Download ANPS 019 Black 11-09

ANPS019
November 9, 2011
CEREBRUM
Chapter 14: 486-476
THE CEREBRUM
Is the largest part of the brain
Controls all conscious thoughts and intellectual functions
Processes somatic and visceral sensory and motor functions
FUNCTIONAL PRINCIPLES OF THE CEREBRUM
Each cerebral hemisphere receives sensory information from and sends motor commands to, the
opposite side of the body
Although their structures are similar, the 2 hemispheres have different functions e.g., language on left,
face recognition of right)
Specific regions of the cerebral cortex have specific functions, but there Is overlap
Primary motor and sensory areas are organized into topographic maps representing specific body
regions
HEMISPHERIC LATERALIZATION
Brain sided-ness does not always correspond to “handed-ness”
Right side – “creative”
Musical and artistic awareness
Spatial and pattern perception
Face recognition
Emotional part of speech
Left side- “analytical”:
Spoken and written language
Numerical and scientific skills
Reasoning
Everyone has the same pattern of gyri and sulci on their cerebral cortex
-Different gyri deal with different types of information
Sulces: shallow depressions
Gyrus: elevated ridge
Different areas of the cortex perform different functions
“Primary” areas: neurons receive sensory information or directly send out motor instructions
“Association” areas: neurons make sense of sensory information of plan motor activities (muscle
movements)
FRONTAL LOBE: MOTOR AND LIMBIC FUNCTIONS
Central Sulcus: Separates frontal and parietal lobes
-Primary Cortex
-Premotor Cortex
-Prefrontal Cortex
Broca’s Ara (Motor Speech)
Frontal Lobe: Primary Motor Cortex
Primary Motor Cortex = Precentral gyrus
-directs voluntary muscle movement
-contains a map of all skeletal muscles
-Pyramidal neurons (multipolar neurons that sends info down to body) in this gyrus that project via the
internal capsule to synapse in the brainstem or spinal cord; they talk to the neurons that contact the
muscles (they do NOT directly synapse on the muscles!!)
Neurons in the primary motor cortex are arranged according to the muscles they control
FRONTAL LOBE: PREMOTOR CORTEX
*learned motor activities, planning of motor activities
--people who this stroke: can execute motor activities, but can’t plan them out
Directs neurons in the primary motor cortex; therefore less discrete topographic map
Contains two specialized regions
-frontal eye fields
-Broca’s speech area: inability to product language
FRONTAL LOBE: FRONTAL EYE FIELDS
The purpose of this region is to keep the eyes directed forward. The right frontal eye field forces both
eyes to the left while the left frontal eye field forces both eyes to the right. In a unilateral lesion, both
eyes will deviate TOWARDS the side of the lesion.
FRONTAL LOBE: BROCA’S SPEECH AREA
Broca’s aphasia: motoraphasia
-nothing wrong with moving tongue and lips
Primarily located in left hemisphere – produces speech
Expressive (motor, non-fluent) aphasia
-anomia (inability to name objects)
Patient aware of deficit
FRONTAL LOBE: PREFRONTAL CORTEX
LIMBIC
Largest part of the frontal lobe
Many connections to other areas
Vague limbic functions (e.g., personality)
PRIETAL LOBE: Somatosensation
(the sense of touch, awareness of body)
PARIETAL LOBE: PRIMARY SOMATOSENSORY CORTEX
Primary somatosensory cortex = postcentral gyrus
Receives somatic sensory information from skin receptors, joints and muscles:
-touch, pressure, vibration
-pain and temperature
-taste
Neurons in the primary somatosensory cortex are arranged according to the body region they receive
information form
PARIETAL LOBE: SOMATOSENSORY ASSOCATION CORTEX
Interpretation of sensations
Shape and texture of object
Orientation of object (where an object is in space)
Relationship of body parts
-stroke to right parietal association cortex results in a fascination syndrome in which the patient
disregards the left side of the body = syndrome of hemineglect
TEMPORAL LOBE: HEARING, LIMBIC FUNCTION, VISUAL ASSOCIATION
Primary auditory cortex
Lateral fissure: separates frontal, parietal and temporal lobes
Wernicke’s Speech Area
TEMPORAL LOBE: PRIMARY AUDITORY COMPLEX
Receives sounds information, sorts by frequency (tonotopic map)
Pitch, rhythm
Auditory Association: sorts sound into speech, music, tone (when song gets stuck in head0
TEMPORAL LOBE: WERNICKE’S SPEECH AREA
Primarily located in left hemisphere
Speech comprehension
Receptive (sensory, fluent) aphasia
-language comprehension affected
-nonsensical speech, but patient unaware of deficit
-anomia, impaired repetition, non-fluent reading
-apraxia (inability to execute motor activity based on verbal command)