This document discusses research on how attention impacts somatosensation, the sense of touch. It describes the primary and secondary somatosensory cortex areas involved in processing touch sensations. It discusses studies using somatosensory evoked potentials (SEPs) and steady-state SEPs to measure brain responses to tactile stimuli at different levels of attention. The research found that attention can modulate SEP components between 125-138ms and alter the neural responses and amplitudes depending on variables like spatial separation of stimuli sites.

1. Attention
in sense of touch
DongNyeok Jeong

2. • What makes somatosensation so different
from other senses to look exclusively into
the impact of attention onto that sensory
system?

3. Somatosensory Cortex
• Areas 1, 2, and 3, which constitute PRIMARY SOMATOSENSORY
AREA I, 40 is SECONDARY SOMATOSENSORY AREA II and areas 5
and 7, which constitute the SOMATOSENSORY ASSOCIATION
AREA.

4. SEP
• Somatosensory evoked potentials
• By combining SEP recordings at
different levels of the somatosensory
pathways, it is possible to assess the
transmission of the afferent volley from
the periphery up to the cortex.

5. • latency of 38 and 68ms
• attentional modulation of SEFs (125 and
138ms)
• one such variable might be the level to
what extend stimuli have to be processed
in order to perform a particular task.

6. • SEP consists of the components P50, N70,
P100, N140 and positive late
component(LC).
• spatial attention alters the neural responses
to transient stimuli is not a hard-wired
mechanism but might be influenced by a
number of variables.

7. • Spatial separation of stimulation sites as
well as inter stimulus intervals play an
important role to determine which
component of the SEP is modulated with
attention.
• The somatosensory system in particular
seems to be organized in a way to
automatically shift attention to that body
location where something happens.

8. • When you search for key-ring in a dark
bag, spatial and non-spatial information
gathered from your sense of touch highly
determines the success of this search.

9. ERP
• ERP(Event Related Potential)
• measured brain response that is directly
the result of a thought or perception.
• measured with EEG, MEG

10. SSSEP
• Somatosensory Steady-Stated Evoked Potentials
• A form of response to repetitive sensory
stimulation in which the constituent frequency
components of the response remain constant with
time in both amplitude and phase
• 20 (left finger), 26 Hz (right finger)
• Amplitude was increased with attention

11. The Neuronal Basis of Preferential
Stimulus Processing
• A sensory gain control mechanism : visual
modality
• Amplification / Suppression
• Attended or not stimulus
• A change in the temporal pattern of action
potentials

12. Topographical distribution

13. Synchronisation of
neuronal responses
• Correlation between pairs of neurons in SII
• Temporal synchronisation of action
potentials of neurons that code the to-be-
attended stimulus produces a ‘pop-out’
from the background noise.