Biopsychological Perspectives

Lecture 1

Functional Neuroanatomy

“I said in Dorian Gray that the great sins of the world take place in the

brain: but it is in the brain that everything takes place.... It is in the brain that the poppy is red, that the apple is odorous, that the skylark

sings…” (Oscar Wilde)

Aims and Objectives

• Basic divisions and sub-divisions of the human nervous system

• Gross neuroanatomy of the human brain

• Localization of function in the brain (especially the cortex)

The Human Nervous System

Peripheral Nervous System

Sense organs and muscles

Peripheral nervous

system

Spinal cord

Brain (sensory / motor specific areas)

Somatic Peripheral Nervous System

• Nerves that convey information:– Sense organs /

muscles spinal cord brain (Afferent)

– Brain spinal cord muscles /glands (Efferent)

• Primarily involved in voluntary muscle control

AutonomicPeripheral Nervous System

Nerves that control involuntary muscles (heart; intestines; lungs, etc)

The two branches of the ANS

Sympathetic Parasympathetic

Adapt the bodies internal / metabolic activity

to meet environmental / perceived needs

Autonomic Nervous System

Sympathetic

↓

Expends energy in “fight or flight”

situation

Parasympathetic

↓

Conserves energy in non-emergency

situations

ANS Control of Organs

• Most organs controlled by both sympathetic and parasympathetic nerves

• Usually active at the same time– dynamic relationship between the two

• Relative balance dependent on immediate needs of individual

Example of Psychological Application of ANS

Investigation

• Lie detection

• Lie increase in sympathetic activity increased sweating picked by electrodes as increased electrical conductance

• Lie detected (as deflection in a waveform)

Central Nervous System - Brain

Central Nervous System

• 3 major divisions• Hindbrain

– most posterior and oldest part

• Midbrain– in centre of brain

• Forebrain– most anterior and prominent part– outer portion = cerebral cortex

Hindbrain

• Medulla

• Pons

• Cerebellum

Medulla

Location - Just above

spinal cord (extension of

spinal cord)

Function – Controls

(via cranial nerves) vital

functions: breathing;

heart rate; salivation;

coughing; sneezing.

Damage fatal.

Pons

Location - above and

in front of medulla

Function – sensory

relay station

Reticular Formation

• Medulla and pons (and other structures) form Reticular Formation

• Raphe system and Locus Coeruleus

• Networks of neurons sending axons up to forebrain; involved in arousal and sleep

Cerebellum

• “little brain” – large convoluted structure behind pons and medulla

• Function - coordination of muscles and maintaining balance

Cerebellar Functions

• Planning movement• Developing newly

learned motor programmes (slow, deliberate) into rapid automated “habits” (driving)

• Lateral cerebellar regions contribute to language development– Dyslexics – often have

cerebellar damage

Midbrain

• Middle of brain (under convoluted outer bit)

• Superior Colliculus• Inferior Colliculus• Substantia Nigra

Superior and Inferior Colliculi

• Two pairs of swellings at top of midbrain section

• Superior Colliculus - route for visual sensory information from eyes (to visual processing areas)

• Inferior Colliculus – route for auditory sensory information from ears (to auditory processing areas)

LeftAuditorycortex

RightAuditorycortex

Cochlea Medial geniculate nucleus

Inferior colliculus

SuperiorOlivarynucleus

IpsilateralCochlearnucleus

Auditorynerve fiber

Substantia Nigra

• Area implicated in control of movement

• Abnormality in SN nerves in Parkinson’s disease (movement / tic disorder)

Forebrain

• Most anterior and prominent part of mammalian brain

• Cerebral Cortex (outer portion – visible)

• Subcortical structures - limbic system (set of structures forming a border, encapsulating the brain stem)

Limbic System

• Structures heavily involved in motivated and emotional behaviours:

eating

drinking

sexual behaviour

anxiety

aggression

Larger Structures of the Limbic System

• Olfactory Bulb

• Hypothalamus

• Thalamus

• Hippocampus

Olfactory Bulb

• Detection and perception of smell

• Through links with rest of limbic system and cortex (higher brain) – association of smell with previous events

Hypothalamus

• Just below thalamus• Contains several

distinct sets of nuclei• Each relates to a

specific “motivated behaviour”

• 4 Fs– Feeding– Fighting– Fear– Sex

Hypothalamus

• Damage to a specific nucleus specific deficit

• Ventromedial and Lateral hypothalamic nuclei eating disorders (in rats)

• Works in conjunction with pituitary gland to alter / regulate release of hormones according to need– Aggression / testosterone

