Brain and Consciousness Class This presentation contains two classes: Brain-machine interface Brain micro-stimulations.

Brain and Consciousness Class

• This presentation contains two classes:

• Brain-machine interface

• Brain micro-stimulations

BMI Control of a Robotic Arm

Nicolelis et al PLoS 2003

Large number (thousands) of electrodes in multiple areas (M1, Pre-motor, supplementary motor)

Leigh R. Hochberg, Mijail D. Serruya, Gerhard M. Friehs, Jon A. Mukand, Maryam Saleh, Abraham H. Caplan, Almut Branner, David Chen, Richard D. Penn and John P. Donoghue

Nature 442, July 2006

EEG-Controlled Action

EEG Electrodes

Walpaw, PNAS 2004

Localized brain activation usingreal-time fMRI

Gabrieli et al, NeuroImage 2004

Elevated activity in a selected voxel in somato-motor cortex (primary motor and somatosensory with surrounding region)

Elevation depended on the fMRI feedback (no feedback, sham)

Voluntary Control of a Brain Region

Larger activity after training

No muscle movement during the activation

Subjective report ?

Which brain areas are under ‘will’ control ?

Brain Micro-stimulation

Micro Stimulation

• General strategy: BA (Brain Activity) under similar conditions, with or without awareness.

• Stimulate an area such as MT, test minimal activation for awareness.

• avoids indirect routs such as via the S.C. and pulvinar. • Test qualia generated by stimulating different areas. • In animals: combined with response about guessing?

Micro-stimulation

Head position, 1 sec

Reward delivered

L or R signal Somato-sensory cortex for navigation

Medial forebrain bundle for reward Chapin et al, Nature 2002

Phosphenes in V1

• Stimulation of V1 in volunteer epileptic patients. • usually a single phosphene, sometimes multiple, • could be small as ‘star in the sky’, or larger, ‘a coin at

arm’s length’. • Some are colored, • fade after 10-15 secs.

• For some reason they are not oriented, not edges and bars?

• Could be interesting, fMRI, minimal activation for perception?

Motion Perception by MT Stimulation

Shadlen et al, Nature Neuroscience  6, 891 - 898 (2003)

Stimulation of humans in medial parieto-occipital cortex evoked visual motion perception Exp Brain Res. Richter et al 1991

Face Microstimulation

Face and non-faces with noise .

Face with no noise is 100% face-signal

Non-face with no noise is -100% face-signal

80%

Microstimulation of Face Regions in Monkey

Bailey CJ, Karmu J, Ilmoniemi, RJ. 2001. Scand J Psych 42: 297–306.

TMS: Blocking Motion Awareness

Pascual-Leone, Walsh. Fast backprojections from the motion to the primary visual area necessary for visual awareness. Science 2001

Stimulation of V5, then sub-threshold to V1

V1 stimulation blocked the perception of moving phosphenes

Where is motion perception generated? TMS study: MT/V5 together with V1 necessary for moving phosphenes

G.Y. patient without V1 – motion perception with sufficient V5 stimulation

Different qualia associated with different brain regions

(general motion in MT, point-wise phosphenes it V1)

fMRI from G.Y: stronger activation of MT with fast (perceived) motion

Brain Stimulation and Perception

• Different brain regions supply different qualia• From simple sensations to complex percpets • (V1 – bright spots, MT – motion, STS – faces)• In humans: can test for qualia• Stimulation of the dorsal stream:

– Do some regions create sensations, others not? – A combination of ‘quale area’ plus ‘enabling’?

• Wilder Penfield (1975): The Mystery of the Mind:– Never elicited ‘free will’

• Monkeys with report on guessing?

• Combined with fMRI, minimal activation