brain imaging techniques pet mikrolesions single cell lesions 2-deoxyglucose multi-unit patch clamp...
TRANSCRIPT
Brain imaging techniques
PET
Mikrolesions
Single cell
Lesions
2-DeoxyglucoseMulti-unit
Patch clamp
EEG & MEGTMS
fMRI
Optical Imaging
millisecundum sec min hour day year -3 -2 -1 0 1 2 3 4 5 6 7 8
Log time (sec)
Lamina
Neuron
Dendrite
Synapse
4
3
2
1
0
-1
-2
-3
-4
Lo g Re
sol
uti
on
(m m)
Brain
Column
Patch-clamp recordings: a single channel
Patch-clamp recording
techniques
Even parallel dendritic and somatic patches are possible
A typical result:the I-V curve
Electric activity of the brain on different scales
Lengyel Máté: Egysejt modellek II / Modellek az idegrendszer-kutatásban - ELTE TTK, 2003 tavaszi félévhttp://www.rmki.kfki.hu/~lmate/kurz/
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Discovery of the electricity in animals:
1792
Galvani, De Viribus - Electricitatis in Motu Musculari.
Lengyel Máté: Egysejt modellek II / Modellek az idegrendszer-kutatásban - ELTE TTK, 2003 tavaszi félévhttp://www.rmki.kfki.hu/~lmate/kurz/
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Discovery of the electroencephalography (EEG)
1924.
Hans Berger
The first EEG recordThe alpha rythmElectric signs of epilepsy
Investigated the telepathy
Elektroencephalography (EEG) and magnetoencephalography (MEG)
ECIC
V
dVext
IC
IR
RECR
ICIaxial
Iaxial
IC
IR
IC
IR
I ~CSD
I ~CSD
I ~CSD
The source of the EC potential is the sumof the capacitive and resistive currents
The sum of IR is not zero,
But the sum of ICSD
is zero
for the whole cell!
Multi ElectrodeArray
Original current sourcedensity distribution
Sink
Source
Zero
T(d)
The forward problem
Multi ElectrodeArray
Original current sourcedensity distribution
Sink
Source
Zero
T(d)
The forward problem
The origin of the EEG and MEG
Normal resting EEG
F z
C z
P z
A 1
A 2
F p 2
F 4
C 4
P 4
O 2
F 8
T4
T6
F p 1
F 3
C 3
P 3
O 1
F 7
T3
T5
F z
C z
P z
A 1
A 2
F p 2
F 4
C 4
P 4
O 2
F 8
T4
T6
F p 1
F 3
C 3
P 3
O 1
F 7
T3
T5
B and:
D el ta
T heta
A lpha
B eta
G am m a
F z
C z
P z
A 1
A 2
F p 2
F 4
C 4
P 4
O 2
F 8
T4
T6
F p 1
F 3
C 3
P 3
O 1
F 7
T3
T5
EEG imaging with dipole localization
Evoked potentials
20 µV
2 µV
The auditory evoked potential:
Extracellular recordings
Extracellular recordings
Identification of excitatory and inhibitoryconnections by correlation requiresparallel recording of hundreds of neurons.
Active feedback via electrodes
Positron emission tomography (PET)
PET-based functional brain imaging
The MRI machine
The MRI machine
The BOLD response: the basis of the fMRI
High resolution functional brain imagingwith fMRI
Mind-reading with fMRI
Results:Learning on 1750 picturesSelection from 120 new pics: 92%Selection from 1000 new pics: 82%
Direction selective neurons in the motor cortex
Both the motor and the somato-sensory cortex represents the whole body
Each cell is tuned to a specific direction
Brain-machine interface in monkeys
The direction and speed of the planed movement could be determined from the activity of the cells and their directional tuning.
BMI with invasive electrodes
BMI with non-invasiv electrodes
Arm prosthesis driven by the nerves
It is more easy to decode the planed motion from the activity of the peripheral nerves.