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Evolution of Vocal Communication > Neurobiology > Flashcards

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
Anterior pathway
Posterior pathway


Secondary auditory regions

Responsible for perception and recognition of tutor song


Anterior pathway

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


Posterior pathway

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


In humans?

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


In humans?

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