Evolutionary development of rostral (anterior) portion of CNS

Resulted in increased number of neurons

Highest level reached in human brain

1.Cerebral hemispheres

2.Diencephalon

3.Brain stem

4.Cerebellum

Where is Gray matter and white matter located

What is short, nonmyelinated neurons and cell bodies

What is myelinated and some nonmyelinated axons

What has additional gray matter nuclei scattered within white matter

Contain outer layer of gray matter called the cortex

What have scattered areas of gray matter nuclei amid white matter

Fluid-filled chambers that are continuous to one another and to central canal of spinal cord

What is filled with cerebrospinal fluid (CSF)

What is lined by ependymal cells (neuroglial cells)

What is large, C-shaped chambers located deep in each hemisphere

What is connected to the third ventricle via interventricular foramen

◦Third ventricle lies in diencephalon

What is connected to the fourth ventricle via cerebral aqueduct

Continuous with central canal of spinal cord

◦Three openings connect fourth ventricle to subarachnoid space that surrounds brain

What form superior part of brain

Account for 83% of brain mass

Gyri

◦Sulci

◦Fissures

◦Longitudinal fissure

◦Separates two hemispheres

◦Transverse cerebral fissure

◦Separates cerebrum and cerebellum

ridges

shallow grooves

deep grooves

1.Frontal

2.Parietal

3.Temporal

4.Occipital

5.Insula

What lobes are named after overlying skull bones

is buried under portions of temporal, parietal, and frontal lobes

separates precentral gyrus of frontal lobe and postcentral gyrus of parietal lobe

separates occipital and parietal lobes

outlines temporal lobes

1.Cerebral cortex of gray matter superficially

2.White matter internally

3.Basal nuclei deep within white matter

is “executive suite” of brain

awareness, sensory perception, voluntary motor initiation, communication, memory storage, understanding

Thin (2–4 mm) superficial layer of gray matter

◦Composed of neuron cell bodies, dendrites, glial cells, and blood vessels, but no axons

40% of mass of brain

Functional imaging (PET and MRI) of brain show specific motor and sensory functions are located in discrete cortical areas called domains

◦Higher functions are spread over many areas

Contains three types of functional areas:

1.Motor areas

2.Sensory areas:

3.Association areas:

2.Each hemisphere is concerned with contralateral (opposite) side of body

3.Lateralization (specialization) of cortical function can occur in only one hemisphere

4.Conscious behavior involves entire cortex in one way or another

control voluntary movement

conscious awareness of sensation

integrate diverse information

located in frontal lobe

primary motor cortex in precentral gyrus

Premotor cortex anterior to precentral gyrus

Broca’s area anterior to inferior premotor area

Frontal eye fieldwithin and anterior to premotor cortex; superior to Broca’s area

◦Conscious control of precise, skilled skeletal muscle movements carried out by Pyramidal cells

Somatotopy

Motor homunculi

all muscles of body can be mapped to area on primary motor cortex

upside-down caricatures represent contralateralmotor innervation of body regions

◦Helps plan movements

◦Staging area for skilled motor activities

◦Controls learned, repetitious, or patterned motor skills

◦Coordinates simultaneous or sequential actions 

◦Controls voluntary actions that depend on sensory feedback

◦Present in one hemisphere (left in 90% of right-handed people and 70% in left-handed people)

◦Motor speech area that directs muscles of speech production

Active in planning speech

◦controls voluntary eye movements

◦Paralyzes muscles controlled by those areas

◦Paralysis occurs on opposite side of body from damage

presents with

◦Apraxia

◦Deficits in contralateral fine motor control, such as the performance of complex serial movements

◦Other premotor neurons can be reprogrammed to take over skill of damaged neurons

◦Would require practice, just as the initial learning process did

areas of cortex concerned with conscious awareness of sensation

◦Occur in parietal, insular, temporal, and occipital lobes

Receives general sensory information from skin and proprioceptorsof skeletal muscle, joints, and tendons

