Biological Psychology, 3,1975,143-155.

@ North-Holland Publishing Company

THE CARDIAC

OF SCHIZOPHRENICS

ORIENTING,

RESPONSES

SIGNAL

AND NON-SIGNAL

TO

TONES

J. H. GRUZELIER* Department of Psychology, Birkbeck

College, University of London, U.K.

Accepted for publication 14 March 1975 The cardiac responses of schizophrenics were examined under three conditions: (1) to repeated 75 dB, 1000 Hz (orienting) tones of no attentional significance; (2) to 75 dB, 1000

and 2000 Hz tones presented randomly and requiring a motor response to the 1000 Hz (signal) tone; (3) to 85 dB, 1000 Hz orienting tones. Responses of non-psychotic psychiatric patients were examined to the 75 dB tones. All patients were subdivided upon the basis of electrodermal

responsivity

during conditions

(1) and (3), into groups of responders - no

habituation of responses; non-responders - no responses; habituators - responses habituated to criterion. All groups exhibited a decelerative response with a latency of less than 1 sec. The groups were differentiated by the second component of the response to the orienting tones: responders - acceleration; habituators - deceleration; non-responders - predominantly no response. All exhibited accelerative responses to the signal tones. Parallels between cardiac and electrodermal responsivity are outlined.

1. Introduction Controversy surrounds the heart rate (HR) orienting activity of schizophrenics. It is contended here that this controversy stems from at least three factors. Firstly, recent examinations of the electrodermal orienting responses of schizophrenics have shown that response patterns may be of two kinds, i.e. schizophrenics exhibit no responses at all, or their responses occur repeatedly and are slow to habituate (Gruzelier and Venables 1972, 1974). Thus, if cardiac orienting activity parallels electrodermal orienting activity to some extent, then in the light of these data, schizophrenics may not be homogeneous with regard to HR orienting responses. Secondly, it is important to ensure when examining the orienting reflex, that the stimulus has no signal connotations apart from its novelty when first presented. This is illustrated by an experiment where schizophrenics distinguished between two tones presented randomly by eliciting a manual response to the tone of lower pitch, defined as the signal tone. Whether or not they exhibited electrodermal responses to non-signal tones, they all exhibited such responses to the signal tone (Gruzelier and Venables, 1973). *Address for correspondence: Dr. J. H. Gruzelier, Department of Clinical Pharmacology, University College Hospital Medical School, 117 Gower Street, London WCIE 6AP, U.K. 143

144

J. H. Gruxlier

The third issue concerns the definition of the cardiac orienting response. Various investigators, reviewed by Graham and Clifton (I 966) and Venables (I 973) have concluded that the response to simple stimuli is monophasic and is alternatively decelerative or accelerative. However, there is consensus emerging in the recent literature that the response is multiphasic with typically three components: (I) a decelerative response with a latency of less than 1 set; (II) an accelerative response with a latency of l-2 set; and (I I I) a long latency decelerative response. The response to signal stimuli is similar except that according to the report of Connor and Lang (1969), the acceleration of component II is of higher amplitude, and the deceleration of component III is of longer duration. A more detailed treatment of this thesis is in preparation. (Gruzelier. 1975). With these issues in mind investigations of the cardiac orienting responses of schizophrenics will be briefly outlined. Reports from Russian laboratories describe either no responses, accelerative responses which habituate slowly, or accelerative responses which habituate within one trial (Traugott, Balanov, Kaufmann and Luchko, 1958; Gamburg, 1958; Lynn, 1963). Many Western investigators, while introducing much-needed quantification, used constant intervals between stimuli, with the consequence that orienting stimuli may have acquired signal connotations through temporal conditioning. Smith (1967) who presented 70-l 10 dB tones for 90 trials at regular intertrial intervals of IO set, found accelerative responses. Zahn, Rosenthal and Lawlor (1968) examined responses to tones and flashes. No consistent response was observed to the flashes, whereas a diphasic response was noted to the tones acceleration occurred within the first three post-stimulus beats followed by an accelerative component II response. Dykman, Reese, Galbrecht, Ackerman and Sunderman (1968) presented schizophrenics with I2 repetitions of a 5 set, 50 dB tone at approximately I min intervals. Temporal attributes of the HR responses were not reported in sufficient detail to evaluate adequately their results. However, schizophrenics described as ‘affect’ showed HR acceleration or wide fluctuations in HR coupled with respiratory changes. The ‘non-affect’ group showed acceleration on early trials and then little or no change. An overall impression gained from these results is that, where schizophrenics exhibit regular HR responses to simple stimuli, deceleration occurs with temporal characteristics of a component I response, whereas acceleration has the temporal attributes of the component II response. This report is an attempt to clarify the nature of the cardiac orienting activity of schizophrenics: (a) by subdividing schizophrenics into groups of responders and nonresponders upon the basis of electrodermal orienting responses; (b) by presenting stimuli which at first had simple orienting characteristics and later acquired signal connotations; and

