Brain and Behavior midterm 2: Chapter 4-7

Anatomy of the Nervous System, Sensory Systems, Sensorimotor Systems, Motor Systems, Brain Damage/Disorders, & Learning and Memory

Planes of brain orientation

Horizontal plane

Sagittal plane

Coronal plane

Horizontal plane

Parallel to floor

Sagittal plane

Splits down middle, left and right

Coronal plane

Dividends front back back Posterior and anterior

Medial or proximal

towards the middle

Lateral or distal

going towards the side

Ipsilateral

Same side

Contralateral

opposite side

Superior

Above

Inferior

Below

Anterior or rostral

near the head

Posterior or caudal

near the feet

Dorsal

Towards the back

Ventral

Towards the belly or front

Afferent

Neurons carry information into a region of interest

Efferent

Neurons carry information away from region of interest

Nervous systems:

The central nervous system

The peripheral nervous system

Central nervous system

consists of the brain and spinal cord

The peripheral nervous system

all other parts of the nervous system outside the brain and spinal cord

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Somatic nervous system

Autonomic nervous system

Somatic nervous system

• Nerves that connect the brain and major muscles and sensory systems of the body

• Voluntary

Autonomic nervous system

• Nerves that connect to the viscera (internal organs)

• Automatic

• Sympathetic nervous system

• Parasympathetic nervous system

Sympathetic nervous system

• Axons that innervate the sympathetic ganglia

• Small clusters of neurons

• “Fight or flight”

  • Sweat, jump, digestion stops, heart rate, blood pressure, pupils

Parasympathetic nervous system

• Helps body relax and recuperate

• “Rest and digest”

  • Calms down body

  • Farther from CNS, closer to organs

Bundles of axons names:

CNS - Tracts

PNS - Nerves

Groups of cell bodies

CNS - Nuclei

PNS - Ganglion, Ganglia (plural)

Myelin made by:

CNS - Oligodendrocytes

PNS - Schwann cells

Motor nerves

Transmit information from the spinal cord and brain to muscles and glands

Sensory nerves

Convey information from the cell body to the central nervous system

Nerves of the somatic nervous system

• Cranial nerves

• Spinal nerves

Cranial nerves

• Coming from head and neck going to visceral organs

• 12 pairs - one right and one left side

• Sensory, motor, or both

• Information from touch receptors in the head enters the CNS through the cranial nerves

• Vagus also has parasympathetic

  • Diaphragm

  • Misfire is vagus nerve

    • Hiccups (literally)

Spinal nerves

31 pairs - named after the vertebrae

• Cervical

• Thoracic

• Lumbar Lower back 5 segments

• Sacral Pelvic 5 segments

• Coccygeal Bottom 1 segment

SAD = sensory afferent dorsal

• Types of info coming to and from spinal cordy

• Depends on where touched

• Information from receptors below the head enters the spinal cord and travel through the 31 spinal nerves to the brain

Cervical

• Neck

• 8 segments

Thoracic

• Trunk

• 12 segments

Lumbar

• Lower back

• 5 segments

Sacral

• Pelvic

• 5 segments

Coccygeal

• Bottom

• 1 segment

cauda equina

• “horse's tail”

• extension of spinal nerves beyond end of spinal cord

• Epidurals are below the spinal cord

dermatomes

• Areas of the body innervated by a specific spinal nerve

• Different areas of the periphery that are innovative by a different spinal nerve

• At all levels, inputs are organized into dermatomes, strips of skin each innervated by a particular spinal nerve

• Essentially is a receptive field

Different effects on organs due to different neurotransmitters released by postganglionic neurons

• All preganglionic neurons release ACh.

• Sympathetic postganglionic neurons release epinephrine (= adrenaline)

• Parasympathetic postganglionic neurons release ACh

Embryonic development of brain and spinal cord

• Neural tube

• Then subdivides

  • Front, forbrain

  • Middle midbrain

  • Hindbrain

• he hindbrain develops into the cerebellum, pons, and medulla.

