synapse sensory neuron stimulates motor neuron
5. propagation of action potential via efferent pathways
6. response

example: stretch/patella reflex

Question 26

what are the steps of polysynaptic reflex and give an example

Answer 26

1. stimulus
2. detection
3. propagation of action potential (afferent)
4. synapse sensory neuron stimulates interneuron
5. propagation of action pot to interneuron
6. synapse interneuron stimulates motor neuron
7. propagation of action potential (efferent)
8. response

example: withdrawal reflex

Question 27

what is afferent and efferent

Answer 27

afferent: periphery -> CNS
efferent: CNS -> periphery