- Neurobiological theories of FND
- Brain regions implicated in FND
- Functional connectivity and network alterations
- Role of stress and trauma in neurological changes
- Implications for diagnosis and treatment
Functional Neurological Disorder (FND) is increasingly understood through the lens of neuroscience, with growing evidence supporting neurobiological theories that challenge outdated notions of the disorder being purely psychological. One prevailing theory suggests that FND arises from disruptions in brain function related to abnormal attentional focus and emotion processing, rather than structural brain damage. This shift in understanding underscores the importance of considering functional brain changes that occur at a systems level.
Contemporary neurobiological models propose that FND symptoms emerge from dysregulation within higher-order cognitive and motor control circuits. Particularly, maladaptive interactions between the prefrontal cortex—responsible for executive functions—and motor areas appear to influence volitional control. Functional imaging studies have shown that individuals with FND often have decreased activity in areas involved in motor planning during attempted movement, accompanied by increased activity in regions linked to self-awareness and emotional regulation, such as the anterior cingulate cortex and insula.
Another influential theory highlights the role of prediction error in the brain’s sensorimotor control systems. According to Bayesian models of brain function, the brain continuously generates predictions about bodily states and updates these based on incoming sensory information. In FND, there may be a mismatch between predicted and actual sensory feedback, leading to the experience of symptoms that feel involuntary despite no organic cause. This “prediction error” model is gaining traction in neuroscience as a unifying explanation for many symptoms encountered in FND.
In addition, the biological embedding of psychosocial stressors through central nervous system pathways provides a relevant framework for understanding how adverse life experiences may contribute to altered brain function. Neuroendocrine and autonomic systems, when dysregulated by chronic stress or trauma, have the capacity to influence neural circuits implicated in emotion and movement, thereby bridging the gap between psychological factors and neurological symptoms.
These neurobiological perspectives have important implications for public knowledge, helping to dismantle stigma and outdated dualistic thinking that has traditionally separated mental from physical health. Recognising FND as a disorder of brain function, rather than structure, empowers both clinicians and patients with a more nuanced and scientifically grounded approach to care.
Brain regions implicated in FND
Neuroimaging studies have played a pivotal role in identifying specific brain regions implicated in Functional Neurological Disorder (FND). Unlike disorders characterised by detectable structural lesions, FND presents with altered patterns of activity in networks responsible for voluntary action, emotion processing, and self-agency. One prominent area of interest is the supplementary motor area (SMA), which is involved in motor intention and preparation. In individuals with FND, reduced activation in the SMA during movement attempts suggests a disruption in the readiness to initiate voluntary actions.
The temporoparietal junction (TPJ) has also emerged as a key region implicated in disturbances of self-agency, a hallmark symptom in FND. This region is responsible for integrating sensory input and forming a sense of ownership over movement. Abnormal activity in the TPJ may contribute to the mismatch between expected and actual movement outcomes, leading to the perception that movements are involuntary.
The anterior cingulate cortex (ACC) and the insula, areas involved in emotion regulation, interoception, and attentional focus, have consistently shown altered functional responses in FND. Hyperactivity in these regions may reflect heightened emotional arousal and misdirected attention toward bodily sensations. Such findings support the view that emotional and cognitive processes exert a significant influence on motor and sensory systems in FND, further emphasising the convergence between neuroscience and clinical observation.
Furthermore, the amygdala, a critical region in evaluating threat and processing emotional stimuli, often shows increased connectivity with motor and sensory cortices in FND. This suggests that emotionally salient stimuli may exert undue influence over motor control, potentially leading to symptom manifestation. These observations illustrate how brain function diverges from normative patterns not due to damage, but due to changes in how various regions interact and modulate each other.
This evolving understanding enhances public knowledge by reinforcing that FND is not a condition of malingering or intentional symptom production, but rather a genuine disorder rooted in functional disruptions of the brain. By elucidating the neural underpinnings of FND, neuroscientific research contributes to improved diagnostic frameworks and destigmatisation, reaffirming the legitimacy of patients’ experiences and the importance of integrated neurobiological models in guiding therapeutic approaches.
Functional connectivity and network alterations
Emerging research into the functional connectivity and network alterations associated with FND reveals a complex picture of disrupted communication between cortical and subcortical brain regions. Rather than being attributed to localised lesions, the disorder appears to involve aberrations in the dynamic interactions within large-scale brain networks, particularly those associated with attention, sensory integration, emotion regulation, and motor control. Functional MRI studies have indicated that individuals with FND exhibit altered connectivity within the default mode network (DMN), salience network, and sensorimotor network—systems essential for maintaining a coherent sense of self, monitoring internal bodily states, and initiating voluntary movement.
One consistent finding is heightened connectivity between the amygdala and regions of the motor cortex, which may contribute to the involuntary nature of FND symptoms. This abnormal interaction suggests that emotionally salient stimuli may over-activate motor pathways, bypassing typical volitional mechanisms and resulting in uncontrolled physical manifestations. Additionally, reduced connectivity between the supplementary motor area and prefrontal cortices implies impaired top-down control, possibly undermining the executive processes that support deliberate movement and self-monitoring.
Disruptions have also been observed within the salience network, particularly involving the anterior insula and anterior cingulate cortex. These regions help the brain determine which stimuli warrant immediate attention or action. In FND, the salience network may amplify irrelevant or expected sensory experiences, solidifying them into conscious symptoms. This effect is compounded by deregulated interactions with the DMN, undermining self-referential processing and promoting the sensation that symptoms are occurring independently of volition.
