1. Mammalian Nervous System
Structure and Higher Functions

2. Nervous System Components
CNS - central nervous system
brain and spinal cord
PNS - peripheral nervous system
nerves extending to/from CNS
cranial and spinal nerves
each nerve transmits information to & from the CNS

3. conceptual organization
afferent information
coming in to the CNS from the PNS
conscious or unconscious
efferent information
flowing from the CNS to the PNS
voluntary or involuntary (autonomic)
hormonal signals
received and sent by CNS

4. information flow diagram Figure 46.1

5. Anatomical development
hollow embryonic neural tube
anterior/posterior extension; dorsal position
three anterior swellings
prospective hindbrain, midbrain, forebrain
posterior portion becomes spinal cord
cranial & spinal nerves (PNS) sprout from neural tube

6. early brain development Figure 46.2

7. Anatomical development
hindbrain produces
medulla basic physiological & motor
pons activities; conduct signals
cerebellum refinement of motor commands

8. later development & adult brain Figure 46.2

9. Anatomical development
midbrain
basic visual/auditory processing centers
conduct signals

10. Anatomical development
forebrain produces two parts
diencephalon: central
thalamus - final relay of information to higher processing areas
hypothalamus - regulates physiological function, biological drives

11. Anatomical development
forebrain produces two parts
telencephalon (cerebrum)
cerebral hemispheres mediate
sensation
learning
memory
conscious behavior

12. Anatomical development
brain stem
medulla, pons, midbrain
conducts, processes information from spinal cord
primitive & autonomic functions are controlled lowest on brain stem

13. Functional subsystems
CNS processes many types of information simultaneously (parallel processing)
different parts of the CNS handle different types of information - functional subsystems
parts of different anatomical regions form the functional subsystems

14. Functional subsystems
spinal cord
conducts information to and from the brain and effectors
processes some information directly
spinal reflex
conversion of afferent to efferent information without brain involvement

15. the knee jerk reflex mono- & polysynaptic pathways Figure 46.3

16. Functional subsystems
spinal cord
conducts information to and from the brain and effectors
gray matter contains cell bodies
white matter contains axons
each spinal nerve bears
neural afferents to the dorsal horn
neural efferents from the ventral horn

17. Functional subsystems
spinal cord
interneurons
reside in gray matter
connect sensory & motor neurons
participate in spinal processing of reflex and repetitive motor activities

18. Functional subsystems
reticular system
through core of medulla, pons & midbrain
complex network of axons & dendrites
distinct nuclei process different types of information
information also continues to centers of conscious recognition
reticular activating system regulates wakefulness/sleep

19. human limbic system Figure 46.4

20. Functional subsystems
limbic system
primitive structures of telencephalon
regulates basic physiological drives, emotions, instincts
amygdala mediates fear & fear memory formation
hippocampus participates in long-term memory formation

21. Functional subsystems
cerebrum
contains many interacting regions
produce consciousness, behavioral control
cerebral cortex
gray matter - cell bodies
surface area increased by convolution
ridges = gyri
valleys = sulci
area ~1 m2
white matter - interconnecting axons

22. Functional subsystems
Cerebrum
anatomical organization
each hemisphere includes four lobes
frontal lobe
parietal lobe
occipital lobe
temporal lobe

23. anatomical organization Figure 46.5

24. Functional subsystems
Cerebrum
functions
frontal lobe
primary motor cortex
motor neurons connect with specific muscles
association areas
contextualization
planning

25. functional organization Figure 46.5

26. Functional subsystems
Cerebrum
functions
parietal lobe
primary somatosenory cortex
information from thalamus about touch & pressure sensations
association areas
attention to complex stimuli
hemispheres are asymmetrical

27. contralateral neglect syndrome: Figure 46.9
due to right parietal damage

28. functional organization Figure 46.7

29. Functional subsystems
Cerebrum
functions
occipital lobe
reception/processing of visual information
association areas
integrate visual images
convert visual information to language

30. Functional subsystems
Cerebrum
functions
temporal lobe
reception/processing of auditory information
association areas
object recognition, identification, naming

31. face recognition in temporal lobe Figure 46.6

32. neuronal networks autonomic nervous system
controls organs & organ systems
two opposed divisions
sympathetic division
parasympathetic division
each division
begins in brain stem or spinal cord
preganglionic neurons use acetylcholine
synapses with ganglia outside the CNS

33. neuronal networks autonomic nervous system sympathetic division
preganglionic neurons
emerge below neck
synapse with ganglia near spinal cord
postganglionic neurons
use norepinephrine as neurotransmitter

34. sympathetic division of autonomic nervous system Figure 46.10

35. neuronal networks autonomic nervous system parasympathetic division
preganglionic neurons
emerge from brain stem or base of spine
synapse with ganglia near target organs
postganglionic neurons
use acetylcholine as neurotransmitter

36. parasympathetic division of autonomic nervous system Figure 46.10

37. neuronal networks autonomic nervous system
organs receiving signals from both divisions respond oppositely to the two different neurotransmitters

38. human retinal organization Figure 45.20

39. neuronal networks
regions of the occipital lobe integrate visual information
visual information
arrives from retinal ganglia through optic nerve
passes through thalamic relay
arrives at visual cortex of occipital lobe

40. neuronal networks visual information processing visual cortex cells
have receptive fields on the retina
simple cells
localized receptive fields
stimulated by bars of specific orientation

41. neuronal networks visual information processing visual cortex cells
have receptive fields on the retina
complex cells
larger receptive fields
composite of several simple cells with same orientation
some respond to movement in specific direction

42. model of cellular processing of visual signals Figure 46.11

43. neuronal networks visual information processing
100,000,000 visual receptors
2,000,000 retinal ganglion axons
>100,000,000 visual cortex neurons
each has specific receptive field
each processing circuit functions in parallel with all others

44. neuronal networks visual information processing-binocular vision
information from left visual field is processed by right hemisphere
information from right visual field is processed by left hemisphere
some information from each eye crosses at the optic chiasm

45. axons cross at the optic chiasm Figure 46.12

46. neuronal networks visual information processing-binocular vision
one location on visual cortex receives information from both eyes about the same spot in the visual field
columns of cells receive left or right eye inputs
cells in each column receive both
binocular cells interpret distance from the disparity between the two retinas

47. binocular interpretation of visual information Figure 46.12