Special perspective an immodest proposal: should treating mental health professionals be barred from testifying about their patients?

Notwithstanding ethical rules that address therapeutic and forensic role conflicts for psychologists and psychiatrists, overzealous patient advocacy by therapists, tightened reimbursement for therapy, and a growth market for forensic psychology and psychiatry, have led many therapists to appear willingly as forensic experts on behalf of their patients. Existing ethical rules, as well as other proposed approaches to address this problem, assume that it can be resolved by modest changes in existing practice that permit therapists to testify as long as their testimony avoids psycholegal opinions. This essay questions whether these modest changes can adequately address this problem and advances consideration of a more radical proposal to address this problem, prohibiting therapists from testifying about their patients.

Topography of C1 nerve- and trigeminal-evoked potentials in the ventrobasal complex of the cat thalamus.

In order to provide information pertaining to the C1 nerve representation in the thalamus, C1 nerve- and trigeminal-evoked potentials were recorded throughout the ventrobasal complex of the cat thalamus. Contralateral electrical stimulation of the C1 nerve and maxillary division of the trigeminal nerve elicited multiphasic positive-to-negative responses with mean maximum positive peak latencies of 2.2 ms and 2.7 ms, respectively. Ipsilateral stimulation failed to elicit a thalamic response. Construction of isopotential contour maps revealed that the foci of activity elicited by contralateral C1 nerve and trigeminal stimulation were located in the dorsolateral and ventromedial sections of ventroposterior medial nucleus (VPM), respectively.

Responses of cat C1 spinal cord dorsal and ventral horn neurons to noxious and non-noxious stimulation of the head and face.

Previous anatomical studies have shown that trigeminal and cervical afferent nerve fibers project to the upper cervical segments of the spinal cord. To determine the response properties of neurons in the upper cervical spinal cord, we studied the response of C1 dorsal and ventral horn cells to electrical and graded mechanical stimulation of the face, head and neck in anesthetized cats. Neurons were classified as low-threshold-mechanoreceptive (LTM), wide-dynamic-range (WDR), nociceptive-specific (NS) or unresponsive, based on their responsiveness to graded mechanical stimulation. Extracellular single unit recordings were obtained from 118 neurons excited by cervical (24), trigeminal (39) or both cervical and trigeminal (55) stimulation and from 24 neurons unresponsive to peripheral stimulation. Based on neuronal mechanical response properties, 52.2% of the responsive neurons were classified as LTM, 35.9% as WDR and 11.9% as NS. WDR neurons exhibited more convergence and had larger receptive fields than either NS or LTM neurons. WDR and NS neurons had longer first spike latencies than LTM neurons at all tested sites. Only WDR neurons were found to project to the contralateral caudal thalamus. Within C1, LTM neurons were located primarily in laminae III and IV, WDR neurons in lamina V and NS neurons in laminae VII and VIII. These data suggest that some neurons in the first cervical segment of the spinal cord receive convergent input from trigeminal and cervical pathways and may be involved in mediating orofacial and cranial pain.

Fluorescent latex microspheres as a retrograde tracer in the peripheral nervous system.

Rhodamine labeled latex microspheres were used as a fluorescent retrograde tracer in the peripheral nervous system. Examination of rabbit trigeminal ganglia following application of microspheres to crushed or intact inferior alveolar nerve revealed that: (1) microspheres were taken up by only damaged axons; (2) microspheres remained in trigeminal cell bodies for up to 3 months without degradation or diffusion to extracellular structures; and (3) cells containing microspheres were capable of regenerating axons as evidenced by the return of evoked sensory action potentials and the retrograde axonal transport of True blue. Thus, fluorescent microspheres may be useful tools for in vivo survival studies of peripheral nervous system regeneration and development.

Evidence for leucine-enkephalin immunoreactive neurons in the medulla which project to spinal cord in squirrel monkey.

