PP 03b-Gross anatomy, in more detail

Anatomy of the Brain Dorsolateral Surface Central Sulcus (fissure of Rolando) Separation of primary motor from sensory cortex Lateral fissure (Sylvian fissure) Separation of frontal from temporal lobe Parieto-occipital sulcus Separation of parietal from occipital lobe Borders between lobes convenient approximations, and lobes are inter-connected

Frontal lobe Largest of the lobes Primary motor cortex (Area 4) Contralateral sensorimotor organization Topologic representation of motor homunculus here Premotor cortex (Area 6) Prefrontal cortex (Area 10-12)-cognitive brain Personality, reasoning, thinking, executive decision Anterior language cortex (Area 44/45) “Broca’s area”

Frontal lobe Clinical Information Prefrontal lobe damage Difficulty with planning, problem solving, thinking, reasoning and performing executive functions Orbital prefrontal damage Personality disorders, emotional disintegration & impulsive social behaviors Medial prefrontal damage Problems with attention, motivation and responsiveness Example of Phineas Gage

Parietal Lobe Primary somatosensory cortex (Area 3,1,2) Topologic representation of sensory homunculus here Superior parietal lobule (5/7) Sensory integration, visual-spatial and construction tasks Inferior parietal lobule (language [dominant], body schema, & spatial orientation [nondominant])

Parietal lobe Clinical Information Contralateral somato- sensory loss Perceptual/conceptual disorders of tactile recognition Impaired constructional (drawing/designing) skills Impaired spatial orientation Visual spatial memory loss Tactile agnosia

Primary motor cortex (posterior frontal lobe) Summary slide: Primary motor cortex and primary somatosensory cortex Primary somato-sensory cortex (anterior parietal lobe) Primary motor cortex (posterior frontal lobe) Larger size of structure represents greater cortical area dedicated to that structure

Occipital lobe Primary Visual Cortex (Area 17, medial surface, on either side of calcarine sulcus) Visual perception Secondary Visual Cortex (Area 18) visual recognition Clinical: Damage here associated with problems with ______________

Temporal Lobe Superior, Middle, & Inferior Gyri Primary auditory cortex Heschl gyri (Area 41, 42) Association language cortex (Area 22) Comprehension of spoken language Hippocampus- verbal/nonverbal memory on medial surface Olfaction

Temporal lobe Clinical presentation if damaged Deficit in auditory perceptual and discriminative skills Wernicke’s Aphasia (dominant temporal lobe) Disorders of nonverbal memory Music (right temporal lobe) Prone to seizures

Ventral Surface Frontal, temporal & occipital lobes Major structures Orbital cortex Olfactory bulb Occipito-temporal gyrus (fusiform) Lingual gyrus Parahippocampal gyrus Uncus

Clinical Information Occipito-temporal region, when damaged, results in: Impaired object recognition, visual hallucinations, and failure of facial recognition

CNS 3-D details (W pp. 9-10 & 97; W&A pp. 25-44 & 48-54) Brain (encephalon) Cerebrum (telencephalon) 2 hemispheres 4 lobes in each hemisphere Deep in each hemisphere: Limbic system Basal ganglia Ventricles Diencephalon (“between brain”) Brainstem Midbrain Pons Medulla Cerebellum Spinal cord Cervical Thoracic Lumbar Sacral Coccygeal (not shown) CNS 3-D details (W pp. 9-10 & 97; W&A pp. 25-44 & 48-54) Notice the shaded structures and structures drawn with dashed lines. Why are they drawn this way? Of the structures in the list, which two are not depicted here? Note: Gradual transitions b/w the parts

Here are 3-D views of the “dashed and shaded” structures in the previous slide’s illustration 3-D views of the rostral spinal cord, brainstem, diencephalon, and basal ganglia Anterior view Posterior view Lateral view

Basal Ganglia Anatomy Structures: Caudate nucleus, putamen, globus pallidus, claustrum, & amygdaloid nucleus Associated Structures: Substantia nigra and Subthalamic nucleus Function Regulation of motor cortical output & muscle tone Cognitive functions with multiple projections to prefrontal lobe Clinical Information Structural damage or reduction/overabundance of specific neurotransmitters Inappropriate movement patterns i.e. tremor, chorea, athetosis, and myoclonic jerks (hyperkinetic) or difficulty initiating movements (hypokinetic)

Diencephalon Central Core of the Brain Structures Thalamus Hypothalamus

Anterior view Posterior view Lateral view 3-D views of the rostral spinal cord, brainstem, diencephalon, and basal ganglia Anterior view Posterior view Lateral view

Thalamus Anatomy Functions: Above the hypothalamus in the floor of lateral ventricle Functions: Transmission of sensorimotor information to cortex Contribution to cortically mediated sensorimotor, speech & language functions (cortico-thalamo-cortical connections

White spaces containing choroid plexus are ventricles Coronal section through deep brain structures, to show relative positions of thalamus, basal ganglia, and internal capsule White spaces containing choroid plexus are ventricles

Hypothalamus Connections to brain, brainstem, & spinal cord by neural & hormonal efferents, provides specialized circuitry for: Autonomic nervous system Body temperature, blood volume, food & water intake, body mass, reproduction, circadian rhythms, drives & emotions