Chapter 4: Anatomy of the Nervous System

Question 1

identify the directional terms for anatomical structures

Answer 1

dorsal = towards the back (top of brain is considered dorsal)
ventral = towards the stomach
anterior= towards front end
posterior=toward the rear end
superior= above another part
inferior= below another part
lateral= toward side away from midline
medial=toward midline, away from side
proximal=close to point of origin or attachment
distal=more distant from point of origin or attachment
ipsilateral=on same side of body (ex 2 parts on left)
contralateral=on opposite sides of body ex 1 on lft 1 on rht
coronal (frontal) plane=shows brain structures from front
sagittal plane=shows brain structures from side
horizontal (transverse) plane=shows brain structures from above

Question 2

describe the structure of the spinal cord and the locations of its sensory inputs and motor outputs

Answer 2

SPINAL CORD
-part of CNS, located inside spinal column
-entering DORSAL ROOTS (axon bundles) carry sensory info and exiting VENTRAL roots carry motor info
-peripheral nervous system=axons to and from skin and muscles
-cell bodies of sensory neurons are dorsal root ganglia located in clusters of neurons outside spinal cord
grey matter=centre of cord, cell bodies and dendrites
white matter=myelinated axons

Question 3

functions, locations, and organization of the two main branches of the autonomic nervous system.

Answer 3

AUTONOMIC NERVOUS SYSTEM
-receive info from heart, intestines, and other organs
2 parts: sympathetic nervous system and parasympathetic nervous system
SNS:
-prepares organs for vigorous activity
-chains of ganglia just to left and right of spinal cord central regions
-fight or flight (increase breathing, increase heart rate, decrease digestive activity)
PSNS:
-vegetative non-emergency responses
-decrease heart rate, increase digestive activity, conserves energy
-cranial nerves and nerves from sacral spinal cord
-not in a chain, have long preganglionic axons extended from spinal cord to parasympathetic ganglia close to each internal organ
-acts more independently than SNS because ganglia are not linked like in SNS

Question 4

three main divisions of the hindbrain and both their unique and their shared functions

Answer 4

HINDBRAIN

-medulla, pons, cerebellum

Question 5

Medulla

Answer 5

• vital reflexes
• breathing, HR, vomiting, salivation, coughing, sneezing
• damage is fatal
• nuclei for cranial nerves
• contain reticular formation and raphe system that controls motor areas

Question 6

Pons

Answer 6

• bridge axons from each half of brain
• cross to opposite side
• nuclei for cranial nerves
• contain reticular formation and raphe system that controls motor area

Question 7

Cerebellum

Answer 7

• control movement, balance, coordination
• shifting attention back and forth,
• timing
• sensory timing

Question 8

two divisions of the midbrain and the major structures in each

Answer 8

Tectum=roof of midbrain
Superior and Inferior Colliculus- swellings on side of tectum (sensory processing)
-superior = vision
-inferior=hearing
Tegmentum=under tectum, nuclei for 3rd and 4th cranial nerves, part of reticular formation and extension of pathway between forebrain and spinal cord/hindbrain
Substantia nigra= gives rise to dopamine pathway that facilitates readiness for movement

Question 9

Basal Ganglia

Answer 9

important for specific aspects of movement
3 major structures:
1) caudate nucleus
2) putamen
3) globus-pallidus
-have subdivisions that exchange info with parts of cortex
-damage impairs movement (Parkinsons, Huntingtons)
-critical for learning and remembering how to do something
-attention, language, planning, and other cognitive functions

Question 10

Limbic System

Answer 10

• motivations and emotions ex) eating, drinking, sexual activity, anxiety, aggressin
• includes: olfactory bulb, hypothalamus, hippocampus, amygdala, cingulate gyrus

Question 11

Diencephalon

Answer 11

Thalamus and Hypothalamus
THALAMUS:
-pair of structures (L + R) in centre of forebrain
-most sensory info goes here first, gets processed, then sends to cerebral cortex
HYPOTHALAMUS
-small area near base of brain
-conveys messages to pituitary gland, alters release of hormones
-damage=abnormal motivated behaviours such as feeding, drinking, temperature regulation, sexual behaviour, fighting, activity level

Question 12

Basal Forebrain

Answer 12

nucleus basalis: receives input from hypothalamus and basal ganglia, sends axons that release ACh to widespread area in cerebral cortex