Rhodamine-labeled latex microsphere injections were combined with horseradish peroxidase immunohistochemistry in squirrel monkeys to reveal neurons in the medullary raphe and medial reticular formation which projected to spinal cord and were positive for leucine-enkephalin-like immunoreactivity. Double-labeled cells were found primarily in nucleus raphe magnus, the reticular nucleus magnocellularis, and the lateral reticular nucleus. These results provide evidence for a descending projection from enkephalin-containing cells of the rostral ventral medulla, a region which has been strongly implicated in antinociception.

Morphology of pontomedullary raphe and reticular formation neurons in the brainstem of the cat: an intracellular HRP study.

In order to understand better the anatomical substrates underlying processing of sensory information, the cytoarchitecture of neurons in the pontomedullary raphe and reticular formation was investigated following intracellular injections of horseradish peroxidase in the cat. Raphe cells studied were located in the nucleus raphe magnus, nucleus raphe obscurus, and nucleus raphe pallidus. The most prominent type had a smooth, oval cell body and oval dendritic tree with dendrites extending laterally into the adjacent reticular formation. Two other raphe cell types, large cells with a dorsoventral orientation of both cell body and dendritic tree, and very small cells, were rarer. The primary dendritic orientation lay in the coronal plane for all three raphe cell types. Wispy, straight, or clublike spines were located on more distal regions of dendrites, although we also found spineless dendrites. Raphe cells lying near longitudinal fiber pathways exhibited bundling of dendrites around the passing axon fascicles. Reticular formation cells studied were located in the nucleus gigantocellularis, nucleus magnocellularis, nucleus paragigantocellularis dorsalis, and nucleus reticularis paramedianus. Two morphological types were found on the basis of dendritic branching patterns: sparsely branched and densely branched. Most reticular formation cells had round dendritic trees as viewed in the coronal plane and polygonal cell bodies that were medium to large in size. There was no correlation between reticular formation cell morphology and nuclear location. Spines were more common on the densely branched cells, but for both reticular cell types they were usually absent from cell bodies and proximal dendrites. Thus, by using the criteria of dendritic branching and arbor shape along with distance from the midline it was possible to identify raphe cells as distinct from reticular formation cells. In contrast, no morphological characteristics were found that would differentiate cells in the two major median reticular formation nuclei, gigantocellularis and magnocellularis.

Amygdalospinal projections in the cat.

Spinal cord injections of rhodamine-labeled fluorescent latex microspheres in the cat resulted in retrograde labeling of a dense, well-defined group of neurons within the central nucleus of the amygdala and a modest number of neurons in the medial nucleus. Amygdalospinal neurons were found to be large cells of variable shape and orientation that were distributed bilaterally with an ipsilateral predominence.

Pontomedullary raphe neurons: intracellular responses to central and peripheral electrical stimulation.

The responses of pontomedullary raphe neurons to electrical stimulation of the medullary reticular formation (MRF) and the mesencephalic ventral periaqueductal gray region (PAG) were studied using intracellular methods in chloralose-anesthetized cats. Single shock stimulation of PAG at the level of the trochelear nucleus evoked short latency, monosynaptic excitatory postsynaptic potentials (EPSPs) in antidromically identified raphe-spinal neurons. Similar large EPSPs were produced by medullary reticular stimulation of either side. The large majority of raphe-spinal neurons responded to sciatic nerve shock, and most responded to tooth pulp or forepaw shock as well; these responses were always bilateral. The responses of cells that could not be antidromically invaded from spinal cord were similar to those of raphe-spinal neurons, but tended to be more variable. Intracellular injection of horseradish peroxidase into electrophysiologically characterized cells revealed that most recordings were made from large and medium sized raphe neurons. These findings are discussed in the context of a potential role for pontomedullary raphe neurons in nociception.

The distribution of substance P-containing neurons in the cat Edinger-Westphal nucleus: relationship to efferent projection systems.

