Neurobiology

Question 1

What do we share with mammals?

Answer 1

musculature of larynx and vocal tract and the nerves that innervate these structures
brain stem structures
midbrain control centres
cortical control systems

Question 2

Brainstem structures involve

and if destroyed

Answer 2

include motor nerves that innervate the face, tongue and larynx
destruction = paralysis of associated muscles

Question 3

Midbrain control centres involve

and if stimulated

Answer 3

core region for vocal control is the PAG
stimulation = automatic vocalisations
this is the main command centre for most vertebrates

Question 4

Medial cortical system

Answer 4

• evolutionarily old
• lesions in humans = mutism, loss of vocal affect expression
• controls speech and laughter and crying sounds

Question 5

Lateral cortical system

Answer 5

• evolutionarily newer
• contains Broca’s Area, associated with voluntary vocal control
• damage = voice loss in humans
• directly relevant to human vocal abilities
• vocal output is associated with complex vocal imitation in this system
• has been partially conolised by the linguistic system

Question 6

How do humans differ from animals with these systems?

Answer 6

double dissociation in humans - those with Broca’s aphasia can still sing and swear
humans have direct connection between frontal motor areas of lateral neocortex and brainstem motor neurons which has strengthened over time, especially those involved in laryngeal control. the neurons that make these direct connections lie in the motor cortex posterior to BA.
animals have less direct access – eg. Fitch says chimps have more control over vocal tract than larynx

Question 7

So.. Kuypers/Jurgens hypothesis

also found in..

Answer 7

direct cortico-laryngeal connections underlie superior human vocal control
also found in songbirds!

Question 8

Vocal learners have..

Answer 8

brain regions that control the acoustic output structure of vocalisations

Question 9

Non-vocal learners have.. – ACC

Answer 9

regions in the midbrain and medulla to control innate vocalisations – the anterior cingulate cortex controls motivations to vocalise innate sounds but not the acoustic structure

Question 10

Which vocal learners have been mostly studied? What are the comparable neurons between the two?

Answer 10

Songbirds and humans

Songbirds have 7 comparable nuclei: 4 posterior and 3 anterior

Question 11

Birdsong involves 3 interconnected networks..

Answer 11

Secondary auditory regions
Anterior pathway
Posterior pathway

Question 12

Secondary auditory regions

Answer 12

Responsible for perception and recognition of tutor song

Question 13

Anterior pathway

Answer 13

Responsible for learning vocalisations, essential for sensorimotor learning and adult song plasticity

• pallial vocal nucleus
• striatal vocal nucleus
• dorsal thalamus which projects back to the pallial vocal nucleus
• • cortical-basal ganglia-thalamic loop

Question 14

Posterior pathway

Answer 14

Responsible for production of learned vocalisations
- vocal nucleus
- second vocal nucleus
- midbrain and medulla vocal neurons
medulla projects onto muscles of syrinx

Question 15

In humans?

Posterior

Answer 15

posterior: face motor cortex tilts projections to midbrain and brain stem
- - do not receive motor projections
- - controls the production of innate sounds

Question 16

In humans?

Anterior

Answer 16

anterior: loop connecting projections from the premotor cortex and anterior cingulate to the thalamus, then back to the cortex
- - controls learning of production of complex aspects of human speech