Curdiac response of schizophrenics

145

Table 1. Summary of groups showing orienting stimulus characteristics, psychiatric subclassification, electrodermal orienting response patterns and number of subjects. Orienting parameters

Psychiatric classification

Electrodermal orienting response characteristic

N

85 dB, 1000 Hz, 1 set duration uncontrolled rise time

schizophrenic schizophrenic

responder non-responder

10 10

75 dB, 1000 Hz, 1 set duration controlled rise time

schizophrenic schizophrenic non-schizophrenic non-schizophrenic non-schizophrenic

responder non-responder responder non-responder habituator

10 10 3 7 10

(c) by examining examine component

HR change for 15 beats post-stimulus I, II and III responses.

onset in order to

2. Subjects A summary of the various groups is shown in table 1. The HR responses of 20 schizophrenics were examined to 85 dB tones. Ten of the schizophrenics were responders, i.e. they exhibited electrodermal orienting responses to the tones, and 10 were non-responders, i.e. no electrodermal responses were exhibited. These groups included schizophrenics from admission and short stay wards as well as chronic patients. The responder group had a mean age of 38.4 yr, range 24-55 yr, and an average length of current hospitalization of 6.5 yr, range 5 weeks-10 yr. The non-responder group had a mean age of 39.2 yr, range 22-58 yr, and an average length of current hospitalization of 7.9 yr, range 3 weeks-12 yr. The HR responses to 75 dB tones were examined with 20 schizophrenics also divided into equal groups of responders and non-responders. The mean age of the responder group was 38.4 yr, range 24-55 yr, and current length of hospitalization, 6 weeks-l 5 yr. The mean age of the non-responder group was 40.2 yr, range 22-56 yr, and current length of hospitalization, 10 weeks-18 yr. The HR responses of 20 non-psychotic psychiatric patients were also measured to the 75 dB tones. The mean age of this group was 35.6 yr, range 19-65 yr, and the current length of hospitalization 8 weeks-5 yr. The non-schizophrenic group was divided into three subgroups: (I) habituators, those whose skin conductance responses habituated to a criterion of three successive noresponses, N = 10; (2) responders, those whose skin conductance orienting responses failed to habituate to criterion, N = 3; (3) non-responders, those without skin conductance orienting responses, N = 7. None of the subjects had abnormal electrocardiograms as defined by Turner (1967), and all had HR levels below 120 beat/min. This latter require-

146

J. H.

Gruzelier

ment was necessary to permit accurate measurement of interbeat intervals with a template. The schizophrenic responders and non-responders receiving the 85 dB tones differed in heart rate levels; those of the responders were higher (p < 0.001). There was no difference in heart-rate levels between the schizophrenic groups given the 75 dB tones. All schizophrenics were prescribed phenothiazine tranquillizers; however, the responder and non-responder groups had a similar variety of drugs and dose levels (Gruzelier and Venables, 1972, 1974). 3. Procedure Skin conductance (SC) was measured bilaterally with a constant voltage system (Lykken and Venables, 1971) feeding two channels of a Grass 5 polygraph. Silver/silver chloride electrodes were used, 1 cm in diameter with a 0.5 % potassium chloride electrolyte. Placements were bipolar from the distal phalanges of the first and second fingers. A SC orienting response was defined as an increase in conductance greater than 0.05 umho between 1 and 5 set after the stimulus. HR was measured from the electrocardiogram. Electrodes, as above, were attached to the ventral surface of each forearm with a sodium chloride electrolyte available commercially (Cambridge electrode jelly). The 85 dB tone orienting sequence consisted of 15 presentations at intervals pseudo randomized between 30 and 60 sec. These tones were of 1000 Hz and I set in duration. Their rise time was not controlled. The 75 dB tone sequence consisted of 15 presentations at intervals between 16 and 25 sec. These tones had a gradual rise time of 25 msec, but otherwise attributes were the same as those of the 85 dB tones. The tone discrimination task entailed the presentation of 1 set, 75 dB tones of either 1000 or 2000 Hz. These were presented in a randomized sequence at intervals between 30 and 60 sec. The subject pressed a button to the 1000 Hz (signal) tone but not the 2000 Hz (non-signal) tone. The tones had a gradual rise time of 25 msec. Timing was controlled electronically (Digitimer Devices Ltd.). The R-R intervals were scored with the aid of a template which converts heart period to beats per minute (Hayes and Venables, 1972). The first five intervals before and 15 intervals after the tone onset were examined for trials 1-6, 9 and 15. As stimulus-evoked changes in HR are superimposed upon termed sinus arrhythmia (Clynes, 1962; respiratory-induced fluctuations, Gautier, 1972), group averaged curves were obtained by computer to determine orienting characteristics. 4. Results 4.1. Oriefltitlg tones The HR orienting responses are shown in fig. I to the 85 dB tones and in fig. 2 to the 75 dB tones. A short latency deceleration beginning within the first post-stimulus interval was common to all groups. This is referred to as a

