1. Central Nervous System (CNS)
CNS consists of the brain and spinal cord
Cephalization
Evolutionary development of the rostral (anterior) portion of the CNS
Increased number of neurons in the head
Highest level is reached in the human brain

2. Embryonic Development
Neural plate forms from ectoderm
Neural plate invaginates to form a neural groove and neural folds

3. Regions and Organization of the CNS
Adult brain regions
Cerebral hemispheres
Diencephalon
Brain stem (midbrain, pons, and medulla)
Cerebellum

4. Cerebral hemisphere Diencephalon Cerebellum Brain stem • Midbrain
• Pons
• Medulla oblongata
(d) Birth
Figure 12.3d

5. Regions and Organization of the CNS
Spinal cord
Central cavity surrounded by a gray matter core
External white matter composed of myelinated fiber tracts

6. Regions and Organization of the CNS
Brain
Similar pattern with additional areas of gray matter
Nuclei in cerebellum and cerebrum
Cortex of cerebellum and cerebrum

7. Central cavity Cortex of gray matter Migratory pattern of neurons
Inner gray
matter
Cerebrum
Outer white
matter
Cerebellum
Gray matter
Region of cerebellum
Central cavity
Inner gray matter
Outer white matter
Gray matter
Brain stem
Central cavity
Outer white matter
Inner gray matter
Spinal cord
Figure 12.4

8. Ventricles of the Brain
Connected to one another and to the central canal of the spinal cord
Lined by ependymal cells

9. Ventricles of the Brain
Contain cerebrospinal fluid
Two C-shaped lateral ventricles in the cerebral hemispheres
Third ventricle in the diencephalon
Fourth ventricle in the hindbrain, dorsal to the pons, develops from the lumen of the neural tube

10. Lateral ventricle Septum pellucidum Anterior horn Posterior horn
Inferior
horn
Interventricular
foramen
Lateral
aperture
Median
aperture
Third ventricle
Inferior horn
Lateral
aperture
Cerebral aqueduct
Fourth ventricle
Central canal
(a) Anterior view
(b) Left lateral view
Figure 12.5

11. Cerebral Hemispheres Surface markings
Ridges (gyri), shallow grooves (sulci), and deep grooves (fissures)
Five lobes
Frontal
Parietal
Temporal
Occipital
Insula

12. Cerebral Hemispheres Surface markings Central sulcus
Separates the precentral gyrus of the frontal lobe and the postcentral gyrus of the parietal lobe
Longitudinal fissure
Separates the two hemispheres
Transverse cerebral fissure
Separates the cerebrum and the cerebellum

13. Cerebral Cortex Thin (2–4 mm) superficial layer of gray matter
40% of the mass of the brain
Site of conscious mind: awareness, sensory perception, voluntary motor initiation, communication, memory storage, understanding
Each hemisphere connects to contralateral side of the body
There is lateralization of cortical function in the hemispheres

14. Functional Areas of the Cerebral Cortex
The three types of functional areas are:
Motor areas—control voluntary movement
Sensory areas—conscious awareness of sensation
Association areas—integrate diverse information
Conscious behavior involves the entire cortex

15. Motor Areas
Primary (somatic) motor cortex
Premotor cortex
Broca’s area
Frontal eye field

16. Sensory areas and related association areas Primary motor cortex
Motor areas
Central sulcus
Sensory areas and related
association areas
Primary motor cortex
Primary somatosensory
cortex
Premotor cortex
Somatic
sensation
Frontal eye field
Somatosensory
association cortex
Broca’s area
(outlined by dashes)
Gustatory cortex
(in insula)
Taste
Prefrontal cortex
Working memory
for spatial tasks
Wernicke’s area
(outlined by dashes)
Executive area for
task management
Working memory for
object-recall tasks
Primary visual
cortex
Visual
association
area
Vision
Solving complex,
multitask problems
Auditory
association area
Hearing
Primary
auditory cortex
(a) Lateral view, left cerebral hemisphere
Primary motor cortex
Motor association cortex
Primary sensory cortex
Sensory association cortex
Multimodal association cortex
Figure 12.8a

17. Primary Motor Cortex
Large pyramidal cells of the precentral gyri
Long axons  pyramidal (corticospinal) tracts
Allows conscious control of precise, skilled, voluntary movements
Motor homunculi: upside-down caricatures representing the motor innervation of body regions

18. Posterior
Motor
Motor map in
precentral gyrus
Anterior
Toes
Jaw
Tongue
Primary motor
cortex
(precentral gyrus)
Swallowing
Figure 12.9

