Behaviourism vs Cognitive science Single cells Correlate with higher processes such as attention Clinical – cognitive deficits Imaging – PET, fMRI, MEG, voltage sensitive dyes, deoxyglucose Computer science, modeling, networks (+ psychophysics) Personal space Peri-personal space Extra-personal space Remembered space

TYPES OF CODING “labeled lines”

SA RA SA RA

fine detail hand grip control stretching vibration

MERKEL (SA) PACINIAN (vRA)

VENTRAL POSTERIOR LATERAL Nucleus of the thalamus SOMATOSENSORY CORTEX 4th Trigeminal system from face 3rd VENTRAL POSTERIOR LATERAL Nucleus of the thalamus 2nd CROSS OVER IN BRAIN STEM DORSAL COLUMNS 1st Somatosensory pathway

Secondary Somatosensory cortex Secondary Somatosensory cortex Multiple representations 3a -- muscle spindles 3b -- SA (cutaneous) 1 ---- RA (cutaneous) 2 ---- joints Secondary Somatosensory cortex

cutaneous mechanoreceptors Muscle spindles Joint receptors LIMB SENSING ORGANS Muscle spindles, cutaneous mechanoreceptors and joint receptors

MONOSYNAPTIC STRETCH REFLEX ARC

WILDER PENFIELD (1891-1976) In 1913

WILDER PENFIELD McGIll (1891-1976)

RECEPTIVE FIELDS ON THE ARM

Area of somatosensory cortex representing finger tip stimulate finger tip over many days Larger area now devoted to this finger tip DEMONSTRATES PLASTICITY

Demonstrates: 1 plasticity, 2 Müller’s law of specific nerve energies

LESIONS in the parietal cortex lead to AGNOSIAs

Lesions to the right produce lack of awareness of the object’s left Lesions to the left produce little lack of awareness because BOTH sides are represented in the right

LOCAL = D vs GLOBAL = L Frontal Parietal v3 v3 v2

EFFECT OF ATTENTION vision…. + planning to look at it + planning to reach to it

PARIETAL activated by: Locations (external space) Locations are updated after saccades (remembered space) Shifts of attention

Duhamel JR, Colby CL, Goldberg ME Duhamel JR, Colby CL, Goldberg ME. The updating of the representation of visual space in parietal cortex by intended eye movements. Science (80- ) 1992; 255: 90–92.

Visual response to a stimulus in the RF Responds to new location (in space) i.e., a different part of the retina (RF moved!) …. … starts BEFORE saccade.