The light microscopic localization of substance P-like immunoreactivity (SPLI) was examined in the cat Edinger--Westphal complex using the peroxidase--antiperoxidase method. A high density of cell bodies and processes staining for SPLI were found in the caudal part of the Edinger--Westphal complex (EWc) capping the somatic divisions of the oculomotor nucleus. This distribution continued rostrally into the anteromedian nucleus (AM). Cells labeled with SPLI were also found arranged in a thin layer dorsally capping the oculomotor nucleus, and scattered cells were found in the periaqueductal gray region at the same level. This distribution of SPLI-positive cells was then compared with the distribution of cells in EWc and AM that are retrogradely labeled by horseradish peroxidase or Nuclear Yellow injections into spinal cord, cerebellum, or ciliary ganglion. Injections of horseradish peroxidase into both cervical and lumbar cord labeled a large number of cells throughout the length of EWc and the more rostral AM. A similar pattern of labeling was seen following injections of Nuclear Yellow into the deep cerebellar nuclei. In contrast, cells innervating the ciliary ganglion were found predominantly outside of the Edinger--Westphal complex in AM, the rostral periaqueductal region, and the tegmentum ventral to the oculomotor complex. The distribution of cells projecting to spinal cord or cerebellum and the pattern of SPLI staining was found to closely overlap, evidence that substance P may be contained in cells that give rise to the central projections of the Edinger--Westphal complex.

Edinger-Westphal neurons that project to spinal cord contain substance P.

Combined retrograde transport and immunocytochemical methods were used to determine whether Edinger-Westphal neurons projecting to spinal cord also demonstrate substance P-like immunoreactivity (SPLI). Large injections of horseradish peroxidase (HRP) into cervical and lumbar enlargements retrogradely labeled cells throughout the length of the Edinger-Westphal complex (EW). Nearly all HRP-labeled EW neurons also stained for SPLI, evidence that EW is the origin of a direct substance P pathway linking rostral mesencephalon with spinal cord.

Electrophysiological studies of d-lysergic acid diethylamide in the visual system.

Experiments involving the use of LSD and observing its effects on neurons involved in the processing of visual information are reviewed. These studies typically involved either intravenous or iontophoretic application of the compound. Both modes of application appeared to block the optic afferent synapse at the level of the dorsal lateral geniculate nucleus and to alter the evoked activity of visual cortical neurons. Increasing the dose of LSD regardless of the manner in which it was applied tended to produce depression of both spontaneous and visually driven activity. The receptive field properties of the neurons at all levels of the visual system appear to remain intact after LSD despite changes in spontaneous activity. The effect of LSD on non-specific afferents to the dorsal lateral geniculate nucleus is depicted in relationship to two of the different kind of relay cells located in this structure. Data on LSD interaction with the effects of midbrain stimulation on "X" and "Y" neurons is presented.

Excitatory projection from the interpeduncular nucleus to central superior raphe neurons.

The projection from the interpeduncular nucleus (IP) to the central superior raphe nucleus (CS) was studied using electrophysiologic methods. IP stimulation generates monosynaptic EPSPs in a large number of CS neurons studied with latency of 1-2 ms. Intracellular peroxidase injections into CS neurons responding to IP shock confirmed the location and somatic origin of intracellular potentials. These findings document the existence of a direct excitatory projection from IP onto CS neurons.

Intracortical microstimulation of neurons in the visual cortex of the cat.

The response of visual cortex neurons to local intracortical microstimulation was measured in the anesthetized cat. When the recording microelectrode was very close (about 20 micrometers) to the tip of the stimulating electrode, threshold currents as low as 10 micro A were capable of firing neurons. Over a 20-fold range in distance from the site of stimulation, an 80-fold increase in threshold current was observed. The mean latency of activation for 30 neurons tested with intracortical stimulation was 2.88 +/- 0.45 msec. The majority of these cells were probably synaptically activated. The mean threshold current for these neurons was 0.55 +/- 0.12 mA (N = 30). These values were significantly smaller than the thresholds found previously when stimulating electrodes were located on the pia-arachnoid surface of the visual cortex.