Brain effects of TMS delivered over prefrontal cortex in depressed adults: role of stimulation frequency and coil-cortex distance.

Relative regional brain blood flow was measured in 23 clinically depressed adults by using ECD SPECT at baseline and again during actual prefrontal transcranial magnetic stimulation (TMS) following 5 daily sessions of TMS. TMS over prefrontal cortex caused increased activity in cortex directly under the stimulation (inversely correlated with distance from scalp to cortex) and decreased activity in remote regions (anterior cingulate and anterior temporal poles). High-frequency rTMS (20 Hz) caused more relative flow immediately below the TMS coil than did low-frequency rTMS (5 Hz). Confirming the hypotheses tested, repeated daily TMS over the prefrontal cortex in medication-free depressed adults appears to change both local and remote blood flow in a manner that may also depend on the frequency of stimulation and coil to outer cortex distance.

Structural and functional neuroimaging of electroconvulsive therapy and transcranial magnetic stimulation.

Neuroimaging has long been utilized to provide a measure of the effects of electroconvulsive therapy (ECT) on brain structure and function as well as to better understand its mechanisms of action. In a similar fashion, functional neuroimaging may provide the means to elucidate both the underlying neurobiological effects and therapeutic potential of transcranial magnetic stimulation (TMS). This article will review findings of neuroimaging studies of both TMS and ECT, concentrating on how such studies may help guide treatment.

Feasibility of using fMRI to study mothers responding to infant cries.

While parenting is a universal human behavior, its neuroanatomic basis is currently unknown. Animal data suggest that the cingulate may play an important function in mammalian parenting behavior. For example, in rodents cingulate lesions impair maternal behavior. Here, in an attempt to understand the brain basis of human maternal behavior, we had mothers listen to recorded infant cries and white noise control sounds while they underwent functional MRI (fMRI) of the brain. We hypothesized that mothers would show significantly greater cingulate activity during the cries compared to the control sounds. Of 7 subjects scanned, 4 had fMRI data suitable for analysis. When fMRI data were averaged for these 4 subjects, the anterior cingulate and right medial prefrontal cortex were the only brain regions showing statistically increased activity with the cries compared to white noise control sounds (cluster analysis with one-tailed z-map threshold of P < 0.001 and spatial extent threshold of P < 0.05). These results demonstrate the feasibility of using fMRI to study brain activity in mothers listening to infant cries and that the anterior cingulate may be involved in mothers listening to crying babies. We are currently replicating this study in a larger group of mothers. Future work in this area may help (1) unravel the functional neuroanatomy of the parent-infant bond and (2) examine whether markers of this bond, such as maternal brain response to infant crying, can predict maternal style (i.e., child neglect), offspring temperament, or offspring depression or anxiety.

Changes in prefrontal cortex and paralimbic activity in depression following two weeks of daily left prefrontal TMS.

Twenty-two depressed adults were scanned with perfusion single-photon computed emission tomography before and after 2 weeks of left perfrontal transcranial magnetic stimulation (TMS) in a parallel design, double-blind treatment study. At medication-free baseline, across all subjects, blood flow in the bilateral medial temporal lobes, left prefrontal cortex, and caudate significantly declined with increased depression severity. Also at baseline, depressed adults who responded to TMS, compared with nonresponders, showed increased inferior frontal lobe activity. Following treatment, there was an even greater difference in inferior frontal blood flow in responders compared with nonresponders, and the negative baseline correlations between depression severity and limbic and prefrontal blood flow disappeared. These results suggest that in depressed adults, 10 days of prefrontal TMS affects prefrontal and paralimbic activity, which may explain its antidepressant effects.

Multiple previous alcohol detoxifications are associated with decreased medial temporal and paralimbic function in the postwithdrawal period.

BACKGROUND: Functional neuroimaging studies after alcohol cessation have demonstrated that chronic alcohol use globally reduces neuronal activity for several weeks. Less is known about the effects of previous alcohol use patterns on regional brain activity. Multiple previous alcohol detoxifications are associated with a worse clinical course and increased risk of seizures, perhaps due to sensitization of key brain structures. We performed the following imaging study in alcoholics in the postwithdrawal period to determine if blood flow in medial temporal structures would differ as a function of previous alcohol use (i.e., whether regions were kindled or sensitized due to multiple detoxifications). METHODS: Fourteen adults meeting DSM-IV criteria for alcohol dependence (mean age 35, 8 SD; 10 men) and participating in a double-blind detoxification medication study underwent a brain perfusion Tc99 m-ECD (Neurolite) single photon emission computed tomography scan on days 7 through 9 (mean 7.6, .5 SD) after their last drink and 2 to 3 days since their last detoxification medication. Seven nonpsychiatrically ill, nonalcohol-dependent healthy adults were scanned as control subjects. RESULTS: Alcoholics compared with controls had widely reduced relative activity in cortical secondary association areas and relatively increased activity in the medial temporal lobes (p < 0.01). Five alcoholic patients with > or = 2 previous detoxifications were compared with five patients in their first detoxification (age and detoxification medication matched). Multiple detoxification patients had significantly lower relative activity in bilateral anterior temporal poles and medial temporal lobes and in visual cortex (p < 0.01) compared with first episode patients. CONCLUSIONS: These studies are consistent with other studies comparing alcoholics and controls. They also suggest that on day 7 of detoxification, alcoholic subjects with multiple previous detoxifications have decreased visual cortex, medial temporal lobes, and anterior paralimbic blood flow, compared with those in their first detoxification. Further studies seem warranted to confirm these initial exploratory results.