Thalamus

Brainstem nuclei

Cuneate, gracile and thalamic nuclei

Thalamic VPM and VPL nuclei

Spinal cord

Segregate discriminative and non-discriminative somatic inputs in different nuclei

Combine some types of discriminative somatic inputs

Combine discriminative and non-discriminative somatic inputs

Segregate discriminative and non-discriminative inputs in some nuclei and combine them in others

Segregate discriminative and non-discriminative inputs in different parts of the same nucleus

Thalamus

Brainstem nuclei

Cuneate, gracile and thalamic nuclei

Thalamic VPM and VPL nuclei

Spinal cord

Because of this, in primary somatosensory cortex, shape but not texture is well signalled

Hence slowly adapting primary cortical neurons cannot signal the form of a tactile stimulus

Because of this, in cortex rapidly adapting not slowly adapting neurons are used to signal the form of a tactile stimulus

Despite this, slowly adapting primary cortical neurons are still able to well signal the form of a tactile stimulus

Because of this, in primary somatosensory cortex, form is no longer well signalled

Contains the same chromophore held in a different position by one of three different opsins

All use a different chromophonre to absorb light energy

Also are able to converge through different PLC-beta pathways on intracellular Ca++

Activates a different G protein, either a Gs or a Gi

Can be of one of three types of chromophonres to absorb light energy at different wavelengths

the cornea

the lens

ciliary muscles

the pupil

It activates the rhodopsin molceule when it is activated by light

It's role in the sequence of phototransduction reactions is to cause ion channels to activate Ca⁺⁺

It pumps out the Na⁺ that enters the photoreceptor outer segment

It is broken down to close off ion channels

When activated by light, it then binds PDE to convert it to an active form

iris 

retina

pupil 

cornea 

lens 

50%

66%

99%

33%

80%