19. Premotor Cortex
Anterior to the precentral gyrus
Controls learned, repetitious, or patterned motor skills
Coordinates simultaneous or sequential actions
Involved in the planning of movements that depend on sensory feedback

20. Broca’s Area
Anterior to the inferior region of the premotor area
Present in one hemisphere (usually the left)
A motor speech area that directs muscles of the tongue
Is active as one prepares to speak

21. Frontal Eye Field
Anterior to the premotor cortex and superior to Broca’s area
Controls voluntary eye movements

22. Sensory Areas Primary somatosensory cortex
Somatosensory association cortex
Visual areas
Auditory areas
Olfactory cortex
Gustatory cortex
Visceral sensory area
Vestibular cortex

23. Sensory areas and related association areas Primary motor cortex
Motor areas
Central sulcus
Sensory areas and related
association areas
Primary motor cortex
Primary somatosensory
cortex
Premotor cortex
Somatic
sensation
Frontal eye field
Somatosensory
association cortex
Broca’s area
(outlined by dashes)
Gustatory cortex
(in insula)
Taste
Prefrontal cortex
Working memory
for spatial tasks
Wernicke’s area
(outlined by dashes)
Executive area for
task management
Working memory for
object-recall tasks
Primary visual
cortex
Visual
association
area
Vision
Solving complex,
multitask problems
Auditory
association area
Hearing
Primary
auditory cortex
(a) Lateral view, left cerebral hemisphere
Primary motor cortex
Motor association cortex
Primary sensory cortex
Sensory association cortex
Multimodal association cortex
Figure 12.8a

24. Primary Somatosensory Cortex
In the postcentral gyri
Receives sensory information from the skin, skeletal muscles, and joints
Capable of spatial discrimination: identification of body region being stimulated

25. Posterior
Sensory
Anterior
Sensory map in
postcentral gyrus
Genitals
Primary somato-
sensory cortex
(postcentral gyrus)
Intra-
abdominal
Figure 12.9

26. Somatosensory Association Cortex
Posterior to the primary somatosensory cortex
Integrates sensory input from primary somatosensory cortex
Determines size, texture, and relationship of parts of objects being felt

27. Primary visual (striate) cortex
Visual Areas
Primary visual (striate) cortex
Extreme posterior tip of the occipital lobe
Most of it is buried in the calcarine sulcus
Receives visual information from the retinas

28. Visual association area
Visual Areas
Visual association area
Surrounds the primary visual cortex
Uses past visual experiences to interpret visual stimuli (e.g., color, form, and movement)
Complex processing involves entire posterior half of the hemispheres

29. Primary auditory cortex
Auditory Areas
Primary auditory cortex
Superior margin of the temporal lobes
Interprets information from inner ear as pitch, loudness, and location
Auditory association area
Located posterior to the primary auditory cortex
Stores memories of sounds and permits perception of sounds

30. Medial aspect of temporal lobes (in piriform lobes)
OIfactory Cortex
Medial aspect of temporal lobes (in piriform lobes)
Part of the primitive rhinencephalon, along with the olfactory bulbs and tracts
(Remainder of the rhinencephalon in humans is part of the limbic system)
Region of conscious awareness of odors

31. Gustatory Cortex
In the insula
Involved in the perception of taste

32. Visceral Sensory Area
Posterior to gustatory cortex
Conscious perception of visceral sensations, e.g., upset stomach or full bladder

33. Vestibular Cortex
Posterior part of the insula and adjacent parietal cortex
Responsible for conscious awareness of balance (position of the head in space)

34. Multimodal Association Areas
Receive inputs from multiple sensory areas
Send outputs to multiple areas, including the premotor cortex
Allow us to give meaning to information received, store it as memory, compare it to previous experience, and decide on action to take

35. Multimodal Association Areas
Three parts
Anterior association area (prefrontal cortex)
Posterior association area
Limbic association area

36. Anterior Association Area (Prefrontal Cortex)
Most complicated cortical region
Involved with intellect, cognition, recall, and personality
Contains working memory needed for judgment, reasoning, persistence, and conscience
Development depends on feedback from social environment

37. Posterior Association Area
Large region in temporal, parietal, and occipital lobes
Plays a role in recognizing patterns and faces and localizing us in space
Involved in understanding written and spoken language (Wernicke’s area)

38. Limbic Association Area
Part of the limbic system
Provides emotional impact that helps establish memories

39. Lateralization of Cortical Function
Division of labor between hemispheres
Cerebral dominance
Designates the hemisphere dominant for language (left hemisphere in 90% of people)

