Bio Psy week two

The nervous system

• Collection of nerves and neurons that communicate with each other and the body in order to interpret and respond to the organism's environment 

• Evolved so that communication is fast and reliable 

• Not all organisms have a nervous system 

1. Plants, sponges, and coral have alternative ways to communicate

Central nervous system (CNS) 

1. Components of the nervous system located within the skull and spine 

2. Brain, spinal cord 

3. Cells in the CNS are neurons 

Peripheral nervous system (PNS)

1. Components of the nervous system located outside of the skull and spine 

2. Sensory and motor nerves 

3. Cells in the PNS are nerves

2 main branches of the PNS

• 1. Somatic nervous system 

1. Nerves carrying sensory information to the CNS 

2. Nerves carrying motor commands from the CNS 

• Autonomic nervous system 

1. Regulates the activity of the internal organs and other involuntary activities 

2 main components of PNS 

• Nerves: enclosed bundles of cables that transmit electrical signals to and from body structures and the CNS 

• Ganglia: Clusters of nerve cell bodies associated with nerves

The CNS includes

1. The spinal cord 

2. The brain: Cerebrum, cerebellum, brain stem

• Gray matter = accumulation of cell bodies 

Nucleus = accumulation of neurons that have similar connections and functions  

White matter = accumulation of axons (due to myelin)

Tract = bundle of axons (usually originate in the same gray matter structure, are organized in parallel, and usually end in the same gray matter region)

Gray matter and white matter 

When talking about a tract, it’s often named after the point of origin and the point of termination 

Neuroanatomical directions

• Anterior vs posterior 

• Dorsal vs ventral 

• Medial vs lateral  

• Afferent connection: neural connection coming at you 

• Efferent connection: Neural connection exiting you 

The spinal cord 

• Functions primarily in the transmission of signals to and from the brain and the rest of the body 

• Acts independently of the brain with local reflexes and other neural circuits 

• Divided into five sections 

1. Cervical 

2. Thoracic 

3. Lumbar 

4. Sacral 

5. Cocoygeal 

Dorsal roots

1. Carry sensory information from the body to the CNS 

2. Afferent pathway 

Ventral roots 

1. Carry motor commands to the body from the CNS 

2. Efferent pathway

Spinal cord injury 

• Physical trauma to the spine 

• Serves communication between the brain and the body 

• Causes numbness and paralysis 

• The higher up the injury occurs, the more of the body is affected 

• The completeness of the break is also important for how bad the injury is 

• >12,000 people experience spinal cord injury each year 

Neuroanatomical directions 

• anterior  vs. posterior 

• Dorsal vs ventral 

• Medial vs lateral 

1. Afferent connection - neural connection coming at you 

2. Efferent connection - neural connection exiting you 

The spinal cord

• Functions primarily in the transmission of signals to and from the brain and rest of the body 

• Acts independently of the brain with local reflexes and other neural circuits 

• Divided into 5 sections 

1. Cervical 

2. Thoracic 

3. Lumbar 

4. Sacral 

5. Cocoygeal 

Gross organization of the CNS

• Cerebrum 

• Cerebellum 

• Brain stem 

• Spinal cord 

Major landmarks of the brain 

• Two hemispheres separated by the longitudinal fissure 

• Two hemispheres connected by the corpus callosum (allows communication between the hemispheres) 

• Contralateral - sensory information is sent to the sensory area on the opposite side of the body 

• Ipsilateral - sensory information is sent to sensory areas on the same side of the body

Cells of the brain are organized into different structures 

• Cortex: layers of cells on the outer part of the brain 

• Nuclei: clusters of neurons within the brain 

Folds of the cortex 

• Gyri (singular gyrus): Bulges/ridges on the brain’s surface 

• Sulci (singular sulcus): grooves. Indentations into the brain’s surface 

• Why is the surface of the brain so folded? What might be the purpose of this?

