Biopsychology top tips - PowerPoint Presentation

Slide1

Biopsychology

top

tips

crammer workshop

!

Slide2

Biopsychology – Check the Spec!

Devise a revision target list.

Slide3

Skip to it!

We are going to have a go at some tailor made revision exercises

Slide4

5 mins for 5 things

Slide5

The Nervous System has 2 main parts – the Central Nervous System (CNS) and the Peripheral Nervous System.

The CNS consists of the brain

and the spinal cord. The brain is within the skull and the spinal cord is within the vertebrae.

Spinal cord responsible for reflex actions (brain not involved!)

Slide6

Peripheral Nervous System

Autonomic Nervous System

Responsible for vital functions and autonomic processes – like breathing, digestion, stress responsesHas two states: normal (parasympathetic) and aroused (sympathetic)Somatic Nervous SystemControls muscle movementReceives sensory information

Slide7

The Fight or Flight Response

This arousal can often be coined as a

“fight or flight response”, which has been seen to have evolved as part of our evolutionary history.

The sympathetic nervous system is agonistic – it creates changes and arousal.

The parasympathetic nervous system is responsible for returning the body to a relaxed state. (rest/digest). This system is antagonistic.

The hypothalamus recognises that there is a threat

It sends messages to

The adrenal gland (specifically the adrenal medulla

This triggers the release of

Adrenaline to the endocrine system and noradrenaline in the brain

This prompts the following changes (PTO)

Slide8

Physiological signs of arousal

Increased pupil size – allows more light to enter the eye

Bronchial tubes dilate – intake more oxygenIncrease in heart rate - greater blood flow, more oxygenGlycogen stored in liver converted to glucose

Sweat glands begin to produce sweat

Adrenal medulla stimulated to release adrenalin.

Slide9

What is involved?

The ANS

controls life-maintaining processes such as heart rate; transmits information to and from internal organs.

The sympathetic division of ANS

prepares body for action and the

parasympathetic division

conserves/stores energy. 

This explain Jim Bob's increased heart rate in emergency action (...my heart was beating so fast...) as well as the increased action of adrenal glands and energising effect (...moved with such speed/shaking).

The brain

alerts Jim Bob to the threat ('I realised it was coming closer...', 'I decided to run…', 'I saw a bus…').

Devise a revision target list.

Slide10

5 mins for 5 things

Slide11

ENDOCRINE SYSTEM

These release

adrenalin directly into the bloodstream which prepares the body for

fight or flight

by constricting blood vessels in the stomach. This inhibits digestion and gives you that sick feeling as well as increasing your heart rate

This

controls

the release of hormones from all other endocrine glands…an important gland!

This facilitates the release of the female hormones –

oestrogen

and

progesterone - reproduction

This facilitates the release of the male hormones –

testosterone

Thyroid gland produces the hormone

thyroxine

. This hormone affects cells in the heart (increases heart rate). It also affects cells throughout the body increasing

metabolic

rates (the chemical processes taking place in the cells). This in turn affects

growth rates

This facilitates the release of the

melatonin

which is responsible for

sleep

This

regulates the pituitary gland

Slide12

The

sympathetic nervous system

controls what has been called the "Fight or Flight" phenomenon It controls the necessary bodily changes needed when we are faced with a situation where we may need to defend ourselves or escape.  FIGHT OR FLIGHT RESPONSEAnxiety and fear are important for survival because they act as a mechanism to

protect

the

body

against stress and

danger

You are walking down a dark street at night by yourself.  Suddenly you hear what you suspect are footsteps approaching you rapidly. 

What happens?  

Your

sympathetic nervous system

kicks in and in an instant, your body is prepares itself for either defence or escape.

Pituitary

gland

releases adrenocorticotrophic hormone – ACHT ACHT affects adrenal glands causing them to release

adrenaline into the bloodstream….enabling the body to take action and protect itself in dangerous situations, either by running away FLIGHT or fighting FIGHT

Now imagine that the footsteps belong to a good friend who catches up to you and offers to walk you home.  You feel relief instantly, but your body takes longer to adjust.  In order to return everything to normal, the parasympathetic nervous system kicks in.  This system is slow acting, unlike its counterpart, and may take several minutes or even longer to get your body back to where it was before the scare.

