The type of stimulus that requires least energy to procure a sensation is called the of a sensory receptor.

The somatosensory system converts m, t and p stimuli.

Sensory receptors and sensory neurons must encode four types of information about a stimulus:

- M
- L
- I
- D

According to the modality is encoded by a discrete pathway from the sensory cell to a modality specific integrating center in the brain.
Exceptions are receptors.

Location can also be encoded in this way or by projections and maps within the brain.

The field is the region of the surface that causes a response when stimulated.
In the somatosensory system receptive fields are regions of the or of internal .

The dynamic range of a neuron is bounded by its
(a) of detection
(b)

Mechanoreceptors sense physical deformation of . In mammals these are of sensory neurons.

Different proprioceptors:

The provides information about changes in muscle length.
The provides information about changes in muscle tension.

The two point limen is a measure of the .

It is determined by the density of and the mechanism (e.g. inhibition).

Neurons can be sensitive to the of an object and its of movement.
In the latter case multiple receptors are needed.

The cell bodies of sensory neurons known as first-order neurons are located in the .

The pathway for touch, proprioception, vibration is called pathway.

The pathway for pain, temperature is called tract.

The topographic projection of the whisker pad is maintained throughout all processing stages:

- nuclei
- nuclei
- Primary

Each whisker is represented by a barrel-like structure in the nucleus of the brain stem.

What are the thalamic relay nuclei of the somatosensory system?
- nucleus (VPM)
- nucleus (VPL)
- complex (PoM)

The projection fields of sensory neurons go further than the specialized region.

This leads to of brain regions.

If a finger is lost for example, in the corresponding cortical region there is no inhibition anymore towards neurons that correspond to other fingers. These will then grow more .

sensory neurons are sensitive to the timing of whisker deflections with sub-millisecond precision. They can also be phasic or tonic.

Receptive fields in the somatosensory cortex of the rat are defined based on:
- whiskers (PW): the one eliciting the response with the shortest latency
- whiskers (AW): smaller responses with longer latencies

The term describes the phenomenon that even a precise stimulus does not excite a single mechanoreceptor but several adjacent mechanoreceptors as well.

is need for a precise stimulus loclization.

A is an area of skin that is mainly supplied by a single spinal nerve.

Topological representations of the whisker field in

brain stem nuclei:
thalamic nuclei:
primary somatosensory cortex:

In rats the nontopographic pathway to the thalamus is called the pathway.

The primary somatosensory cortex consists of Brodman Areas , and .

Brodman Area is also involved in the somatosensory system.

In total there are (write out) somatosensory fields for the whole body that code different information (superficial or deep touch, complex touch, active touch).

In rodents, the is the first part of the pathway from the whiskers to the brain.

These sensory neurons are sensitive to the timing of whisker deflections with sub-millisecond precision.