1. Folding the brain’s surface significantly increases its surface area. 

3 main subdivisions of the brain 

Forebrain,Midbrain, Hindibrain

Forebrain

1. Cerebral cortex 

2. Basal ganglia 

3. Limbic system 

4. Basal forebrain

Midbrain

1. Tectum 

2. Hypothalamus 

3. Substantia nigra

Hindibrain

1. Cerebellum 

2. Pons 

3. Medulla oblongata

Lobes of the brain 

Frontal lobe, Temporal lobe, Occipital lobe, Somatosensation, proprioception, focuses attention, integration of sensory input, helps generate a picture of our surroundings 

Frontal lobe

Motor control, executive functions, decision making, personality, working memory

Temporal lobe

Memories, emotion, language, comprehension, links words with their meanings, recognition of objects, people, and places

1. Includes Wernicke’s area 

• Somatosensation, proprioception, focuses attention, integration of sensory input, helps generate a picture of our surroundings 

1. Includes our primary somatosensory cortex

Occipital lobe

Vision, recognizing objects, where things are in space

Includes our primary visual cortex

Brodmann’s areas 

• Used cytoarchitecture to divide up the neocortex 

• Cortical areas that had similar cytoarchitecture were grouped into an “area” together 

• He guessed that each “area” had a different function 

Important neocortical areas 

• Primary sensory cortices, Secondary sensory cortices, Mortar cortices, Association cortices 

Primary sensory cortices

1. Area of the cortex that first receives sensory information 

2.  Body -> spinal cord -> brain 

• Secondary sensory cortices 

Area of the cortex that receives sensory information from the primary cortex

• Mortar cortices 

1. Area of the cortex that generates a motor response 

2. Brain -> spinal cord -> muscles

Association cortices

Areas of the cortex that receive input from other cortical areas and non-cortical brain areas to integrate all the information and produce a response involved in complex brain functions

Limbic system functions 

• Main functions  

1. Motivation, emotion, learning, memory 

• Main structures: 

1. Entorhinal cortex: bridges the cortex to the hippocampus 

2. Hippocamous: long term memory, spatial memory 

amygdala

emotions , fear, aggression, anxiety

hypothalamus

1. Regulates important bodily functions (temperature regulation, circadian rhythms, social bonding, thirst, hunger) 

2. Links the nervous system to the endocrine system 

3. Pituitary gland 

1. Produces and releases hormones 

Thalamus

1. Relays information about our senses to the cortex and rest of the brain 

2. “Grand central station” of the brain 

3. Filters sensory information

Basal Ganglia functions 

• Main functions 

1. Voluntary movement 

2. Habitual behaviors 

3. Emotions 

• Consists of the following structures 

1. Caudate nucleus 

2. Putamen 

3. Globus pallidus 

4. Subthalamic nucleus 

5. Substantia nigra 

6. Nucleus accumbens

Main Brainstem func

• Main functions 

1. Essential activities, sleep/ wakefulness, heart rate, breathing, attention, temperature regulation, vision, hearing, motor control of face and neck

Brainstem main structures

• Main structures  

1. Midbrain 

2. Pons (part of hindbrain) 

3. Medulla oblongata part of the hindbrain 

Cerebellum

• Functions in detecting and adjusting for movement errors 

• Also important for learning motor skills

Major landmarks for the Brain 

• Two hemispheres separated by the longitudinal fissure 

• Two hemispheres connected by the corpus callosum (allows communication between the hemispheres) 

• Contralateral: sensory information is sent to sensory areas on the opposite side of the body 

• Ipsilateral: Sensory information is sent to sensory areas on the same side of the body

Cells of the Brain are organized into different structures

• Cortex: layers of cells on the outer part of the brain 

• Nuclei: cluster of neurons within the brain 

Folds of the Cortex 

• Gyri(singular gyrus): bulges/ridges on the brain’s surface 

• Sulci(singular sulcus): groves/ indepentations into the brain’s surface 

• Why is the surface of the brain folded? What might be the purpose of this?: Folding of the brain’s surface significantly increases its surface area. 

3 main subdivisions of the brain

Forebrain, Midbrain, Hindibrain

Forebrain

1. Cerebral cortex 

2. Basal ganglia 

3. Limbic system 

4. Basal forebrain 

Midbrain

1. Tetcum 

2. Hypothalamus 

3. Substantia nirgra 

Hindibrain

1. Cerebellum 

2. Pons 

3. Medulla oblongata

Frontal lobe: motor, control, executive functions, decision-making, personality, working memory

Includes the prefrontal cortex(PFC), orbitofrontal cortex (OFC), and more  

Temporal lobe: Memories, emotion, language, comprehension, links words with their meanings, recognition of objects, people, and places

•  (includes Wernicke’s area) 

Parietal lobe

•  somatosensation, proprioception, focuses attention, integration of sensory input, helps generate a picture of our surroundings: includes our primary somatosensory cortex 

Occipital lobe 🙂

 Vision, recognizing objects, where things are in space; includes our primary visual cortex.