Parasympathetic is like a

brake…reducing

activity that the

sympathetic

caused

Also know as the rest and digest response

These two subsystems are at work constantly

shifting your body to more prepared states and more relaxed statesEvery time a potentially threatening experience occurs (e.g., someone slams on their breaks in front of you), your body reacts

Slide13

Slide14

Slide15

5 mins for 5 things

Slide16

Human nervous

system

Peripheral nervous system (PNS)

Central nervous system (CNS)

Autonomic nervous system

Somatic nervous system

Spinal cord

Brain

Sympathetic nervous system

Parasympathetic nervous system

NERVOUS SYSTEM

Slide17

Generally arouses the body

Generally creates a physiological calm

Complete “Are you Sympathetic (or Parasympathetic)?

prepares the body to use energy for fight or flight

maintains and conserves body energy and functions

Slide18

Nucleus -

the control centre of a cell, which contains the cell's chromosomal DNA

Dendrite -

Receives the nerve impulse or signal from adjacent neurons

Axon

Where the electrical signals pass along

Myelin sheath

Insulates /protects the axon from external influences that might effect the transmission of the nerve impulse down the axon

Nodes of

ranvier

These

speed up the transmission of the impulse by forcing it to ‘jump’

Terminal buttons

Terminal buttons send signals to an adjacent cell

NEURONS AND NEUROTRANSMITTERS

Slide19

Three types of neurons

Relay Neuron

Carries messages from the

CNS

to effectors such as muscles and glands

Short dendrites and long axons

Transfers messages from sensory neurons to other interconnecting neurons or motor neuron

Short dendrites and short or long axons

Carries messages from the

PNS

to the brain and spinal cord

Long dendrites and short axon

Slide20

nerve impulse travels down an axon

nerve impulse reaches synaptic terminal

this triggers the release of neurotransmitters

the neurotransmitters are fired into the synaptic gap

neurotransmitter binds with receptors on the dendrite of the adjacent neuron

if successfully transmitted the neurotransmitter is taken up by the post-synaptic neuron

the message will continue to be passed in this way via electrical impulses

Synaptic transmission

Excitatory

-

they make it more likely the next neuron will fire

(such as acetylcholine)

Inhibitory

-

they make it less likely the next neuron will fire

(such as GABA

)

Slide21

Slide22

Slide23

5 mins for 5 things

Slide24

LOCALISATION OF FUNCTION

Specific functions of the brain have specific locations in the brain

Franz Gall’s

theory of phrenology (looking at the structure of the skull to determine a persons character) was influential but quickly discredited

Visual centres

Auditory centres

Motor cortex

Somatosensory cortex

Language centres (

Broca’s

area and Wernicke’s area)

Slide25

Slide26

Visual centres

Located in the visual cortex in the

occipital lobe

Visual processing begins in

retina

(light enters and strikes the photoreceptors (rods and cones))

Nerve impulses from the retina travel to areas of the brain

via the optic nerve

Some travel to areas of the brain involved in coordination of circadian rhythms

Most terminate in the thalamus, this acts as a relay station

passing info to visual cortex

6. Visual cortex spans both hemispheres

7. The right hemisphere receiving its input from the left-hand side of the visual field and vice versa

8. Visual cortex contains different areas that process different types of visual info such as colour, shape and movement

Slide27

Hemispheric

Lateralisation

Hemispheric lateralisation - this is when one hemisphere carries out a particular functionLeft hand side of body is controlled by RIGHT motor cortex. Lateralised

means that one particular side of the brain deals with that task

Left Hemisphere

Right Hemisphere

Language

(speech production and comprehension)

Spatial processing

Holistic processing

Slide28

Motor cortex

Responsible for generation of voluntary motor movements

Located in frontal lobe along the bumpy region (!) the precentral gyrusOn both hemispheres – motor cortex on right hemisphere controlling muscles on left side of body and vice versaDifferent parts of the motor cortex control different parts of the bodyThese are arranged logically – the region that controls the foot is next to the region that controls the leg

Slide29

Somatosensory cortex

Detects sensory events from different regions of the body

In parietal lobe along a region called the postcentral gyrusDedicated to the processing of sensory info related to touchUses sensory info from skin to produce sensations such as touch pressure, pain, temperature which it then localises to specific body regions

5. Both hemispheres have a somatosensory cortex

6. The cortex on one side of the brain receives sensory info from the opposite side of the body

Slide30

Language centres – Broca’s area

Named after Paul Broca, French neurosurgeon

Treated a patient called ‘Tan’ – unable to speak other than this one word (but did understand language)Studied 8 other patients who similar language deficits, along with lesions in their left frontal hemispherePatients with damage to their right frontal hemisphere did not have the same problemsThis lead him to identify the existence of a language centre in the back portion of the frontal lobe of the left hemisphere (Broca 1865)

6. Believed to be critical for speech production

7. HOWEVER neuroscientist have found that when people perform cognitive tasks (nothing to do with language) their

Broca

area is active

8.