Hippocampus

• Implicated in memory (I.e. storing “new” information)

• Infant amnesia - – cant remember much

of first 5 years of life – due to relatively slow hippocampal maturation

• Age-related memory loss – gradual loss of

hippocampal neurons

Thalamus

• Resembles two small round pillows (side by side)

• Sits on top of hypothalamus / under cortex / centre of brain

Thalamus

• Function - Main source of sensory input to cortex

• Not just passive relay station – further processes info already processed by midbrain structures

Thalamic Nuclei

• Like hypothalmus has distinct nuclei

• Each nucleus synapses onto a sensory-specific area of the cortex

• E.g. Lateral Geniculate Nucleus (LGN) visual processing areas of cortex.

The Cerebral Cortex

• Most important part of the the brain to psychologists

• Divided into two hemispheres (covers all the other forebrain structures)

Contralateral Control

• Each hemisphere receives sensory information from contralateral (opposite) side of body

• Each hemisphere controls movement on opposite side

Each hemisphere controls

movement on opposite side

Each hemisphere receives

sensory information from

contralateral (opposite)

side of body

• Two hemispheres are connnected (communicate/integrate info) by two bundles of nerve fibres

• Corpus Callosum• Anterior

Commisures

Commisures

• Corpus Callosum

• Anterior Commisures

“Areas” in the Cerebral Cortex – The Cortical Lobes

• Can distinguish 50+ areas within the cortex (thickness / appearance of cells)

• Usually divided in 4 cortical lobes

• Occipital• Parietal• Temporal• Frontal

Occipital Lobe

• Located – back of head

• Function – Main recipient of visual info

• Very posterior part = Primary Visual Cortex – damage “cortical blindness” (normal eyes but cannot see)

Occipital Lobe

• Also involved in spatial orientation (e.g. maze learning)

• Damaged in rats – no ability to maze learn

Parietal Lobe

• Located – between occipital lobe and central sulcus – (deep groove from

top of head down sides of each hemipshere)

Parietal Lobe

• Functions:• Somatosensation -

immediately behind central sulcus = somatosensory cortex

• Mediates “body information”– Touch– Muscle stretch– Joint movement

Parietal Lobe

• Direct electrical stimulation “feeling” or sensation in particular part of body represented

• RH left side of body sensation

• Representation of body parts based on species needs (hands)

The sensoryhomunculous

This model shows what a man's body would look like if each part grew in proportion to the area of the cortex of the brain concerned with its sensory perception.

Other Parietal Lobe Functions

• Relating visual information to spatial information (object constancy)

• Ability to draw and follow maps and describe how to go somewhere

• Ability to identify objects by touch (damage loss of Braille ability)

• Body image (what the body looks like and how it is functioning)

Temporal Lobe

• Located – side of each hemisphere (near temples)

• Functions– Hearing– Balance– Auditory attention– Complex visual

processing (faces) Tumours visual hallucinations

Other Temporal Lobe Functions

• In majority - left temporal lobe contains language comprehension area

• Wernickes Area

• Damage receptive aphasia

Frontal Lobe

• Located – anterior to central sulcus (front of brain)

• Posterior part of lobe = precentral gyrus

• Motor cortex (control of fine movement)

• As with somatosensory cortex – Contralateral contro– Different parts responsible

for different body parts

Primary motor cortex (M1)

Foot

Hip

Trunk

Arm

Hand

Face

Tongue

Larynx

Motor homunculus

This model shows what a man's body would look like if each part grew in proportion to the area of the cortex of the brain concerned with its movement.

Prefrontal Cortex

• Anterior to motor strip• Large area• Function – receives

information from all sensory areas and “integrates” and “represents” receives sensory information

• Understanding / thinking• Memory

Prefrontal Cortex and Language Ability

• In humans (most) left hemisphere contains language production area

• Brocas Area• Damage difficulty

producing spoken language (“telegraphic speech”)

• Comprehension ok

Summary

• The main divisions of the nervous system are the Central Nervous System and the Peripheral Nervous System

• The CNS consists of the spinal cord and the brain (hindbrain, midbrain and forebrain)

• The PNS consists of the somatic and autonomic NS (sympathetic and parasympathetic)

Summary

• Aspects of functioning (sensory, motor and “cognitive”) are localized to particular cortical areas and sub-cortical structures.

Summary

• BUT brain areas and structures work together and integrate their processing to achieve global functions

3D Brain Anatomy

http://www.pbs.org/wnet/brain/scanning/index.html