◦Somatosensory homunculus: upside-down caricatures represent contralateral sensory input from body regions

Posterior to primary somatosensory cortex

Integrates sensory input from primary somatosensory cortex for understanding of object

◦Primary visual (striate) cortex located on extreme posterior tip of occipital lobe

◦Receives visual information from retinas

◦Damage to the primary visual cortex results in functional blindness

surrounds primary visual cortex

◦Uses past visual experiences to interpret visual stimuli (color, form, or movement)

◦Example: ability to recognize faces

◦Individuals with a damaged visual association area can see, but they do not comprehend what they are looking at

Primary auditory cortex

◦Superior margin of temporal lobes

◦Interprets information from inner ear as pitch, loudness, and location

Auditory association area

◦Located posterior to primary auditory cortex

◦Stores memories of sounds and permits perception of sound stimulus

◦Posterior part of insula and adjacent parietal cortex

◦Responsible for conscious awareness of balance (position of head in space)

◦Medial aspect of temporal lobes

◦Involved in conscious awareness of odors

◦In insula just deep to temporal lobe

◦Involved in perception of taste

in insula posterior to gustatory cortex

◦Conscious perception of visceral sensations, such as upset stomach or full bladder

Receive inputs from multiple sensory areas

◦Send outputs to multiple areas

◦Allows us to give meaning to information received, store in memory, tie to previous experience, and decide on actions

Sensations, thoughts, emotions become conscious: makes us who we are

◦Broadly divided into three parts: anterior association area,posterior association area, and limbic association area

Also called prefrontal cortex

◦Most complicated cortical region

◦Involved with intellect, cognition, recall, and personality

◦Contains working memory needed for abstract ideas, judgment, reasoning, persistence, and planning

Development depends on feedback from social environment

◦Tumors or other lesions of the anterior association area may cause mental and personality disorders, including loss of judgment, attentiveness, and inhibitions

◦Affected individual may be oblivious to social restraints, perhaps becoming careless about personal appearance, or take risks

◦Large region in temporal, parietal, and occipital lobes

◦Plays role in recognizing patterns and faces and localizing us in space

◦Involved in understanding written and spoken language (Wernicke’s area)

Different problems arise for individuals with lesions in the part of the posterior association area that provides awareness of self in space

Individual may refuse to wash or dress the side of the body opposite to lesion because“thatdoesn’t belong to me”

Part of limbic system

◦Involves cingulate gyrus, parahippocampal gyrus, and hippocampus

◦Provides emotional impact that makes a scene important to us and helps establish memories

Lateralization

Hemispheres are not identical

Cerebral dominance

90% of right handed humans have left-sided dominance

70% of left handed humans have left-sided dominance

◦Left hemisphere

◦Controls language, math, and logic

◦Right hemisphere

◦Visual-spatial skills, intuition, emotion, and artistic and musical skills

◦Hemispheres communicate almost instantaneously via fiber tracts and functional integration

division of labor between hemispheres

refers to hemisphere that is dominant for language

Second of the three basic regions of cerebral hemispheres

Responsible for communication between cerebral areas, and between cortex and lower CNS

Consists of myelinated fibers bundled into large tracts

Classified according to direction they run: 

◦Association, commissural, and projection fibers

Third of the three basic regions of cerebrum

Each hemisphere’s basal nuclei include a:

◦Caudate nucleus

◦Putamen

◦Globus pallidus

◦Caudate nucleus + putamen = striatum

Functions are thought to:

◦Influence muscle movements

◦Play role in cognition and emotion

◦Regulate intensity of slow or stereotyped movements

◦Filter out incorrect/inappropriate responses

◦Inhibit antagonistic/unnecessary movements

Parkinson’s disease and Huntington’s disease are disorders of i

horizontal running fibers that connect different parts of same hemisphere

horizontal fibers that  connect gray matter of two hemispheres

vertical fibers that connect hemispheres with lower brain or spinal cord