Chapter 3: Anatomy and Research Methods

Anterior

In front of

Posterior

Towards the back

Superior

Above

Inferior

Below

Ventral

Towards the stomach, bottom of the head

Dorsal

Toward the back, crown of the head

Lateral

Closer to the side/ears

Medial

Toward the midline

Ipsilateral

Same side

Contralateral

Opposite hemispheres

Horizontal/Transverse

A plane that shows brain structures as seen from above

The theoretical “slice” of a body organ

Saggital

A plane that shows brain structures as seen from the side

Right or left hemisphere

Can see both anterior and posterior structures within the same hemisphere

Coronal

A plane that shows brain structures as seen from the front

Can generally see both hemispheres

Can only see anterior or posterior; not both

Lamina

A row or layer of cell bodies separated from other cell bodies by a layer of axons and dendrites

Column

A set of cells perpendicular to the surface of the cortex, with similar properties

Tract

A set of axons within the CNS, also known as a projection

Nerve

A set of axons in the periphery, either from the CNS to a muscle or gland, or from a sensory organ to the CNS

Nucleus

A cluster of cell bodies

Ganglion

A cluster of neuron cell bodies, usually outside the CNS

Gyrus

A protuberance/ridge on the surface of the brain

Sulcus

A fold or groove that separates one gyrus from another

Furrows

Fissure

A long, deep sulcus

Peripheral Nervous System

Connect brain and spinal cord to the rest of the body

Includes the somatic nervous system and the autonomic nervous system

Somatic Nervous System

Consists of axons conveying messages from sensory organs to the CNS to the muscles

• Motor neurons

• Voluntary control of movement

• Sensory neurons from sense organs

Peripheral Neuropathy

Damage to the somatic nervous system

Motor symptoms: Spasms, tremors, twitches, loss of control

Ventral roots

Carries motor information away from the spinal cord to the muscles of the body

Motor/efferent

Dorsal roots

Carries sensory information information away from the body to the spinal cord

Sensory/efferent

Cell bodies are outside the spinal cord (ganglia)

Gray matter

Located in the center of the cord

Densely packed with cell bodies and dendrites

Many neurons from this area of the spinal cord send axons to the brain other parts of the spinal cord through white matter

Axons travel to white matter from here

Damage to the Spinal Cord

If the spinal cord is cut at a given segment, the brain loses sensation from that segment and below

Also loss motor control over all parts of the body severed by that segment, and the lower one

Autonomic Nervous System

Consists of neurons of that receive information from and send commands to the parts, intestines, and other organs

Sympathetic

A network of nerves that prepares the organs for a burst of vigorous activity

Origins: thoracic and lumbar nerves

Axons increase breathing and heart rate, and decrease digestive activity

Ganglia work as one system, because they are arranged in a chain near the spinal cord

Sweat glands, adrenal glands, muscles that constrict blood vessels, and muscles that erect the hairs of the skin have sympathetic output only

Primary neurotransmitter: norepinephrine

Parasympathetic

Facilitates vegetative, nonemergent response

Axons decrease heart rate and sexual arousal, and increase digestive activity

Ganglia works independently, as they are not arranged in a chain near the spinal cord

Origin: Cranial and sacral nerves

Primary neurotransmitter=acetylcholine

The Hindbrain

The posterior part of the brain

Medula, pons, cerebellum

Medulla

Can be regarded as an enlarged extension of the spinal cord

12 pairs of cranial nerves allow the head and organs to connect to the medulla and other adjacent areas

Vital reflexes such as breathing, heart rate, vomiting, salivation, coughing, and sneezing

Contains an abundance of opiate receptors so that opioids can produce a deadly decrease in breathing and heart rate

Pons

Anterior and ventral to the medulla

Like the medulla, it contains nuclei for several cranial nerves

The bridge between the cerebellum and the rest of the brain, motor/sensory control

Left hemisphere controls muscles on the right side of the body and vice versa

Cerebellum

Large hindbrain structure with many deep folds

One of the first brain areas to start developing, and one of the last to complete developement

Movement, balance, and coordination

Damage can cause difficulty with timing

Ability to detect the sequence of events

The Midbrain

Between the hindbrain and forebrain

More prominent in reptiles, amphibians, and fish

Tectum, tegmentum, reticular formation

Tectum

The roof of the midbrain

The swellings on each side are superior and inferior colliculus

Superior colliculus

Vision

Inferior colliculus

Hearing

Tegmentum

Located under the tectum/covered by the tectum

The intermediate level of the midbrain

Covers other midbrain structures

Motor control and coordination

Arousal and consciousness

Reticular formation

Consciousness, alertness, attention

Includes substantia nigra

Substantia nigra

Gives rise to a dopamine-containing pathway that facilitates readiness for movement

The Forebrain

The most prominent brain area for mammals and birds

Consists of two cerebral hemispheres, left and right

Controls muscles, mostly on the contralateral side, by way of axons to the spinal cord and the cranial nerve nuclei

