Nervous System - PowerPoint PPT Presentation

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Nervous System

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V = A' log (S/S'o) for the linear range. S: Physical stimulus intensity ... We cannot understand how a bird flies by only studying its wings, but need, in ... – PowerPoint PPT presentation

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Title: Nervous System


1
Nervous System
Perception Memory Planning
Sensory inputs light, sound, skin pressure, odor

Motor responses limb movement, facial
expression, speech
2
Sensory Systems
Modality Stimulus Receptor Class Receptors
Vision Light Photoreceptors Rods, cones
Audition Sound Mechanoreceptor Hair cells (cochlea)
Vestibular Gravity, acceleration Mechanoreceptors Hair cells (vestibular labyrinth)
Somatic Touch Proprioception Temperature Pain Itch Pressure Displacement Thermal Chemical, thermal, or mechanical Chemical Mechanoreceptor Mechanoreceptor Thermoreceptor Chemoreceptor, themoreceptor, or mechanoreceptor Chemoreceptor Dorsal root ganglion neurons Cutaneous mechanoreceptors Muscle and joint receptors Cold and warm receptors Chemical, thermal, and mechanical nociceptors Chemical nociceptor
Taste Chemical Chemoreceptor Taste buds
Smell Chemical Chemoreceptor Olfactory sensory neurons
3
Light Projection on Retina
4
Transduction
5
(No Transcript)
6
Cone Response
7
Fechners Law
Membrane Response V
Subjective Intensity I
Log S
Log S
Log So
Log So
Fechners law I A log (S/So)
for S gt So I 0
for S lt So S Physical stimulus
intensity So Threshold stimulus intensity A
Constant
V A log (S/So) for the linear range S
Physical stimulus intensity So Threshold
stimulus intensity A Constant
8
Webers Law
I
I
?I
?I
Log S
S
Log So
?S
?S
Fechners law I A log (S/So) Differentiat
e ?I A ?S/S ?S needed to get a fixed
?I ?S (?I/A) S Webers Law ?S K S
where K ?I/A
9
Visual Pathway
10
Decussation
11
Hierar chical and Parallel Processing
12
Receptive Field
13
(No Transcript)
14
(No Transcript)
15
(No Transcript)
16
Geometry of Projection
17
Geometry of Projection
Retinal image size is inversely proportional to
distance
18
Left eye
Right eye
19
Ponzos Illusion
20
(No Transcript)
21
Muller-Lyer Illusion
22
(No Transcript)
23
(No Transcript)
24
Circular World of the Zulus (South Africa)
25
David Marrs Concept of a Computational Theory
for Understanding an Information Processing Task
in the Brain
We cannot understand how a bird flies by only
studying its wings, but need, in addition, an
aerodynamic theory of lift generation by the flow
patterns around the wings. We cannot understand
how a computer works by only studying the
transistors on the circuit boards and their
connections, but need, in addition, concepts of
operating system, data structure, and application
programs.
26
David Marrs Concept of a Computational Theory
for Understanding an Information Processing Task
in the Brain
Therefore, even if some day we had complete
knowledge of every molecule in the brain, and
could record the electrical activities of every
cell at any time, we would still not understand
how the brain processes information. We need, in
addition, a computational theory which specifies
how the electrical signals carried by a large
number of neurons could act in concert to solve a
certain perceptual problem.
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