Neuroscience Lecture #3
Terms
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- Somatic Nervous System
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Afferent and Efferent
Voluntary Muscles
Convey Sensory Info to CNS - Autonomic Nervous System
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Sympathetic and Parasympathetic
Involuntary Muscles
Conserves Energy, Maintains Homeostasis - Spinal Cord - Location
- Base of skull to first lumbar vertebra
- Spinal Cord - Root Differentiation
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Dorsal - Sensory
Ventral - Motor - Spinal Cord - Gray vs. White Matter
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Gray matter is surrounded by white matter
Gray Matter = Cell Bodies
White Matter = Axons
Dorsal Horn = Gray
Ventral Horn = White - Number of Spinal Nerves
- 31 Pairs (sensory and motor)
- Brain Stem Contains
- Medulla, Pons, Midbrain
- Brain Stem Function
- Regulation of parasympathetic reflexes
- Network of Neurons in Brainstem
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Reticular Formation - Receives sensory information and influences arousal level of organism
Crucial for basic functions of arousal - sleepful and wakefulness - Medulla Location and Function
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-Most caudal of brain stem
-Participates in respiration and blood pressure
-Participates in control of neck and facial muscles - Pons Location and contents
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Rostral to medulla
Contains - Pontine Nuclei, Dorsal nuclei - Pontine Nuclei
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(Ventral)
Relay information from cerebral cortex to cerebellum - Dorsal Nuclei (Pons)
- Respiration, sleep and taste
- Midbrain Functions
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Most Raustral of Brain Stem
Important for connections between subcortical structures and cerebral cortex
Components of auditory and visual systems
Control of extra-ocular eye muscles - Inferior Colliculus
- Auditory System
- Superior Colliculus
- Visual System - Top of midbrain
- Cerebellum functions
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Balance, coordination of head and eye movements, motor learning
Involved in language and cognition - Cerebellum Input
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Receives somatosensory input from spinal cord
Motor information from cortex
Input from Vestibular Organs
*Relatively few neuronal types although the most neurons
*No direct connection to spinal cord - Diencephalon Contains
- Thalamus, Hypothalamus
- Thalamus Functions
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Essential in relay of sensory information
Important for gating of sensory information
Integrates motor information from basal ganglia and cerebellum and projects to cortex
Influence on levels of attention and consciousness - Hypothalamus Functions
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Regulates homeostasis and reproduction
Regulates hormonal secretion of pituitary
Essential component of motivational system - Suprachiasmatic Nucleus
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Part of Hypothalamus
Regulates circadian rhythms (light-dark cycle) - Cerebral Hemispheres - Contents
- Cerebral cortex, underlying white matter, Basal Ganglia, Amygdala, Hippocampal Formation, Corpus Callosum
- Amygdala Involved In
- Emotion - Pleasure/Pain Memories
- Hippocampus Involved In
- Memory Storage
- Basal Ganglia Involved In
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Movement
(Substantia Nigra) Where 80% of Brains Dopamine is produced - Five Principles Of Organization of Major Functional Systems
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1 - Each functional system involves several brain regions that carry out different types of information processing
2 - Identifiable Pathways Link Components of a Functional System
3 - Each Part of the Brain Projects in an Orderly Fashin Onto the Next, Creating Topographical Maps
4 - Functional Systems are Hierarchically Organized
5 - Functional Systems on One Side of Brain Control the Other Side of Body - Serial Processing - Two types of neurons
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Principal Neurons (projection)
-Project to next stage of processing, usually excitatory
Local Interneurons
-Contact local neurons, usually inhibitory - Primary Areas of Cortex
- Receive information from thalamus or project directly to spinal cord
- Secondary Areas of Cortex
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Unimodal association area
Higher order processing within single modality - Tertiary Areas
- Multimodal association area
- Cortex Organization - Layer 1
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Molecular Layer
Contains dendrites of cells located deeper - Cortex Organization - Layer 2
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External cell granule layer
Contains small speherical cells - Cortex Organization - Layer 3
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External pyramidal cell layer
Larger and pyramidal shaped - Cortex Organization - Layer 4
- Internal granule cell layer
- Cortex Organization - Layer 5
- Internal pyramidal cell layer
- Cortex Organization - Layer 6
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Multiform layer
Blends into white matter - Layers Organize Inputs and Outputs - Layer 1 & 2
- Local cortico-cortical feedback connections from layers 5 and 6
- Layers Organize Inputs and Outputs - Layer 2 & 3
- Lateral Cortico-cortical connections
- Layers Organize Inputs and Outputs - Layer 4
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Main target of sensory information from thalamus
Receives all info from senses
Thickest layer of sensory system - Layers Organize Inputs and Outputs - Layer 5 & 6
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Primary output layers to subcortical regions
Thickest region of motor system - Cortical Neuron Types
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Projection Neurons
Local Interneurons - Projection Neurons (Shape, Location, Example)
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Pyramidal shaped
Layers 3, 5, 6
Glutamate - primary neurotransmitter: excitatory - Local Interneurons (Layer, Example)
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All layers
GABA: inhibitory - 4 Groups of Nuclei
- Anterior, Medial, Ventral, Posterior
- Anterior Nuclei
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Receives input from hypothalamus and hippocampal formation
Thought to participate in memory and emotion - Medial Nuclei
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Receives input from basal ganglia, amygdala and midbrain
Implicated in memory - Ventral Nuclei
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Ventral anterior and lateral carry information from basal ganglia and cerebellum to cortex
Important for motor control
Ventral posterior conveys somatosensory information - Posterior Nuclei
- Includes medial geniculate (auditory system), latgeral geniculate (visual system), pulvinar (interconnected with parietal, occipital and temporal regions)
- Additional Non-specific nuclei
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Located along midline
Play role in arousal and integration of information from different sensory modalities - Reticular Nucleus
- Sheet like covering that provides a feedback loop and helps modulate thalamic activity