PSB2000 Neuroscience Quiz Functional Anatomy of the Central Nervous System CNS Major brain regions and their functions Forebrain Thinking perceiving big part of emotion and memory drive related behaviors Cortex which is the folded stuff Structures deep to the cortex thalamus hypothalamus hippocampus amygdale bsal ganglia etc Midbrain Sensory pathways visual and auditory processing reflexes Top portion of the brainstem Reflexive orienting to visual and auditory stimuli Intrinsic descending pain control Substantia nigra Parkinson s disease Some motor control reflexes breathing heart rate etc Bottom of brainstem pons medulla and cerebellum Hindbrain Medulla Controls vital reflexes breathing heart rate vomiting salivation coughing sneezing Control via cranial nerves sensory and motor control of head and parasympathetic output to organs vagus nerve Damage to medulla can be fatal Large doses of opiates can be fatal b c suppress activity of medulla Cerebellum Movement Rate range force direction Well learned movements Sensory timing Balance postural control Structures in the forebrain Cortex Thalamus Hypothalamus Pineal gland Pituitary gland Basal ganglia Limbic system Thalamus Relay station filter for sensory info on its way to cortex Involved in many other systems motor emotional memory etc Many specialized nuclei Also gets input from cortex reciprocal connections Hypothalamus Communicates with pituitary gland to alter hormone release Involved in drive related behaviors and maintenance of homeostasis feeding drinking temperature regulation sexual behavior fighting arousal activity level sleep wake rhythms Connects to forebrain and midbrain Distinct nuclei Pituitary gland Endocrine gland hormone producing Attached to hypothalamus by pituitary stalk Makes and releases hormones into bloodstream Attached to base of hypothalamus by stalk Pineal gland Makes and secretes melatonin Daily and seasonal rhythms Unpaired structure on midline Basal ganglia Several interconnected structures deep to cortex circled plus a few others Facilitate or inhibit cortical activity Motor control damage leads primarily to movement disorders but also memory and emotional expression Lose Substantia Nigra Parkinson s Disease Caudate putamen Huntington s chorea Structures of the Basal Ganglia Caudate Putamen Globus pallidus Some also include the Substanita Nigra and Subthalamic nucleus Putamen Motor functions Input from motor and sensory ctx Output to motor cortices Individual neurons Specific movements Caudate Cognitive functions From association ctx To prefrontal ctx Ventral striatum drive related behavior Limbic connections Heavily connected with cortex and thalamus Limbic system Several interconnected structures most importantly Amygdala emotion and Hippocampus spatial and declarative memory Hippocampus temporal lobes removed for intractable epilepsy no longer formed Hemispheres communicate mainly via corpus callosum Also communication b t parts of cortex w in a hemisphere see Inquiring Minds Conscious awareness of sensory stimuli High level cognitive tasks new memories Cortex Lobes of the cortex Frontal Parietal Temporal Occipital Frontal lobe Prefrontal cortex executive functions Planning Working memory Socially appropriate behavior Foresight Insight Impulse control This is called association cortex Highly evolved in humans Motor cortex Somatosensory cortex Voluntary movement Somatotopic organization homunculus Other motor areas between this prefrontal cortex Language Broca s area First cortex to process somatosensory info Proprioception too Somatotopic organization homunculus again Spatial organization Especially in non dominant hemisphere side where language is not or is less A tumor in temporal lobe can lead to elaborate visual or auditory hallucinations Contralateral neglect Where pathway for visual info Temporal Lobe Auditory cortex hearing Spoken language comprehension Wernike s aphasia Primary secondary visual cortex Damage causes cortical blindness Visual association cortex Face recognition What pathway Occipital Lobe Vision Meninges 3 layers Dura mater Arachnoid Pia mater Mechanically Stabilize protect the CNS head CSF within meninges b t arachnoid and pia for buoyancy Brain anchored to meninges and meninges anchored to skull so brain must move with Ventricles Dura attached to inner surface of skull Arachnoid adheres to inner surface of dura Pia attached to surface of brain follows all contours and grooves Contain cerebrospinal fluid CSF CSF is made in walls of ventricles CSF then circulates around the brain CSF finally reabsorbed into blood vessels so continuous turnover Protective Reservoir for hormones nutrients Basal forebrain Includes Nucleus basalis Input from hypothalamus and basal ganglia Ach thruout brain Arousal Wakefulness Attention Problems w attention intellect in PD and AD due to degeneration of NB Superior Inferior Colliculi sensory processing especially visual and auditory Brain Regions Associated with Diseases We Discussed Dementia Basal forebrain is damaged Acetylcholine system is the first to go Alzheimer s Disease Brain atrophy Loss of neurons Loss of spines synapses Loss of connections between neurons also malfunctioning of neurons as severity of symptoms varies dramatically at different times Korsakoff s Syndrome Shrinkage of neurons esp in mammillary bodies dorsomedial nucleus of thalamus which sends axons to prefrontal cortex Damage of axons myelin The lesions have a characteristic anatomical distribution which includes the mammillary bodies the hypothalamus thalamus periaqueductal gray matter colliculi and the floor of the fourth ventricle The mammillary bodies are involved in all cases Loss of cells in caudate putamen basal ganglia Loss of dopaminergic cells in substantia nigra that project to striatum less excitation of Huntington s Disease Parkinson s Disease cortex Schizophrenia Thinner cortex but same cell number Smaller cell bodies esp in hippocampus and prefrontal cortex Increased ventricle size Larger sulci Smaller thalamus Decreased white matter Dopamine transmission is elevated in some brain regions Too much in some regions such as reinforcement circuit nucleus accumbens About 2x dopamine receptor occupancy in schizophrenic patients compared to controls D2 receptors in accumbens too much activation D1 receptors in PFC too little activation Decreased activity in glutamate neurons might lead to alterations in dopamine in PFC and nucleus accumbens Lower glutamate
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