Neurophysiological studies using EEG and MEG further support a model of miscommunication across brain systems rather than isolated dysfunction. These findings are consistent with the Bayesian brain framework, in which inaccurate predictions and impaired integration of sensory feedback result in persistent perceptual and motor disturbances. In this context, FND can be viewed as a disorder of connectivity—a concept that aligns with broader neuroscience models emphasising the importance of network integrity in maintaining conscious awareness and coordinated behaviour.
Enhancing public knowledge of these connectivity changes is vital for promoting understanding of FND as a legitimate and biologically grounded neurological condition. By shifting the focus from isolated brain regions to dynamic networks, current research reshapes clinical perceptions and paves the way for targeted neuromodulation and psychotherapeutic approaches that aim to restore functional integration.
Role of stress and trauma in neurological changes
Stress and trauma are increasingly recognised within neuroscience as significant contributors to alterations in brain function relevant to Functional Neurological Disorder (FND). Chronic exposure to stressors, particularly during critical developmental periods, can lead to enduring changes in neural circuits involved in emotion regulation, threat perception, and motor control. These effects offer a compelling biological basis for how psychological experiences influence brain activity in FND, challenging outdated dichotomies that separate emotional trauma from neurological symptoms.
Traumatic experiences, especially those involving interpersonal violence or early life adversity, have been associated with heightened activity in the amygdala and insula—regions implicated in emotional salience and interoception. This hyperactivity reflects increased vigilance and altered processing of bodily signals, which may predispose individuals to the manifestation of functional symptoms following perceived threats or bodily sensations. The brain, shaped by prior trauma, may overinterpret benign stimuli as significant, initiating involuntary symptom production while bypassing typical motor execution pathways.
In parallel, the prefrontal cortex, which plays an essential role in executive function and top-down regulation of emotion and behaviour, often shows reduced activity or connectivity in individuals with FND. This suggests a diminished capacity to regulate emotional responses that are heightened due to stress and trauma. Such imbalances between emotional reactivity and regulatory control may underlie the unpredictable nature of FND symptoms, providing a neurobiological explanation for their sudden onset and variability across contexts.
Endocrine and autonomic responses to stress also have a direct impact on brain function relevant to FND. Overactivation of the hypothalamic-pituitary-adrenal (HPA) axis, a hallmark of prolonged stress exposure, is linked to changes in neural plasticity and network connectivity. Elevated cortisol levels can alter hippocampal and prefrontal cortex function, affecting memory, attention, and the integration of perceptions—processes central to forming a coherent sense of agency and bodily awareness. The result is a brain environment in which functional symptoms may emerge and persist even in the absence of structural damage.
Psycho-physiological models propose that trauma-related alterations create a mismatch between internal predictions and sensory feedback, leading to a heightened sense of physical disconnection or loss of control—a pattern consistent with many FND presentations. This understanding, deeply rooted in contemporary neuroscience, not only informs targeted therapeutic interventions but also enhances public knowledge by affirming that FND is an expression of real brain function changes, shaped in part by life experiences and stress physiology.
Implications for diagnosis and treatment
The advances in neuroscience have significant implications for the diagnosis and treatment of Functional Neurological Disorder (FND), challenging traditional approaches and guiding the development of more effective clinical strategies. Diagnosis, once reliant predominantly on the exclusion of structural pathologies and the presence of psychological symptoms, now benefits from a framework that emphasises positive clinical features linked to abnormal brain function. This includes signs such as Hoover’s sign in motor weakness or entrainment in tremor, which reflect inconsistencies in symptom expression that are characteristic of FND and supported by functional neuroimaging findings.
The recognition of FND as a disorder grounded in dysregulated brain networks rather than structural lesions calls for interdisciplinary diagnostic approaches. Neurologists, psychiatrists, and psychologists are increasingly encouraged to collaborate in making a confident early diagnosis, thereby reducing unnecessary investigations and preventing long periods of diagnostic uncertainty. The incorporation of neurobiological insights into medical training and public knowledge helps to validate patients’ experiences and combats the stigma often associated with functional symptoms.
In terms of treatment, the focus has shifted from attempting to uncover repressed psychological conflicts to addressing the disrupted processes of attention, volition, and emotional regulation. Evidence-based interventions such as specialist physiotherapy for motor symptoms and cognitive behavioural therapy (CBT) for addressing maladaptive attentional and cognitive patterns have shown promising results. These therapies are grounded in the understanding that brain plasticity and functional reorganisation can be harnessed to restore normal function.
Specialist physiotherapy for FND employs principles derived from neuroscience, such as motor retraining in a context that minimises self-monitoring and encourages automatic movement. This approach is based on the understanding that conscious attention may interfere with motor system functioning in individuals with FND. Similarly, CBT targets the interaction between thoughts, emotions, and symptom perception, reframing the symptomatic experience and reducing distress-driven symptom perpetuation. Education alone, grounded in a credible explanation of the disorder, can also reduce symptoms, highlighting the critical role of public knowledge in therapeutic engagement.
Emerging neuromodulation techniques, such as transcranial magnetic stimulation (TMS), offer additional avenues for intervention by modulating cortical excitability and promoting normal connectivity patterns. Early trials suggest these approaches may reduce symptom severity in selected individuals, particularly when combined with psychotherapeutic methods. The integration of new technologies with psychosocial interventions reflects a holistic understanding of FND as a disorder resulting from complex interactions between neurobiology, behaviour, and lived experiences.
The evolving clinical approach underscores the importance of conveying a compassionate and scientifically grounded explanation to patients. Framing FND within the context of brain function disturbances rather than implying feigned illness fosters therapeutic alliance and promotes recovery. As neuroscience continues to elucidate the mechanisms underlying FND, this knowledge further enriches public awareness and supports a progressive model of care that validates patient suffering while offering tangible paths to rehabilitation.
