1094562
Descripción
Mapa Mental por Kristi Brogden, actualizado hace más de 1 año
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Creado por Kristi Brogden
hace más de 10 años
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The cerebellum
- 40% of brain surface area
- >50% of the brains neurons
- 10 to the 11 granule cells alone
- 10 to the 11 granule cells alone
- Competitive advantage
- Evolutionary (darwinian) perspective
- Population characteristics are
selected if they convey an
evolutionary advantage
- I.e. for a given individual
showing that characteristic,
there is an increased
probability of surviving and
producing offspring
- I.e. for a given individual
showing that characteristic,
there is an increased
probability of surviving and
producing offspring
- Evolutionary pedigree of cerebellum
- Killer organ for vertebrates
- Fish and reptiles
- left-right movement controller
- Adaptation of
movement to different
environments
- left-right movement controller
- Sensorimotor stabilization
- Vestibular-occular reflex
- N.B senses are directly linked to actions
- whisking
- Ear pricking
- Eye moving
and focusing
- whisking
- Vestibular-occular reflex
- Killer organ for vertebrates
- Population characteristics are
selected if they convey an
evolutionary advantage
- Individual (developmental) perspective
- Individuals need to compete
for the best mates etc and so
will strive to attain skills that
will give them a competitive
advantage
- And the propensity to
acquire such skills (via
epigenetic programming)
can be passed down to the
next generation
- Individuals need to compete
for the best mates etc and so
will strive to attain skills that
will give them a competitive
advantage
- Potential evolutionary advantages
- Adaptive behaviour - different situations
- Speed of action - the real time constraint on cognition
- Enormous evolutionary
pressure to respond
faster and better
- Enhance
sophistication of
sensory
analysis
- Increased
speed of action
- Synchronise
sensory
analysis with
appropriate
action
- Both
between
and within
species
- Enhance
sophistication of
sensory
analysis
- Most species have
fixed action patterns
(reflexes)
- Primates manage to
create automatic actions
through appropriate
experience and practice
- Enormous evolutionary
pressure to respond
faster and better
- Socialisation - Important characteristic for social primates
- Adaptive behaviour - different situations
- Evolutionary (darwinian) perspective
- 10-15% of brain weight
- Connections everywhere
- Body as well as brain
- Body as well as brain
- Learning mechanisms and the brain
- All regions of the brain support unsupervised
learning (statistical learning)
- Only the basal ganglia support
reinforcement learning (i.e. success based)
- Only cerebellum supports supervised
learning (target and error signal)
- Hence brain regions need to work together through networks
- Cerebellum and skill
- Tool use and the cerebellum
- While human subjects learned to use a new tool (a
computer mouse with a novel rotational
transformation), cerebellar activity was measured
by functional magnetic resonance imaging
- Two types of activity were
observed
- One was spread over wide areas of
the cerebellum and was precisely
proportional to the error signal that
guides the acquisition of internal
models during learning
- The other was confined to the
area near the posterior
superior fissure and remained
even after learning, when the
error levels had been
equalized
- Thus probably reflecting
an acquired internal
model of the new tool
- Thus probably reflecting
an acquired internal
model of the new tool
- One was spread over wide areas of
the cerebellum and was precisely
proportional to the error signal that
guides the acquisition of internal
models during learning
- Two types of activity were
observed
- Imamizu et al (2000)
- While human subjects learned to use a new tool (a
computer mouse with a novel rotational
transformation), cerebellar activity was measured
by functional magnetic resonance imaging
- Co-ordinator
- sequential
- Parallel
- sequential
- Adaptive timer
- Response optimisation
- Response optimisation
- Bricolage
- Building blocks
- Building blocks
- Encapsulation and
stimulation
- Disembodied actions
- Mental objects
- Disembodied actions
- Forward modeller
- If execute A
at t0, then
predict state
S at time t
- If execute A
at t0, then
predict state
S at time t
- sensorimotor
context detector
- In sensorimotor
context C,
execute action A
after time T
- In sensorimotor
context C,
execute action A
after time T
- Writing
- A 'conspiracy' of neural circutis
- A 'conspiracy' of neural circutis
- Tool use and the cerebellum
- Ito's (1990) CNMC concept
- The major signal flow from a mossy fiber
pathway to the nuclear group is modulated
by its sidepath signal flow through the
microzone, and this modulation is modified
according to error signals mediated by the
inferior olive neurons (1993, p.448)
- Adaptive reflex control: The vestibular-occular reflex
- Head velocity h• (monitored via vestibular
system) is fed into the controller, whose task is
to maintain eye velocity e• at -h• so that retinal
slip is zero. Retinal slip is fed back to the CNMC
via the IO. To make an effective correction the
CNMC must learn the ‘inverse dynamics’ g-1 of
the eye-muscle system
- Head velocity h• (monitored via vestibular
system) is fed into the controller, whose task is
to maintain eye velocity e• at -h• so that retinal
slip is zero. Retinal slip is fed back to the CNMC
via the IO. To make an effective correction the
CNMC must learn the ‘inverse dynamics’ g-1 of
the eye-muscle system
- Voluntary motor learning: Finger to nose
- Through practice, the CNMC learns
equivalent dynamics (g’) to the dynamics g of
the skeleto-muscular system. This allows a
transition from feedback control to
feedforward control. g’ reflects an
‘internalisation’ of the muscle dynamics
system.
- NB. Also the re-entrant loop,
with precise timing, which
allows sophisticated learning
and prediction
- NB. Also the re-entrant loop,
with precise timing, which
allows sophisticated learning
and prediction
- Through practice, the CNMC learns
equivalent dynamics (g’) to the dynamics g of
the skeleto-muscular system. This allows a
transition from feedback control to
feedforward control. g’ reflects an
‘internalisation’ of the muscle dynamics
system.
- The major signal flow from a mossy fiber
pathway to the nuclear group is modulated
by its sidepath signal flow through the
microzone, and this modulation is modified
according to error signals mediated by the
inferior olive neurons (1993, p.448)
- All regions of the brain support unsupervised
learning (statistical learning)
- Cerebellum and cognitive skill
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