• arousal, wakefulness, attention
• deterioration=Alzheimers and Parkinsons

Question 13

Occipital Lobe

Answer 13

• posterior/caudal end of cortex
• visual info
• eyes provide stimulus, visual cortex provides experience

Question 14

Parietal Lobe

Answer 14

• between occipital lobe and central sulcus
• post central gyrus receives sensations from touch, muscle stretch and join receptors
• info re: touch and body location
• monitors all info about eye, head, and body position and passes info onto areas of brain that control movement
• spatial and numerical info ex) initially use fingers to count on

Question 15

Temporal Lobe

Answer 15

• lateral portion of each hemisphere
• left=understanding spoken language, contributes to complex parts of vision (perception of movement, recognition of faces)
• emotional and motivational behaviours
• damage=Kluver Bucy Syndrome (fail to display normal fears and anxieties)

Question 16

Frontal Lobe

Answer 16

• primary motor cortex and prefrontal cortex
• precentral gyrus=control of fine movements (1 finger)
• prefrontal cortex= 16x as many dendrite spines as other neurons in cortical area, processes and integrates huge amounts of info, working memory, making decisions, planning movements

Question 17

the “binding problem” and a possible means of coordinating neural activity throughout a large portion of the brain to form a unified perception

Answer 17

• question of how brain areas produce a perception of a single object
• early research-> various kind of sensory info converged onto association areas of cortex that associate vision with hearing/touch/current sensations
• later research-> association areas peform advanced processing on a particular sensory system but few cells combine/sense with another
• not 100% sure how binding happens
• it occurs if you perceive 2 sensations happening at the same time from approximately the same location

Question 18

EEG

Answer 18

electroencephalograph- records electrical activity of brain through electrodes, can record spontaneous brain activity or activity in response to stimulus

Question 19

MEG

Answer 19

magnetoencephalograph- measures faint magnetic fields generated by brain activity

• excellent temporal resolution
• identify times when brain areas respond and trace a wave of brain activity from point of origin to all other areas that process it

Question 20

PET

Answer 20

positron emission tomography

• provides high resolution image of activity from injection of chemicals in the living brain by recording emission of radioactive chemical decays and release positron that collides with electron, emits gamma rays
• gamma ray detectors worn on head
• looks at how many gamma rays are coming from each part of brain

Question 21

fMRI

Answer 21

function magnetic resonance imaging

• less expensive and risky than PET scan
• hemoglobin with oxygen reacts to magnetic fields differently than hemoglobin without oxygen, this is picked up by the scanner
• more active area=more blood flow and increase oxygen use

Question 22

CT/CAT Scan

Answer 22

computerized axial tomography

• inject dye into blood
• x-rays pass through side of head and recorded by detectors on opposite side
• computer uses measurements to construct image of the brain
• detects tumours and abnormalities

Question 23

MRI

Answer 23

magnetic resonance imaging

• uses powerful magnetic field to align all axes of rotation and tilt with brief radio frequency
• radio frequency off=atomic nuclei release electromagnetic energy as they relax and return to original axis
• MRI creates image by measuring energy that is released

Question 24

identify the major ways of inactivating parts of the brain, temporarily or permanently, and of stimulating parts of the brain

Answer 24

ABLATION: removal of a brain area usually with surgical knife (permanent)
LESION: damage to a specific structure in interior of brain with steroaxic instrument (permanent)
GENE-KNOCKOUT APPROACH: use chemical to direct a mutation to a particular gene (permanent)
TRANSCRANIAL MAGNETIC STIMULATION: application of intense magnetic field that temporarily deactivates neurons below the magnetic (temporary)
-brain stimulation completed by inserting electrodes
OPTOGENETICS: brain stimulation with a laser

Question 25

problems of interpretation of the effects of lesions

Answer 25

• do not know the exact reason behind the change in behaviour and may need to do further behavioural studies to figure it out
• very difficult to specify exact behavioural deficit

Question 26

ender-specific differences in size of brain and brain structures, including the limitations of interpreting these correlation data

Answer 26

• male brains tend to be larger than female
• unable to pinpoint exact reasons for few correlations that do exist
• differ structurally but accomplish the same thing
• organized differently
• there is no data to support larger brain=more intelligent
• need to look at anatomy, chemistry, and other specific brain area features and how they relate to specific aspects of behaviour