147

Fig. 1. HR responses of the schizophrenic groups to the 85 dB orienting tones.

CONTROL

9594-

. -

. .*



.

,.

.

*

RESPONDERS

.m..*

. .

-’

Fig. 2. HR responses of all groups to the 75 dB orienting tones.

component I response. The direction or absence of change occurring during component II, in most cases the subsequent eight intervals, differentiated the groups. A precise description of component II was obtained by polynomial regression analysis. A summary of these analyses is found in table 2. The responder groups, whatever their diagnosis, exhibited acceleration in component 11. With the non-responder groups, again whether or not they were schizophrenic, the initial deceleration of component I was followed by a

J. H. Gruzelirr

148

Levels of significance

of polynomial

Group

Table 2. regression analysis

of component

Significant

11 responses.

terms

85 dB tones Schizophrenic Schizophrenic

responders non-responders

quadratic term (F= 10.24, df = 2,5, p i 0.01) linear term (F= 20.16, df = I ,6, p -C 0.01)

75 dB tones Schizophrenic Schizophrenic

responders non-responders

quadratic term (F= 9.93, df = 2,8, p < 0.01) linear term (F= 10.47, df = 1,8, p < 0.08) accounting for 59% of variance quadratic term (F= 5.07, df = 2,8, p i 0.05) accounting for 2’/, of variance. quadratic term (F= 30.47, df = 2,8, p < 0.001) linear term (F= 18.12, df = 1,8, p < 0.01) accounting for 72% of variance quadratic term (F= 13.49, df = 2,8, p < 0.01) accounting for 12% of variance quadratic term (F= 8.10, df= 2,8, p i 0.05)

Non-schizophrenic Non-schizophrenic

habituators non-responders

Non-schizophrenic

responders

gradual return to pre-stimulus level, i.e. no response as such was elicited. The remaining group, the non-schizophrenic habituators, exhibited deceleration in both components I and II. Comparing the schizophrenic responder groups, the peaking of the second component occurred earlier to the more intense tone, and incidentally this peaking occurred earlier for all schizophrenic responders compared with the non-schizophrenics. In all cases where a second component occurred, it was followed by a third component, the mirror image of component II. These results, obtained by averaging responses across trials, were consistent with the definition of the cardiac orienting responses obtained from the review of the earlier literature. The reliability of the averaging procedure, for which the practice of averaging cortical evoked responses, which are also superimposed upon ongoing sinusoidal fluctuations, was used as a precedent, was checked by examining the curves of each subject separately with a changedetection statistic devised by Jones, Crowell and Kapuniai (1969). Poststimulus changes are predicted upon the basis of pre-stimulus variation and an F ratio is obtained between observed and predicted values. This statistical procedure was carried out on both the mean response functions of trials l-4 and of trials 5,6,9 and 15, referred to as blocks I and II respectively. They were compared for evidence of a change in the form of the curves, a possible consequence of habituation. On the basis of the group mean responses, see figs. I-2, a significant change within the post-stimulus intervals 3-8 was considered a response. When on some occasions a diphasic response occurred within this interval, the response occurring in intervals 4-6 was regarded as the response; the intervals in which peaking was observed in the group averaged curves. The incidence of acceleration, deceleration and no change is shown in table 3. Groups were compared with Fisher’s exact probability test. The

