Central nervous system (CNS) Brain + Spinal Cord Forebrain –telencephalon cortex, basal ganglia...
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Central nervous system (CNS) Brain + Spinal Cord
• Forebrain– telencephalon
• cortex, basal ganglia
– diencephalon• thalamus, hypothalamus
• Midbrain• tectum, tegmentum
• Hindbrain• cerebellum, pons, medulla
brain stem
cerebral hemispheres
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Cerebral cortex
• Surface is folded to increase area:– Sulcus (pl. sulci) = groove– Gyrus (pl. gyri) = bulge between sulci
• Grey matter = cell bodies• White matter = axons
central sulcuspostcentral gyrus
grey matterwhite matter
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Cerebral hemispheres
• Left & right hemispheres are connected by white matter tracts called commissures.– These allow communication between lateralized
brain areas.– Largest commisure is the corpus callosum.– In “split brain” patients the corpus callosum is
transected, leading to neuropsychological deficits.
corpus callosum
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Lobes of the cerebral cortex
frontal lobe-motor-executive functions
parietal lobe -body sense -multimodal integration
occipital lobe -visual
temporal lobe-memory-auditory
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Primary & association cortex
• Primary cortical areas are most directly linked to the sensory or motor systems in the body.
• These areas project to association cortex, allowing integration of information.
• Association cortex is where sophisticated, higher-level processing takes place, e.g.:– planning of a sequence of movements - motor
association cortex, frontal lobe– perceiving a visual object - visual association
cortex, temporal lobe– making decisions - multimodal association cortex,
frontal lobe
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Primary cortical areasprimary somatosensory area
medial surface of right hemisphere
lateral surface of left hemisphere
primary motor area
central sulcus
primary visual area
primary auditory area
lateral fissure (Sylvian fissure)
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Functional Distribution of Cortex1. Primary Cortex (Direct
Projection Areas) • 3 Sensory—Visual,
Auditory, Somatosensory—
• 1 Motor.
2. Secondary Cortex (unimodal)
3. Tertiary Cortex (Association, polymodal)
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Subcortical structures
• In the forebrain, these are:– in the telencephalon, the basal ganglia
and the limbic system.– in the diencephalon, the thalamus and
hypothalamus.
basal gangliathalamus
hypothalamus
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Basal ganglia• important in motor control
and cognition.• Damage to the basal ganglia
occurs in Parkinson’s disease and Huntington’s disease.
5 Components:1. Caudate Nucleus2. Putamen3. Globus Pallidus4. Subthalamic Nucleus5. Substantia Nigra
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Limbic system
• Functions include emotion and memory.• Limbic system includes cortical & subcortical
structures:– Cingulate gyrus (cognitive control).– Hippocampus, fornix & mamillary bodies
(episodic memory).– Amygdala (emotion).
amygdalahippocampus
cingulate gyrus
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Diencephalon• Thalamus:
– Closely connected with cerebral cortex & its functions.
– Thalamic nuclei have distinct functions, e.g. lateral geniculate nucleus in vision.
• Hypothalamus:– Controls autonomic nervous
system and endocrine system (hormones).
•Last sensory way station on the way to the cortex.
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• Thalamic nuclei• 1. Ventral Posterior Nuclei: Somatosensory• 2. Lateral Geniculate: Visual• 3. Medial Geniculate: Auditory
Pulvinar connects with parietal lobe and is a major part of an attentional control system.
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Midbrain
tectum
tegmentum
• Midbrain (and hindbrain) structures perform relatively primitive functions, e.g. reflexes.
• Tectum comprises:– superior colliculi, fish’s visual system– inferior colliculi, fish’s auditory system.
• Tegmentum includes nuclei involved with :– arousal (reticular formation)– species-specific behavior (periaqueductal grey) – motor control (red nucleus, substantia nigra)
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Hindbrain
• Cerebellum– important for precise movement
control and learning.– also involved in cognition.
• Pons:– nucleus relays info. from cortex to cerebellum.– contains reticular formation - arousal.
• Medulla (oblongata):– necessary for vital functions: breathing, heartbeat.
pons
medulla
cerebellum
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• BRAINSTEM– Many neurotransmitter systems– Reticular Activating System– Sleep & wakefulness control– Controls respiration and other bodily functions
– Midbrain– Pons– Medulla
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Brainstem Components
• Midbrain– Superior Colliculus:
Eye movements and visual reflex functions.
– Inferior Colliculus: Auditory reflex functions.
– Pons & Medulla.– Ascending sensory
and descending motor pathways. Bulge of Pons caused by pathways to the cerebellum.
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Cerebellum
• Inputs from sensory & motor centers and vestibular system.
• Outputs to spinal cord and thalamus (then cortex).
• Functions: – Maintenance of posture, and fine
motor control (timing).– Also involved in higher functions
including language
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