Fedorenko

(2012) discovered 2 regions of

Broca’s

area – one selectively involved in language, the other involved in responding to many demanding cognitive tasks (such as performing maths problems)

Slide31

Language centres – Wernicke’s area

German neurologist called Carl Wernicke

Discovered another area of the brain that was involved in understanding languageBack portion of left temporal lobePatients with lesions on their Wernicke’s area could speak but were unable to understand languageProposed that language involved separate motor and sensory regions located in different cortical regionsThe motor region, located in Broca’s area, is close to the area that controls the mouth, tongue and vocal cords.

The sensory region, located in

Wernickes

area, is close to the regions of the brain responsible for auditory and visual input

Input from these regions transferred to Wernicke’s area when recognised as language and associated meaning

There is a neural loop (arcuate fasciculus) running between

Broca’s

area and Wernicke’s area

At one end lies

Broca’s

area – responsible for the production of language

At the other lies Wernicke’ area – responsible for the processing of spoken language

Slide32

A03

Not all researchers agree that cognitive functions

are localised in the brain. It’s the extent of the damage rather than the location we need to look atThere are individual differences in language areas – for example women have proportionally larger

Broca’s

and Wernicke’s areas than men, the result of greater use of language (

Harasty

et al (1997)

Damage

to the brain e.g. after a stroke can result in aphasia – the inability (or impaired ability) to understand or produce language

Lots of support comes from case studies (e.g. Phineas

Gage) which allow for rich in-depth data….

However

, case studies are very unique to that particular person so there may be issues with generalizability

Two

of

Broca’s

patients had their brains preserved. This has allowed for MRI scanning. The findings revealed that other areas of the brain could have also contributed to the patients’ reduced speech abilities. (Dronkers et al (2007)Support also comes from neurological evidence – Dougherty et al (2002) demonstrated that OCD symptoms and behaviours are localised (lesions to the cingulate

gyrus (frontal lobe) and 1/3 showed positive response rate to the surgery)Plasticity causes some contradicitry evidence as when the brain is damaged, the brain is able to reorganise itself to recover… challenges the localisation theory ~

Lashley called this the law of equipotentiality (other areas chip in so action can still be achieved)What might be more important is how brain areas communicate with each other, rather than which specific brain regions control a particular cognitive process (see

Lashley 1950 in PHG)

Slide33

SPLIT BRAIN RESEARCH

language

The left and right side communicates through the corpus callosum

Visual motor tasks

Remember

Broca

? He found that damage to a particular area of the left brain hemisphere lead to language problems, yet damage to the same area in the right side did not have the same consequence

Slide34

Sperry (1968) split brain research

Split-brain patients originally came about by accident. There was a treatment for severe epilepsy whereby a surgeon would cut through the corpus callosum, the aim was to prevent the violent electrical activity that accompanies the seizure crossing from one hemisphere to the other

Slide35

Sperry and

Gazzaniga

(1967)

Tested

capabilities of

separated

hemispheres

Left visual field goes to right hemisphere, right visual field goes to left hemisphere

Corpus callosum is cut in split-brain patients

The information presented to one hemisphere has no way of travelling to the other hemisphere and can only be processed in the hemisphere that received it

In a study the split-brain patient would focus on a dot in the centre of a screen

Info was presented to either the left or right visual field

Asked to respond with either their left hand (controlled by the RH) or right hand (controlled by the LH) or verbally (which is controlled by the LH), without being able to see what their hands were doing

The information from the LVF is processed in the RH which can see the picture, but as it has no language centre, cannot respond verbally.

The LH, which does have a language centre, does not receive the information about the picture, therefore cannot say it has seen it.

What can we learn from split-brain research?

