copyright © 2010 pearson education, inc. the brain
TRANSCRIPT
Copyright © 2010 Pearson Education, Inc.
The Brain
Copyright © 2010 Pearson Education, Inc.
Copyright © 2010 Pearson Education, Inc.
Cerebral Hemispheres
How is the brain organized?– Define the major lobes– Distinguish between gyri and sulci– Compare the functional areas of the cerebral
cortex
Copyright © 2010 Pearson Education, Inc.
The cerebrum is divided into three major areas:• Cerebral Cortex• Internal White Matter• Basal Nuclei
Copyright © 2010 Pearson Education, Inc.
The cerebral hemispheres form the superior part of the brain.
It makes up most of the mass of the brain.
Copyright © 2010 Pearson Education, Inc.
A. The Cerebral Cortex
The cortex is composed of gray matter which contains neuron cell bodies, dendrites, glial cells and blood vessels.
It is only 2 to 4 mm in thickness.
The folds increase the surface area.
Copyright © 2010 Pearson Education, Inc.
The surface of the hemispheres is marked by elevated ridges called gyri and shallow grooves called sulci.
Copyright © 2010 Pearson Education, Inc.
Lissencephaly, which literally means smooth brain, is a rare brain formation disorder caused by defective neuronal migration during the 12th to 24th weeks of gestation resulting in a lack of development of brain folds (gyri) and grooves (sulci).
Copyright © 2010 Pearson Education, Inc.
Normal Brain Lissencephaly
Copyright © 2010 Pearson Education, Inc.
Lissencephaly Normal Brain
Copyright © 2010 Pearson Education, Inc.
The prognosis for children with lissencephaly varies depending on the malformation.
Many individuals remain in a 3-5 month developmental level, while others may appear to have near normal intelligence and development.
Some children with lissencephaly will be able to roll over, sit, reach for objects, and smile socially.
Copyright © 2010 Pearson Education, Inc.
The cortex contains three kinds of functional areas:– Motor area– Sensory areas– Association areas
Copyright © 2010 Pearson Education, Inc.
Each hemisphere is primarily concerned with sensory and motor function on the opposite (contralateral) side of the body.
Copyright © 2010 Pearson Education, Inc.
Each hemisphere is not equal in function. There is lateralization (specialization) of cortical functions.
Left hemisphere is logical while the right is creative
Copyright © 2010 Pearson Education, Inc.
Copyright © 2010 Pearson Education, Inc.
The motor areas control voluntary movement and are found primarily in the posterior part of the frontal lobes and include:– the primary motor cortex, – premotor cortex, – Broca’s area and – the frontal eye field.
Copyright © 2010 Pearson Education, Inc.
Figure 12.8a Functional and structural areas of the cerebral cortex.
Gustatory cortex(in insula)
Primary motor cortex
Premotor cortex
Frontal eye field
Working memoryfor spatial tasksExecutive area fortask managementWorking memory forobject-recall tasks
Broca’s area(outlined by dashes)
Solving complex,multitask problems
(a) Lateral view, left cerebral hemisphere
Motor areas
Prefrontal cortex
Sensory areas and relatedassociation areas
Central sulcus
Primary somatosensorycortexSomatosensoryassociation cortex
Somaticsensation
Taste
Wernicke’s area(outlined by dashes)
Primary visualcortexVisualassociation area
Vision
Auditoryassociation areaPrimaryauditory cortex
Hearing
Primary motor cortex Motor association cortex Primary sensory cortex
Sensory association cortex Multimodal association cortex
Copyright © 2010 Pearson Education, Inc.
Primary motor cortex is located in the precentral gyrus of the frontal lobe.
Their function is to control the precise voluntary movements of the skeletal muscles.
Copyright © 2010 Pearson Education, Inc.
Figure 12.9 Body maps in the primary motor cortex and somatosensory cortex of the cerebrum.
Genitals
Toes
Intra-abdominalSwallowing
Tongue
Jaw
Primary motorcortex(precentral gyrus)
Primary somato-sensory cortex(postcentral gyrus)
Motor
Motor map inprecentral gyrus
Sensory
Sensory map inpostcentral gyrus
Posterior
Anterior
Copyright © 2010 Pearson Education, Inc.
Common disorders include stroke, tumors or traumatic brain injury.
Effects include loss of specific motor functions.
Stroke
Copyright © 2010 Pearson Education, Inc.
Premotor cortex is located just anterior precentral gyrus of the frontal lobe.
It's function is to control learned motor skills of a repetitive or patterned nature, for example typing.
Copyright © 2010 Pearson Education, Inc.
Disorders of the premotor cortex are commonly due to stroke, tumors or trauma.
One condition is known as Apraxia or the inability to recognize objects by touch.
Copyright © 2010 Pearson Education, Inc.
Broca’s Area lies anterior and inferior to the premotor cortex.
It is typically found only in the left hemisphere and is the motor speech area.
Copyright © 2010 Pearson Education, Inc.
Aphasia is a disorder caused by damage to the parts of the brain that control language.
It can make it hard for you to read, write, and say what you mean to say.
Copyright © 2010 Pearson Education, Inc.
There are four main types:• Expressive aphasia - you know what you
want to say, but you have trouble saying or writing what you mean
Copyright © 2010 Pearson Education, Inc.
There are four main types:• Expressive aphasia• Receptive aphasia - you hear the voice or
see the print, but you can't make sense of the words
Copyright © 2010 Pearson Education, Inc.
There are four main types:• Expressive aphasia • Receptive aphasia • Anomic aphasia - you have trouble using
the correct word for objects, places, or events
Copyright © 2010 Pearson Education, Inc.