Brodmann’s Areas 

• Used cytoarchitecture to divide up the neocortex

• Cortical areas that had similar cytoarchitecture were grouped into an “area” together 

• He guessed that each “area” had a different function 

 Primary sensory cortices 

1. Area of the cortex that first receives sensory information 

2. body-> spinal cord-> brain 

Secondary sensory cortices

1. Area of the cortex that receives sensory information from the primary sensory cortex 

• Motor cortices 

1. Area of the cortex that generates a motor response 

2. Brain-> spinal cord-> muscles 

Associated cortices

1. Areas of the cortex that receive input from the cortical areas and non-cortical brain areas to integrate all the information and produce a response 

2. Involved in complex brain functions 

Limbic system functions 

• Main functions

1. Motivation, emotion, learning, memory 

• Main structures: 

1. Entorhinal cortex: bridges the cortex to the hippocampus 

2. Hippocampus: long-term memory, spatial memory 

3. Amygdala: emotions, fear, aggression, anxiety

Hypothalamus

1. Regulates important bodily functions (temp regulation, circadian rhythms, social bonding, thirst, hunger) 

2. Links the nervous system to the endocrine system

Pituitary gland

1. Produces and releases hormones 

Thalamus

1. Relays information about our senses to the cortex and rest of the brain  

2. “Grand central station” of the brain 

3. Filters sensory information 

Basal Ganglia main functions 

Voluntary movement

Habitual behaviors

Emotions

Basal Ganglia functions 

1. Caudate nucleus 

2. Putamen 

3. Globus pallidus 

4. Subthalamic nucleus 

5. Substantia nigra 

6. Nucleus accumbens 

Brainstem functions

• Main functions: essential activities, sleep/wakefulness, heart rate, breathing, attention, temperature regulation, vision, hearing, motor control of face and neck 

• Main structures: 

• Midbrain 

• Pons (part of hindbrain)

• Medulla oblongata (part of hindbrain) 

Cerebellum

• Functions in detecting and adjusting for movement errors 

• Also important for learning motor skills

Non-neuronal structures of the brain

• Meninges 

• Ventricles 

• Blood-brain barrier (BBB) 

Meningeal layers

• Dura mater - “hard mother” 

1. Outermost layer 

2. Very tough 

• Arachnoid membrane 

Spider web-like middle layer

• Subararchnid space 

1. Where cerebrospinal fluid is 

• Pia mater = “gentle mother”

1. Adheres to brain and spinal cord 

• Meningitis: infection or inflammation of the protective membranes surrounding the brain 

• Can be viral or bacterial 

• Most common symptoms: headache, stiff neck, fever, confusion, altered consciousness, vomiting, inability to tolerate light (photophobia) or loud noises (phonophobia)

• ~40,000 people get meningitis every year in the US 

Ventricles

• Function: produces and distributes cerebrospinal fluid (CSF)

1. CSF= cushions the brain; removes toxins; provides nutrients to the brain 

2. Choroid plexus = within the ventricles; produces CSF

• 4 ventricles 

1. 2 lateral ventricles 

2. 3rd ventricle 

3. 4th ventricle (CSF exits the brain from here)

Hydrocephalus

• Hydrocephalus = blockage of the drainage of CSF through prores in the ventricles, causing the ventricles to swell and crush the brain 

• Usually caused by infection 

• Can cause brain damage if not reversed 

• Symptoms: Excessive head size and “sundowning’ (deviation of eyes downward due to high intracranial pressure) 

• antibiotics /antivirals can reduce the infection; medical shunts to reduce intracranial pressure 

Blood-brain barrier (BBB) 

• Blood vessels in the brain are lined with tightly packed endothelial cells 

• What comes in/out of the brain is highly regulated due to this barrier 

1. Allows entry of essential nutrients 

2. Prevents other things from entering

Stroke

• Stroke = decrease in blood supply providing oxygen to a part of the brain, resulting in death of neurons downstream of the blockage 

• Often happens unilaterally (one side of the brain), resulting in decreases in sensory and motor function to one side of the body 

• Functions affected depend on where the stroke is 

• Aphasia = loss of ability to understand or make language 

• FAST: face drooping, arm weakness, speech difficulty, TIME to call 9-1-1

• ~800,000 people have a stroke each year in america