Cerebral cortex

The outer portion of the forebrain

The largest part of the mammalian brain

Similar in all mammals, but the size differs

Occipital lobe, parietal lobe, temporal lobe, temporoparietal junction, frontal lobe, central sulcus, sylvian fissure, laminae

Thalamus

A pair of structures (left and right) in the center of the forebrain

Underneath the cerebral cortex

Most sensory information (excluding olfactory information) goes here first, where it gets processed then sends output to the cerebral cortex

Main source of input to the cortex

Processes vision and working memory

Hypothalamus

Small area just ventral to the thalamus

Has widespread connections to the rest of the brain

Essential for control of eating, drinking, body temperature, and reproductive behaviors

Damage can lead to abnormalities in these behaviors, as well as fighting

Communicates with the pituitary gland partly through nerves and partly by releasing hormones

Amygdala

Part of a circuit that is central for evaluating emotional information, especially concerning fear and anxiety

Pituitary gland

Master gland

Relays hormones that direct many other glands, including the hypothalamus

Olfactory bulb

Smell

Does not get routed through the thalamus

Basal Ganglia

A group of subcortical structures lateral to the thalamus

Integrate motivation and emotional behavior to increase the vigor of selected actions

Other than movement, they play a critical role in the gradual learning of skills and habits

Damage impairs movement and can lead to conditions like Parkinson’s disease and Huntington’s disease

Nucleus Basalis

A structure on the ventral surface of the forebrain that receives input from the hypothalamus and basal ganglia and sends axons that release acetylcholine to widespread areas in the cerebral cortex

A key system for arousal, wakefulness, attention, and intellect, especially in patients with Alzheimer’s and Parkinson’s disease

Hippocampus

A large structure between the thalamus and cerebral cortex, mostly toward the posterior of the forebrain

Critical for memories, especially memories of individual events

Essential for monitoring where you are and where you are going

Damage leads to trouble making new memories and is associated with dementia and cognitive decay

The Ventricals

4 fluid-filled cavities within the brain

Each hemisphere connects to one of the two large lateral ones

Towards their posterior, they connect to the third one, positioned at the midline, separating the left and right thalamus

The third one connects to the fourth one in the center of the medulla

Choroid plexus

Cells along the walls of the 4 ventricles that produce cerebrospinal fluid (CSF)

Cerebrospinal fluid (CSF)

Cushions the brain against mechanical shock when head moves

Provides buoyancy, supporting the weight of the brain

Provides a reservoir of hormones and nutrition for the brain and spinal cord

When CSF fluid is obstructed

Pressure on the brain increases

When this occurs in infants, the skull bones spread, causing overgrown head

This condition, known as hydrocephalus, cam impair cognitive developement

Meninnges

Membranes that surround brain and spinal cord

Have pain receptors, despite the brain not having any

Meningitus

Inflammation of the menginges

Central sulcus

Divides frontal and parietal lobes

Sylvian fussure

Divides temporal from the frontal and parietal lobes (on both hemispheres)

Laminae

Up to 6 distinct layers of cell bodies parallel to the surface of the cerebral cortex

Corpus collosum

Contains bundles of axons and allow for communication between the right and left hemispheres main point where both hemispheres communicate

Lamina IV

Receives sensory information

Prominent in the sensory areas of the cortex but absent from the motor cortex

Lamina V

Sends long axons to the spinal cord, is thickest in the motor cortex

Layer I

Many axons and dendrites but few cells, is a site for many connections, including those that are essential for learning

Cells of the cerebral cortex

Organized into columns perpendicular to the laminae

Not very straight in nature, despite being depicted as so

Those within one column have similar properties to one another

Occipital lobe

In the posterior end of the cortex

The main target for visual information

Damage causes blindness in related part of the visual field

Cortical blindness

Damage to occipital lobe

No conscious visual perception or imagery, even in dreams

Parietal Lobe

Lies between the occipital lobe and the central sulcus

Primary somatosensory cortex

Monitors information about eye, head, and body positions and passes it on to brain areas that control movement

Essential for spatial and numerical information

Has the postcentral gyrus on its surface

Postcentral gyrus

Includes four bands of cells parallel to the central sulcus

Separates areas along each band, receives simultaneous information from different parts of the body

Two of the bands receive light-touch information, one receives deep-pressure information, and one receives a combination of both

Includes the primary somatosensory cortex

Primary somatosensory cortex

Processes fundamental bodily sensations like touch, pain, temperature, and body awareness

Located in the postcentral gyrus

Temporal Lobe

The lateral portion of each hemisphere near the temples

Primary auditory cortex

Essential for speech (Wernicke’s area, in the left lobe)

Contributes to complex aspects of vision, such as perception of movement and recognition of faces and other objects

Associated with schizophrenia

Important for emotional and motivational behaviors

Wernicke’s area

Located in the left temporal lobe

Essential for speech

Damage causes difficulty in understanding/pulling the correct words

Kluver-Bucy Syndrome

Damage to the temporal lobe

Leads to inappropriate or sexual behaviors, overeating, excessive lip-smacking or other mouth movements

