Cerebrum Chapter 12 and 13 p. 430

Cerebrum – surrounded by a thin layer of gray matter called cerebral cortex (rind or bark)  Consists of six layers of nerve cell bodies Beneath the cortex lies cerebral white matter

Embryonic Development of the brain During development, the gray matter of the cerebral cortex increases faster than the underlying white matter  Folds upon itself – Gyri pl.(gyrus =sing.)  Deep folds are fissures with the grooves called sulci pl. (sulcus=sing.) Longitudinal Fissure = separates the cerebrum into 2 hemispheres

Development of the brain

Corpus callosum - connects the two hemispheres  Composed of bundles of transverse fibers made of white matter  Larger in females than males Males only have emotional capacities in just one hemisphere (right side) Female has emotional capacities in both  Info flow in males is slower between the emo right side and the verbal left side of the male brain

Agenesis of the corpus callosum AGCC – Born without a corpus callosum AGCC – Born without a corpus callosum

Lobes 4 lobes – frontal, parietal, temporal, occipital  Central sulcus – divides frontal and parietal lobes  Precentral gyrus – anterior to central sulcus. Controls primary motor area of cerebral cortex  Postcentral gyrus – posterior to central sulcus. Contains somatosensory area.

The brain of a genius – Discovery Channel The brain of a genius – Discovery Channel

Limbic System Portions of the cerebral hemisphere and diencephalon Wishbone shaped group of structures surrounding the brainstem, functions in emotions such as  Pain, pleasure, anger, rage, fear, sorrow sexual feelings, affection  Controls involuntary aspects of emotion such as survival and also functions in memory

The limbic system of the brain is a group of structures which govern emotions and behavior. The limbic system, and in particular the hippocampus and amygdala, is involved in the formation of long-term memory, and is closely associated with the olfactory structures (having to do with the sense of smell).

Memory and stress

Functional Areas of the Cerebral Cortex 3 Areas – Motor – muscular movement Sensory – receiving and interpreting sensory impulses Association – memory, emotions, reasoning, will, judgment, personality and intelligence

Sensory Sensory input into the cerebral cortex flows mainly to the posterior half of the cerebral hemispheres 1. Primary somatosensory – receives sensations from cutaneous (skin) and muscular receptors  Function – localize exactly the points of the body where the sensations originate

Sensory 2. Primary Visual – occipital lobe, receives sensory impulses from the eyes and interprets shape, color, and movement 3. Primary auditory – temporal lobe, interprets basic characteristics of sound such as pitch and rhythm

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Sensory 4. Primary Gustatory area – base of postcentral gyrus, interprets sensations related to taste 5. Primary olfactory – temporal lobe, interprets sensations related to smell

Motor Areas Motor cortex are found in both hemispheres 1. Primary motor area – in precentral gyrus of frontal, consists of regions that control muscle groups  Stimulation of a specific point results in a muscle contraction

Motor Area 2. Motor speech area – broca’s area, frontal lobe (left) superior to the lateral cerebral sulcus  Damage to this area can result in – Aphasia – inability to speak Agraphia – inability to write Word deafness – inability to understand spoken words Word blindness – inability to understand written words

Association Areas Association tracts that connect motor and sensory areas and large parts of the occipital, parietal, and temporal lobes anterior to motor areas

1. Somatosensory association area – posterior to primary somatosenory area  Determine shape and texture of an object without looking at it, sense relationship of one body part to another, and orientation of one object to another as they are felt

2. Visual association area – occipital lobe  Relates present to past visual experiences with recognition and eval of what is seen

3. Auditory association area – below primary auditory area in temporal cortex  Determines if sound is speech, music, noise  Translates words into thoughts

4. Gnostic – integrates sensory interpretations from the association areas and impulses from other areas so that a common thought can be formed from various sensory inputs

5. Premotor Area – in front of the primary motor area  Deals with learned motor activities of complex and sequential nature  Ex: specific muscles contract in order to write a word

6.Frontal eye field area – frontal cortex  Controls voluntary scanning movements of the eyes Searching for a word in a dictionary

7. Language areas – broca’s area  Nerve impulses pass to premotor regions that control the muscles of the larynx, pharnyx, and mouth  Impulses reach your breathing muscles to regulate the proper flow of air past the vocal cords

Memory Short term and long term  Associated with association cortex of the frontal, parietal, occipital, and temporal lobes; part of the limbic system; and the diencephalon  Dori Dori

Cerebellum Second largest portion of the brain Behind the medulla and pons and below the occipital lobes of the cerebrum

Cerebellum Compares the intended movement programmed by motor areas in the cerebrum with what is actually occurring. Helps to smooth and coordinate skeletal muscle contractions Main region that regulates posture, balance and skills for motor activities

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