Cardiac response of schizophrenics

Incidence

of acceleration,

Table 3. and no-change

deceleration

149

in component II of the cardiac

orienting response. Acceleration

Tone Group Schizophrenic Non-responders Non-schizophrenic resuonders Non-responders Habituators

responders

Deceleration

No-change _~_ BII Bl

(dB)

N

BI

BU

Bl

BII

85 75 85 15

10 10 10 10

9 7 5 2

6 4 1 1

1 2 3 1

5 5 2 1

0 1 2 I

0 0 7 8

75 15 75

3 7 10

3 2 2

2 2 0

0 3 8

1 2 8

0 2 0

0 3 2

majority of schizophrenic responders exhibited acceleration in block I (p < O.OOl), whereas in block II accelerative and decelerative responses occurred in equal numbers. This decrease in accelerative responses across blocks was significant (p < 0.05, binomial expansion). Fifty per cent of the schizophrenic non-responders exhibited an accelerative response in block I in response to the 85 dB tone. In contrast, in response to the lower intensity tone only two exhibited acceleration while seven showed no change. The incidence ofaccelerative responses to the 75 dB tone in block I was significantly lower in the nonresponder group compared with the responders. In block II the majority of non-responders (7.5 %) showed no change, while the responder group showed more decelerative responses compared with block I (p < 0.005). With the exception of responses to the 85 dB tone in block I, the absence of component II responses in the non-responder group was consistent, both with the group mean functions in figs. 1-2, and their absence of SC orienting responses. Eighty per cent of the non-schizophrenic habituators exhibited a decelerative response in both blocks to the 75 dB tone. This response distinguished them from the schizophrenic responders in block I (p < O.OOS),and the schizophrenic non-responders in blocks I and II (y < 0.005; p < 0.01). Decelerative responses were common to both schizophrenic responders and control habituators in block 11. The three non-schizophrenic responders showed an accelerative response in block I, and two showed similar responses in block II. The non-schizophrenic non-responder group did not exhibit a consistent mode of response: approximately equal numbers showed acceleration, or deceleration, or no change. 4.2. Signal and non-signal tones Responses to the first five signal tones and five non-signal tones were examined by measuring the five R-R intervals before, and the I5 after, stimulus onset. Each individual’s mean response functions to the signal and non-signal tones were examined with the change-detection statistic. The schizophrenics showed

150

J. H. Gruzelier SCHlZOPHRENlC 101

Fig. 3. HR responses

RESPONDERS

-

of the schizophrenic

groups

to the signal and non-signal

tones.

consistent responses within each group. The group curves were plotted and polynomial description was obtained for component I1 or components II and III. The responses of the schizophrenic non-responder group are shown in fig. 3. As before, a short latency deceleration occurred, beginning during the first post-stimulus interval. This was followed by a return to baseline in the case of the non-signal tone (linear term, F = 23.92, df = 1,15, p < O.OOl), but in response to the signal tone a pronounced acceleration is observed (quadratic term, F = 22.41, df = 2,13, p < 0.00 1). A response to the signal tone and the absence of a response to the non-signal tone parallels the SC activity of this group. The schizophrenic responders exhibited an accelerative response to the non-signal tones (quadratic term, F = 24.62, df = 2,13, p < O.OOl), see fig. 3. However, to the signal tones responses were bi- or tri-phasic, beginning in four subjects acceleration-deceleration, and in six subjects deceleration-acceleration. An accelerative response was the predominant feature of the group mean curve (quadratic term, F = 29.85, df = 2,14, p < 0.001). The responses of the non-schizophrenic groups are shown in figs. 4-6. The responder, non-responder and habituator groups were subdivided according to response pattern. The responders all showed a consistent response to the non-signal tone in the direction of acceleration and deceleration (quadratic term, F = 10.26, df = 2,8, p < O.OOl), see fig. 4. Responses to the signal tones show more lability with in all cases multiphasic responses occurring, see fig. 5. Nevertheless, the overall response was accelerative (quadratic term, F = 6.22, df=2,13,p

The cardiac responses of schizophrenics to orienting, signal and non-signal tones.

The cardiac responses of schizophrenics were examined under three conditions: (1) to repeated 75 dB, 1000 Hz (orienting) tones of no attentional signi...
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