Temporoparietal Junction

Where the parietal lobe and temporal lobe meet

Close to the occipital lobe

Receives input from vision, hearing, and body senses

Serves functions including body awareness, attention, and social cognition

Disruption to this area (especially in the right hemisphere) impairs the ability to imagine how something would appear from someone else’s perspective

Frontal Lobe

Contains the primary motor cortex/precentral gyrus and the prefrontal cortex

Extends from the central sulcus to the anterior limit of the brain

Personality expression

Related to the brain’s ability to recover after an injury

Cognitive ability

Includes brocas area

Prefrontal cortex

In the frontal lobe

Posterior part of this area is associated with movement

Middle zone is pertains to cognitive control, emotional reactions, and certain aspects of memory

Damage can result in people not applying formed memories to situations that call them

Anterior zone is important for decision making

Damage can cause people to make impulsive choices

Primary motor cortex/pre-central gyrus

Specialized for the control of fine movements, such as moving a finger

Prefrontal lobotomy

Surgery that consists of damaging the prefrontal cortex or cutting its connections to the rest of the body

Consequences include apathy, lack of initiative, memory disorders, distractibility, a loss of emotional expression, and impulsivity

Dropped when drug therapies became available

The Human Connectome Project

An effort to map all the long-distance connections of the brain

Focus on white matter

Will help researches identify abnormal connections responsible for many psychological disorders

the Blinding Problem/Large-Scale Integration Problem

The question of how various brain areas produce a perception of a single object

Occurs when you perceive two sensations as happening at the same time, at approximately the same place

Brocas area

Located in the frontal lobe

Controls speech production, motor articulation, and grammar

Damage causes a loss of the ability to speak

Ablation

The removal of a brain area, generally with a surgical knife

Lesion

Damage by means of a stereotaxic instrument

Used to help guide tools to damage a very precise area of the brain

Can be used to implant electrodes

Stereotaxic instrument

A device for the precise placement of electrodes in the brain

Gene-knockout approach

Directs a mutation to a gene that regulates one type of cell, transmitter, or receptor

Transcranial magnetic stimulation (TMS)

The application of magnetic stimulation to a portion of the scalp stimulates neurons

Applying a magnetic field in a very precise way

Temporarily inhibits brain activity

High dose

Enables researchers to study behavior with a brain area active, inactive, and then active again

Optogenics

Using a light to control a limited population of neurons

An investigator can excite or inhibit a single type of neuron in a small brain area with millisecond accuracy, determining the function of cells in greater detail than ever before

Invasive, so only used in humans when it might produce a medical benefit

Electroencephalograph (EEG)

Records electrical activity of the brain through electrodes, ranging from just a few to more than a hundred, attached to the scalp

Noninvasive

Recording outside of the skull

Useful for distinguishing between wakefulness and various stages of sleep

Diagnose epilepsy

Record brain activity in response to a stimulus

Provide precise information about timing, but only approximate information about location

Only sensitive to cells near the surface of the brain area

Magnetoecephalograph (MEG)

Measures the faint magnetic response generated by brain activity

Has excellent temporal resolution, being able to record changes from one millisecond to the next

Can identify the times when various brain areas respond and thereby trace a wave of brain activity from its origin to the other areas that possess it

Provide the precise information about timing and location

Only sensitive to cells near the surface of the brain

Positron-Emission Tomography (PET)

Provides a high-resolution image of activity in a living brain

The patient receives a glucose injection

Because most active brain areas increase their intake of glucose, tracking the glucose identifies areas of increased activity

Exposes the brain to radiation

Only used in research hospitals

Not the best method

Provides detailed information about the location, but only approximate information about the timing

Requires a lot of time and effort

Hard to use on a large sample of people

Functional Magnetic Resonance Imaging (fMRI)

Measures changes in blood oxygen (hemoglobin)

Areas using more oxygen are more active/functional

Less expensive and less risky than PET scans

Provides detailed information about the location, but only approximate detail about the timing

Asking people to do different activities to measure brain activity in real time

Requires a lot of time and effort

Hard to use on large samples of people

Readings mean nothing without comparing to something else/control group

Better to use on a group than a single individual

Phrenology

The process of relating skull anatomy to behavior

A pseudoscience

Lead to CT/CAT scans

Computerized Axial Tomography (CT/CAT scan)

A physician injects a dye into the blood to increase contrast in the image

X-rays

Takes images of the brain

Can help detect tumors and other structural abnormalities

Magnetic Resonance Imaging (MRI)

Applies a powerful magnetic field to align all axes of rotation, and then tilts them with a brief radio frequency field

Atomic nuclei release electromagnetic energy, which then gets measured

Forms an image of the brain that can depict tiny details

Not suitable for children or people who fear enclosed spaces

Researches use this method to relate behaviors to the size of brain areas