BIOM2006 Biorhythms Module www.uq.edu.aunuqjackPL206.html

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BIOM2006 Biorhythms Module www.uq.edu.aunuqjackPL206.html

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Don't forget this for questions about lectures ... Higher resolution than PET (positron emission tomography) No isotope source required ... – PowerPoint PPT presentation

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Title: BIOM2006 Biorhythms Module www.uq.edu.aunuqjackPL206.html

1
BIOM2006 Biorhythms Modulewww.uq.edu.au/nuq/jack/
PL206.html
Or, click from Resources page of BIOM2006 on SBMS
site or find Jack Pettigrews webpage on the UQ
site, then click on BIOM2006 under Teaching

Exams
Midsemester 10 MCQ questions (5 alternative)
End of semester 10-13 MCQ (TBA)
All material derived from lectures
2. Bulletin Board
Dont forget this for questions about lectures

2
Demonstration of Individual Uniqueness of Each
Human Brain

Rivalrous figures
Everyone sees the same sensory input
Everyone experiences different switches
Each individuals clock keeps good time
Switching rate is the basis of practical class

3
Brain as Integrator

Integration is the theme of the course
Human brain can integrate 1015 -1016 different
inputs
To give a single, united, conscious self
?How
Knowledge of connectivity not sufficient
Time needed to complement spatial dimension
i.e. Dynamic aspect of brain needed to supplement
static view

4
How Complex is the Human Brain?

1010 neurons of which 1011 are in the
cerebellum
So 1011-1012 neurons
103 (101-106) input connections per neuron
1015-16 possible input states
Combinatorial possibilities in the brain exceed
Diracs BIG NUMBER (1040).
Cf. Brain (1012 complex objects interacting
complexly) with a Galaxy (109 objects
interacting relatively simply)

Simple neuron from Layer IV of primary visual
cortex.
103 synapses
Note that frontal cortex pyramidal cells and
Purkinje cells may be 103X more complex than
this.
(106 synapses)

6
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7
Moo Ming Poo and team

Simultaneous intracellular recording
from many interconnected neurons
Use-dependent synaptic connections
Timing dependence

Long Term
Depression (LTD)
Action spike before synaptic input

Long Term
Potentiation (LTP)
Action spike
after synaptic input

9
Input B
Input A
Inhibitory Input
Output
10
Hebbs Rule If the activity of synapse A is
coupled with other synapses that are effective
in driving the neuron, its efficacy will be
enhanced.
11
Input B
Input A
Inhibitory Input
Output
12
fMRI (functional Magnetic Resonance Imaging)

Higher resolution than PET (positron emission
tomography)
No isotope source required
Intense magnetic field
Radio- frequency pulses from coil around head
Functional activity picked up from desoxyHb
signal (venous blood)
Spatial reconstruction coil pulses

13
Ramachandrans cotton bud experiment on a phantom
limb

Stroking of face is also felt on phantom
Water poured down on gives sensation of water on
phantom
Thumb mapped to jaw, fingers to face
Same kind of remapping in different individuals
Reorganisation of S1 verified by imaging studies
Mirror therapy can free phantom and lead to its
disappearance
Animal experiments show that the reorganisation
is instantaneous not d/t new anatomical
connections

14
S1 cortex
Amputation
15
Cortical map of body surface
16
Examples of immediate reorganisation that are
probably due to forebrain plasticity, NMDA
receptors and coincidence detection