5.1 Brain functioning 1

Question 1

What’s the nervous system composed of ?

Answer 1

Brain, spinal cord, nerves

Question 2

What’s the aim of neurosciences ?

Answer 2

Understand the nervous system and the pathologies that might affect it

Question 3

What’s the nervous influx ?

Answer 3

• An electrical current, conveyed by neurons,

- that allows neurons to communicate with each other and the rest of the organisme

Question 4

Who were the first to work on the nervous influx ?

Answer 4

• Luigi Galvani (18th century) : first to observe animal electricity whil working on muscle contractions in frog’s legs
• Herman Von Helmholtz (19th century) : measured the speed of the nervous influx flow, slower than the speed of light

Question 5

How are memories encoded in the brain ?

Answer 5

By the activation of a neural network (chain of neurons)

Question 6

What procedure was used in the recent investigations about fear memory in rodents.

Answer 6

• Fear conditioning procedure on rodents : electric shocks in the paws while hearing an auditory signal
• The auditory signal later induces fear in the mice

Question 7

How can the fear response be quantified ?

Answer 7

By the freezing of the mice : stop moving for a few seconds :
behavioral fear response that can be quantified

Question 8

How does the rodents brain function ?

Answer 8

• neurons selectively activated in the amygdalae when the mouse hears the fear-inducing tone
• When the neurons are erased, the mice no longer present the fear behavior

Question 9

What important discovery on the brain has been made during WWII ?

Answer 9

Brain insensitivity, the brain does not have pain receptors

Question 10

What did Wilder Penfield discovered ?

Answer 10

Electrical stimulation of a specific cortical area can induce :
- movement
- or sensation
in some body parts

Question 11

What are the homonculus ?

Answer 11

Schematic representation of the body on the surface of the brain :

• motor homonculus for movement
• sensory homonculus for sensations

Question 12

Which part of the brain stimulates which part of the body ?

Answer 12

• upper part of the precentral gyrus (frontal lobe) : movements in the lower part of the body (feet and legs)
• inferior part of the precentral gyrus : movements of the tongue
• postcentral gyrus : induces sensations in the corresponding body part

Question 13

What is epilepsy ?

Answer 13

An incapacitating disease caused by a sudden and massive electrical activity of some neurons in a specific part of the brain

Question 14

What is important if brain tissue has to be removed ?

Answer 14

Cut out the malfunctioning tissue and leave the healthy tissue intact (otherwise, cerebral activity can be irremediably lost)

Question 15

How are surgical resections of tumors or epileptic foci (postcentral gyrus) performed ?

Answer 15

• The neurosurgeon stimulates tissues while the neurophysiologist questions the patients about what he feels.
• If tingling perceid, the tissue is functional, if nothing is perceived, non-functioning area.

Question 16

How is Parkinson’s disease characterized ?

Answer 16

Progressive loss of neurons in the basal ganglia of the brain, leading to motor dysfunction

Question 17

How can Parkinson’s trembling be stopped ?

Answer 17

Introducing electrodes in the affected region, with a small amount of current, raise the activity of the remaining intact neurons, to replace the activity of the dead neurons.