There are differences between the two hemispheres

LH responsible for speech and language

RH specialises in visual-spatial processing and facial recognition

Connectivity is as important as the functions of specific parts

Slide36

Slide37

Slide38

Neural Plasticity

The concept of the brain developing and changing in response to the environment is referred to as

plasticity

Slide39

Example of Plasticity – Maguire et al.

MRI scans of brains of 50 healthy, right handed, male, non taxi drivers aged 33 - 61 were analysed to establish a comparison data base of ‘average hippocampi’.

Slide40

Example of Plasticity – Maguire et al.

Maguire found that the right posterior (back) hippocampus was larger for taxi drivers than those who were not. The taxi drivers had a smaller anterior hippocampus (front).

There was a positive correlation between amount of change and time spent as a taxi driver. Maguire suggested that their job had caused their brain to change and matter moved from the front to the back to support their spatial navigation abilities.

Slide41

Functional Recovery

There are three main anatomical ways that the body can replace axon function in the brain after trauma:

Increased brain stimulation. As neurons are damaged there is an effect on the neighbouring neurons as they no longer have input. This happens with the hemispheres too. Although damage may only be on one side, the other hemisphere functions at a lower level too, as it has reduced input. Work by Takatsuru et al. (2009), demonstrated that if the undamaged hemisphere is stimulated, recovery from a stroke can be improved.Axon sprouting. When an axon is damaged its connection with a neighbouring neuron is lost. In some cases, other axons that already connect with that neuron will sprout extra connections to the neuron, replacing the ones that have been destroyed. It is compensating for the loss of a neighbour. This occurs for the most part two weeks after the damage happens. It helps replace function, but only if the damaged axon and the compensatory axons do a similar job. If not, problems can occur with function.

Denervation supersensitivity.

This occurs when axons that do a similar job become aroused to a higher level to compensate for the ones that are lost. However, it can have the unfortunate consequence of over-sensitivity to messages such as pain. This increases the pain levels in an individual.

Slide42

Factors affecting recovery of the brain after trauma

Perseverance.

Functional recovery after brain trauma is dependent on assessment and perseverance. Sometimes a function may appear to be lost but that may be because the individual affected may not be trying and takes the view that it is unrecoverable. Physical exhaustion, stress and alcohol consumption. When function is recovered in an individual it is important to remember that often the f unction is used with considerable effort and although the person can do a task, they are often fatigued by the effort.

Age.

There is a deterioration of the brain in old age and this therefore affects the extent and speed of recovery (

Corkin

et al, 1989)

.

Gender.

There is research to suggest that women recover better from brain injury as their function is not as lateralised (concentrated in one hemisphere).

Slide43

Exam Question

Slide44

Slide45

5 mins for 5 things

Slide46

WAYS OF STUDYING THE BRAIN

PET SCANNING

It is hard to pinpoint exact areas of the brain so even if PET scans are clear; they are still fairly broad in their imaging.

They are ethical up to a point because they are relatively non-evasive compared with surgery;

however, the injection is invasive. They can be distressing.

PET scans are reliable; they are replicable and the same areas are highlighted.

PET scans are valid because their findings match other findings and they do measure what they claim to measure (e.g. the area pinpointed for speech is the same as that found by other methods).

Radioactive material (tracer) is injected

(the

brain uses glucose as energy), the areas of the brain which are most active absorb it. Computer produces coloured images of the level of activity occurring throughout the brain.

fMRI SCANNING

They are scientific, replicable and reliable.

They are valid in that what is found by the scans is real.

Highly ethical as non-invasive and virtually risk-free

In comparison to other techniques, rather expensive and needs the patient to lie very still to capture image

Hard to pin point exactly what is occurring in the brain as the scan only shows blood flow and not specific activity in the brain

Measures brain activity in specific areas by detecting associated changes in blood flow.

EEG SCANNING

The resolution on and EEG is much better than scans such as fMRI so brain activity can be detected to a single millisecond

EEG’s are useful with the diagnosing of disorders such as epilepsy, which can be easily detected on screen. Has also helped with understanding biological sleep rhythms

 

EEG’s receive information from thousands of neurons – this in itself provides difficultly pinpointing exact source of brain activity

A record of the brain wave patterns produced by millions of neurons, producing characteristic patterns.

