The document summarizes research on the potential neurophysiological basis of pathological lying. It outlines the pathways in the brain involved in normal lying, including the limbic system, Broca's area, premotor cortex, amygdala, and anterior thalamic nucleus. Studies using MRI have found increased white matter volume in the prefrontal cortex of pathological liars compared to normal individuals and those with antisocial disorders. To better understand if pathological lying is innate or developed, the document proposes a longitudinal study using repeated MRI scans to examine changes in white matter from repeated lying behavior over time in young adult subjects.
2. DEFINING PATHOLOGICAL LYING?
PATHOLOGYCAL LYING (PL) was first recognised and mentioned in psychiatric
literature in 1891 by the German physician Antony Delbruck under the name of
Pseudologia Phantastica.
PL has been and remains a controversial topic that has yet to be clearly defined.
Dike (2008) characterised PL as a long history (maybe lifelong) of frequent and
repeated lying for which no apparent physiological motive or external benefit can
be discerned.
Furthermore, Gogineni and Newmark (2014) believe that a pathological liar is lying
in a manner that is intriguing to the listener, about any aspect of their history or
symptoms and furthermore, these lies are not the result of an immediate pressure
or stress but are ongoing.
3. AIM
PL has been researched based on hereditary,
neurocognitive and psycho-social aetiologies,
however, little research has been carried out on
the possibility of there being a
neurophysiological aetiology.
For this reason, the aim of the research is to
review PL from a neurophysiological perspective
in order to assess whether it develops from pre-
existent conditions or is the manifestation of
increased efficiency, which is a consequence of
repeated use of the neuronal circuits involved in
the lying processes.
4. RESEARCH
METHODOLOG
Y
In order to accomplish this, the research
methodology employed is focused on secondary
research which consists of a critical analysis of
the available literature.
5. GAP IN THE NEUROSCIENCE LITERATURE
Due to the scarce amount of research available on the functioning of
the brain, we only encounter superficial concepts on what each part of
the nervous system is responsible for, therefore leaving us with limited
knowledge on the exact processes that the CNS accomplishes .
Taking this into consideration we have tried to create our own map of
what we believe is the normal circuits of the lie fabrication.
7. LIES AND THE LIMBIC SYSTEM
The limbic system represents a set of structures in the brain that deal with emotions and
memory.
It regulates autonomic and endocrine functions in response to emotional stimuli and also
is involved in reinforcing behavior .
The limbic system is composed of four main parts: the hypothalamus, the amygdala, the
thalamus, and the hippocampus.
Taking into account the definition of the limbic system, lying represents a behavioral
pattern which is triggered by emotions and, therefore, it is associated with this system.
Sharot’s (2017) research demonstrated that when a normal lie is formulated and
expressed, the amygdala lights up during an fMRI scan. On top of that, it was revealed
that the more a person lies, the less the amygdala lights up on the scan.
Which, basically, shows the correlation of the limbic system with the action of telling lies ,
without even mentioning the thalamic nuclei groups that are also related!!
8. 1. DORSAL-MEDIAL THALAMUS NUCLEI
The dorsal-medial nucleus of the
thalamus:
adjusts the behavioural and
psychological state according to the
individual’s mood;
represents the main part of the
thalamus that is involved in lying.
receives stimuli via axons from all the
neighbouring nuclei of the thalamus (
from the Globus pallidus of the
Lentiform nucleus and from the
substantia nigra),
then sends fibres to the prefrontal
cortex region.
The prefrontal cortex region = the
region associated with the individual’s
9. 2.BROCA’S AREA
Represents an area found in the frontal lobe region, close to
the prefrontal region, that works with language analyzing
and formation.
It is forming parts of the prefrontal area BA44, BA45 from the
ventrolateral subdivision.
Indefrey and Levelt (2004) suggest that from Broca’s area of
the prefrontal region there are axons sent to the motor
region where the transition into articulatory code is made.
10. 3. PREMOTOR CORTEX
Fibers from the prefrontal cortex go out as
corticostriatal fibers which stop in the
lentiform nucleus and from there they go to 2
destinations:
- either to substantia nigra and from there
continue to the ventrolateral thalamus
nucleus;
- or directly to the ventrolateral nucleus of the
thalamus;
From the ventrolateral nucleus of the
thalamus the fibers finally arrive to the
premotor cortex, where they works with the
muscles movement to produce the speech
11. EMOTIONS AS AN IMPULSE FROM THE
AMYGDALA
Normally as you lie and during the lie you would feel anxiety and fear
that your lie might be discovered, while a pathological liar won’t feel
this, because they are already professional lairs.
Dr. Sharot (2017) found out that the more you lie the less the amygdala
activity is observed when scanned by the FMRI machine.
So what does the amygdala have to do with lying ?
Well, it plays a primary role in the processing of memory, decision-
making and emotional responses (including fear, anxiety, and
aggression) as the amygdalae are considered to be part of the limbic
system.
12. 4. AMYGDALA AND ANTERIOR THALAMIC
NUCLEUS
The amygdala is connected to the parahypocampus that continues
as the fornix, all around to the hypothalamus; mamillary bodies.
From there, fibers jump to the anterior thalamic nucleus using the
Mamillothalamic tract and further on to the cingulate gyrus which is
as well a part of the limbic system (forming the PAPEZ CIRCUIT)
13. The fact that all the nuclei of the thalamus are
interconnected to each other, explains the association of
the anterior thalamic nucleus in our emotions while
lying.
While the pathological liars do not feel any guilt after
lying does that means that no impulses are coming from
the amygdala any more ???
Is it because the amygdala already made the decision of
lying before all the steps that where mentioned before?!.
Furthermore, the hypothalamus is also involved to an
extent into the lying process from the point that it contain
the reward and punishment system.
It should be generally agreed that people usually lie to
gain a benefit, therefore we can assume that those
centers are activated all along, from the moment we
14. YANG- GROUP SELECTION
Yang et al. (2005) aimed to find if there’s any change in the brain of PL
defined subjects as PL if they fulfilled one of the following:
• Criteria for pathological lying on the psychopathy checklist- revised (PCL-R;
Have, 1991).
• Criteria for conning/manipulative behavior on the PCL-R.
• Deceitfulness criterion for DSM-IV (American psychiatric Association, 1994)
antisocial personality disorder (lifelong repeated lying, use of aliases or
conning others for personal profit or pleasure).
• Criteria for malingering as indicated by admitting to telling lies to obtain
sickness benefits in a self-report crime interview.
Because the PL group was highly antisocial, an antisocial control group was
established, and it consisted of people who didn’t fulfill the criteria for PL but
did scored as highly as the liars on DSM-IV measures of antisocial personality
disorder & conduct disorder.
17. YANG 2007- RESULTS AND THE PATHWAYS
OF LIES
In Schmithorst’s (2001) study regarding the difference in white matter
architectonics between musicians and non-musicians , it was concluded
that intensive music training leads to distinct changes in white matter
18. SO, HOW CAN WE KNOW FOR SURE?
Taking into consideration everything that we have presented up to this point we
recommend further research to be carried out on pathological lying.
So far, previous research has shown that pathological liars present a greater volume
of white matter than normal individuals or individuals with antisocial disorders.
However, what we want to find out is whether a PL is made and not born. In order to
find out, we propose a longitudinal study that will use subjects aged between 18-22,
that do not fulfill the criteria for PL as established by Yang et al. (2005).
The subjects will be asked to engage in a repeated and continuous lying behavior.
The subjects will undergo several MRI scans with the 1st scan of each subject acting
as their control sample.