40. Lateralization of Cortical Function
Left hemisphere
Controls language, math, and logic
Right hemisphere
Insight, visual-spatial skills, intuition, and artistic skills
Left and right hemispheres communicate via fiber tracts in the cerebral white matter

41. Myelinated fibers and their tracts Responsible for communication
Cerebral White Matter
Myelinated fibers and their tracts
Responsible for communication
Commissures (in corpus callosum)—connect gray matter of the two hemispheres
Association fibers—connect different parts of the same hemisphere
Projection fibers—(corona radiata) connect the hemispheres with lower brain or spinal cord

42. Commissural fibers (corpus Longitudinal fissure callosum) Superior
Lateral
ventricle
Association
fibers
Basal nuclei
• Caudate
Corona radiata
• Putamen
• Globus pallidus
Fornix
Internal
capsule
Thalamus
Gray matter
Third
ventricle
White matter
Projection
fibers
Pons
Decussation
of pyramids
Medulla oblongata
(a)
Figure 12.10a

43. Basal Nuclei (Ganglia)
Subcortical nuclei
Consists of the corpus striatum
Caudate nucleus
Lentiform nucleus (putamen + globus pallidus)
Functionally associated with the subthalamic nuclei (diencephalon) and the substantia nigra (midbrain)

44. Functions of Basal Nuclei
Though somewhat elusive, the following are thought to be functions of basal nuclei
Influence muscular control
Help regulate attention and cognition
Regulate intensity of slow or stereotyped movements
Inhibit antagonistic and unnecessary movements

45. Three paired structures
Diencephalon
Three paired structures
Thalamus
Hypothalamus
Epithalamus
Encloses the third ventricle

46. Cerebral hemisphere Septum pellucidum Corpus callosum Interthalamic
adhesion
(intermediate
mass of
thalamus)
Fornix
Choroid plexus
Thalamus
(encloses third
ventricle)
Interven-
tricular
foramen
Posterior commissure
Pineal gland
(part of epithalamus)
Anterior
commissure
Corpora
quadrigemina
Mid-
brain
Hypothalamus
Cerebral
aqueduct
Optic chiasma
Arbor vitae (of
cerebellum)
Pituitary gland
Fourth ventricle
Mammillary body
Choroid plexus
Pons
Cerebellum
Medulla oblongata
Spinal cord
Figure 12.12

47. Thalamus
80% of diencephalon
Superolateral walls of the third ventricle
Connected by the interthalamic adhesion (intermediate mass)
Contains several nuclei, named for their location
Nuclei project and receive fibers from the cerebral cortex

48. Dorsal nuclei Medial Lateral dorsal Lateral posterior Pulvinar
Anterior
nuclear
group
Medial
geniculate
body
Reticular
nucleus
Lateral
geniculate
body
Ventral
postero-
lateral
Ventral
anterior
Ventral
lateral
Ventral nuclei
(a) The main thalamic nuclei. (The reticular nuclei that “cap” the thalamus laterally are depicted as curving translucent structures.)
Figure 12.13a

49. Thalamic Function Gateway to the cerebral cortex
Sorts, edits, and relays information
Afferent impulses from all senses and all parts of the body
Impulses from the hypothalamus for regulation of emotion and visceral function
Impulses from the cerebellum and basal nuclei to help direct the motor cortices
Mediates sensation, motor activities, cortical arousal, learning, and memory

50. Forms the inferolateral walls of the third ventricle
Hypothalamus
Forms the inferolateral walls of the third ventricle
Contains many nuclei
Example: mammillary bodies
Paired anterior nuclei
Olfactory relay stations
Infundibulum—stalk that connects to the pituitary gland

51. (b) The main hypothalamic nuclei.
Paraventricular
nucleus
Anterior
commissure
Dorsomedial
nucleus
Fornix
Preoptic
nucleus
Posterior
hypothalamic
nucleus
Anterior
hypothalamic
nucleus
Lateral
hypothalamic
area
Supraoptic
nucleus
Ventromedial
nucleus
Supra-
chiasmatic
nucleus
Mammillary
body
Arcuate
nucleus
Optic
chiasma
Pituitary
gland
Infundibulum
(stalk of the
pituitary gland)
(b) The main hypothalamic nuclei.
Figure 12.13b

52. Hypothalamic Function
Autonomic control center for many visceral functions (e.g., blood pressure, rate and force of heartbeat, digestive tract motility)
Center for emotional response: Involved in perception of pleasure, fear, and rage and in biological rhythms and drives