ERP’s

Many of the weaknesses of EEG are strengths of ERP’s. E.g.; can specify neural activity

ERP’s can be applied to cognitive approach and has helped identify different cognitive processes such as working memory

Lacks reliability as standardisation has been hard to determine – findings have not been consistent

Extraneous variables have been hard to control when ERP’s have been conducted so the validity of the findings could be questioned.

Isolating specific responses of neurons to specific stimuli or tasks

Post mortems

Broca

and Wernicke relied on post mortems to identify

language

centres of the brain

Post mortems

improve

medical knowledge and help

generate

hypothesis

Cause of death

always

an issue

/ something

to be wary of - Some brains may have deficits.

Ethical issue in relation to patients giving informed consent before dying

Correlating behaviours before death with brain structures after death

Slide47

5 mins for 5 things

Slide48

CIRCADIAN

RHYTHMSA circadian rhythm is one that occurs about once a day. An example of this is the sleep-wake cycle. This cycle is controlled by endogenous pacemakers which are the internal biological clocks and by the exogenous zeitgebers which are external factors in the environment that affect the cycle (such as light/dark and temperature). The pacemakers work together to regulate our daily pattern of sleeping and being awake.The suprachiasmatic

nucleus (SCN) is a tiny bundle of nerve cells located in the hypothalamus in each hemisphere in the brain. IT is one of the primary endogenous pacemakers in mammalian species including humans and is influential in maintaining circadian rhythms such as the sleep-wake cycle. Nerve fibers connected to the eye cross is an area called the optic chiasm on the way to the visual area of the cerebral curt. The SCN lies just above the optic chiasm. It receives information about light directly from the structure. This continues even when our eyes are closed enabling the biological clock adjust to changing patterns of daylight whilst we are asleep.

The SCN passes the information on day length and light that it receives to the pineal gland. (a pea-like structure in the brain just behind the hypothalamus). During the night the pineal gland increases production of melatonin (a chemical that induces sleep and is inhibited during periods of wakefulness). Melatonin has also been suggested to be a casual factor in Seasonal Affective Disorder (SAD).

The German work

zeitgebers

means time-giver. Exogenous

zeitgebers

are external factors in the environment that reset our biological clocks that controls the sleep-wake cycle continues to tick in a distinct cynical pattern. Thus sleeping and wakefulness would seem to be determined by an interaction between internal and external factors.

Light is a key

zeitgebers

in humans. It can reset the bodies’ main endogenous pacemaker. The SCN and thus plays a role in the maintenance of the sleep-wake cycle. Light also has an indirect influence on the key processes in the body that control such functions as hormones secretion and blood circulation.

Slide49

Research into Circadian rhythms

DeCoursey

(1998)

Behaviour of SCN-

lesioned

chipmunks in natural

habitat

The

sample consisted of 30 chipmunks with

suprachiasmatic

nucleus-targeted lesions, 24 surgical controls and 20 intact controls. After functionally removing the SCN in 30 chipmunks and returning them to their natural habitat it was observed that after 80 days significantly more of those chipmunks had died when compared to a control group with normal functioning SCNs. Mortality during the first 14 days was 37.5% for surgical controls and 50% for the SCN-

lesioned

animals, while none of the intact controls were killed.

Duffy

et al

.’s (2000)

research showed early rising individuals prefer 6am to 10pm, whereas late risers prefer 10am until 1pm.

Folkard

et al (1985)

studied a group of 12 people who agreed to live in the dark for three weeks retiring to bed when the clock said 11.45pm and rising when they clock said 7.45a.m Over the course of the study the researchers gradually speeded up the clock (unknown to the participants) so an apparent 24 hour day eventually lasted only 22 hours. It was revealed that one of the participants was able to comfortably adjust to the new regime

Practical applications:

Dawson & Campbell (1991)

found that workers exposed to a 4-hour pulse of bright light showed improvements in work performance. This shows that light acts as an exogenous

zeitgeber

in maintaining the rhythm of the SCN. Consequently, bright light has been used as a substitute for sunlight to reset the SCN.

Practical applications:

Consuming melatonin may help resynchronise the sleep-wake cycle more quickly.

