MGH Martinos Center for Biomedical Imaging 2017 | Page 33

the higher cognitive functions are
actually consequences of “lower”
processes, like sensory-motor ones.
This is where personal space comes
in.
In 2014 Holt and colleagues pub-
lished a study looking at a particular
sensory-motor circuit in the brains
of healthy subjects using functional
MRI. They found that the circuit
displayed a specific type of response
in the subjects, and that the response
increased as objects appeared to
“loom” toward them (as opposed to
withdrawing from them). Notably,
the experiments also showed that
the responses were greatest when
social stimuli like human faces were
involved, suggesting a role for the
circuit in basic social behaviors.
Among them: the regulation of
personal space.
Realizing the possible significance of
this with respect to social dysfunc-
tion in schizophrenia, the research-
ers extended the study to explore
the role the circuit plays in patients
struggling with the disease. “We
began these experiments because it
has been well established that the
size of personal space is abnormally
enlarged in schizophrenia,” Holt
says. “Consistent with this, our
fMRI study found that both the
magnitude of negative symptom
burden and the responses of the
‘looming’ circuit to personal space
intrusions in schizophrenia patients
predicted the degree of personal
space enlargement in these patients.”
basic sensory-motor circuit leads to
abnormalities in non-verbal social
communication, including personal
space-related behaviors. If this
proves to be the case, Holt and col-
leagues will have found something
of a holy grail in the management of
social dysfunction: a neural mecha-
nism that can be specifically targeted
by novel treatment approach es.
The researchers are now seeking to
extend their findings, both by trying
to understand better the normal
functioning of the “looming”
circuit and its role in a range of
social processes and by working to
determine which parts of the circuit
are affected in schizophrenia—and
The relationships they found— which negative symptoms and
between looming stimuli, personal social functions might be linked to
space regulation and negative these changes.
symptoms—point to the important
possibility that disruption of this
Researchers are exploring the networks in the brain that regulate personal space, and in doing so are shedding light
on the mechanisms of social dysfunction in schizophrenia patients.
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