• Brainstem refers to the midbrain, pons, and medulla combined

Protection of the nervous system:

• Chemical protection

• Physical protection

• Meninges

Chemical protection

* Blood brain barrier 
* Tightly packed blood vessel cells and astrocytes

Physical protection

• Skull and vertebral column(spine)

• Meninges

• Cerebrospinal fluid (CSF)

Meninges

• Dura mater

• Arachnoid membrane

• Subarachnoid space

• Pia mater

• Meningitis - acute infection of the meninges

• Meningiomas - tumors formed in meninges

Dura mater

• outer layer

• “Tough mother”

Arachnoid membrane

• middle layer

• Spider weblike membrane

• Below dura mater

Subarachnoid space

• below the arachnoid membrane

• Containing many blood vessels and cerebrospinal fluid

• Looks like spider web

Pia mater

• “Pious mother”

• Layer closest to brain and spinal cord

**Ventricular system** 

• Ensuring the brain doesn’t “dry out”

• Chambers filled with cerebrospinal fluid (CSF)

• Lateral ventricle

  • In each hemisphere

  • Extends to all four lobes and lined with choroid plexus

• CSF flows into the third ventricle at the midline, through the cerebral aqueduct, and into the fourth ventricle where it exits to circulate over the brain and via the central canal of the spinal cord

Too much cerebrospinal fluid 

• Absorbed into sinuses (large, blood filled spaces)

  • Run through dura and drain into jugular veins of neck

• Hydrocephalus

  • (water head)

  • Expansion of ventricles

    • Ex: due to blockage by tumor, etc

  • Need to drain

Glymphatic System

• Glial cells (picking up junk) take info and take it to blood vessels to CSF

  • Clear the gunk out

• More active while a person is sleeping

  • Deep sleep

  • If can't sleep: excess debris

• Problems with glymphatic system can relate to alzheimer’s disease

  • Build up

Cerebral blood flow and stroke

• Brain depends on a an ample supply of oxygenated blood from the cerebral arteries

  • Need good supply!!

• Stroke: rupture, break, or blockage of blood vessels to prevent significant oxygen supply

• Types of stroke: (completely opposite)

  • Ischemic

  • Hemorrhagic

Ischemic

• Blood flow restricted by clot or other obstruction

• Treat by breaking the clot up

Hemorrhagic

• Artery ruptures causing blood to leak within the brain

• Only way to stop is naturally or to cauterize it

Warning signs of stroke:

• Sudden numbness or weakness

• Altered vision

• Dizziness

• Severe headache

• Confusion or difficulty speaking

Cerebral cortex

• Covering over the brain

• Outermost layer of the brain

• NOT FLAT FOR HUMAN

  • Has ridges/bulges

• Gyri

• Sulci

• Grey = cell bodies

• White = axons

• Split into two:

  • Cerebral hemispheres divided by the longitudinal fissure

  • Longitudinal fissure - large sulcus

Gyri

Ridges or raised portions (mountains)

Sulci

Furrows (valleys)

Four cerebral hemispheres

• Frontal lobe

• Parietal lobe

• Occipital lobe

• Temporal lobe

Frontal lobe

* most anterior region 
* Prefrontal cortex - planning, attention much of frontal cortex devoted to motor control 

Parietal lobe

* Lies between the frontal and occipital lobes; somatosensory functions

Occipital lobe

* Posterior region, visual processing 

Temporal lobe

* Lateral region, auditory processing

Lateral (sylvian) fissure

* boundary of the temporal lobe

Longitudinal fissure

* Splits the left and right hemisphere

Central sulcus

* Divides the frontal lobe from the parietal lobe

Corpus callosum

* a bundle of axons that connects the two cerebral hemispheres

Postcentral gyrus

* a strip of parietal cortex posterior to the central sulcus
* primary somatosensory cortex
* In sensory cortex

Precentral gyrus

* posterior gyrus of **frontal lobe**
* primary motor cortex
* In motor cortex

Forebrain/cerebral hemispheres

• Basal ganglia

• Limbic system

• Thalamus

Basal ganglia

• Two major functions: motor system and cognitive process

• Consists of: caudate nucleus, putamen, globus pallidus

  • (Caudate + putamen = Striatum)

  • Nigrostriatal pathway

Limbic system

• Groups of structure

• Structures important for emotion and learning

• Form a border around the brainstem

• Consists of:

  • Amygdala

  • Hippocampus(aka seahorse) and fornix(connected fibers)

  • Cingulate gyrus

  • Olfactory bulb

  • Hypothalamus

Amygdala

* emotion regulation and perception of odor, fear

Hippocampus(aka seahorse) and fornix(connected fibers)

