Flashcards in Neurobiology Deck (16):
What do we share with mammals?
musculature of larynx and vocal tract and the nerves that innervate these structures
brain stem structures
midbrain control centres
cortical control systems
Brainstem structures involve
and if destroyed
include motor nerves that innervate the face, tongue and larynx
destruction = paralysis of associated muscles
Midbrain control centres involve
and if stimulated
core region for vocal control is the PAG
stimulation = automatic vocalisations
this is the main command centre for most vertebrates
Medial cortical system
- evolutionarily old
- lesions in humans = mutism, loss of vocal affect expression
- controls speech and laughter and crying sounds
Lateral cortical system
- 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
How do humans differ from animals with these systems?
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
So.. Kuypers/Jurgens hypothesis
also found in..
direct cortico-laryngeal connections underlie superior human vocal control
also found in songbirds!
Vocal learners have..
brain regions that control the acoustic output structure of vocalisations
Non-vocal learners have.. -- ACC
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
Which vocal learners have been mostly studied? What are the comparable neurons between the two?
Songbirds and humans
Songbirds have 7 comparable nuclei: 4 posterior and 3 anterior
Birdsong involves 3 interconnected networks..
Secondary auditory regions
Secondary auditory regions
Responsible for perception and recognition of tutor song
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
Responsible for production of learned vocalisations
- vocal nucleus
- second vocal nucleus
- midbrain and medulla vocal neurons
medulla projects onto muscles of syrinx
posterior: face motor cortex tilts projections to midbrain and brain stem
-- do not receive motor projections
-- controls the production of innate sounds