Beaumont et al (2004)

found that taking melatonin at bed time for 3 days before travel and 5 days after significantly reduced the symptoms of jet lag

Slide50

ULTRADIAN RHYTHMS

Slide51

Research into

Ultradian rhythms

Dement and Kleitman (1957)Aim: The aim of this laboratory experiment was to investigate the relationship between eye movements and dreaming. Method: The nine participants were seven adult males and two adult females. The participants were studied under controlled laboratory conditions. Participants had to report to the laboratory at bedtime where they were connected to an EEG. The EEG took measurements throughout their time asleep all night. P's were asked not to drink caffeine.

Results:

The results show that REM sleep is predominantly, though not exclusively, associated with dreaming, and N-REM sleep is associated with periods of non-dreaming sleep. P's were able to recall dreams when awakened during REM periods. If they were awakened in other stages they were less likely to report dreaming. Rapid eye movements of p's during REM occurred according to dream type

Conclusions:

From these findings (which are robust as there has been much replication) It can be said that the stages of sleep follow a typical pattern throughout the night and

dreams

mostly occur in

REM

Kleitman

(1969)

referred to the 90

minuite

cycle found during sleep as the Basic Rest Activity Cycle or BRAC.

Kleitman

suggested this also continued throughout the day but rather than moving through sleep stages we move though states of

alterness into physiological fatigue, Research has found that the human mind can focus for a period of about 90 minutes until it then runs out of resources resulting in a lack of concentration, fatigue and hunger,

Kleitman argued that this can be evidenced through the familiar morning coffee break allowing workers to divide their morning into two 90 minute phases. This supports the role of internal

Ultraidan

rhythms during both sleeping and waking hours

Ericsson (2006)

studied a group of violinists and found that the groups practice sessions were normally limited to 90 minutes. Their practising day was divided up into 90 minute segments and the violinists frequently napped to recover from practice with the very best violinists napping the most. Ericsson discovered this same pattern among other musicians, athletes and writers. This supports the Basic Rest Activity Cycle previously proposed by

Klietman

Slide52

INFRADIAN RHYTHMS

Overview

Definition: Frequency of less than one cycle in 24 hours, such as menstruation and seasonal affective disorder. (Depression associated with seasonal changes, usually the onset of winter and decreased darkness).

Menstrual cycle (endogenous) occurs in females about every 28 days, endogenous control by the hormones

oestrogen

and progesterone.

The female menstrual cycle, an example of an

Infradian

rhythm, is governed by monthly changes in hormone levels, which require ovulation. The cycle refers to the time between the first day of a woman’s period when the womb lining is shed to the day before her next period. The typical cycle takes approximately 28 days to complete though anywhere between 24 days and 35 days is considered normal. During each cycle rising levels of the hormone oestrogen cause the ovary to develop an egg and release it (ovulation). After ovulation the hormones progesterone help the womb lining to grow quicker, readying the body for pregnancy. If pregnancy does not occur, the egg is absorbed into the body; the womb lining comes away and leaves the body (menstrual flow)

Slide53

Reinberg

(

1967) Conducted a study where one female participant spent three months in a cave with only light from a small lamp. As a result her days lengthened to 24.9 hours and her menstrual cycle shortened to 35.7 days. This shows that the levels of light in the cave could have affected the woman's menstrual cycle suggesting Infradian biological rhythms could be influenced by exogenous zeitgebers such as light

Research into

Infradian

rhythm

Although the menstrual cycle is an endogenous system, evidence suggests that it may be influenced by exogenous factors such as the cycle of other women.

 

McClintock and Stern (1998)

McClintock showed that female cycles entrained through exposure to

odour

donors’ pheromones (exogenous

zeitgebers

)

Aim:

to show that the menstrual cycle is influenced by

pheromonal

secretions from other women.

Sample: female university students, not taking birth control pills.

Design:

A Longitudinal experiment with independent measures.

Method:

A control group of women wore alcohol soaked pad in their armpits. The fumes from these were inhaled by another group of women (the experimental group) and their menstrual cycles monitored.

Result:

when the experimental group inhaled secretions from women who were about to ovulate, their menstrual cycles became shorter. When they inhaled secretions from women who had just ovulated, their menstrual cycles became longer. The experimental groups’ menstrual cycles were affected by the secretions from the control group. On 68% of occasions the recipients of the sweat donation had responded to the pheromones. This explains why when a group of women live in close proximity their menstrual cycles tend to synchronise and provides support for the role of exogenous

zeitgebers

(pheromones) in

infradian

rhythms

Slide54

Slide55

Slide56