What neurons are firing too much or too little in dissociative disorders?

Neural Dysfunction in Dissociative Disorders

The current evidence suggests that dissociative disorders involve underactivation of prefrontal cortical regions (particularly the medial prefrontal cortex and dorsolateral prefrontal cortex) combined with altered activity in limbic structures including the hippocampus, amygdala, and anterior cingulate cortex, though the specific patterns vary by dissociative subtype. 1

Prefrontal Cortical Hypoactivation

The most consistent finding across dissociative disorders is dysfunction of the prefrontal cortex, which appears to be firing too little during dissociative episodes. 1 This prefrontal hypoactivation represents a failure of top-down cognitive control mechanisms that normally maintain integrated consciousness and memory.

• Prefrontal cortex dysfunction is prominent across multiple dissociative disorder subtypes, including dissociative identity disorder (DID), depersonalization disorder, and dissociative amnesia 1
• The medial prefrontal cortex shows underactivation, which is implicated in impaired cognitive control during dissociative states 2
• This pattern contrasts with psychotic disorders where dopaminergic overactivity drives symptoms, whereas dissociative disorders involve a failure of cortical integration rather than excessive neurotransmitter activity 3

Hippocampal and Temporal Lobe Alterations

Patients with complex dissociative disorders demonstrate smaller hippocampal volumes and altered hippocampal function, suggesting these neurons are compromised or underactive. 4

• Hippocampal volume reductions correlate with severity of both psychoform and somatoform dissociative symptoms 4
• The parahippocampal gyrus also shows reduced volume in dissociative disorders 4
• These structural changes likely contribute to the memory disturbances and context-dependent amnesia characteristic of dissociative states 5
• Temporal cortex dysfunction has been documented in functional neuroimaging studies of dissociative disorders 1

Subcortical and Limbic Network Dysfunction

In dissociative identity disorder specifically, the caudate nucleus shows altered functional activity related to identity state switching and maintenance of altered mental status. 1

• Changes in the functional neural network of the caudate are specifically related to alterations of identity state in DID 1
• The anterior cingulate gyrus demonstrates dysfunction in DID, which may contribute to impaired integration of cognitive and emotional processing 1
• Amygdala volume is reduced in complex dissociative disorders, suggesting underactivity in threat detection and emotional processing circuits 4
• Insular cortex dysfunction has been reported, potentially contributing to altered interoceptive awareness during dissociative episodes 1

Cognitive Control and Executive Function Deficits

High dissociators show evidence of prefrontal and hippocampal dysfunction even before developing clinical dissociative disorders, manifesting as executive control deficits. 5

• Healthy individuals with high dissociative tendencies demonstrate performance deficiencies in visuospatial working memory and executive control functions 5
• These individuals show heightened perseveration tendency and false positive errors, consistent with prefrontal dysfunction 5
• Memory deficits for associative, context-dependent verbal material suggest hippocampal dysfunction as a core factor 5
• These mild cognitive impairments may constitute a risk factor for later development of PTSD or dissociative disorders 5

Parietal Cortex Involvement

Parietal cortex dysfunction has been documented in dissociative disorders, potentially contributing to altered body perception and depersonalization symptoms. 1

Clinical Implications for Grounding Techniques

The pattern of prefrontal underactivation explains why sensory grounding techniques are therapeutically effective—they aim to increase prefrontal cortical engagement and prevent dissociation. 2

• Sensory grounding techniques (noticing environmental details, cognitive distractions, sensory-based distractors) work by keeping people present in the moment and focusing attention to prevent dissociation 2
• These strategies essentially attempt to "turn on" the underactive prefrontal regions that normally maintain integrated consciousness 2

Important Caveats

The neurobiological understanding of dissociative disorders remains incomplete compared to other psychiatric conditions. 1 The evidence base consists primarily of small studies with heterogeneous patient populations, and functional neuroimaging findings vary somewhat by dissociative disorder subtype. 1 Unlike psychotic disorders where dopamine receptor hyperactivity provides a clear pharmacological target, dissociative disorders lack a single neurotransmitter system that can be targeted, which explains why psychotherapy rather than medication remains the primary evidence-based treatment. 6