There are four main types:• Expressive aphasia • Receptive aphasia • Anomic aphasia • Global aphasia - you can't speak,
understand speech, read, or write
Aphasia
Copyright © 2010 Pearson Education, Inc.
Frontal eye field is located on or near the premotor cortex and is above Broca’s area. This region controls the voluntary movement of the eyes.
Copyright © 2010 Pearson Education, Inc.
The sensory area of the cerebral cortex is concerned with conscious awareness.
Areas involved with this function are found in the parietal, temporal and occipital lobes.
Copyright © 2010 Pearson Education, Inc.
Primary somatosensory cortex receive information from the sensory receptors in the skin and proprioceptors (position receptors) in the skeletal muscles, joints and tendons.
Copyright © 2010 Pearson Education, Inc.
Figure 12.9 Body maps in the primary motor cortex and somatosensory cortex of the cerebrum.
Genitals
Toes
Intra-abdominalSwallowing
Tongue
Jaw
Primary motorcortex(precentral gyrus)
Primary somato-sensory cortex(postcentral gyrus)
Motor
Motor map inprecentral gyrus
Sensory
Sensory map inpostcentral gyrus
Posterior
Anterior
Copyright © 2010 Pearson Education, Inc.
• Somatosensory association cortex serves to integrate sensory information such as temperature, pressure to produce an understanding of what is being touched.
Copyright © 2010 Pearson Education, Inc.
Association Areas
Multimodal association areas receive input from multiple senses and sends outputs to multiple areas. There are 3 main areas:
• Anterior association area • Posterior association area • Limbic association area
Copyright © 2010 Pearson Education, Inc.
Anterior association area
Is located in the frontal lobe.
It is considered the most complicated and is involved with learning (cognition), recall and personality.
Additional functions include working memory, abstraction and planning.
Copyright © 2010 Pearson Education, Inc.
Posterior association area
Covers the temporal, parietal and occipital lobes.
This area is involved with pattern recognition.
It is what allows us to recognize familiar places.
An additional function understands of written and spoken language.
Copyright © 2010 Pearson Education, Inc.
Isolated problems with these association areas are rare.
Trauma or stroke often leads to large areas of affliction.
The case of Phineas Gage
Copyright © 2010 Pearson Education, Inc.
Limbic association area
This area is sometimes called the pleasure center. In animal studies it is correlated with sexual arousal, behavior and olfaction (think about this last one).
Big Bang
Copyright © 2010 Pearson Education, Inc.
Copyright © 2010 Pearson Education, Inc.
B. Cerebral White Matter
The cerebral white matter is responsible for communicating between the cerebral areas and the lower CNS centers.
This area consists largely of myelinated fibers bundled into large tracts.
Copyright © 2010 Pearson Education, Inc.
The white fibers or tracts are classified based on which direction they run.– Commissural fibers connect gray areas of
the two hemispheres allowing them to coordinate.
– Association fibers connect different parts of the same hemisphere
– Projection fibers either enter the cerebral cortex from the lower brain or descend to the lower areas from the cortex.
Copyright © 2010 Pearson Education, Inc.
Corpus Callosum (Commissures)
Copyright © 2010 Pearson Education, Inc.
Association Fibers
Copyright © 2010 Pearson Education, Inc.
Figure 12.10 Types of fiber tracts in white matter.
Coronaradiata
Projectionfibers
Longitudinal fissure
Gray matter
White matter
Association fibers
Lateral ventricle
Fornix
Thirdventricle
Thalamus
Pons
Medulla oblongataDecussationof pyramids
Commissural fibers(corpus callosum)
Internalcapsule
Superior
Basal nuclei• Caudate• Putamen• Globus
pallidus
(a) (b)
Copyright © 2010 Pearson Education, Inc.
C. Basal Nuclei
These represent the third region of the cerebral hemisphere. The basal nuclei consist of the:– caudate nucleus, – putamen and – the globus pallidus.
Copyright © 2010 Pearson Education, Inc.
The basal nuclei receive input from the entire cerebral cortex.
They appear to be important in starting and stopping the intensity of movements initiated by the cerebral cortex.
They are important in our ability to multitask.
Copyright © 2010 Pearson Education, Inc.
Together the putamen and globus pallidus form the lentiform nucleus that flanks the internal capsule
Copyright © 2010 Pearson Education, Inc.
Figure 12.11b Basal nuclei (1 of 2).
Corpus callosumAnterior hornof lateral ventricleCaudate nucleusPutamen
Lentiformnucleus
(b)
Globuspallidus
ThalamusTail of caudate nucleusThird ventricle
Cerebral cortexCerebral white matter
Anterior
Posterior
Inferior hornof lateral ventricle
Copyright © 2010 Pearson Education, Inc.
Figure 12.11b Basal nuclei (2 of 2).
Corpus callosumAnterior hornof lateral ventricleCaudate nucleus
Lentiform nucleus
(b)
Thalamus
Third ventricle
Cerebral cortexCerebral white matter
Inferior hornof lateral ventricle
Copyright © 2010 Pearson Education, Inc.
Disorders of the Basal Nucleus
The basal ganglia play a central role in a number of neurological conditions. The most notable are, Parkinson’s disease and Huntington's disease.
Basal ganglia dysfunction is also implicated in some other disorders of behavior control such as Tourette’s syndrome, and obsessive compulsive disorder (OCD),
Copyright © 2010 Pearson Education, Inc.
Copyright © 2010 Pearson Education, Inc.
Question
1. What is meant by lateralization?
Copyright © 2010 Pearson Education, Inc.
Question
2. How thick is the cerebral cortex?
Copyright © 2010 Pearson Education, Inc.
Question
3. What are the three types of functional areas found in the cerebrum?
Copyright © 2010 Pearson Education, Inc.
Question
4.