* learning and memory, emotion is tied to memory 

Cingulate gyrus

• attention

• processing emotions and behavior regulation

Olfactory bulb

* sense of smell

Hypothalamus

* contains nuclei with many functions; also controls pituitary 
* many nuclei
* below thalamus
* motivated behaviors (feeding, drinking, temp regulation, rhythms, sex behavior, sleep)
* connections with limbic system
* input to pituitary gland

Thalamus

• Single structure

• Cluster of nuclei that relay sensory information

  • Ex: train station → stuff coming in and stuff going out

• Lateral geniculate nucleus – visual

• Medial geniculate nucleus – auditory

  • Optic nerve into the thalamus and optic tract brings it out

Midbrain

• the “house”

• Tectum(roof)

• Tegmentum (basement)

Tectum(roof)

*  includes sensory areas: 
* Superior colliculi  - visual processing
* Inferior colliculi  - auditory processing 
* Colliculi - “little hills” - feel little bumps 

Tegmentum (basement)

• Substantia nigra - connects to basal ganglia, motor system

  • Nigrostriatal tract - degenerates in Perkinson’s Disease

• Red Nucleus - sensorimotor integration (somewhat middle)

• Periaqueductal gray - around the cerebral aqueduct, pain perception, site of opiate receptors

Reticular formation

• involved with sleep and arousal

• Running from hindbrain through midbrain

Hindbrain

• Certain vital body functions are controlled by the brainstem

  • If we damage the hindbrain you are dead

• Cerebellum

• Pons

• Medulla

Cerebellum

• big structure on back

• Coordination and control

• Participates in come types of learning

Pons (bridge)

• fiber crossings

• Axons going from left ot right side and vise versa

• Origin of some cranial nerves

Medulla

• Transition from brain to spinal cord

• Essential processes such as respiration and heart rate

• Origin of some cranial nerves

Ways to study the brain: based on structure

• CT/CAT scans

• MRI scans

Ways to study the brain: based on function

• fMRI

• PET

• TMS

• MEG (Magnetoencephalography)

• DTI

• EEG

CT/CAT scans

• (computerized tomography)

• Telling you what the brain looks like

• Image

• Measure of X-ray absorption at several position

MRI scans

• (magnetic resonance imaging)

• Uses magnets

fMRI

• (functional Magnetic Resonance Imaging)

• MRI, but looking at function

• Where in the brain is there a lot of activity

• Using oxygen

PET

• (Positron Emission Tomography)

• Only at high medical center

TMS

• (Transcranial Magnetic Stimulation)

• Using magnet to control what is going on in the brain

DTI

• (Diffusion Tensor Imaging)

• Shows the circuits

• Looking at fiber tracts (measuring water in the brain)

EEG

• (Electroencephalography)

• Put the electrodes on head

• Useful when measuring sleep patterns

Senses, understanding, how we understand:

• Detection of sense requires receptors, specialized for that stimulus modality

  • A protein that whatever the stimulus is can react

  • Ex: hair cells moving can detect wind

• Stimulus must be transduced (changed) into the language that the neurons can speak

  • Neurons speak through action potential

  • The “language” of sensory input is in the form of chemicals, sound waves, temperature, etc.

  • The “language” of neurons includes action potentials, depolarization, hyperpolarization

• The concept of labeled lines(what she drew) says that the brain recognizes distinct senses because action potentials travel along separate nerve tracts.

• When information gets to the brain it will based on method of coding

  • Coding is done in the cerebral cortex!!!!

Sensory transduction

• The detector is able to take stimulus energy and convert it to polarization or depolarization

  • Uses ionotropic or metabotropic receptors

• Generator potentials = local changes in membrane potential, resemble EPSPs

Labeled lines

• Sensory information going to the brain to be coded

• Stimulus binds to a receptor to allow ion channels to open, action potentials start happening then labeled lines

Pacinian corpuscle

* Related to the **touch to skin**
* Before touched, at rest
* A stimulus to the corpuscle opens sodium channels and produces a graded generator potential
* Smaller stimulus, smaller response
* Bigger stimulus, bigger response
* If the potential is big enough, a threshold is reached, and an action potential is **generated**.
* Responds to vibration and pressure

Vestibular system

• Related to sound

• Receptors respond to mechanical stimuli which indicate position and movement of head

• Also helps with balance

• Could have spontaneous action potential firing, moving head can increase or decrease it

• Vestibular neuron normally active

  • Activity increases or decreases, depending on which direction hair cells bend