16 october 2009 chapter 7 sensory physiology
DESCRIPTION
16 October 2009 Chapter 7 Sensory Physiology. Quiz on Cranial Nerves: Wednesday Lab next week: Sensory Physiology and the Auditory System. Receptors:. Encapsulated. 5 different receptor types (but not all in the same cell). Receptors for gustation. Figure 7.08. - PowerPoint PPT PresentationTRANSCRIPT
16 October 2009
Chapter 7 Sensory Physiology
Quiz on Cranial Nerves: Wednesday
Lab next week:Sensory Physiology
and theAuditory System
Receptors:
Encapsulated
• Receptors for gustation
5 different receptor types (but not all in the same cell)
Figure 7.08
Receptive fields of different neurons often overlap such that any patch of skin may have several receptors of the same type (modality) and receptors of different types (different modalities I.e. touch, pain temperature, etc.)
Overlapping receptive fields of touch receptors (Meissners, Merkels) allow for more precise localization of a stimulus via the mechanism of lateral inhibition (next slide.)
Stimulus Localization& Intensity
Figure 7.09
Lateral inhibition exaggerates the difference in stimulus intensity detected by adjacent neurons.
Stimulus Localization& Intensity
Figure 7.10
Lateral inhibition improves stimulus
localization.
Stimulus Localization& Intensity
Demonstration: circles in carpet of
McMillan Theater = receptive fields
Somatosensory: sensation of touch, vibration, pain, and temperature
Deep
Superficial
Sustained stimulus
Fluctuating stimulus
Misleading diagram: implies different receptor types
connected to one sensory axon.
Figure 7.15 Stimulus Localization& Modality & Intensity
Three neurons to the cortex!
Labeled Line
Wilder Penfield, neurosurgeon and epilepsy
Figure 7.14
=Post-central gyrus
Damage to specific areas (stroke) is correlated with specific sensory deficits.
Thalamus
Figure 7.19
Anterolateral (spinothalamic) tract1st order synapses onto 2nd order in spinal cord, 2nd order axon decussates in spinal cord, travels to thalamus in contralateral anterolateral tract, synpases onto 3rd order neuron in thalamus, which sends its axon to SSC.
Dorsal column-medial lemniscal tract1st order axons ascend in ipsilateral dorsal columns to synapses onto 2nd order in dorsal column nuclei of brainstem, 2nd order axon decussates in brainstem, travel to thalamus to synpases onto 3rd order neuron, which sends it axons to SSC.
Right side
Right sideRight side
Right side
Proprioception
Figure 7.20
Homunculus: representation of body in the SSC;somatic sensations from adjacent parts of the body are processed by adjacent regions of SSC, with those body regions more densely innervated by sensory receptors occupying more cortical tissue.
Somatotopy in the SSC (post-central gyrus.)
Dermatomes
Figure 7.18
Referred Pain
http://michaelscomments.wordpress.com/2008/09/19/very-interesting-test-of-perception/
Watch this 2-3 minute YouTube video. You’ll find it very interesting!